Programs & Examples On #Naming conventions

Naming conventions refer to general rules governing names assigned to programming constructs such as variables and methods. These conventions facilitate readability, and thus improved maintainability of code by enforcing naming consistency across disparate modules.

PostgreSQL naming conventions

There isn't really a formal manual, because there's no single style or standard.

So long as you understand the rules of identifier naming you can use whatever you like.

In practice, I find it easier to use lower_case_underscore_separated_identifiers because it isn't necessary to "Double Quote" them everywhere to preserve case, spaces, etc.

If you wanted to name your tables and functions "@MyA??! ""betty"" Shard$42" you'd be free to do that, though it'd be pain to type everywhere.

The main things to understand are:

  • Unless double-quoted, identifiers are case-folded to lower-case, so MyTable, MYTABLE and mytable are all the same thing, but "MYTABLE" and "MyTable" are different;

  • Unless double-quoted:

    SQL identifiers and key words must begin with a letter (a-z, but also letters with diacritical marks and non-Latin letters) or an underscore (_). Subsequent characters in an identifier or key word can be letters, underscores, digits (0-9), or dollar signs ($).

  • You must double-quote keywords if you wish to use them as identifiers.

In practice I strongly recommend that you do not use keywords as identifiers. At least avoid reserved words. Just because you can name a table "with" doesn't mean you should.

Unit test naming best practices

the name of the the test case for class Foo should be FooTestCase or something like it (FooIntegrationTestCase or FooAcceptanceTestCase) - since it is a test case. see http://xunitpatterns.com/ for some standard naming conventions like test, test case, test fixture, test method, etc.

C# naming convention for constants?

The recommended naming and capitalization convention is to use PascalCasing for constants (Microsoft has a tool named StyleCop that documents all the preferred conventions and can check your source for compliance - though it is a little bit too anally retentive for many people's tastes). e.g.

private const int TheAnswer = 42;

The Pascal capitalization convention is also documented in Microsoft's Framework Design Guidelines.

What is the javascript filename naming convention?

I generally prefer hyphens with lower case, but one thing not yet mentioned is that sometimes it's nice to have the file name exactly match the name of a single module or instantiable function contained within.

For example, I have a revealing module declared with var knockoutUtilityModule = function() {...} within its own file named knockoutUtilityModule.js, although objectively I prefer knockout-utility-module.js.

Similarly, since I'm using a bundling mechanism to combine scripts, I've taken to defining instantiable functions (templated view models etc) each in their own file, C# style, for maintainability. For example, ProductDescriptorViewModel lives on its own inside ProductDescriptorViewModel.js (I use upper case for instantiable functions).

Are there best practices for (Java) package organization?

Are there best practices with regards to the organisation of packages in Java and what goes in them?

Not really no. There are lots of ideas, and lots opinions, but real "best practice" is to use your common sense!

(Please read No best Practices for a perspective on "best practices" and the people who promote them.)

However, there is one principal that probably has broad acceptance. Your package structure should reflect your application's (informal) module structure, and you should aim to minimize (or ideally entirely avoid) any cyclic dependencies between modules.

(Cyclic dependencies between classes in a package / module are just fine, but inter-package cycles tend to make it hard understand your application's architecture, and can be a barrier to code reuse. In particular, if you use Maven you will find that cyclic inter-package / inter-module dependencies mean that the whole interconnected mess has to be one Maven artifact.)

I should also add that there is one widely accepted best practice for package names. And that is that your package names should start with your organization's domain name in reverse order. If you follow this rule, you reduce the likelihood of problems caused by your (full) class names clashing with other peoples'.

What is a good naming convention for vars, methods, etc in C++?

There are probably as many naming conventions as there are individuals, the debate being as endless (and sterile) as to which brace style to use and so forth.

So I'll have 2 advices:

  • be consistent within a project
  • don't use reserved identifiers (anything with two underscores or beginning with an underscore followed by an uppercase letter)

The rest is up to you.

What is the convention for word separator in Java package names?

The official naming conventions aren't that strict, they don't even 'forbid' camel case notation except for prefix (com in your example).

But I personally would avoid upper case letters and hyphenations, even numbers. I'd choose com.stackoverflow.mypackage like Bragboy suggested too.

(hyphenations '-' are not legal in package names)

EDIT

Interesting - the language specification has something to say about naming conventions too.

In Chapter 7.7 Unique Package Names we see examples with package names that consist of upper case letters (so CamelCase notation would be OK) and they suggest to replace hyphonation by an underscore ("mary-lou" -> "mary_lou") and prefix java keywords with an underscore ("com.example.enum" -> "com.example._enum")

Some more examples for upper case letters in package names can be found in chapter 6.8.1 Package Names.

Maven artifact and groupId naming

Consider this to get a fully unique jar file:

  • GroupID - com.companyname.project
  • ArtifactId - com-companyname-project
  • Package - com.companyname.project

Interface naming in Java

As another poster said, it's typically preferable to have interfaces define capabilities not types. I would tend not to "implement" something like a "User," and this is why "IUser" often isn't really necessary in the way described here. I often see classes as nouns and interfaces as adjectives:

class Number implements Comparable{...}  
class MyThread implements Runnable{...}
class SessionData implements Serializable{....}

Sometimes an Adjective doesn't make sense, but I'd still generally be using interfaces to model behavior, actions, capabilities, properties, etc,... not types.

Also, If you were really only going to make one User and call it User then what's the point of also having an IUser interface? And if you are going to have a few different types of users that need to implement a common interface, what does appending an "I" to the interface save you in choosing names of the implementations?

I think a more realistic example would be that some types of users need to be able to login to a particular API. We could define a Login interface, and then have a "User" parent class with SuperUser, DefaultUser, AdminUser, AdministrativeContact, etc suclasses, some of which will or won't implement the Login (Loginable?) interface as necessary.

Naming conventions for Java methods that return boolean

The convention is to ask a question in the name.

Here are a few examples that can be found in the JDK:

isEmpty()

hasChildren()

That way, the names are read like they would have a question mark on the end.

Is the Collection empty?
Does this Node have children?

And, then, true means yes, and false means no.

Or, you could read it like an assertion:

The Collection is empty.
The node has children

Note:
Sometimes you may want to name a method something like createFreshSnapshot?. Without the question mark, the name implies that the method should be creating a snapshot, instead of checking to see if one is required.

In this case you should rethink what you are actually asking. Something like isSnapshotExpired is a much better name, and conveys what the method will tell you when it is called. Following a pattern like this can also help keep more of your functions pure and without side effects.

If you do a Google Search for isEmpty() in the Java API, you get lots of results.

Using underscores in Java variables and method names

  • I happen to like leading underscores for (private) instance variables, it seems easier to read and distinguish.Of course this thing can get you into trouble with edge cases (e.g. public instance variables (not common, I know) - either way you name them you're arguably breaking your naming convention:
  • private int _my_int; public int myInt;? _my_int? )

-as much as I like the _style of this and think it's readable I find it's arguably more trouble than it's worth, as it's uncommon and it's likely not to match anything else in the codebase you're using.

-automated code generation (e.g. eclipse's generate getters, setters) aren't likely to understand this so you'll have to fix it by hand or muck with eclipse enough to get it to recognize.

Ultimately, you're going against the rest of the (java) world's prefs and are likely to have some annoyances from that. And as previous posters have mentioned, consistency in the codebase trumps all of the above issues.

Naming Classes - How to avoid calling everything a "<WhatEver>Manager"?

When I find myself thinking about using Manager or Helper in a class name, I consider it a code smell that means I haven't found the right abstraction yet and/or I'm violating the single responsibility principle, so refactoring and putting more effort into design often makes naming much easier.

But even well-designed classes don't (always) name themselves, and your choices partly depend on whether you're creating business model classes or technical infrastructure classes.

Business model classes can be hard, because they're different for every domain. There are some terms I use a lot, like Policy for strategy classes within a domain (e.g., LateRentalPolicy), but these usually flow from trying to create a "ubiquitous language" that you can share with business users, designing and naming classes so they model real-world ideas, objects, actions, and events.

Technical infrastructure classes are a bit easier, because they describe domains we know really well. I prefer to incorporate design pattern names into the class names, like InsertUserCommand, CustomerRepository, or SapAdapter. I understand the concern about communicating implementation instead of intent, but design patterns marry these two aspects of class design - at least when you're dealing with infrastructure, where you want the implementation design to be transparent even while you're hiding the details.

Underscore prefix for property and method names in JavaScript

JavaScript actually does support encapsulation, through a method that involves hiding members in closures (Crockford). That said, it's sometimes cumbersome, and the underscore convention is a pretty good convention to use for things that are sort of private, but that you don't actually need to hide.

Java Interfaces/Implementation naming convention

Name your Interface what it is. Truck. Not ITruck because it isn't an ITruck it is a Truck.

An Interface in Java is a Type. Then you have DumpTruck, TransferTruck, WreckerTruck, CementTruck, etc that implement Truck.

When you are using the Interface in place of a sub-class you just cast it to Truck. As in List<Truck>. Putting I in front is just Hungarian style notation tautology that adds nothing but more stuff to type to your code.

All modern Java IDE's mark Interfaces and Implementations and what not without this silly notation. Don't call it TruckClass that is tautology just as bad as the IInterface tautology.

If it is an implementation it is a class. The only real exception to this rule, and there are always exceptions, could be something like AbstractTruck. Since only the sub-classes will ever see this and you should never cast to an Abstract class it does add some information that the class is abstract and to how it should be used. You could still come up with a better name than AbstractTruck and use BaseTruck or DefaultTruck instead since the abstract is in the definition. But since Abstract classes should never be part of any public facing interface I believe it is an acceptable exception to the rule. Making the constructors protected goes a long way to crossing this divide.

And the Impl suffix is just more noise as well. More tautology. Anything that isn't an interface is an implementation, even abstract classes which are partial implementations. Are you going to put that silly Impl suffix on every name of every Class?

The Interface is a contract on what the public methods and properties have to support, it is also Type information as well. Everything that implements Truck is a Type of Truck.

Look to the Java standard library itself. Do you see IList, ArrayListImpl, LinkedListImpl? No, you see List and ArrayList, and LinkedList. Here is a nice article about this exact question. Any of these silly prefix/suffix naming conventions all violate the DRY principle as well.

Also, if you find yourself adding DTO, JDO, BEAN or other silly repetitive suffixes to objects then they probably belong in a package instead of all those suffixes. Properly packaged namespaces are self documenting and reduce all the useless redundant information in these really poorly conceived proprietary naming schemes that most places don't even internally adhere to in a consistent manner.

If all you can come up with to make your Class name unique is suffixing it with Impl, then you need to rethink having an Interface at all. So when you have a situation where you have an Interface and a single Implementation that is not uniquely specialized from the Interface you probably don't need the Interface.

Naming convention - underscore in C++ and C# variables

The Microsoft naming standard for C# says variables and parameters should use the lower camel case form IE: paramName. The standard also calls for fields to follow the same form but this can lead to unclear code so many teams call for an underscore prefix to improve clarity IE: _fieldName.

Can someone explain the dollar sign in Javascript?

The $ sign is an identifier for variables and functions.

https://web.archive.org/web/20160529121559/http://www.authenticsociety.com/blog/javascript_dollarsign

That has a clear explanation of what the dollar sign is for.

Here's an alternative explanation: http://www.vcarrer.com/2010/10/about-dollar-sign-in-javascript.html

Function names in C++: Capitalize or not?

If you look at the standard libraries the pattern generally is my_function, but every person does seem to have their own way :-/

Why are exclamation marks used in Ruby methods?

From themomorohoax.com:

A bang can used in the below ways, in order of my personal preference.

1) An active record method raises an error if the method does not do what it says it will.

2) An active record method saves the record or a method saves an object (e.g. strip!)

3) A method does something “extra”, like posts to someplace, or does some action.

The point is: only use a bang when you’ve really thought about whether it’s necessary, to save other developers the annoyance of having to check why you are using a bang.

The bang provides two cues to other developers.

1) that it’s not necessary to save the object after calling the method.

2) when you call the method, the db is going to be changed.

http://www.themomorohoax.com/2009/02/11/when-to-use-a-bang-exclamation-point-after-rails-methods

Why would a JavaScript variable start with a dollar sign?

${varname} is just a naming convention jQuery developers use to distinguish variables that are holding jQuery elements.

Plain {varname} is used to store general stuffs like texts and strings. ${varname} holds elements returned from jQuery.

You can use plain {varname} to store jQuery elements as well, but as I said in the beginning this distinguishes it from the plain variables and makes it much easier to understand (imagine confusing it for a plain variable and searching all over to understand what it holds).

For example :

var $blah = $(this).parents('.blahblah');

Here, blah is storing a returned jQuery element.

So, when someone else see the $blah in the code, they'll understand it's not just a string or a number, it's a jQuery element.

What's the name for hyphen-separated case?

This casing can also be called a "slug", and the process of turning a phrase into it "slugify".

https://hexdocs.pm/slugify/Slug.html

Why use prefixes on member variables in C++ classes

According to JOINT STRIKE FIGHTER AIR VEHICLE C++ CODING STANDARDS (december 2005):

AV Rule 67

Public and protected data should only be used in structs—not classes. Rationale: A class is able to maintain its invariant by controlling access to its data. However, a class cannot control access to its members if those members non-private. Hence all data in a class should be private.

Thus, the "m" prefix becomes unuseful as all data should be private.

But it is a good habit to use the p prefix before a pointer as it is a dangerous variable.

Python naming conventions for modules

Just nib. Name the class Nib, with a capital N. For more on naming conventions and other style advice, see PEP 8, the Python style guide.

What are some examples of commonly used practices for naming git branches?

I've mixed and matched from different schemes I've seen and based on the tooling I'm using.
So my completed branch name would be:

name/feature/issue-tracker-number/short-description

which would translate to:

mike/blogs/RSSI-12/logo-fix

The parts are separated by forward slashes because those get interpreted as folders in SourceTree for easy organization. We use Jira for our issue tracking so including the number makes it easier to look up in the system. Including that number also makes it searchable when trying to find that issue inside Github when trying to submit a pull request.

What is the standard naming convention for html/css ids and classes?

I think it is platform dependent. When developing in .Net MVC, I use bootstrap style lower case and hyphens for class names, but for ids I use PascalCase.

The reasoning for this is that my views are backed by strongly typed view models. Properties of C# models are pascal case. For the sake of model binding with MVC it makes sense that the names of HTML elements that bind to the model are consistent with the view model properties which are pascal case. For simplicity my ids are use the same naming convention as element names except for radio buttons and check boxes which require unique ids for each element in the named input group.

Enum Naming Convention - Plural

Best Practice - use singular. You have a list of items that make up an Enum. Using an item in the list sounds strange when you say Versions.1_0. It makes more sense to say Version.1_0 since there is only one 1_0 Version.

Should I use "camel case" or underscores in python?

PEP 8 advises the first form for readability. You can find it here.

Function names should be lowercase, with words separated by underscores as necessary to improve readability.

Foreign Key naming scheme

How about FK_TABLENAME_COLUMNNAME?

Keep It Simple Stupid whenever possible.

What are naming conventions for MongoDB?

Naming convention for collection

In order to name a collection few precautions to be taken :

  1. A collection with empty string (“”) is not a valid collection name.
  2. A collection name should not contain the null character because this defines the end of collection name.
  3. Collection name should not start with the prefix “system.” as this is reserved for internal collections.
  4. It would be good to not contain the character “$” in the collection name as various driver available for database do not support “$” in collection name.

Things to keep in mind while creating a database name are :

  1. A database with empty string (“”) is not a valid database name.
  2. Database name cannot be more than 64 bytes.
  3. Database name are case-sensitive, even on non-case-sensitive file systems. Thus it is good to keep name in lower case.
  4. A database name cannot contain any of these characters “/, , ., “, *, <, >, :, |, ?, $,”. It also cannot contain a single space or null character.

For more information. Please check the below link : http://www.tutorial-points.com/2016/03/schema-design-and-naming-conventions-in.html

For a boolean field, what is the naming convention for its getter/setter?

Suppose you have

boolean active;

Accessors method would be

public boolean isActive(){return this.active;}

public void setActive(boolean active){this.active = active;}

See Also

How to name Dockerfiles

I have created two Dockerfiles in same directory,

# vi one.Dockerfile
# vi two.Dockerfile

to build both Dockerfiles use,

# docker build . -f one.Dockerfile
# docker build . -f two.Dockerfile

Note: you should be in present working directory..

Are there any naming convention guidelines for REST APIs?

Look closely at URI's for ordinary web resources. Those are your template. Think of directory trees; use simple Linux-like file and directory names.

HelloWorld isn't a really good class of resources. It doesn't appear to be a "thing". It might be, but it isn't very noun-like. A greeting is a thing.

user-id might be a noun that you're fetching. It's doubtful, however, that the result of your request is only a user_id. It's much more likely that the result of the request is a User. Therefore, user is the noun you're fetching

www.example.com/greeting/user/x/

Makes sense to me. Focus on making your REST request a kind of noun phrase -- a path through a hierarchy (or taxonomy, or directory). Use the simplest nouns possible, avoiding noun phrases if possible.

Generally, compound noun phrases usually mean another step in your hierarchy. So you don't have /hello-world/user/ and /hello-universe/user/. You have /hello/world/user/ and hello/universe/user/. Or possibly /world/hello/user/ and /universe/hello/user/.

The point is to provide a navigation path among resources.

What are the rules about using an underscore in a C++ identifier?

From MSDN:

Use of two sequential underscore characters ( __ ) at the beginning of an identifier, or a single leading underscore followed by a capital letter, is reserved for C++ implementations in all scopes. You should avoid using one leading underscore followed by a lowercase letter for names with file scope because of possible conflicts with current or future reserved identifiers.

This means that you can use a single underscore as a member variable prefix, as long as it's followed by a lower-case letter.

This is apparently taken from section 17.4.3.1.2 of the C++ standard, but I can't find an original source for the full standard online.

See also this question.

Is there a naming convention for git repositories?

The problem with camel case is that there are often different interpretations of words - for example, checkinService vs checkInService. Going along with Aaron's answer, it is difficult with auto-completion if you have many similarly named repos to have to constantly check if the person who created the repo you care about used a certain breakdown of the upper and lower cases. avoid upper case.

His point about dashes is also well-advised.

  1. use lower case.
  2. use dashes.
  3. be specific. you may find you have to differentiate between similar ideas later - ie use purchase-rest-service instead of service or rest-service.
  4. be consistent. consider usage from the various GIT vendors - how do you want your repositories to be sorted/grouped?

Is there a naming convention for MySQL?

Thankfully, PHP developers aren't "Camel case bigots" like some development communities I know.

Your conventions sound fine.

Just so long as they're a) simple, and b) consistent - I don't see any problems :)

PS: Personally, I think 5) is overkill...

What is the difference between .yaml and .yml extension?

As @David Heffeman indicates the recommendation is to use .yaml when possible, and the recommendation has been that way since September 2006.

That some projects use .yml is mostly because of ignorance of the implementers/documenters: they wanted to use YAML because of readability, or some other feature not available in other formats, were not familiar with the recommendation and and just implemented what worked, maybe after looking at some other project/library (without questioning whether what was done is correct).

The best way to approach this is to be rigorous when creating new files (i.e. use .yaml) and be permissive when accepting input (i.e. allow .yml when you encounter it), possible automatically upgrading/correcting these errors when possible.

The other recommendation I have is to document the argument(s) why you have to use .yml, when you think you have to. That way you don't look like an ignoramus, and give others the opportunity to understand your reasoning. Of course "everybody else is doing it" and "On Google .yml has more pages than .yaml" are not arguments, they are just statistics about the popularity of project(s) that have it wrong or right (with regards to the extension of YAML files). You can try to prove that some projects are popular, just because they use a .yml extension instead of the correct .yaml, but I think you will be hard pressed to do so.

Some projects realize (too late) that they use the incorrect extension (e.g. originally docker-compose used .yml, but in later versions started to use .yaml, although they still support .yml). Others still seem ignorant about the correct extension, like AppVeyor early 2019, but allow you to specify the configuration file for a project, including extension. This allows you to get the configuration file out of your face as well as giving it the proper extension: I use .appveyor.yaml instead of appveyor.yml for building the windows wheels of my YAML parser for Python).


On the other hand:

The Yaml (sic!) component of Symfony2 implements a selected subset of features defined in the YAML 1.2 version specification.

So it seems fitting that they also use a subset of the recommended extension.

Table Naming Dilemma: Singular vs. Plural Names

I stick with singular for table names and any programming entity.

The reason? The fact that there are irregular plurals in English like mouse ? mice and sheep ? sheep. Then, if I need a collection, i just use mouses or sheeps, and move on.

It really helps the plurality stand out, and I can easily and programatically determine what the collection of things would look like.

So, my rule is: everything is singular, every collection of things is singular with an s appended. Helps with ORMs too.

Should you use .htm or .html file extension? What is the difference, and which file is correct?

Here is some food for thought.

If you had been using all .htm files on your website and now, for example, you have changed the editor that you are using, and your new editor is outputting all your files with the .html extension. When you re-publish your site to the server, it would seem to me that you could really hurt your SEO position/ranking as many of the links out there in the web, including Google, that were looking for the .htm and not the new .html for that same page. This assumes that you are still using the same page names from your old editor which would make sense.

Anyway... My point is, be careful not to loose that link juice you have build up. So I guess in this example, there is a reason to stick with .htm... But other then that as mentioned by everyone else they seem to be the same.

Please correct if I'm wrong.

The reason I mention all this is because this is what I was in the process of doing when it occurred to me I may be damaging the site SEO with the new editor.

The original editor was MS Front Page, which always outputted .htm, dead now, and the new editor "90 Second Web Builder 9" which outputs all .html files... Luckily, they must have thought about this and they included a way to change the output extension back to .htm

Anyway, that's my 2 cents... hope it helps someone..

What is the purpose of the single underscore "_" variable in Python?

As far as the Python languages is concerned, _ has no special meaning. It is a valid identifier just like _foo, foo_ or _f_o_o_.

Any special meaning of _ is purely by convention. Several cases are common:

  • A dummy name when a variable is not intended to be used, but a name is required by syntax/semantics.

    # iteration disregarding content
    sum(1 for _ in some_iterable)
    # unpacking disregarding specific elements
    head, *_ = values
    # function disregarding its argument
    def callback(_): return True
    
  • Many REPLs/shells store the result of the last top-level expression to builtins._.

    The special identifier _ is used in the interactive interpreter to store the result of the last evaluation; it is stored in the builtins module. When not in interactive mode, _ has no special meaning and is not defined. [source]

    Due to the way names are looked up, unless shadowed by a global or local _ definition the bare _ refers to builtins._ .

    >>> 42
    42
    >>> f'the last answer is {_}'
    'the last answer is 42'
    >>> _
    'the last answer is 42'
    >>> _ = 4  # shadow ``builtins._`` with global ``_``
    >>> 23
    23
    >>> _
    4
    

    Note: Some shells such as ipython do not assign to builtins._ but special-case _.

  • In the context internationalization and localization, _ is used as an alias for the primary translation function.

    gettext.gettext(message)

    Return the localized translation of message, based on the current global domain, language, and locale directory. This function is usually aliased as _() in the local namespace (see examples below).

What are the most common naming conventions in C?

The most important thing here is consistency. That said, I follow the GTK+ coding convention, which can be summarized as follows:

  1. All macros and constants in caps: MAX_BUFFER_SIZE, TRACKING_ID_PREFIX.
  2. Struct names and typedef's in camelcase: GtkWidget, TrackingOrder.
  3. Functions that operate on structs: classic C style: gtk_widget_show(), tracking_order_process().
  4. Pointers: nothing fancy here: GtkWidget *foo, TrackingOrder *bar.
  5. Global variables: just don't use global variables. They are evil.
  6. Functions that are there, but shouldn't be called directly, or have obscure uses, or whatever: one or more underscores at the beginning: _refrobnicate_data_tables(), _destroy_cache().

Database, Table and Column Naming Conventions?

our preference:

  1. Should table names be plural?
    Never. The arguments for it being a collection make sense, but you never know what the table is going to contain (0,1 or many items). Plural rules make the naming unnecessarily complicated. 1 House, 2 houses, mouse vs mice, person vs people, and we haven't even looked at any other languages.

    Update person set property = 'value' acts on each person in the table.
    Select * from person where person.name = 'Greg' returns a collection/rowset of person rows.

  2. Should column names be singular?
    Usually, yes, except where you are breaking normalisation rules.

  3. Should I prefix tables or columns?
    Mostly a platform preference. We prefer to prefix columns with the table name. We don't prefix tables, but we do prefix views (v_) and stored_procedures (sp_ or f_ (function)). That helps people who want to try to upday v_person.age which is actually a calculated field in a view (which can't be UPDATEd anyway).

    It is also a great way to avoid keyword collision (delivery.from breaks, but delivery_from does not).

    It does make the code more verbose, but often aids in readability.

    bob = new person()
    bob.person_name = 'Bob'
    bob.person_dob = '1958-12-21'
    ... is very readable and explicit. This can get out of hand though:

    customer.customer_customer_type_id

    indicates a relationship between customer and the customer_type table, indicates the primary key on the customer_type table (customer_type_id) and if you ever see 'customer_customer_type_id' whilst debugging a query, you know instantly where it is from (customer table).

    or where you have a M-M relationship between customer_type and customer_category (only certain types are available to certain categories)

    customer_category_customer_type_id

    ... is a little (!) on the long side.

  4. Should I use any case in naming items? Yes - lower case :), with underscores. These are very readable and cross platform. Together with 3 above it also makes sense.

    Most of these are preferences though. - As long as you are consistent, it should be predictable for anyone that has to read it.

Why shouldn't I use "Hungarian Notation"?

I tend to use Hungarian Notation with ASP.NET server controls only, otherwise I find it too hard to work out what controls are what on the form.

Take this code snippet:

<asp:Label ID="lblFirstName" runat="server" Text="First Name" />
<asp:TextBox ID="txtFirstName" runat="server" />
<asp:RequiredFieldValidator ID="rfvFirstName" runat="server" ... />

If someone can show a better way of having that set of control names without Hungarian I'd be tempted to move to it.

REST URI convention - Singular or plural name of resource while creating it

Whereas the most prevalent practice are RESTful apis where plurals are used e.g. /api/resources/123 , there is one special case where I find use of a singular name more appropriate/expressive than plural names. It is the case of one-to-one relationships. Specifically if the target item is a value object(in Domain-driven-design paradigm).

Let us assume every resource has a one-to-one accessLog which could be modeled as a value object i.e not an entity therefore no ID. It could be expressed as /api/resources/123/accessLog. The usual verbs (POST, PUT, DELETE, GET) would appropriately express the intent and also the fact that the relationship is indeed one-to-one.

Valid characters in a Java class name

Identifiers are used for class names, method names, and variable names. An identifiermay be any descriptive sequence of uppercase and lowercase letters, numbers, or theunderscore and dollar-sign characters. They must not begin with a number, lest they beconfused with a numeric literal. Again, Java is case-sensitive, so VALUE is a differentidentifier than Value. Some examples of valid identifiers are:

AvgTemp ,count a4 ,$test ,this_is_ok

Invalid variable names include:

2count, high-temp, Not/ok

JavaScript naming conventions

That's an individual question that could depend on how you're working. Some people like to put the variable type at the begining of the variable, like "str_message". And some people like to use underscore between their words ("my_message") while others like to separate them with upper-case letters ("myMessage").

I'm often working with huge JavaScript libraries with other people, so functions and variables (except the private variables inside functions) got to start with the service's name to avoid conflicts, as "guestbook_message".

In short: english, lower-cased, well-organized variable and function names is preferable according to me. The names should describe their existence rather than being short.

What is the naming convention in Python for variable and function names?

There is PEP 8, as other answers show, but PEP 8 is only the styleguide for the standard library, and it's only taken as gospel therein. One of the most frequent deviations of PEP 8 for other pieces of code is the variable naming, specifically for methods. There is no single predominate style, although considering the volume of code that uses mixedCase, if one were to make a strict census one would probably end up with a version of PEP 8 with mixedCase. There is little other deviation from PEP 8 that is quite as common.

Naming Conventions: What to name a boolean variable?

A simple semantic name would be last. This would allow code always positive code like:

if (item.last)
    ...

do {
   ...
} until (item.last);

What is the meaning of single and double underscore before an object name?

Accroding to https://dbader.org/blog/meaning-of-underscores-in-python

  • Single Leading Underscore(_var): Naming convention indicating a name is meant for internal use. Generally not enforced by the Python interpreter (except in wildcard imports) and meant as a hint to the programmer only.
  • Single Trailing Underscore(var_): Used by convention to avoid naming conflicts with Python keywords.
  • Double Leading Underscore(__var): Triggers name mangling when used in a class context. Enforced by the Python interpreter.
  • Double Leading and Trailing Underscore(__var__): Indicates special methods defined by the Python language. Avoid this naming scheme for your own attributes.
  • Single Underscore(_): Sometimes used as a name for temporary or insignificant variables (“don’t care”). Also: The result of the last expression in a Python REPL.

CFLAGS, CCFLAGS, CXXFLAGS - what exactly do these variables control?

As you noticed, these are Makefile {macros or variables}, not compiler options. They implement a set of conventions. (Macros is an old name for them, still used by some. GNU make doc calls them variables.)

The only reason that the names matter is the default make rules, visible via make -p, which use some of them.

If you write all your own rules, you get to pick all your own macro names.

In a vanilla gnu make, there's no such thing as CCFLAGS. There are CFLAGS, CPPFLAGS, and CXXFLAGS. CFLAGS for the C compiler, CXXFLAGS for C++, and CPPFLAGS for both.

Why is CPPFLAGS in both? Conventionally, it's the home of preprocessor flags (-D, -U) and both c and c++ use them. Now, the assumption that everyone wants the same define environment for c and c++ is perhaps questionable, but traditional.


P.S. As noted by James Moore, some projects use CPPFLAGS for flags to the C++ compiler, not flags to the C preprocessor. The Android NDK, for one huge example.

Pass a JavaScript function as parameter

You just need to remove the parenthesis:

addContact(entityId, refreshContactList);

This then passes the function without executing it first.

Here is an example:

function addContact(id, refreshCallback) {
    refreshCallback();
    // You can also pass arguments if you need to
    // refreshCallback(id);
}

function refreshContactList() {
    alert('Hello World');
}

addContact(1, refreshContactList);

Chrome ignores autocomplete="off"

I've just tried the following, and it appears to do the trick on Chrome 53 - it also disables the "Use password for:" drop down when entering the password field.

Simply set your password input type to text, and then add the onfocus handler (inline or via jQuery/vanilla JS) to set the type to password:

onfocus="this.setAttribute('type','password')"

Or even better:

onfocus="if(this.getAttribute('type')==='text') this.setAttribute('type','password')"

Different between parseInt() and valueOf() in java?

Integer.parseInt can just return int as native type.

Integer.valueOf may actually need to allocate an Integer object, unless that integer happens to be one of the preallocated ones. This costs more.

If you need just native type, use parseInt. If you need an object, use valueOf.

Also, because of this potential allocation, autoboxing isn't actually good thing in every way. It can slow down things.

What is the difference between ManualResetEvent and AutoResetEvent in .NET?

AutoResetEvent maintains a boolean variable in memory. If the boolean variable is false then it blocks the thread and if the boolean variable is true it unblocks the thread.

When we instantiate an AutoResetEvent object, we pass the default value of boolean value in the constructor. Below is the syntax of instantiate an AutoResetEvent object.

AutoResetEvent autoResetEvent = new AutoResetEvent(false);

WaitOne method

This method blocks the current thread and wait for the signal by other thread. WaitOne method puts the current thread into a Sleep thread state. WaitOne method returns true if it receives the signal else returns false.

autoResetEvent.WaitOne();

Second overload of WaitOne method wait for the specified number of seconds. If it does not get any signal thread continues its work.

static void ThreadMethod()
{
    while(!autoResetEvent.WaitOne(TimeSpan.FromSeconds(2)))
    {
        Console.WriteLine("Continue");
        Thread.Sleep(TimeSpan.FromSeconds(1));
    }

    Console.WriteLine("Thread got signal");
}

We called WaitOne method by passing the 2 seconds as arguments. In the while loop, it wait for the signal for 2 seconds then it continues its work. When the thread got the signal WaitOne returns true and exits the loop and print the "Thread got signal".

Set method

AutoResetEvent Set method sent the signal to the waiting thread to proceed its work. Below is the syntax of calling Set method.

autoResetEvent.Set();

ManualResetEvent maintains a boolean variable in memory. When the boolean variable is false then it blocks all threads and when the boolean variable is true it unblocks all threads.

When we instantiate a ManualResetEvent, we initialize it with default boolean value.

ManualResetEvent manualResetEvent = new ManualResetEvent(false);

In the above code, we initialize the ManualResetEvent with false value, that means all the threads which calls the WaitOne method will block until some thread calls the Set() method.

If we initialize ManualResetEvent with true value, all the threads which calls the WaitOne method will not block and free to proceed further.

WaitOne Method

This method blocks the current thread and wait for the signal by other thread. It returns true if its receives a signal else returns false.

Below is the syntax of calling WaitOne method.

manualResetEvent.WaitOne();

In the second overload of WaitOne method, we can specify the time interval till the current thread wait for the signal. If within time internal, it does not receives a signal it returns false and goes into the next line of method.

Below is the syntax of calling WaitOne method with time interval.

bool isSignalled = manualResetEvent.WaitOne(TimeSpan.FromSeconds(5));

We have specify 5 seconds into the WaitOne method. If the manualResetEvent object does not receives a signal between 5 seconds, it set the isSignalled variable to false.

Set Method

This method is used for sending the signal to all waiting threads. Set() Method set the ManualResetEvent object boolean variable to true. All the waiting threads are unblocked and proceed further.

Below is the syntax of calling Set() method.

manualResetEvent.Set();

Reset Method

Once we call the Set() method on the ManualResetEvent object, its boolean remains true. To reset the value we can use Reset() method. Reset method change the boolean value to false.

Below is the syntax of calling Reset method.

manualResetEvent.Reset();

We must immediately call Reset method after calling Set method if we want to send signal to threads multiple times.

Setting a PHP $_SESSION['var'] using jQuery

Might want to try putting the PHP function on another PHP page, and use an AJAX call to set the variable.

Installing tkinter on ubuntu 14.04

Try writing the following in the terminal:

sudo apt-get install python-tk

Don't forget to actually import Tkinter module at the beginning of your program:

import Tkinter

What is a PDB file?

I had originally asked myself the question "Do I need a PDB file deployed to my customer's machine?", and after reading this post, decided to exclude the file.

Everything worked fine, until today, when I was trying to figure out why a message box containing an Exception.StackTrace was missing the file and line number information - necessary for troubleshooting the exception. I re-read this post and found the key nugget of information: that although the PDB is not necessary for the app to run, it is necessary for the file and line numbers to be present in the StackTrace string. I included the PDB file in the executable folder and now all is fine.

If Else If In a Sql Server Function

ALTER FUNCTION [dbo].[fnTally] (@SchoolId nvarchar(50))
    RETURNS nvarchar(3)
AS BEGIN 

    DECLARE @Final nvarchar(3)
    SELECT @Final = CASE 
        WHEN yes_ans > no_ans  AND yes_ans > na_ans THEN 'Yes'
        WHEN no_ans  > yes_ans AND no_ans  > na_ans THEN 'No'
        WHEN na_ans  > yes_ans AND na_ans  > no_ans THEN 'N/A' END
    FROM dbo.qrc_maintally
    WHERE school_id = @SchoolId

Return @Final
End

As you can see, this simplifies the code a lot. It also makes other errors in your code more obvious: you're returning an nvarchar, but declared the function to return an int (corrected in the code above).

How can I wait for set of asynchronous callback functions?

This is the most neat way in my opinion.

Promise.all

FetchAPI

(for some reason Array.map doesn't work inside .then functions for me. But you can use a .forEach and [].concat() or something similar)

Promise.all([
  fetch('/user/4'),
  fetch('/user/5'),
  fetch('/user/6'),
  fetch('/user/7'),
  fetch('/user/8')
]).then(responses => {
  return responses.map(response => {response.json()})
}).then((values) => {
  console.log(values);
})

How to create Haar Cascade (.xml file) to use in OpenCV?

How to create CascadeClassifier :

  1. Open this link : https://github.com/opencv/opencv/tree/master/data/haarcascades
  2. Right click on where you find "haarcascade_frontalface_default.xml"
  3. Click on "Save link as"
  4. Save it into the same folder in which your file is.
  5. Include this line in your file face_cascade = cv2.CascadeClassifier(cv2.data.haarcascades + "haarcascade_frontalface_default.xml")

How to get "their" changes in the middle of conflicting Git rebase?

If you want to pull a particular file from another branch just do

git checkout branch1 -- filenamefoo.txt

This will pull a version of the file from one branch into the current tree

How do I test a website using XAMPP?

Make a new folder inside htdocs and access it in browser.Like this or this. Always start Apache when you start working or check whether it has started (in Control panel of xampp).

Remove trailing comma from comma-separated string

Use Guava to normalize all your commas. Split the string up around the commas, throw out the empties, and connect it all back together. Two calls. No loops. Works the first time:

import com.google.common.base.Joiner;
import com.google.common.base.Splitter;

public class TestClass {

    Splitter splitter = Splitter.on(',').omitEmptyStrings().trimResults();
    Joiner joiner = Joiner.on(',').skipNulls();

    public String cleanUpCommas(String string) {
        return joiner.join(splitter.split(string));
    }

}



public class TestMain {

    public static void main(String[] args) {
        TestClass testClass = new TestClass();

        System.out.println(testClass.cleanUpCommas("a,b,c,d,e"));
        System.out.println(testClass.cleanUpCommas("a,b,c,d,e,,,,,"));
        System.out.println(testClass.cleanUpCommas("a,b,,, ,c,d,  ,,e,,,,,"));
        System.out.println(testClass.cleanUpCommas("a,b,c,d,  e,,,,,"));
        System.out.println(testClass.cleanUpCommas(",,, ,,,,a,b,c,d,  e,,,,,"));
    }

}

Output:

a,b,c,d,e
a,b,c,d,e
a,b,c,d,e
a,b,c,d,e
a,b,c,d,e

Personally, I hate futzing around with counting limits of substrings and all that nonsense.

Open terminal here in Mac OS finder

Ok, I realize that this is a bit late... maybe this alternative wasn't available at the moment of writing the post?

Anyway, I've found installing the pos package via Fink (a prerequisite in this case, maybe there is something similar for those who uses MacPorts?) to be the easiest solution. You get two commands:

  1. posd - which gives the current directory of the frontmost Finder window (for which you presumably make an alias cdf=cd posd)
  2. fdc - which switches the current directory of the frontmost Finder window to the Terminal pwd. This is slightly different from 'open .' which always opens a new finder window.

Yes, you have to switch to the Terminal window before writing cdf, but I suppose that's quite cheap comparing to clicking a button in the Finder toolbar. And it works with iTerm as well, you don't have to download a separate Finder toolbar button that opens an iTerm window. This is the same approach as proposed by PCheese, but you don't have to clutter your .bash_profile.

What’s the best way to get an HTTP response code from a URL?

Here's an httplib solution that behaves like urllib2. You can just give it a URL and it just works. No need to mess about splitting up your URLs into hostname and path. This function already does that.

import httplib
import socket
def get_link_status(url):
  """
    Gets the HTTP status of the url or returns an error associated with it.  Always returns a string.
  """
  https=False
  url=re.sub(r'(.*)#.*$',r'\1',url)
  url=url.split('/',3)
  if len(url) > 3:
    path='/'+url[3]
  else:
    path='/'
  if url[0] == 'http:':
    port=80
  elif url[0] == 'https:':
    port=443
    https=True
  if ':' in url[2]:
    host=url[2].split(':')[0]
    port=url[2].split(':')[1]
  else:
    host=url[2]
  try:
    headers={'User-Agent':'Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:26.0) Gecko/20100101 Firefox/26.0',
             'Host':host
             }
    if https:
      conn=httplib.HTTPSConnection(host=host,port=port,timeout=10)
    else:
      conn=httplib.HTTPConnection(host=host,port=port,timeout=10)
    conn.request(method="HEAD",url=path,headers=headers)
    response=str(conn.getresponse().status)
    conn.close()
  except socket.gaierror,e:
    response="Socket Error (%d): %s" % (e[0],e[1])
  except StandardError,e:
    if hasattr(e,'getcode') and len(e.getcode()) > 0:
      response=str(e.getcode())
    if hasattr(e, 'message') and len(e.message) > 0:
      response=str(e.message)
    elif hasattr(e, 'msg') and len(e.msg) > 0:
      response=str(e.msg)
    elif type('') == type(e):
      response=e
    else:
      response="Exception occurred without a good error message.  Manually check the URL to see the status.  If it is believed this URL is 100% good then file a issue for a potential bug."
  return response

How to put attributes via XElement

Add XAttribute in the constructor of the XElement, like

new XElement("Conn", new XAttribute("Server", comboBox1.Text));

You can also add multiple attributes or elements via the constructor

new XElement("Conn", new XAttribute("Server", comboBox1.Text), new XAttribute("Database", combobox2.Text));

or you can use the Add-Method of the XElement to add attributes

XElement element = new XElement("Conn");
XAttribute attribute = new XAttribute("Server", comboBox1.Text);
element.Add(attribute);

How can I remove the first line of a text file using bash/sed script?

As Pax said, you probably aren't going to get any faster than this. The reason is that there are almost no filesystems that support truncating from the beginning of the file so this is going to be an O(n) operation where n is the size of the file. What you can do much faster though is overwrite the first line with the same number of bytes (maybe with spaces or a comment) which might work for you depending on exactly what you are trying to do (what is that by the way?).

constant pointer vs pointer on a constant value

To parse complicated types, you start at the variable, go left, and spiral outwards. If there aren't any arrays or functions to worry about (because these sit to the right of the variable name) this becomes a case of reading from right-to-left.

So with char *const a; you have a, which is a const pointer (*) to a char. In other words you can change the char which a is pointing at, but you can't make a point at anything different.

Conversely with const char* b; you have b, which is a pointer (*) to a char which is const. You can make b point at any char you like, but you cannot change the value of that char using *b = ...;.

You can also of course have both flavours of const-ness at one time: const char *const c;.

PHP validation/regex for URL

And there is your answer =) Try to break it, you can't!!!

function link_validate_url($text) {
$LINK_DOMAINS = 'aero|arpa|asia|biz|com|cat|coop|edu|gov|info|int|jobs|mil|museum|name|nato|net|org|pro|travel|mobi|local';
  $LINK_ICHARS_DOMAIN = (string) html_entity_decode(implode("", array( // @TODO completing letters ...
    "&#x00E6;", // æ
    "&#x00C6;", // Æ
    "&#x00C0;", // À
    "&#x00E0;", // à
    "&#x00C1;", // Á
    "&#x00E1;", // á
    "&#x00C2;", // Â
    "&#x00E2;", // â
    "&#x00E5;", // å
    "&#x00C5;", // Å
    "&#x00E4;", // ä
    "&#x00C4;", // Ä
    "&#x00C7;", // Ç
    "&#x00E7;", // ç
    "&#x00D0;", // Ð
    "&#x00F0;", // ð
    "&#x00C8;", // È
    "&#x00E8;", // è
    "&#x00C9;", // É
    "&#x00E9;", // é
    "&#x00CA;", // Ê
    "&#x00EA;", // ê
    "&#x00CB;", // Ë
    "&#x00EB;", // ë
    "&#x00CE;", // Î
    "&#x00EE;", // î
    "&#x00CF;", // Ï
    "&#x00EF;", // ï
    "&#x00F8;", // ø
    "&#x00D8;", // Ø
    "&#x00F6;", // ö
    "&#x00D6;", // Ö
    "&#x00D4;", // Ô
    "&#x00F4;", // ô
    "&#x00D5;", // Õ
    "&#x00F5;", // õ
    "&#x0152;", // Œ
    "&#x0153;", // œ
    "&#x00FC;", // ü
    "&#x00DC;", // Ü
    "&#x00D9;", // Ù
    "&#x00F9;", // ù
    "&#x00DB;", // Û
    "&#x00FB;", // û
    "&#x0178;", // Ÿ
    "&#x00FF;", // ÿ 
    "&#x00D1;", // Ñ
    "&#x00F1;", // ñ
    "&#x00FE;", // þ
    "&#x00DE;", // Þ
    "&#x00FD;", // ý
    "&#x00DD;", // Ý
    "&#x00BF;", // ¿
  )), ENT_QUOTES, 'UTF-8');

  $LINK_ICHARS = $LINK_ICHARS_DOMAIN . (string) html_entity_decode(implode("", array(
    "&#x00DF;", // ß
  )), ENT_QUOTES, 'UTF-8');
  $allowed_protocols = array('http', 'https', 'ftp', 'news', 'nntp', 'telnet', 'mailto', 'irc', 'ssh', 'sftp', 'webcal');

  // Starting a parenthesis group with (?: means that it is grouped, but is not captured
  $protocol = '((?:'. implode("|", $allowed_protocols) .'):\/\/)';
  $authentication = "(?:(?:(?:[\w\.\-\+!$&'\(\)*\+,;=" . $LINK_ICHARS . "]|%[0-9a-f]{2})+(?::(?:[\w". $LINK_ICHARS ."\.\-\+%!$&'\(\)*\+,;=]|%[0-9a-f]{2})*)?)?@)";
  $domain = '(?:(?:[a-z0-9' . $LINK_ICHARS_DOMAIN . ']([a-z0-9'. $LINK_ICHARS_DOMAIN . '\-_\[\]])*)(\.(([a-z0-9' . $LINK_ICHARS_DOMAIN . '\-_\[\]])+\.)*('. $LINK_DOMAINS .'|[a-z]{2}))?)';
  $ipv4 = '(?:[0-9]{1,3}(\.[0-9]{1,3}){3})';
  $ipv6 = '(?:[0-9a-fA-F]{1,4}(\:[0-9a-fA-F]{1,4}){7})';
  $port = '(?::([0-9]{1,5}))';

  // Pattern specific to external links.
  $external_pattern = '/^'. $protocol .'?'. $authentication .'?('. $domain .'|'. $ipv4 .'|'. $ipv6 .' |localhost)'. $port .'?';

  // Pattern specific to internal links.
  $internal_pattern = "/^(?:[a-z0-9". $LINK_ICHARS ."_\-+\[\]]+)";
  $internal_pattern_file = "/^(?:[a-z0-9". $LINK_ICHARS ."_\-+\[\]\.]+)$/i";

  $directories = "(?:\/[a-z0-9". $LINK_ICHARS ."_\-\.~+%=&,$'#!():;*@\[\]]*)*";
  // Yes, four backslashes == a single backslash.
  $query = "(?:\/?\?([?a-z0-9". $LINK_ICHARS ."+_|\-\.~\/\\\\%=&,$'():;*@\[\]{} ]*))";
  $anchor = "(?:#[a-z0-9". $LINK_ICHARS ."_\-\.~+%=&,$'():;*@\[\]\/\?]*)";

  // The rest of the path for a standard URL.
  $end = $directories .'?'. $query .'?'. $anchor .'?'.'$/i';

  $message_id = '[^@].*@'. $domain;
  $newsgroup_name = '(?:[0-9a-z+-]*\.)*[0-9a-z+-]*';
  $news_pattern = '/^news:('. $newsgroup_name .'|'. $message_id .')$/i';

  $user = '[a-zA-Z0-9'. $LINK_ICHARS .'_\-\.\+\^!#\$%&*+\/\=\?\`\|\{\}~\'\[\]]+';
  $email_pattern = '/^mailto:'. $user .'@'.'(?:'. $domain .'|'. $ipv4 .'|'. $ipv6 .'|localhost)'. $query .'?$/';

  if (strpos($text, '<front>') === 0) {
    return false;
  }
  if (in_array('mailto', $allowed_protocols) && preg_match($email_pattern, $text)) {
    return false;
  }
  if (in_array('news', $allowed_protocols) && preg_match($news_pattern, $text)) {
    return false;
  }
  if (preg_match($internal_pattern . $end, $text)) {
    return false;
  }
  if (preg_match($external_pattern . $end, $text)) {
    return false;
  }
  if (preg_match($internal_pattern_file, $text)) {
    return false;
  }

  return true;
}

submit the form using ajax

Nobody has actually given a pure javascript answer (as requested by OP), so here it is:

function postAsync(url2get, sendstr)    {
    var req;
    if (window.XMLHttpRequest) {
        req = new XMLHttpRequest();
        } else if (window.ActiveXObject) {
        req = new ActiveXObject("Microsoft.XMLHTTP");
        }
    if (req != undefined) {
        // req.overrideMimeType("application/json"); // if request result is JSON
        try {
            req.open("POST", url2get, false); // 3rd param is whether "async"
            }
        catch(err) {
            alert("couldnt complete request. Is JS enabled for that domain?\\n\\n" + err.message);
            return false;
            }
        req.send(sendstr); // param string only used for POST

        if (req.readyState == 4) { // only if req is "loaded"
            if (req.status == 200)  // only if "OK"
                { return req.responseText ; }
            else    { return "XHR error: " + req.status +" "+req.statusText; }
            }
        }
    alert("req for getAsync is undefined");
}

var var_str = "var1=" + var1  + "&var2=" + var2;
var ret = postAsync(url, var_str) ;
    // hint: encodeURIComponent()

if (ret.match(/^XHR error/)) {
    console.log(ret);
    return;
    }

In your case:

var var_str = "video_time=" + document.getElementById('video_time').value 
     + "&video_id=" + document.getElementById('video_id').value;

Delete with Join in MySQL

You can also use ALIAS like this it works just used it on my database! t is the table need deleting from!

DELETE t FROM posts t
INNER JOIN projects p ON t.project_id = p.project_id
AND t.client_id = p.client_id

Is it possible to get multiple values from a subquery?

View this web: http://www.w3resource.com/sql/subqueries/multiplee-row-column-subqueries.php

Use example

select ord_num, agent_code, ord_date, ord_amount  
from orders  
where(agent_code, ord_amount) IN  
(SELECT agent_code, MIN(ord_amount)  
FROM orders   
GROUP BY agent_code);    

How to append one file to another in Linux from the shell?

Note: if you need to use sudo, do this:

sudo bash -c 'cat file2 >> file1'

The usual method of simply prepending sudo to the command will fail, since the privilege escalation doesn't carry over into the output redirection.

Convert an image (selected by path) to base64 string

You can convert it like this

  string test = @"C:/image/1.gif";
  byte[] bytes = System.Text.ASCIIEncoding.ASCII.GetBytes(test);
  string base64String = System.Convert.ToBase64String(bytes);
  Console.WriteLine("Base 64 string: " + base64String);

Output

  QzovaW1hZ2UvMS5naWY=

select and echo a single field from mysql db using PHP

$eventid = $_GET['id'];
$field = $_GET['field'];
$result = mysql_query("SELECT $field FROM `events` WHERE `id` = '$eventid' ");
$row = mysql_fetch_array($result);
echo $row[$field];

but beware of sql injection cause you are using $_GET directly in a query. The danger of injection is particularly bad because there's no database function to escape identifiers. Instead, you need to pass the field through a whitelist or (better still) use a different name externally than the column name and map the external names to column names. Invalid external names would result in an error.

Change the Bootstrap Modal effect

Here is pure Bootstrap 4 with CSS 3 solution.

<div class="modal fade2" id="exampleModal" tabindex="-1" role="dialog" aria-labelledby="exampleModalLabel" aria-hidden="true">
  <div class="modal-dialog" role="document">
    <div class="modal-content">
      <div class="modal-header">
      </div>
      <div class="modal-body">
      </div>
      <div class="modal-footer">
        <button type="button" class="btn btn-primary" data-dismiss="modal">OK</button>
      </div>
    </div>
  </div>
</div>
.fade2 {
    transform: scale(0.9);
    opacity: 0;
    transition: all .2s linear;
    display: block !important;
}

.fade2.show {
    opacity: 1;
    transform: scale(1);
}
$('#exampleModal').modal();

function afterModalTransition(e) {
  e.setAttribute("style", "display: none !important;");
}
$('#exampleModal').on('hide.bs.modal', function (e) {
    setTimeout( () => afterModalTransition(this), 200);
})

Full example here.

Maybe it will help someone.

--

Thank you @DavidDomain too.

What does SQL clause "GROUP BY 1" mean?

It means to group by the first column regardless of what it's called. You can do the same with ORDER BY.

LINQ to SQL - How to select specific columns and return strongly typed list

Basically you are doing it the right way. However, you should use an instance of the DataContext for querying (it's not obvious that DataContext is an instance or the type name from your query):

var result = (from a in new DataContext().Persons
              where a.Age > 18
              select new Person { Name = a.Name, Age = a.Age }).ToList();

Apparently, the Person class is your LINQ to SQL generated entity class. You should create your own class if you only want some of the columns:

class PersonInformation {
   public string Name {get;set;}
   public int Age {get;set;}
}

var result = (from a in new DataContext().Persons
              where a.Age > 18
              select new PersonInformation { Name = a.Name, Age = a.Age }).ToList();

You can freely swap var with List<PersonInformation> here without affecting anything (as this is what the compiler does).

Otherwise, if you are working locally with the query, I suggest considering an anonymous type:

var result = (from a in new DataContext().Persons
              where a.Age > 18
              select new { a.Name, a.Age }).ToList();

Note that in all of these cases, the result is statically typed (it's type is known at compile time). The latter type is a List of a compiler generated anonymous class similar to the PersonInformation class I wrote above. As of C# 3.0, there's no dynamic typing in the language.

UPDATE:

If you really want to return a List<Person> (which might or might not be the best thing to do), you can do this:

var result = from a in new DataContext().Persons
             where a.Age > 18
             select new { a.Name, a.Age };

List<Person> list = result.AsEnumerable()
                          .Select(o => new Person {
                                           Name = o.Name, 
                                           Age = o.Age
                          }).ToList();

You can merge the above statements too, but I separated them for clarity.

Jenkins CI Pipeline Scripts not permitted to use method groovy.lang.GroovyObject

I ran into this when I reduced the number of user-input parameters in userInput from 3 to 1. This changed the variable output type of userInput from an array to a primitive.

Example:

myvar1 = userInput['param1']
myvar2 = userInput['param2']

to:

myvar = userInput

Setting PayPal return URL and making it auto return?

one way i have found:

try to insert this field into your generated form code:

<input type='hidden' name='rm' value='2'>

rm means return method;

2 means (post)

Than after user purchases and returns to your site url, then that url gets the POST parameters as well

p.s. if using php, try to insert var_dump($_POST); in your return url(script),then make a test purchase and when you return back to your site you will see what variables are got on your url.

How do I POST XML data to a webservice with Postman?

Send XML requests with the raw data type, then set the Content-Type to text/xml.


  1. After creating a request, use the dropdown to change the request type to POST.

    Set request type to POST

  2. Open the Body tab and check the data type for raw.

    Setting data type to raw

  3. Open the Content-Type selection box that appears to the right and select either XML (application/xml) or XML (text/xml)

    Selecting content-type text/xml

  4. Enter your raw XML data into the input field below

    Example of XML request in Postman

  5. Click Send to submit your XML Request to the specified server.

    Clicking the Send button

How to make for loops in Java increase by increments other than 1

Simply try this

for(int i=0; i<5; i=i+2){//value increased by 2
//body
}

OR

for(int i=0; i<5; i+=2){//value increased by 2
//body
}

member names cannot be the same as their enclosing type C#

As Constructor should be at the starting of the Class , you are facing the above issue . So, you can either change the name or if you want to use it as a constructor just copy the method at the beginning of the class.

Meaning of .Cells(.Rows.Count,"A").End(xlUp).row

The first part:

.Cells(.Rows.Count,"A")

Sends you to the bottom row of column A, which you knew already.

The End function starts at a cell and then, depending on the direction you tell it, goes that direction until it reaches the edge of a group of cells that have text. Meaning, if you have text in cells C4:E4 and you type:

Sheet1.Cells(4,"C").End(xlToRight).Select

The program will select E4, the rightmost cell with text in it.

In your case, the code is spitting out the row of the very last cell with text in it in column A. Does that help?

Finding the 'type' of an input element

To check input type

<!DOCTYPE html>
<html>
<body>

    <input type=number id="txtinp">
    <button onclick=checktype()>Try it</button>

    <script>
        function checktype() 
        {
            alert(document.getElementById("txtinp").type);
        }
    </script>

</body>
</html> 

jQuery slide left and show

You can add new function to your jQuery library by adding these line on your own script file and you can easily use fadeSlideRight() and fadeSlideLeft().

Note: you can change width of animation as you like instance of 750px.

$.fn.fadeSlideRight = function(speed,fn) {
    return $(this).animate({
        'opacity' : 1,
        'width' : '750px'
    },speed || 400, function() {
        $.isFunction(fn) && fn.call(this);
    });
}

$.fn.fadeSlideLeft = function(speed,fn) {
    return $(this).animate({
        'opacity' : 0,
        'width' : '0px'
    },speed || 400,function() {
        $.isFunction(fn) && fn.call(this);
    });
}

How do I toggle an element's class in pure JavaScript?

I know that I am late but, I happen to see this and I have a suggestion.. For those looking for cross-browser support, I wouldn't recommend class toggling via JS. It may be a little more work but it is more supported through all browsers.

_x000D_
_x000D_
document.getElementById("myButton").addEventListener('click', themeswitch);

function themeswitch() {
  const Body = document.body
  if (Body.style.backgroundColor === 'white') {
    Body.style.backgroundColor = 'black';
  } else {
    Body.style.backgroundColor = 'white';
  }
}
_x000D_
body {
  background: white;
}
_x000D_
<button id="myButton">Switch</button>
_x000D_
_x000D_
_x000D_

Why am I getting "void value not ignored as it ought to be"?

  int a = srand(time(NULL));

The prototype for srand is void srand(unsigned int) (provided you included <stdlib.h>).
This means it returns nothing ... but you're using the value it returns (???) to assign, by initialization, to a.


Edit: this is what you need to do:

#include <stdlib.h> /* srand(), rand() */
#include <time.h>   /* time() */

#define ARRAY_SIZE 1024

void getdata(int arr[], int n)
{
    for (int i = 0; i < n; i++)
    {
        arr[i] = rand();
    }
}

int main(void)
{
    int arr[ARRAY_SIZE];
    srand(time(0));
    getdata(arr, ARRAY_SIZE);
    /* ... */
}

Using NSLog for debugging

The proper way of using NSLog, as the warning tries to explain, is the use of a formatter, instead of passing in a literal:

Instead of:

NSString *digit = [[sender titlelabel] text];
NSLog(digit);

Use:

NSString *digit = [[sender titlelabel] text];
NSLog(@"%@",digit);

It will still work doing that first way, but doing it this way will get rid of the warning.

Static link of shared library function in gcc

In gcc, this isn't supported. In fact, this isn't supported in any existing compiler/linker i'm aware of.

How to check for an empty struct?

As an alternative to the other answers, it's possible to do this with a syntax similar to the way you originally intended if you do it via a case statement rather than an if:

session := Session{}
switch {
case Session{} == session:
    fmt.Println("zero")
default:
    fmt.Println("not zero")
}

playground example

How should I escape strings in JSON?

The methods here that show the actual implementation are all faulty.
I don't have Java code, but just for the record, you could easily convert this C#-code:

Courtesy of the mono-project @ https://github.com/mono/mono/blob/master/mcs/class/System.Web/System.Web/HttpUtility.cs

public static string JavaScriptStringEncode(string value, bool addDoubleQuotes)
{
    if (string.IsNullOrEmpty(value))
        return addDoubleQuotes ? "\"\"" : string.Empty;

    int len = value.Length;
    bool needEncode = false;
    char c;
    for (int i = 0; i < len; i++)
    {
        c = value[i];

        if (c >= 0 && c <= 31 || c == 34 || c == 39 || c == 60 || c == 62 || c == 92)
        {
            needEncode = true;
            break;
        }
    }

    if (!needEncode)
        return addDoubleQuotes ? "\"" + value + "\"" : value;

    var sb = new System.Text.StringBuilder();
    if (addDoubleQuotes)
        sb.Append('"');

    for (int i = 0; i < len; i++)
    {
        c = value[i];
        if (c >= 0 && c <= 7 || c == 11 || c >= 14 && c <= 31 || c == 39 || c == 60 || c == 62)
            sb.AppendFormat("\\u{0:x4}", (int)c);
        else switch ((int)c)
            {
                case 8:
                    sb.Append("\\b");
                    break;

                case 9:
                    sb.Append("\\t");
                    break;

                case 10:
                    sb.Append("\\n");
                    break;

                case 12:
                    sb.Append("\\f");
                    break;

                case 13:
                    sb.Append("\\r");
                    break;

                case 34:
                    sb.Append("\\\"");
                    break;

                case 92:
                    sb.Append("\\\\");
                    break;

                default:
                    sb.Append(c);
                    break;
            }
    }

    if (addDoubleQuotes)
        sb.Append('"');

    return sb.ToString();
}

This can be compacted into

    // https://github.com/mono/mono/blob/master/mcs/class/System.Json/System.Json/JsonValue.cs
public class SimpleJSON
{

    private static  bool NeedEscape(string src, int i)
    {
        char c = src[i];
        return c < 32 || c == '"' || c == '\\'
            // Broken lead surrogate
            || (c >= '\uD800' && c <= '\uDBFF' &&
                (i == src.Length - 1 || src[i + 1] < '\uDC00' || src[i + 1] > '\uDFFF'))
            // Broken tail surrogate
            || (c >= '\uDC00' && c <= '\uDFFF' &&
                (i == 0 || src[i - 1] < '\uD800' || src[i - 1] > '\uDBFF'))
            // To produce valid JavaScript
            || c == '\u2028' || c == '\u2029'
            // Escape "</" for <script> tags
            || (c == '/' && i > 0 && src[i - 1] == '<');
    }



    public static string EscapeString(string src)
    {
        System.Text.StringBuilder sb = new System.Text.StringBuilder();

        int start = 0;
        for (int i = 0; i < src.Length; i++)
            if (NeedEscape(src, i))
            {
                sb.Append(src, start, i - start);
                switch (src[i])
                {
                    case '\b': sb.Append("\\b"); break;
                    case '\f': sb.Append("\\f"); break;
                    case '\n': sb.Append("\\n"); break;
                    case '\r': sb.Append("\\r"); break;
                    case '\t': sb.Append("\\t"); break;
                    case '\"': sb.Append("\\\""); break;
                    case '\\': sb.Append("\\\\"); break;
                    case '/': sb.Append("\\/"); break;
                    default:
                        sb.Append("\\u");
                        sb.Append(((int)src[i]).ToString("x04"));
                        break;
                }
                start = i + 1;
            }
        sb.Append(src, start, src.Length - start);
        return sb.ToString();
    }
}

How to check if X server is running?

You can use xdpyinfo (can be installed via apt-get install x11-utils).

How do I use the built in password reset/change views with my own templates

The documentation says that there only one context variable, form.

If you're having trouble with login (which is common), the documentation says there are three context variables:

  • form: A Form object representing the login form. See the forms documentation for more on Form objects.
  • next: The URL to redirect to after successful login. This may contain a query string, too.
  • site_name: The name of the current Site, according to the SITE_ID setting.

Access denied for user 'test'@'localhost' (using password: YES) except root user

First I created the user using :

CREATE user user@localhost IDENTIFIED BY 'password_txt';

After Googling and seeing this, I updated user's password using :

SET PASSWORD FOR 'user'@'localhost' = PASSWORD('password_txt');

and I could connect afterward.

Check if a string is a valid Windows directory (folder) path

I haven't had any problems with this code:

private bool IsValidPath(string path, bool exactPath = true)
{
    bool isValid = true;

    try
    {
        string fullPath = Path.GetFullPath(path);

        if (exactPath)
        {
            string root = Path.GetPathRoot(path);
            isValid = string.IsNullOrEmpty(root.Trim(new char[] { '\\', '/' })) == false;
        }
        else
        {
            isValid = Path.IsPathRooted(path);
        }
    }
    catch(Exception ex)
    {
        isValid = false;
    }

    return isValid;
}

For example these would return false:

IsValidPath("C:/abc*d");
IsValidPath("C:/abc?d");
IsValidPath("C:/abc\"d");
IsValidPath("C:/abc<d");
IsValidPath("C:/abc>d");
IsValidPath("C:/abc|d");
IsValidPath("C:/abc:d");
IsValidPath("");
IsValidPath("./abc");
IsValidPath("/abc");
IsValidPath("abc");
IsValidPath("abc", false);

And these would return true:

IsValidPath(@"C:\\abc");
IsValidPath(@"F:\FILES\");
IsValidPath(@"C:\\abc.docx\\defg.docx");
IsValidPath(@"C:/abc/defg");
IsValidPath(@"C:\\\//\/\\/\\\/abc/\/\/\/\///\\\//\defg");
IsValidPath(@"C:/abc/def~`!@#$%^&()_-+={[}];',.g");
IsValidPath(@"C:\\\\\abc////////defg");
IsValidPath(@"/abc", false);

Concatenating strings in Razor

Use the parentesis syntax of Razor:

@(Model.address + " " + Model.city)

or

@(String.Format("{0} {1}", Model.address, Model.city))

Update: With C# 6 you can also use the $-Notation (officially interpolated strings):

@($"{Model.address} {Model.city}")

Facebook OAuth "The domain of this URL isn't included in the app's domain"

I had the same problem, and it came from a wrong client_id / Facebook App ID.

Did you switch your Facebook app to "public" or "online ? When you do so, Facebook creates a new app with a new App ID.

You can compare the "client_id" parameter value in the url with the one in your Facebook dashboard.

PopupWindow $BadTokenException: Unable to add window -- token null is not valid

Following many hours of search and testing i found following solution(by implementing different SO solutions) here it what didn't failed in any case i was getting crash.

     Runnable runnable = new Runnable() {
            @Override
            public void run() {

          //displayPopup,progress dialog or what ever action. example

                ProgressDialogBox.setProgressBar(Constants.LOADING,youractivityName.this);
            }};

Where logcat is indicating the crash is happening.. start a runnable .in my case at receiving broadcast.

runOnUiThread(new Runnable() {
            @Override
            public void run() {
                if(!isFinishing()) {
                    new Handler().postAtTime(runnable,2000);
                }
            }
        });

Find size and free space of the filesystem containing a given file

For the second part of your question, "get usage statistics of the given partition", psutil makes this easy with the disk_usage(path) function. Given a path, disk_usage() returns a named tuple including total, used, and free space expressed in bytes, plus the percentage usage.

Simple example from documentation:

>>> import psutil
>>> psutil.disk_usage('/')
sdiskusage(total=21378641920, used=4809781248, free=15482871808, percent=22.5)

Psutil works with Python versions from 2.6 to 3.6 and on Linux, Windows, and OSX among other platforms.

How to use callback with useState hook in react

_x000D_
_x000D_
function Parent() {_x000D_
  const [Name, setName] = useState("");_x000D_
  getChildChange = getChildChange.bind(this);_x000D_
  function getChildChange(value) {_x000D_
    setName(value);_x000D_
  }_x000D_
_x000D_
  return <div> {Name} :_x000D_
    <Child getChildChange={getChildChange} ></Child>_x000D_
  </div>_x000D_
}_x000D_
_x000D_
function Child(props) {_x000D_
  const [Name, setName] = useState("");_x000D_
  handleChange = handleChange.bind(this);_x000D_
  collectState = collectState.bind(this);_x000D_
  _x000D_
  function handleChange(ele) {_x000D_
    setName(ele.target.value);_x000D_
  }_x000D_
_x000D_
  function collectState() {_x000D_
    return Name;_x000D_
  }_x000D_
  _x000D_
   useEffect(() => {_x000D_
    props.getChildChange(collectState());_x000D_
   });_x000D_
_x000D_
  return (<div>_x000D_
    <input onChange={handleChange} value={Name}></input>_x000D_
  </div>);_x000D_
} 
_x000D_
_x000D_
_x000D_

useEffect act as componentDidMount, componentDidUpdate, so after updating state it will work

Click event on select option element in chrome

I use a two part solution

  • Part 1 - Register my click events on the options like I usually would
  • Part 2 - Detect that the selected item changed, and call the click handler of the new selected item.

HTML

<select id="sneaky-select">
  <option id="select-item-1">Hello</option>
  <option id="select-item-2">World</option>
</select>

JS

$("#select-item-1").click(function () { alert('hello') });
$("#select-item-2").click(function () { alert('world') });

$("#sneaky-select").change(function ()
{
   $("#sneaky-select option:selected").click();
});

Where to place and how to read configuration resource files in servlet based application?

It's your choice. There are basically three ways in a Java web application archive (WAR):


1. Put it in classpath

So that you can load it by ClassLoader#getResourceAsStream() with a classpath-relative path:

ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
InputStream input = classLoader.getResourceAsStream("foo.properties");
// ...
Properties properties = new Properties();
properties.load(input);

Here foo.properties is supposed to be placed in one of the roots which are covered by the default classpath of a webapp, e.g. webapp's /WEB-INF/lib and /WEB-INF/classes, server's /lib, or JDK/JRE's /lib. If the propertiesfile is webapp-specific, best is to place it in /WEB-INF/classes. If you're developing a standard WAR project in an IDE, drop it in src folder (the project's source folder). If you're using a Maven project, drop it in /main/resources folder.

You can alternatively also put it somewhere outside the default classpath and add its path to the classpath of the appserver. In for example Tomcat you can configure it as shared.loader property of Tomcat/conf/catalina.properties.

If you have placed the foo.properties it in a Java package structure like com.example, then you need to load it as below

ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
InputStream input = classLoader.getResourceAsStream("com/example/foo.properties");
// ...

Note that this path of a context class loader should not start with a /. Only when you're using a "relative" class loader such as SomeClass.class.getClassLoader(), then you indeed need to start it with a /.

ClassLoader classLoader = getClass().getClassLoader();
InputStream input = classLoader.getResourceAsStream("/com/example/foo.properties");
// ...

However, the visibility of the properties file depends then on the class loader in question. It's only visible to the same class loader as the one which loaded the class. So, if the class is loaded by e.g. server common classloader instead of webapp classloader, and the properties file is inside webapp itself, then it's invisible. The context class loader is your safest bet so you can place the properties file "everywhere" in the classpath and/or you intend to be able to override a server-provided one from the webapp on.


2. Put it in webcontent

So that you can load it by ServletContext#getResourceAsStream() with a webcontent-relative path:

InputStream input = getServletContext().getResourceAsStream("/WEB-INF/foo.properties");
// ...

Note that I have demonstrated to place the file in /WEB-INF folder, otherwise it would have been public accessible by any webbrowser. Also note that the ServletContext is in any HttpServlet class just accessible by the inherited GenericServlet#getServletContext() and in Filter by FilterConfig#getServletContext(). In case you're not in a servlet class, it's usually just injectable via @Inject.


3. Put it in local disk file system

So that you can load it the usual java.io way with an absolute local disk file system path:

InputStream input = new FileInputStream("/absolute/path/to/foo.properties");
// ...

Note the importance of using an absolute path. Relative local disk file system paths are an absolute no-go in a Java EE web application. See also the first "See also" link below.


Which to choose?

Just weigh the advantages/disadvantages in your own opinion of maintainability.

If the properties files are "static" and never needs to change during runtime, then you could keep them in the WAR.

If you prefer being able to edit properties files from outside the web application without the need to rebuild and redeploy the WAR every time, then put it in the classpath outside the project (if necessary add the directory to the classpath).

If you prefer being able to edit properties files programmatically from inside the web application using Properties#store() method, put it outside the web application. As the Properties#store() requires a Writer, you can't go around using a disk file system path. That path can in turn be passed to the web application as a VM argument or system property. As a precaution, never use getRealPath(). All changes in deploy folder will get lost on a redeploy for the simple reason that the changes are not reflected back in original WAR file.

See also:

Your content must have a ListView whose id attribute is 'android.R.id.list'

One other thing that affected me: If you have multiple test devices, make sure you are making changes to the layout used by the device. In my case, I spent a while making changes to xmls in the "layout" directory until I discovered that my larger phone (which I switched to halfway through testing) was using xmls in the "layout-sw360dp" directory. Grrr!

Count number of cells with any value (string or number) in a column in Google Docs Spreadsheet

Shorter and dealing with a column (entire, not just a section of a column):

=COUNTA(A:A)

COUNTA

Beware, a cell containing just a space would be included in the count.

Executing <script> elements inserted with .innerHTML

A solution without using "eval":

var setInnerHtml = function(elm, html) {
  elm.innerHTML = html;
  var scripts = elm.getElementsByTagName("script");
  // If we don't clone the results then "scripts"
  // will actually update live as we insert the new
  // tags, and we'll get caught in an endless loop
  var scriptsClone = [];
  for (var i = 0; i < scripts.length; i++) {
    scriptsClone.push(scripts[i]);
  }
  for (var i = 0; i < scriptsClone.length; i++) {
    var currentScript = scriptsClone[i];
    var s = document.createElement("script");
    // Copy all the attributes from the original script
    for (var j = 0; j < currentScript.attributes.length; j++) {
      var a = currentScript.attributes[j];
      s.setAttribute(a.name, a.value);
    }
    s.appendChild(document.createTextNode(currentScript.innerHTML));
    currentScript.parentNode.replaceChild(s, currentScript);
  }
}

This essentially clones the script tag and then replaces the blocked script tag with the newly generated one, thus allowing execution.

How to use greater than operator with date?

In my case my column was a datetime it kept giving me all records. What I did is to include time, see below example

SELECT * FROM my_table where start_date > '2011-01-01 01:01:01';

How to commit a change with both "message" and "description" from the command line?

There is also another straight and more clear way

git commit -m "Title" -m "Description ..........";

window.onload vs $(document).ready()

window.onload is provided by DOM api and it says " the load event fires when a given resource has loaded".

"The load event fires at the end of the document loading process. At this point, all of the objects in the document are in the DOM, and all the images, scripts, links and sub-frames have finished loading." DOM onload

But in jQuery $(document).ready() will only run once the page Document Object Model (DOM) is ready for JavaScript code to execute. This does not include images, scripts, iframes etc. jquery ready event

So the jquery ready method will run earlier than the dom onload event.

Script to get the HTTP status code of a list of urls?

wget --spider -S "http://url/to/be/checked" 2>&1 | grep "HTTP/" | awk '{print $2}'

prints only the status code for you

How to turn off the Eclipse code formatter for certain sections of Java code?

@xpmatteo has the answer to disabling portions of code, but in addition to this, the default eclipse settings should be set to only format edited lines of code instead of the whole file.

Preferences->Java->Editor->Save Actions->Format Source Code->Format Edited Lines

This would have prevented it from happening in the first place since your coworkers are reformatting code they didn't actually change. This is a good practice to prevent mishaps that render diff on your source control useless (when an entire file is reformatted because of minor format setting differences).

It would also prevent the reformatting if the on/off tags option was turned off.

What's the difference between '$(this)' and 'this'?

Yeah, by using $(this), you enabled jQuery functionality for the object. By just using this, it only has generic Javascript functionality.

Can I create view with parameter in MySQL?

CREATE VIEW MyView AS
   SELECT Column, Value FROM Table;


SELECT Column FROM MyView WHERE Value = 1;

Is the proper solution in MySQL, some other SQLs let you define Views more exactly.

Note: Unless the View is very complicated, MySQL will optimize this just fine.

module.exports vs. export default in Node.js and ES6

Felix Kling did a great comparison on those two, for anyone wondering how to do an export default alongside named exports with module.exports in nodejs

module.exports = new DAO()
module.exports.initDAO = initDAO // append other functions as named export

// now you have
let DAO = require('_/helpers/DAO');
// DAO by default is exported class or function
DAO.initDAO()

Keep the order of the JSON keys during JSON conversion to CSV

The most safe way is probably overriding keys method that is used to generate output:

new JSONObject(){
  @Override
  public Iterator keys(){
    TreeSet<Object> sortedKeys = new TreeSet<Object>();
    Iterator keys = super.keys();
    while(keys.hasNext()){
      sortedKeys.add(keys.next());
    }
    return sortedKeys.iterator();
  }
};

Why does ++[[]][+[]]+[+[]] return the string "10"?

  1. Unary plus given string converts to number
  2. Increment operator given string converts and increments by 1
  3. [] == ''. Empty String
  4. +'' or +[] evaluates 0.

    ++[[]][+[]]+[+[]] = 10 
    ++[''][0] + [0] : First part is gives zeroth element of the array which is empty string 
    1+0 
    10
    

Convert a negative number to a positive one in JavaScript

I did something like this myself.

num<0?num*=-1:'';

It checks if the number is negative and if it is, multiply with -1 This does return a value, its up to you if you capture it. In case you want to assign it to something, you should probably do something like:

var out = num<0?num*=-1:num; //I think someone already mentioned this variant.

But it really depends what your goal is. For me it was simple, make it positive if negative, else do nothing. Hence the '' in the code. In this case i used tertiary operator cause I wanted to, it could very well be:

if(num<0)num*=-1;

I saw the bitwise solution here and wanted to comment on that one too.

~--num; //Drawback for this is that num original value will be reduced by 1

This soultion is very fancy in my opinion, we could rewrite it like this:

~(num = num-1);

In simple terms, we take the negative number, take one away from it and then bitwise invert it. If we had bitwise inverted it normally we would get a value 1 too small. You can also do this:

~num+1; //Wont change the actual num value, merely returns the new value

That will do the same but will invert first and then add 1 to the positive number. Although you CANT do this:

~num++; //Wont display the right value.

That will not work cause of precedence, postfix operators such as num++ would be evaluated before ~ and the reason prefix ++num wouldnt work even though it is on the same precedence as bitwise NOT(~), is cause it is evaluated from right to left. I did try to swap them around but it seems that prefix is a little finicky compared to bitwise NOT. The +1 will work because '+' has a higher precedence and will be evaluated later.

I found that solution to be rather fun and decided to expand on it as it was just thrown in there and post people looking at it were probably ignoring it. Although yes, it wont work with floats.

My hopes are that this post hasn't moved away from the original question. :/

Put icon inside input element in a form

I had situation like this. It didn't work because of background: #ebebeb;. I wanted to put background on the input field and that property was constantly showing up on the top of the background image, and i couldn't see the image! So, I moved the background property to be above the background-image property and it worked.

input[type='text'] {
    border: 0;
    background-image: url('../img/search.png');
    background-position: 9px 20px;
    background-repeat: no-repeat;
    text-align: center;
    padding: 14px;
    background: #ebebeb;
}

Solution for my case was:

input[type='text'] {
    border: 0;
    background: #ebebeb;
    background-image: url('../img/search.png');
    background-position: 9px 20px;
    background-repeat: no-repeat;
    text-align: center;
    padding: 14px;
}

Just to mention, border, padding and text-align properties are not important for the solution. I just replicated my original code.

Changing the "tick frequency" on x or y axis in matplotlib?

Since None of the above solutions worked for my usecase, here I provide a solution using None (pun!) which can be adapted to a wide variety of scenarios.

Here is a sample piece of code that produces cluttered ticks on both X and Y axes.

# Note the super cluttered ticks on both X and Y axis.

# inputs
x = np.arange(1, 101)
y = x * np.log(x) 

fig = plt.figure()     # create figure
ax = fig.add_subplot(111)
ax.plot(x, y)
ax.set_xticks(x)        # set xtick values
ax.set_yticks(y)        # set ytick values

plt.show()

Now, we clean up the clutter with a new plot that shows only a sparse set of values on both x and y axes as ticks.

# inputs
x = np.arange(1, 101)
y = x * np.log(x)

fig = plt.figure()       # create figure
ax = fig.add_subplot(111)
ax.plot(x, y)

ax.set_xticks(x)
ax.set_yticks(y)

# which values need to be shown?
# here, we show every third value from `x` and `y`
show_every = 3

sparse_xticks = [None] * x.shape[0]
sparse_xticks[::show_every] = x[::show_every]

sparse_yticks = [None] * y.shape[0]
sparse_yticks[::show_every] = y[::show_every]

ax.set_xticklabels(sparse_xticks, fontsize=6)   # set sparse xtick values
ax.set_yticklabels(sparse_yticks, fontsize=6)   # set sparse ytick values

plt.show()

Depending on the usecase, one can adapt the above code simply by changing show_every and using that for sampling tick values for X or Y or both the axes.

If this stepsize based solution doesn't fit, then one can also populate the values of sparse_xticks or sparse_yticks at irregular intervals, if that is what is desired.

What is a bus error?

A specific example of a bus error I just encountered while programming C on OS X:

#include <string.h>
#include <stdio.h>

int main(void)
{
    char buffer[120];
    fgets(buffer, sizeof buffer, stdin);
    strcat("foo", buffer);
    return 0;
}

In case you don't remember the docs strcat appends the second argument to the first by changing the first argument(flip the arguments and it works fine). On linux this gives a segmentation fault(as expected), but on OS X it gives a bus error. Why? I really don't know.

Create a zip file and download it

I just ran into this problem. For me the issue was with:

readfile("$archive_file_name");

It was resulting in a out of memory error.

Allowed memory size of 134217728 bytes exhausted (tried to allocate 292982784 bytes)

I was able to correct the problem by replacing readfile() with the following:

    $handle = fopen($zipPath, "rb");
    while (!feof($handle)){
        echo fread($handle, 8192);
    }
    fclose($handle);

Not sure if this is your same issue or not seeing that your file is only 1.2 MB. Maybe this will help someone else with a similar problem.

Label python data points on plot

How about print (x, y) at once.

from matplotlib import pyplot as plt

fig = plt.figure()
ax = fig.add_subplot(111)

A = -0.75, -0.25, 0, 0.25, 0.5, 0.75, 1.0
B = 0.73, 0.97, 1.0, 0.97, 0.88, 0.73, 0.54

plt.plot(A,B)
for xy in zip(A, B):                                       # <--
    ax.annotate('(%s, %s)' % xy, xy=xy, textcoords='data') # <--

plt.grid()
plt.show()

enter image description here

I want to execute shell commands from Maven's pom.xml

2 Options:

  1. You want to exec a command from maven without binding to any phase, you just type the command and maven runs it, you just want to maven to run something, you don't care if we are in compile/package/... Let's say I want to run npm start with maven, you can achieve it with the below:

mvn exec:exec -Pstart-node

For that you need the below maven section

  <profiles>
    <profile>
      <id>start-node</id>
      <build>
        <plugins>
          <plugin>
            <groupId>org.codehaus.mojo</groupId>
            <artifactId>exec-maven-plugin</artifactId>
            <version>1.3.2</version>
            <executions>
              <execution>
                <goals>
                  <goal>exec</goal>
                </goals>
              </execution>
            </executions>
            <configuration>
              <executable>npm</executable>
              <arguments><argument>start</argument></arguments>
            </configuration>
          </plugin>
        </plugins>
      </build>
    </profile>

  </profiles>
  1. You want to run an arbitrary command from maven while you are at a specific phase, for example when I'm at install phase I want to run npm install you can do that with:

mvn install

And for that to work you would need the below section:

  <plugin>
    <groupId>org.codehaus.mojo</groupId>
    <artifactId>exec-maven-plugin</artifactId>
    <version>1.3.2</version>
    <executions>

      <execution>
        <id>npm install (initialize)</id>
        <goals>
          <goal>exec</goal>
        </goals>
        <phase>initialize</phase>
        <configuration>
          <executable>npm</executable>
          <arguments>
            <argument>install</argument>
          </arguments>
        </configuration>
      </execution>

How do I read configuration settings from Symfony2 config.yml?

Like it was saying previously - you can access any parameters by using injection container and use its parameter property.

"Symfony - Working with Container Service Definitions" is a good article about it.

Unused arguments in R

The R.utils package has a function called doCall which is like do.call, but it does not return an error if unused arguments are passed.

multiply <- function(a, b) a * b

# these will fail
multiply(a = 20, b = 30, c = 10)
# Error in multiply(a = 20, b = 30, c = 10) : unused argument (c = 10)
do.call(multiply, list(a = 20, b = 30, c = 10))
# Error in (function (a, b)  : unused argument (c = 10)

# R.utils::doCall will work
R.utils::doCall(multiply, args = list(a = 20, b = 30, c = 10))
# [1] 600
# it also does not require the arguments to be passed as a list
R.utils::doCall(multiply, a = 20, b = 30, c = 10)
# [1] 600

Is there a NumPy function to return the first index of something in an array?

There are lots of operations in NumPy that could perhaps be put together to accomplish this. This will return indices of elements equal to item:

numpy.nonzero(array - item)

You could then take the first elements of the lists to get a single element.

Redis connection to 127.0.0.1:6379 failed - connect ECONNREFUSED

Try upgrading your node to latest version.

sudo npm cache clean -f
sudo npm install -g n
sudo n stable

version 0.4 may not work properly.

How to leave space in HTML

Use white-space: pre:

_x000D_
_x000D_
<!DOCTYPE html>_x000D_
<html>_x000D_
<span style="white-space: pre">    My spaces   </span>_x000D_
<br>_x000D_
<span>     My spaces   </span>_x000D_
</html>
_x000D_
_x000D_
_x000D_

How to search a list of tuples in Python

[k for k,v in l if v =='delicia']

here l is the list of tuples-[(1,"juca"),(22,"james"),(53,"xuxa"),(44,"delicia")]

And instead of converting it to a dict, we are using llist comprehension.

*Key* in Key,Value in list, where value = **delicia**

'uint32_t' identifier not found error

There is an implementation available at the msinttypes project page - "This project fills the absence of stdint.h and inttypes.h in Microsoft Visual Studio".

I don't have experience with this implementation, but I've seen it recommended by others on SO.

Laravel 5 – Remove Public from URL

Even if i do not recommend putting Laravel on the root folder there are some cases when it could not be avoided; for those cases the above methods do not work for assets so i made a quick fix changing the htaccess: after copying server.php to index.php edit the .htaccess file like so:

<IfModule mod_rewrite.c>
    <IfModule mod_negotiation.c>
        Options -MultiViews
    </IfModule>

    RewriteEngine On

    ### fix file rewrites on root path ###
    #select file url
    RewriteCond %{REQUEST_URI} ^(.*)$
    #if file exists in /public/<filename>
    RewriteCond %{DOCUMENT_ROOT}/public/$1 -f
    #redirect to /public/<filename>
    RewriteRule ^(.*)$ public/$1 [L]
    ###############

    # Redirect Trailing Slashes If Not A Folder...
    RewriteCond %{REQUEST_FILENAME} !-d
    RewriteRule ^(.*)/$ /$1 [L,R=301]

    # Handle Front Controller...

    #RewriteCond %{REQUEST_FILENAME} -d # comment this rules or the user will read non-public file and folders!
    #RewriteCond %{REQUEST_FILENAME} -f #
    RewriteRule ^ index.php [L]
</IfModule>

This was a quick fix i had to make so anyone is welcome to upgrade it.

Java Scanner class reading strings

use sc.nextLine(); two time so that we can read the last line of string

sc.nextLine() sc.nextLine()

Submit form without page reloading

This should solve your problem.
In this code after submit button click we call jquery ajax and we pass url to post
type POST/GET
data: data information you can select input fields or any other.
sucess: callback if everything is ok from server
function parameter text, html or json, response from server
in sucess you can write write warnings if data you got is in some kind of state and so on. or execute your code what to do next.

<form id='tip'>
Tip somebody: <input name="tip_email" id="tip_email" type="text" size="30" onfocus="tip_div(1);" onblur="tip_div(2);"/>
 <input type="submit" id="submit" value="Skicka Tips"/>
 <input type="hidden" id="ad_id" name="ad_id" />
 </form>
<script>
$( "#tip" ).submit(function( e ) {
    e.preventDefault();
    $.ajax({
        url: tip.php,
        type:'POST',
        data:
        {
            tip_email: $('#tip_email').val(),
            ad_id: $('#ad_id').val()
        },
        success: function(msg)
        {

            alert('Email Sent');
        }               
    });
});
</script>

How to create an array for JSON using PHP?

Just typing this single line would give you a json array ,

echo json_encode($array);

Normally you use json_encode to read data from an ios or android app. so make sure you do not echo anything else other than the accurate json array.

How to make an autocomplete address field with google maps api?

I really doubt it--google maps API is great for geocoding known addresses, but it generally return data that is suitable for autocomplete-style operations. Nevermind the challenge of not hitting the API in such a way as to eat up your geocoding query limit very quickly.

SQL like search string starts with

COLLATE UTF8_GENERAL_CI will work as ignore-case. USE:

SELECT * from games WHERE title COLLATE UTF8_GENERAL_CI LIKE 'age of empires III%';

or

SELECT * from games WHERE LOWER(title) LIKE 'age of empires III%';

Run Excel Macro from Outside Excel Using VBScript From Command Line

I tried the above methods but I got the "macro cannot be found" error. This is final code that worked!

Option Explicit

Dim xlApp, xlBook

Set xlApp = CreateObject("Excel.Application")
xlApp.Visible = True

  ' Import Add-Ins
xlApp.Workbooks.Open "C:\<pathOfXlaFile>\MyMacro.xla"
xlApp.AddIns("MyMacro").Installed = True

'
Open Excel workbook
Set xlBook = xlApp.Workbooks.Open("<pathOfXlsFile>\MyExcel.xls", 0, True)

' Run Macro
xlApp.Run "Sheet1.MyMacro"

xlBook.Close
xlApp.Quit

Set xlBook = Nothing
Set xlApp = Nothing

WScript.Quit

In my case, MyMacro happens to be under Sheet1, thus Sheet1.MyMacro.

importing go files in same folder

I just wanted something really basic to move some files out of the main folder, like user2889485's reply, but his specific answer didnt work for me. I didnt care if they were in the same package or not.

My GOPATH workspace is c:\work\go and under that I have

/src/pg/main.go      (package main)
/src/pg/dbtypes.go   (pakage dbtypes)

in main.go I import "/pg/dbtypes"

How to implement an STL-style iterator and avoid common pitfalls?

I was trying to solve the problem of being able to iterate over several different text arrays all of which are stored within a memory resident database that is a large struct.

The following was worked out using Visual Studio 2017 Community Edition on an MFC test application. I am including this as an example as this posting was one of several that I ran across that provided some help yet were still insufficient for my needs.

The struct containing the memory resident data looked something like the following. I have removed most of the elements for the sake of brevity and have also not included the Preprocessor defines used (the SDK in use is for C as well as C++ and is old).

What I was interested in doing is having iterators for the various WCHAR two dimensional arrays which contained text strings for mnemonics.

typedef struct  tagUNINTRAM {
    // stuff deleted ...
    WCHAR   ParaTransMnemo[MAX_TRANSM_NO][PARA_TRANSMNEMO_LEN]; /* prog #20 */
    WCHAR   ParaLeadThru[MAX_LEAD_NO][PARA_LEADTHRU_LEN];   /* prog #21 */
    WCHAR   ParaReportName[MAX_REPO_NO][PARA_REPORTNAME_LEN];   /* prog #22 */
    WCHAR   ParaSpeMnemo[MAX_SPEM_NO][PARA_SPEMNEMO_LEN];   /* prog #23 */
    WCHAR   ParaPCIF[MAX_PCIF_SIZE];            /* prog #39 */
    WCHAR   ParaAdjMnemo[MAX_ADJM_NO][PARA_ADJMNEMO_LEN];   /* prog #46 */
    WCHAR   ParaPrtModi[MAX_PRTMODI_NO][PARA_PRTMODI_LEN];  /* prog #47 */
    WCHAR   ParaMajorDEPT[MAX_MDEPT_NO][PARA_MAJORDEPT_LEN];    /* prog #48 */
    //  ... stuff deleted
} UNINIRAM;

The current approach is to use a template to define a proxy class for each of the arrays and then to have a single iterator class that can be used to iterate over a particular array by using a proxy object representing the array.

A copy of the memory resident data is stored in an object that handles reading and writing the memory resident data from/to disk. This class, CFilePara contains the templated proxy class (MnemonicIteratorDimSize and the sub class from which is it is derived, MnemonicIteratorDimSizeBase) and the iterator class, MnemonicIterator.

The created proxy object is attached to an iterator object which accesses the necessary information through an interface described by a base class from which all of the proxy classes are derived. The result is to have a single type of iterator class which can be used with several different proxy classes because the different proxy classes all expose the same interface, the interface of the proxy base class.

The first thing was to create a set of identifiers which would be provided to a class factory to generate the specific proxy object for that type of mnemonic. These identifiers are used as part of the user interface to identify the particular provisioning data the user is interested in seeing and possibly modifying.

const static DWORD_PTR dwId_TransactionMnemonic = 1;
const static DWORD_PTR dwId_ReportMnemonic = 2;
const static DWORD_PTR dwId_SpecialMnemonic = 3;
const static DWORD_PTR dwId_LeadThroughMnemonic = 4;

The Proxy Class

The templated proxy class and its base class are as follows. I needed to accommodate several different kinds of wchar_t text string arrays. The two dimensional arrays had different numbers of mnemonics, depending on the type (purpose) of the mnemonic and the different types of mnemonics were of different maximum lengths, varying between five text characters and twenty text characters. Templates for the derived proxy class was a natural fit with the template requiring the maximum number of characters in each mnemonic. After the proxy object is created, we then use the SetRange() method to specify the actual mnemonic array and its range.

// proxy object which represents a particular subsection of the
// memory resident database each of which is an array of wchar_t
// text arrays though the number of array elements may vary.
class MnemonicIteratorDimSizeBase
{
    DWORD_PTR  m_Type;

public:
    MnemonicIteratorDimSizeBase(DWORD_PTR x) { }
    virtual ~MnemonicIteratorDimSizeBase() { }

    virtual wchar_t *begin() = 0;
    virtual wchar_t *end() = 0;
    virtual wchar_t *get(int i) = 0;
    virtual int ItemSize() = 0;
    virtual int ItemCount() = 0;

    virtual DWORD_PTR ItemType() { return m_Type; }
};

template <size_t sDimSize>
class MnemonicIteratorDimSize : public MnemonicIteratorDimSizeBase
{
    wchar_t    (*m_begin)[sDimSize];
    wchar_t    (*m_end)[sDimSize];

public:
    MnemonicIteratorDimSize(DWORD_PTR x) : MnemonicIteratorDimSizeBase(x), m_begin(0), m_end(0) { }
    virtual ~MnemonicIteratorDimSize() { }

    virtual wchar_t *begin() { return m_begin[0]; }
    virtual wchar_t *end() { return m_end[0]; }
    virtual wchar_t *get(int i) { return m_begin[i]; }

    virtual int ItemSize() { return sDimSize; }
    virtual int ItemCount() { return m_end - m_begin; }

    void SetRange(wchar_t (*begin)[sDimSize], wchar_t (*end)[sDimSize]) {
        m_begin = begin; m_end = end;
    }

};

The Iterator Class

The iterator class itself is as follows. This class provides just basic forward iterator functionality which is all that is needed at this time. However I expect that this will change or be extended when I need something additional from it.

class MnemonicIterator
{
private:
    MnemonicIteratorDimSizeBase   *m_p;  // we do not own this pointer. we just use it to access current item.
    int      m_index;                    // zero based index of item.
    wchar_t  *m_item;                    // value to be returned.

public:
    MnemonicIterator(MnemonicIteratorDimSizeBase *p) : m_p(p) { }
    ~MnemonicIterator() { }

    // a ranged for needs begin() and end() to determine the range.
    // the range is up to but not including what end() returns.
    MnemonicIterator & begin() { m_item = m_p->get(m_index = 0); return *this; }                 // begining of range of values for ranged for. first item
    MnemonicIterator & end() { m_item = m_p->get(m_index = m_p->ItemCount()); return *this; }    // end of range of values for ranged for. item after last item.
    MnemonicIterator & operator ++ () { m_item = m_p->get(++m_index); return *this; }            // prefix increment, ++p
    MnemonicIterator & operator ++ (int i) { m_item = m_p->get(m_index++); return *this; }       // postfix increment, p++
    bool operator != (MnemonicIterator &p) { return **this != *p; }                              // minimum logical operator is not equal to
    wchar_t * operator *() const { return m_item; }                                              // dereference iterator to get what is pointed to
};

The proxy object factory determines which object to created based on the mnemonic identifier. The proxy object is created and the pointer returned is the standard base class type so as to have a uniform interface regardless of which of the different mnemonic sections are being accessed. The SetRange() method is used to specify to the proxy object the specific array elements the proxy represents and the range of the array elements.

CFilePara::MnemonicIteratorDimSizeBase * CFilePara::MakeIterator(DWORD_PTR x)
{
    CFilePara::MnemonicIteratorDimSizeBase  *mi = nullptr;

    switch (x) {
    case dwId_TransactionMnemonic:
        {
            CFilePara::MnemonicIteratorDimSize<PARA_TRANSMNEMO_LEN> *mk = new CFilePara::MnemonicIteratorDimSize<PARA_TRANSMNEMO_LEN>(x);
            mk->SetRange(&m_Para.ParaTransMnemo[0], &m_Para.ParaTransMnemo[MAX_TRANSM_NO]);
            mi = mk;
        }
        break;
    case dwId_ReportMnemonic:
        {
            CFilePara::MnemonicIteratorDimSize<PARA_REPORTNAME_LEN> *mk = new CFilePara::MnemonicIteratorDimSize<PARA_REPORTNAME_LEN>(x);
            mk->SetRange(&m_Para.ParaReportName[0], &m_Para.ParaReportName[MAX_REPO_NO]);
            mi = mk;
        }
        break;
    case dwId_SpecialMnemonic:
        {
            CFilePara::MnemonicIteratorDimSize<PARA_SPEMNEMO_LEN> *mk = new CFilePara::MnemonicIteratorDimSize<PARA_SPEMNEMO_LEN>(x);
            mk->SetRange(&m_Para.ParaSpeMnemo[0], &m_Para.ParaSpeMnemo[MAX_SPEM_NO]);
            mi = mk;
        }
        break;
    case dwId_LeadThroughMnemonic:
        {
            CFilePara::MnemonicIteratorDimSize<PARA_LEADTHRU_LEN> *mk = new CFilePara::MnemonicIteratorDimSize<PARA_LEADTHRU_LEN>(x);
            mk->SetRange(&m_Para.ParaLeadThru[0], &m_Para.ParaLeadThru[MAX_LEAD_NO]);
            mi = mk;
        }
        break;
    }

    return mi;
}

Using the Proxy Class and Iterator

The proxy class and its iterator are used as shown in the following loop to fill in a CListCtrl object with a list of mnemonics. I am using std::unique_ptr so that when the proxy class i not longer needed and the std::unique_ptr goes out of scope, the memory will be cleaned up.

What this source code does is to create a proxy object for the array within the struct which corresponds to the specified mnemonic identifier. It then creates an iterator for that object, uses a ranged for to fill in the CListCtrl control and then cleans up. These are all raw wchar_t text strings which may be exactly the number of array elements so we copy the string into a temporary buffer in order to ensure that the text is zero terminated.

    std::unique_ptr<CFilePara::MnemonicIteratorDimSizeBase> pObj(pFile->MakeIterator(m_IteratorType));
    CFilePara::MnemonicIterator pIter(pObj.get());  // provide the raw pointer to the iterator who doesn't own it.

    int i = 0;    // CListCtrl index for zero based position to insert mnemonic.
    for (auto x : pIter)
    {
        WCHAR szText[32] = { 0 };     // Temporary buffer.

        wcsncpy_s(szText, 32, x, pObj->ItemSize());
        m_mnemonicList.InsertItem(i, szText);  i++;
    }

Using Keras & Tensorflow with AMD GPU

The original question on this post was: How to get Keras and Tensorflow to run with an AMD GPU.

The answer to this question is as followed:

1.) Keras will work if you can make Tensorflow work correctly (optionally within your virtual/conda environment).

2.) To get Tensorflow to work on an AMD GPU, as others have stated, one way this could work is to compile Tensorflow to use OpenCl. To do so read the link below. But for brevity I will summarize the required steps here:

  • You will need AMDs proprietary drivers. These are currently only available on Ubuntu 14.04 (the version before Ubuntu decided to change the way the UI is rendered). Support for Ubuntu 16.04 is at the writing of this post limited to a few GPUs through AMDProDrivers. Readers who want to do deep learning on AMD GPUs should be aware of this!

  • Compiling Tensorflow with OpenCl support also requires you to obtain and install the following prerequisites: OpenCl headers, ComputeCpp.

  • After the prerequisites are fulfilled, configure your build. Note that there are 3 options for compiling Tensorflow: Std Tensorflow (stable), Benoits Steiner's Tensorflow-opencl (developmental), and Luke Iwanski's Tensorflow-opencl (highly experimental) which you can pull from github. Also note that if you decide to build from any of the opencl versions, the question to use opencl will be missing because it is assumed that you are using it. Conversely, this means that if you configure from the standard tensorflow, you will need to select "Yes" when the configure script asks you to use opencl and "NO" for CUDA.

  • Then run tests like so:

    $ bazel test --config=sycl -k --test_timeout 1600 -- //tensorflow/... -//tensorflow/contrib/... -//tensorflow/java/... -//tensorflow /compiler/...

Update: Doing this on my setup takes exceedingly long on my setup. The part that takes long are all the tests running. I am not sure what this means but a lot of my tests are timeing out at 1600 seconds. The duration can probably be shortened at the expense of more tests timeing out. Alternatively, you can just build tensor flow without tests. At the time of this writing, running the tests has taken 2 days already.

Or just build the pip package like so:

bazel build --local_resources 2048,.5,1.0 -c opt --config=sycl //tensorflow/tools/pip_package:build_pip_package

Please actually read the blog post over at Codeplay: Lukas Iwansky posted a comprehensive tutorial post on how to get Tensorflow to work with OpenCl just on March 30th 2017. So this is a very recent post. There are also some details which I did not write about here.

As indicated in the many posts above, little bits of information are spread throughout the interwebs. What Lukas' post adds in terms of value is that all the information was put together into one place which should make setting up Tensforflow and OpenCl a bit less daunting. I will only provide a link here:

https://www.codeplay.com/portal/03-30-17-setting-up-tensorflow-with-opencl-using-sycl

A slightly more complete walk-through has been posted here:

http://deep-beta.co.uk/setting-up-tensorflow-with-opencl-using-sycl/

It differs mainly by explicitly telling the user that he/she needs to:

  • create symlinks to a subfolder
  • and then actually install tensorflow via "python setup.py develop" command.

Note an alternative approach was mentioned above using tensorflow-cl:

https://github.com/hughperkins/tensorflow-cl

I am unable to discern which approach is better at this time though it appears that this approach is less active. Fewer issues are posted, and fewer conversations to resolve those issues are happening. There was a major push last year. Additional pushes have ebbed off since November 2016 although Hugh seems to have pushed some updates a few days ago as of the writing of this post. (Update: If you read some of the documentation readme, this version of tensorflowo now only relies on community support as the main developer is busy with life.)

UPDATE (2017-04-25): I have some notes based on testing tensorflow-opencl below.

  • The future user of this package should note that using opencl means that all the heavy-lifting in terms of computing is shifted to the GPU. I mention this because I was personally thinking that the compute work-load would be shared between my CPU and iGPU. This means that the power of your GPU is very important (specifically, bandwidth, and available VRAM).

Following are some numbers for calculating 1 epoch using the CIFAR10 data set for MY SETUP (A10-7850 with iGPU). Your mileage will almost certainly vary!

  • Tensorflow (via pip install): ~ 1700 s/epoch
  • Tensorflow (w/ SSE + AVX): ~ 1100 s/epoch
  • Tensorflow (w/ opencl & iGPU): ~ 5800 s/epoch

You can see that in this particular case performance is worse. I attribute this to the following factors:

  • The iGPU only has 1GB. This leads to a lot of copying back and forth between CPU and GPU. (Opencl 1.2 does not have the ability to data pass via pointers yet; instead data has to be copied back and forth.)
  • The iGPU only has 512 stream processors (and 32 Gb/s memory bandwidth) which in this case is slower than 4 CPUs using SSE4 + AVX instruction sets.
  • The development of tensorflow-opencl is in it's beginning stages, and a lot of optimizations in SYCL etc. have not been done yet.

If you are using an AMD GPU with more VRAM and more stream processors, you are certain to get much better performance numbers. I would be interested to read what numbers people are achieving to know what's possible.

I will continue to maintain this answer if/when updates get pushed.

3.) An alternative way is currently being hinted at which is using AMD's RocM initiative, and miOpen (cuDNN equivalent) library. These are/will be open-source libraries that enable deep learning. The caveat is that RocM support currently only exists for Linux, and that miOpen has not been released to the wild yet, but Raja (AMD GPU head) has said in an AMA that using the above, it should be possible to do deep learning on AMD GPUs. In fact, support is planned for not only Tensorflow, but also Cafe2, Cafe, Torch7 and MxNet.

How do I add multiple conditions to "ng-disabled"?

Actually the ng-disabled directive works with the " || " logical operator for me. The " && " evaluate only one condition.

http://jsbin.com/kuqilejesi/2/edit?html,js,output

Android Animation Alpha

Try this

AlphaAnimation animation1 = new AlphaAnimation(0.2f, 1.0f);
animation1.setDuration(1000);
animation1.setStartOffset(5000);
animation1.setFillAfter(true);
iv.startAnimation(animation1);

(Excel) Conditional Formatting based on Adjacent Cell Value

I don't know if maybe it's a difference in Excel version but this question is 6 years old and the accepted answer didn't help me so this is what I figured out:

Under Conditional Formatting > Manage Rules:

  1. Make a new rule with "Use a formula to determine which cells to format"
  2. Make your rule, but put a dollar sign only in front of the letter: $A2<$B2
  3. Under "Applies to", Manually select the second column (It would not work for me if I changed the value in the box, it just kept snapping back to what was already there), so it looks like $B$2:$B$100 (assuming you have 100 rows)

This worked for me in Excel 2016.

MySQL joins and COUNT(*) from another table

Maybe I am off the mark here and not understanding the OP but why are you joining tables?

If you have a table with members and this table has a column named "group_id", you can just run a query on the members table to get a count of the members grouped by the group_id.

SELECT group_id, COUNT(*) as membercount 
FROM members 
GROUP BY group_id 
HAVING membercount > 4

This should have the least overhead simply because you are avoiding a join but should still give you what you wanted.

If you want the group details and description etc, then add a join from the members table back to the groups table to retrieve the name would give you the quickest result.

Get Date Object In UTC format in Java

A Date doesn't have any time zone. What you're seeing is only the formatting of the date by the Date.toString() method, which uses your local timezone, always, to transform the timezone-agnostic date into a String that you can understand.

If you want to display the timezone-agnostic date as a string using the UTC timezone, then use a SimpleDateFormat with the UTC timezone (as you're already doing in your question).

In other terms, the timezone is not a property of the date. It's a property of the format used to transform the date into a string.

how to remove new lines and returns from php string?

Something a bit more functional (easy to use anywhere):

function replace_carriage_return($replace, $string)
{
    return str_replace(array("\n\r", "\n", "\r"), $replace, $string);
}

Using PHP_EOL as the search replacement parameter is also a good idea! Kudos.

Centering FontAwesome icons vertically and horizontally

I just lowered the height to 28px on the .login-icon [class*='icon-'] Here's the fiddle: http://jsfiddle.net/mZHg7/

.login-icon [class*='icon-']{
    height: 28px;
    width: 50px;
    display: inline-block;
    text-align: center;
    vertical-align: baseline;
}

Bootstrap: change background color

Not Bootstrap specific really... You can use inline styles or define a custom class to specify the desired "background-color".

On the other hand, Bootstrap does have a few built in background colors that have semantic meaning like "bg-success" (green) and "bg-danger" (red).

Fully change package name including company domain

I have not changed any package name. The following two steps worked for me. After doing the following, the application was installed as a NEW one , eventhough there was two applications with the same package name.

1) In the build.gradle

applicationId "mynew.mynewpackage.com"

2) In the AndroidManifest.xml android:authorities="mynew.mynewpackage.com.fileprovider"

java.lang.RuntimeException: Unable to instantiate activity ComponentInfo

This error can also be the ultimate sign of a dumb mistake (like when I - I mean, cough, like when a friend of mine who showed me their code once) where they try to execute code outside of a method like trying to do this:

SQLiteDatabase db = openOrCreateDatabase("DB", MODE_PRIVATE, null); //trying to perform function where you can only set up objects, primitives, etc

@Override
public void onCreate(Bundle savedInstanceState) {
....
}

rather than this:

SQLiteDatabase db;

@Override
public void onCreate(Bundle savedInstanceState) {
db = openOrCreateDatabase("DB", MODE_PRIVATE, null);
....
}

Table border left and bottom

Give a class .border-lb and give this CSS

.border-lb {border: 1px solid #ccc; border-width: 0 0 1px 1px;}

And the HTML

<table width="770">
  <tr>
    <td class="border-lb">picture (border only to the left and bottom ) </td>
    <td>text</td>
  </tr>
  <tr>
    <td>text</td>
    <td class="border-lb">picture (border only to the left and bottom) </td>
  </tr>
</table>

Screenshot

Fiddle: http://jsfiddle.net/FXMVL/

How to format a URL to get a file from Amazon S3?

Documentation here, and I'll use the Frankfurt region as an example.

There are 2 different URL styles:

But this url does not work:

The message is explicit: The bucket you are attempting to access must be addressed using the specified endpoint. Please send all future requests to this endpoint.

I may be talking about another problem because I'm not getting NoSuchKey error but I suspect the error message has been made clearer over time.

@class vs. #import

When I develop, I have only three things in mind that never cause me any problems.

  1. Import super classes
  2. Import parent classes (when you have children and parents)
  3. Import classes outside your project (like in frameworks and libraries)

For all other classes (subclasses and child classes in my project self), I declare them via forward-class.

Convert Select Columns in Pandas Dataframe to Numpy Array

the easy way is the "values" property df.iloc[:,1:].values

a=df.iloc[:,1:]
b=df.iloc[:,1:].values

print(type(df))
print(type(a))
print(type(b))

so, you can get type

<class 'pandas.core.frame.DataFrame'>
<class 'pandas.core.frame.DataFrame'>
<class 'numpy.ndarray'>

SSIS Excel Connection Manager failed to Connect to the Source

As discussed in the below:

Solution: Go to https://marketplace.visualstudio.com/items?itemName=ProBITools.MicrosoftAnalysisServicesModelingProjects and install the latest version, it has a fix in there to resolve this issue.

Reference: https://developercommunity.visualstudio.com/content/problem/745991/could-not-load-file-or-assembly-microsoftdatawareh.html

A fix for this issue has been internally implemented and is being prepared for release. We’ll update you once it becomes available for download. For now, please install latest SSAS from https://marketplace.visualstudio.com/items?itemName=ProBITools.MicrosoftAnalysisServicesModelingProjects to work around the issue. Sorry for any inconvenience.

Export data from Chrome developer tool

I had same issue for which I came here. With some trials, I figured out for copying multiple pages of chrome data as in the question I zoomed out till I got all the data in one page, that is, without scroll, with very small font size. Now copy and paste that in excel which copies all the records and in normal font. This is good for few pages of data I think.

Is JavaScript a pass-by-reference or pass-by-value language?

JavaScript is always pass-by-value; everything is of value type.

Objects are values, and member functions of objects are values themselves (remember that functions are first-class objects in JavaScript). Also, regarding the concept that everything in JavaScript is an object; this is wrong. Strings, symbols, numbers, booleans, nulls, and undefineds are primitives.

On occasion they can leverage some member functions and properties inherited from their base prototypes, but this is only for convenience. It does not mean that they are objects themselves. Try the following for reference:

x = "test";
alert(x.foo);
x.foo = 12;
alert(x.foo);

In both alerts you will find the value to be undefined.

ASP.NET Core form POST results in a HTTP 415 Unsupported Media Type response

For forms, use the [FromForm] attribute instead of the [FromBody] attribute.

The below controller works with ASP.NET Core 1.1:

public class MyController : Controller
{
    [HttpPost]
    public async Task<IActionResult> Submit([FromForm] MyModel model)
    {
        //...
    }
}

Note: [FromXxx] is required if your controller is annotated with [ApiController]. For normal view controllers it can be omitted.

Convert a string representation of a hex dump to a byte array using Java?

Late to the party, but I have amalgamated the answer above by DaveL into a class with the reverse action - just in case it helps.

public final class HexString {
    private static final char[] digits = "0123456789ABCDEF".toCharArray();

    private HexString() {}

    public static final String fromBytes(final byte[] bytes) {
        final StringBuilder buf = new StringBuilder();
        for (int i = 0; i < bytes.length; i++) {
            buf.append(HexString.digits[(bytes[i] >> 4) & 0x0f]);
            buf.append(HexString.digits[bytes[i] & 0x0f]);
        }
        return buf.toString();
    }

    public static final byte[] toByteArray(final String hexString) {
        if ((hexString.length() % 2) != 0) {
            throw new IllegalArgumentException("Input string must contain an even number of characters");
        }
        final int len = hexString.length();
        final byte[] data = new byte[len / 2];
        for (int i = 0; i < len; i += 2) {
            data[i / 2] = (byte) ((Character.digit(hexString.charAt(i), 16) << 4)
                    + Character.digit(hexString.charAt(i + 1), 16));
        }
        return data;
    }
}

And JUnit test class:

public class TestHexString {

    @Test
    public void test() {
        String[] tests = {"0FA1056D73", "", "00", "0123456789ABCDEF", "FFFFFFFF"};

        for (int i = 0; i < tests.length; i++) {
            String in = tests[i];
            byte[] bytes = HexString.toByteArray(in);
            String out = HexString.fromBytes(bytes);
            System.out.println(in); //DEBUG
            System.out.println(out); //DEBUG
            Assert.assertEquals(in, out);

        }

    }

}

How to respond with HTTP 400 error in a Spring MVC @ResponseBody method returning String?

Easiest way is to throw a ResponseStatusException

    @RequestMapping(value = "/matches/{matchId}", produces = "application/json")
    @ResponseBody
    public String match(@PathVariable String matchId, @RequestBody String body) {
        String json = matchService.getMatchJson(matchId);
        if (json == null) {
            throw new ResponseStatusException(HttpStatus.NOT_FOUND);
        }
        return json;
    }

Math.random() explanation

If you want to generate a number from 0 to 100, then your code would look like this:

(int)(Math.random() * 101);

To generate a number from 10 to 20 :

(int)(Math.random() * 11 + 10);

In the general case:

(int)(Math.random() * ((upperbound - lowerbound) + 1) + lowerbound);

(where lowerbound is inclusive and upperbound exclusive).

The inclusion or exclusion of upperbound depends on your choice. Let's say range = (upperbound - lowerbound) + 1 then upperbound is inclusive, but if range = (upperbound - lowerbound) then upperbound is exclusive.

Example: If I want an integer between 3-5, then if range is (5-3)+1 then 5 is inclusive, but if range is just (5-3) then 5 is exclusive.

Flask at first run: Do not use the development server in a production environment

If for some people (like me earlier) the above answers don't work, I think the following answer would work (for Mac users I think) Enter the following commands to do flask run

$ export FLASK_APP = hello.py
$ export FLASK_ENV = development
$ flask run

Alternatively you can do the following (I haven't tried this but one resource online talks about it)

$ export FLASK_APP = hello.py
$ python -m flask run

source: For more

how to install apk application from my pc to my mobile android

To install an APK on your mobile, you can either:

  1. Use ADB from the Android SDK, and do the following command: adb install filename.apk. Note, you'll need to enable USB debugging for this to work.
  2. Transfer the file to your device, then open it with a file manager, such as Linda File Manager.

Note, that you'll have to enable installing packages from Unknown Sources in your Applications settings.

As for getting USB to work, I suggest consulting the Android StackExchange for advice.

In Python, how do I create a string of n characters in one line of code?

The first ten lowercase letters are string.lowercase[:10] (if you have imported the standard library module string previously, of course;-).

Other ways to "make a string of 10 characters": 'x'*10 (all the ten characters will be lowercase xs;-), ''.join(chr(ord('a')+i) for i in xrange(10)) (the first ten lowercase letters again), etc, etc;-).

Using Docker-Compose, how to execute multiple commands

You can use entrypoint here. entrypoint in docker is executed before the command while command is the default command that should be run when container starts. So most of the applications generally carry setup procedure in entrypoint file and in the last they allow command to run.

make a shell script file may be as docker-entrypoint.sh (name does not matter) with following contents in it.

#!/bin/bash
python manage.py migrate
exec "$@"

in docker-compose.yml file use it with entrypoint: /docker-entrypoint.sh and register command as command: python manage.py runserver 0.0.0.0:8000 P.S : do not forget to copy docker-entrypoint.sh along with your code.

How to send a POST request from node.js Express?

As described here for a post request :

var http = require('http');

var options = {
  host: 'www.host.com',
  path: '/',
  port: '80',
  method: 'POST'
};

callback = function(response) {
  var str = ''
  response.on('data', function (chunk) {
    str += chunk;
  });

  response.on('end', function () {
    console.log(str);
  });
}

var req = http.request(options, callback);
//This is the data we are posting, it needs to be a string or a buffer
req.write("data");
req.end();

for each loop in groovy

you can use below groovy code for maps with foreachloop

def map=[key1:'value1',key2:'value2']

for(item in map)
{
log.info item.value // this will print value1 value2
log.info item // this will print key1=value1 key2=value2
}

Android toolbar center title and custom font

we don't have direct access to the ToolBar title TextView so we use reflection to access it.

  private TextView getActionBarTextView() {
    TextView titleTextView = null;

    try {
        Field f = mToolBar.getClass().getDeclaredField("mTitleTextView");
        f.setAccessible(true);
        titleTextView = (TextView) f.get(mToolBar);
    } catch (NoSuchFieldException e) {
    } catch (IllegalAccessException e) {
    }
    return titleTextView;
}

Best Practice to Organize Javascript Library & CSS Folder Structure

 root/
   assets/
      lib/-------------------------libraries--------------------
          bootstrap/--------------Libraries can have js/css/images------------
              css/
              js/
              images/  
          jquery/
              js/
          font-awesome/
              css/
              images/
     common/--------------------common section will have application level resources             
          css/
          js/
          img/

 index.html

This is how I organized my application's static resources.

Creating an array from a text file in Bash

This answer says to use

mapfile -t myArray < file.txt

I made a shim for mapfile if you want to use mapfile on bash < 4.x for whatever reason. It uses the existing mapfile command if you are on bash >= 4.x

Currently, only options -d and -t work. But that should be enough for that command above. I've only tested on macOS. On macOS Sierra 10.12.6, the system bash is 3.2.57(1)-release. So the shim can come in handy. You can also just update your bash with homebrew, build bash yourself, etc.

It uses this technique to set variables up one call stack.

initializing a boolean array in java

The main difference is that Boolean is an object and boolean is an primitive.

  • Object default value is null;
  • boolean default value is false;

Append text with .bat

You need to use ECHO. Also, put the quotes around the entire file path if it contains spaces.

One other note, use > to overwrite a file if it exists or create if it does not exist. Use >> to append to an existing file or create if it does not exist.

Overwrite the file with a blank line:

ECHO.>"C:\My folder\Myfile.log"

Append a blank line to a file:

ECHO.>>"C:\My folder\Myfile.log"

Append text to a file:

ECHO Some text>>"C:\My folder\Myfile.log"

Append a variable to a file:

ECHO %MY_VARIABLE%>>"C:\My folder\Myfile.log"

How to filter data in dataview

Eg:

Datatable newTable =  new DataTable();

            foreach(string s1 in list)
            {
                if (s1 != string.Empty) {
                    dvProducts.RowFilter = "(CODE like '" + serachText + "*') AND (CODE <> '" + s1 + "')";
                    foreach(DataRow dr in dvProducts.ToTable().Rows)
                    {
                       newTable.ImportRow(dr);
                    }
                }
            }
ListView1.DataSource = newTable;
ListView1.DataBind();

Split page vertically using CSS

Alternatively, you can also use a special function known as the linear-gradient() function to split browser screen into two equal halves. Check out the following code snippet:

body
{
  background-image:linear-gradient(90deg, lightblue 50%, skyblue 50%);
}

Here, linear-gradient() function accepts three arguments

  1. 90deg for vertical division of screen.( Similarly, you can use 180deg for horizontal division of screen)
  2. lightblue color is used to represent the left half of the screen.
  3. skyblue color has been used to represent the right half of the split screen. Here, 50% has been used for equal division of the browser screen. You can use any other value if you don't want an equal division of the screen. Hope this helps. :) Happy Coding!

phpMyAdmin + CentOS 6.0 - Forbidden

None of the configuration above worked for me on my CentOS 7 server. After hours of searching, that's what worked for me:

Edit file phpMyAdmin.conf

sudo nano /etc/httpd/conf.d/phpMyAdmin.conf

And replace this at the top:

<Directory /usr/share/phpMyAdmin/>
   AddDefaultCharset UTF-8

   <IfModule mod_authz_core.c>
     # Apache 2.4
     <RequireAny>
       #Require ip 127.0.0.1
       #Require ip ::1
       Require all granted
     </RequireAny>
   </IfModule>
   <IfModule !mod_authz_core.c>
     # Apache 2.2
     Order Deny,Allow
     Deny from All
     Allow from 127.0.0.1
     Allow from ::1
   </IfModule>
</Directory>

Why is Tkinter Entry's get function returning nothing?

you need to put a textvariable in it, so you can use set() and get() method :

var=StringVar()
x= Entry (root,textvariable=var)

Check whether variable is number or string in JavaScript

function IsNumeric(num) {
    return ((num >=0 || num < 0)&& (parseInt(num)==num) );
}

How to Check whether Session is Expired or not in asp.net

Use Session.Contents.Count:

if (Session.Contents.Count == 0)
{
    Response.Write(".NET session has Expired");
    Response.End();
}
else
{
    InitializeControls();
}

The code above assumes that you have at least one session variable created when the user first visits your site. If you don't have one then you are most likely not using a database for your app. For your case you can just manually assign a session variable using the example below.

protected void Page_Load(object sender, EventArgs e)
{
    Session["user_id"] = 1;
}

Best of luck to you!

Pointer to 2D arrays in C

int *pointer[280]; //Creates 280 pointers of type int.

In 32 bit os, 4 bytes for each pointer. so 4 * 280 = 1120 bytes.

int (*pointer)[100][280]; // Creates only one pointer which is used to point an array of [100][280] ints.

Here only 4 bytes.

Coming to your question, int (*pointer)[280]; and int (*pointer)[100][280]; are different though it points to same 2D array of [100][280].

Because if int (*pointer)[280]; is incremented, then it will points to next 1D array, but where as int (*pointer)[100][280]; crosses the whole 2D array and points to next byte. Accessing that byte may cause problem if that memory doen't belongs to your process.

How do I update Node.js?

Any OS (including Windows, Mac & Linux)

Updated February 2021


Just go to the official Node.js site (nodejs.org), download and execute the installer program.

It will take care of everything and with a few clicks of 'Next' you'll get the latest Node.js version running on your machine. Since 2020 it's the recommended way to update NodeJS. It's the easiest and least frustrating solution.

Download NodeJS for Windows buttons

Download NodeJS for Win/Mac/Source Code buttons


Pro tips

  • NodeJS installation includes NPM (Node package manager).

  • To check your NPM version use npm version or node --version.

  • If you prefer CLI, to update NPM use npm install -g npm and then npm install -g node.

  • For more details, see the docs for install command.

  • Keep an eye on NodeJS blog - Vulnerabilities so you don't miss important security releases. Keep your NodeJS up-to-date.

  • Operating systems supported by Node.js: Windows, Linux, MacOS, SunOS, IBM AIX.

  • For Docker users, here's the official Node.js image.

  • Troubleshooting for Windows:

    If anyone gets file error 2502/2503 like myself during install, run the .msi via Administrator command prompt with command msiexec /package [node msi]


If my answer is helpful, don't forget to upvote it
(here is the original answer by Anmol Saraf, upvote it too)

How to convert a HTMLElement to a string

You can get the 'outer-html' by cloning the element, adding it to an empty,'offstage' container, and reading the container's innerHTML.

This example takes an optional second parameter.

Call document.getHTML(element, true) to include the element's descendents.

document.getHTML= function(who, deep){
    if(!who || !who.tagName) return '';
    var txt, ax, el= document.createElement("div");
    el.appendChild(who.cloneNode(false));
    txt= el.innerHTML;
    if(deep){
        ax= txt.indexOf('>')+1;
        txt= txt.substring(0, ax)+who.innerHTML+ txt.substring(ax);
    }
    el= null;
    return txt;
}

Dynamic WHERE clause in LINQ

This project on CodePlex have what you want.

System.Linq.Dynamic - http://dynamiclinq.codeplex.com/

Project Description

Extends System.Linq.Dynamic to support Execution of Lambda expressions defined in a string against Entity Framework or any provider that supports IQueryable.

As it is an extension of the source code you can find on Scott Guthrie's Blog it will allow you to do things like this:

enter image description here

And things like this:

enter image description here

How to get controls in WPF to fill available space?

Each control deriving from Panel implements distinct layout logic performed in Measure() and Arrange():

  • Measure() determines the size of the panel and each of its children
  • Arrange() determines the rectangle where each control renders

The last child of the DockPanel fills the remaining space. You can disable this behavior by setting the LastChild property to false.

The StackPanel asks each child for its desired size and then stacks them. The stack panel calls Measure() on each child, with an available size of Infinity and then uses the child's desired size.

A Grid occupies all available space, however, it will set each child to their desired size and then center them in the cell.

You can implement your own layout logic by deriving from Panel and then overriding MeasureOverride() and ArrangeOverride().

See this article for a simple example.

RSA Public Key format

Starting from the decoded base64 data of an OpenSSL rsa-ssh Key, i've been able to guess a format:

  • 00 00 00 07: four byte length prefix (7 bytes)
  • 73 73 68 2d 72 73 61: "ssh-rsa"
  • 00 00 00 01: four byte length prefix (1 byte)
  • 25: RSA Exponent (e): 25
  • 00 00 01 00: four byte length prefix (256 bytes)
  • RSA Modulus (n):

    7f 9c 09 8e 8d 39 9e cc d5 03 29 8b c4 78 84 5f
    d9 89 f0 33 df ee 50 6d 5d d0 16 2c 73 cf ed 46 
    dc 7e 44 68 bb 37 69 54 6e 9e f6 f0 c5 c6 c1 d9 
    cb f6 87 78 70 8b 73 93 2f f3 55 d2 d9 13 67 32 
    70 e6 b5 f3 10 4a f5 c3 96 99 c2 92 d0 0f 05 60 
    1c 44 41 62 7f ab d6 15 52 06 5b 14 a7 d8 19 a1 
    90 c6 c1 11 f8 0d 30 fd f5 fc 00 bb a4 ef c9 2d 
    3f 7d 4a eb d2 dc 42 0c 48 b2 5e eb 37 3c 6c a0 
    e4 0a 27 f0 88 c4 e1 8c 33 17 33 61 38 84 a0 bb 
    d0 85 aa 45 40 cb 37 14 bf 7a 76 27 4a af f4 1b 
    ad f0 75 59 3e ac df cd fc 48 46 97 7e 06 6f 2d 
    e7 f5 60 1d b1 99 f8 5b 4f d3 97 14 4d c5 5e f8 
    76 50 f0 5f 37 e7 df 13 b8 a2 6b 24 1f ff 65 d1 
    fb c8 f8 37 86 d6 df 40 e2 3e d3 90 2c 65 2b 1f 
    5c b9 5f fa e9 35 93 65 59 6d be 8c 62 31 a9 9b 
    60 5a 0e e5 4f 2d e6 5f 2e 71 f3 7e 92 8f fe 8b
    

The closest validation of my theory i can find it from RFC 4253:

The "ssh-rsa" key format has the following specific encoding:

  string    "ssh-rsa"
  mpint     e
  mpint     n

Here the 'e' and 'n' parameters form the signature key blob.

But it doesn't explain the length prefixes.


Taking the random RSA PUBLIC KEY i found (in the question), and decoding the base64 into hex:

30 82 01 0a 02 82 01 01 00 fb 11 99 ff 07 33 f6 e8 05 a4 fd 3b 36 ca 68 
e9 4d 7b 97 46 21 16 21 69 c7 15 38 a5 39 37 2e 27 f3 f5 1d f3 b0 8b 2e 
11 1c 2d 6b bf 9f 58 87 f1 3a 8d b4 f1 eb 6d fe 38 6c 92 25 68 75 21 2d 
dd 00 46 87 85 c1 8a 9c 96 a2 92 b0 67 dd c7 1d a0 d5 64 00 0b 8b fd 80 
fb 14 c1 b5 67 44 a3 b5 c6 52 e8 ca 0e f0 b6 fd a6 4a ba 47 e3 a4 e8 94 
23 c0 21 2c 07 e3 9a 57 03 fd 46 75 40 f8 74 98 7b 20 95 13 42 9a 90 b0 
9b 04 97 03 d5 4d 9a 1c fe 3e 20 7e 0e 69 78 59 69 ca 5b f5 47 a3 6b a3 
4d 7c 6a ef e7 9f 31 4e 07 d9 f9 f2 dd 27 b7 29 83 ac 14 f1 46 67 54 cd 
41 26 25 16 e4 a1 5a b1 cf b6 22 e6 51 d3 e8 3f a0 95 da 63 0b d6 d9 3e 
97 b0 c8 22 a5 eb 42 12 d4 28 30 02 78 ce 6b a0 cc 74 90 b8 54 58 1f 0f 
fb 4b a3 d4 23 65 34 de 09 45 99 42 ef 11 5f aa 23 1b 15 15 3d 67 83 7a 
63 02 03 01 00 01

From RFC3447 - Public-Key Cryptography Standards (PKCS) #1: RSA Cryptography Specifications Version 2.1:

A.1.1 RSA public key syntax

An RSA public key should be represented with the ASN.1 type RSAPublicKey:

  RSAPublicKey ::= SEQUENCE {
     modulus           INTEGER,  -- n
     publicExponent    INTEGER   -- e
  }

The fields of type RSAPublicKey have the following meanings:

  • modulus is the RSA modulus n.
  • publicExponent is the RSA public exponent e.

Using Microsoft's excellent (and the only real) ASN.1 documentation:

30 82 01 0a       ;SEQUENCE (0x010A bytes: 266 bytes)
|  02 82 01 01    ;INTEGER  (0x0101 bytes: 257 bytes)
|  |  00          ;leading zero because high-bit, but number is positive
|  |  fb 11 99 ff 07 33 f6 e8 05 a4 fd 3b 36 ca 68 
|  |  e9 4d 7b 97 46 21 16 21 69 c7 15 38 a5 39 37 2e 27 f3 f5 1d f3 b0 8b 2e 
|  |  11 1c 2d 6b bf 9f 58 87 f1 3a 8d b4 f1 eb 6d fe 38 6c 92 25 68 75 21 2d 
|  |  dd 00 46 87 85 c1 8a 9c 96 a2 92 b0 67 dd c7 1d a0 d5 64 00 0b 8b fd 80 
|  |  fb 14 c1 b5 67 44 a3 b5 c6 52 e8 ca 0e f0 b6 fd a6 4a ba 47 e3 a4 e8 94 
|  |  23 c0 21 2c 07 e3 9a 57 03 fd 46 75 40 f8 74 98 7b 20 95 13 42 9a 90 b0 
|  |  9b 04 97 03 d5 4d 9a 1c fe 3e 20 7e 0e 69 78 59 69 ca 5b f5 47 a3 6b a3 
|  |  4d 7c 6a ef e7 9f 31 4e 07 d9 f9 f2 dd 27 b7 29 83 ac 14 f1 46 67 54 cd 
|  |  41 26 25 16 e4 a1 5a b1 cf b6 22 e6 51 d3 e8 3f a0 95 da 63 0b d6 d9 3e 
|  |  97 b0 c8 22 a5 eb 42 12 d4 28 30 02 78 ce 6b a0 cc 74 90 b8 54 58 1f 0f 
|  |  fb 4b a3 d4 23 65 34 de 09 45 99 42 ef 11 5f aa 23 1b 15 15 3d 67 83 7a 
|  |  63 
|  02 03          ;INTEGER (3 bytes)
|     01 00 01

giving the public key modulus and exponent:

  • modulus = 0xfb1199ff0733f6e805a4fd3b36ca68...837a63
  • exponent = 65,537

Update: My expanded form of this answer in another question

Check if a PHP cookie exists and if not set its value

Cookies are only sent at the time of the request, and therefore cannot be retrieved as soon as it is assigned (only available after reloading).

Once the cookies have been set, they can be accessed on the next page load with the $_COOKIE or $HTTP_COOKIE_VARS arrays.

If output exists prior to calling this function, setcookie() will fail and return FALSE. If setcookie() successfully runs, it will return TRUE. This does not indicate whether the user accepted the cookie.

Cookies will not become visible until the next loading of a page that the cookie should be visible for. To test if a cookie was successfully set, check for the cookie on a next loading page before the cookie expires. Expire time is set via the expire parameter. A nice way to debug the existence of cookies is by simply calling print_r($_COOKIE);.

Source

Alert after page load

Another option is to use the defer attribute on the script, but it's only appropriate for external scripts with a src attribute:

<script src = "exampleJsFile.js" defer> </script>

Why is there no Constant feature in Java?

What does const mean
First, realize that the semantics of a "const" keyword means different things to different people:

  • read-only reference - Java final semantics - reference variable itself cannot be reassigned to point to another instance (memory location), but the instance itself is modifiable
  • readable-only reference - C const pointer/reference semantics - means this reference cannot be used to modify the instance (e.g. cannot assign to instance variables, cannot invoke mutable methods) - affects the reference variable only, so a non-const reference pointing to the same instance could modify the instance
  • immutable object - means the instance itself cannot be modified - applies to instance, so any non-const reference would not be allowed or could not be used to modify the instance
  • some combination of the the above?
  • others?

Why or Why Not const
Second, if you really want to dig into some of the "pro" vs "con" arguments, see the discussion under this request for enhancement (RFE) "bug". This RFE requests a "readable-only reference"-type "const" feature. Opened in 1999 and then closed/rejected by Sun in 2005, the "const" topic was vigorously debated:

http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4211070

While there are a lot of good arguments on both sides, some of the oft-cited (but not necessarily compelling or clear-cut) reasons against const include:

  • may have confusing semantics that may be misused and/or abused (see the What does const mean above)
  • may duplicate capability otherwise available (e.g. designing an immutable class, using an immutable interface)
  • may be feature creep, leading to a need for other semantic changes such as support for passing objects by value

Before anyone tries to debate me about whether these are good or bad reasons, note that these are not my reasons. They are simply the "gist" of some of the reasons I gleaned from skimming the RFE discussion. I don't necessarily agree with them myself - I'm simply trying to cite why some people (not me) may feel a const keyword may not be a good idea. Personally, I'd love more "const" semantics to be introduced to the language in an unambiguous manner.

Curl: Fix CURL (51) SSL error: no alternative certificate subject name matches

I had the same issue. In my case I was using digitalocean and nginx.
I have first setup a domain example.app and a subdomain dev.exemple.app in digitalocean. Second,I purchased two ssl certificat from godaddy. And finaly, I configured two domain in nginx to use those two ssl certificat with the following snipet

My example.app domain config

    server {
    listen 7000 default_server;
    listen [::]:7000 default_server;

     listen 443 ssl default_server;
     listen [::]:443 ssl default_server;

    root /srv/nodejs/echantillonnage1;

    # Add index.php to the list if you are using PHP
    index index.html index.htm index.nginx-debian.html;

    server_name echantillonnage.app;
    ssl_certificate /srv/nodejs/certificatSsl/widcardcertificate/echantillonnage.app.chained.crt;
    ssl_certificate_key /srv/nodejs/certificatSsl/widcardcertificate/echantillonnage.app.key;

    location / {
            # First attempt to serve request as file, then
            # as directory, then fall back to displaying a 404.
            proxy_pass http://127.0.0.1:8090;
            proxy_http_version 1.1;
            proxy_set_header Upgrade $http_upgrade;
            proxy_set_header Connection 'upgrade';
            proxy_set_header Host $host;
            proxy_cache_bypass $http_upgrade;
    #try_files $uri $uri/ =404;
    }
 }

My dev.example.app

   server {
    listen 7000 default_server;
    listen [::]:7000 default_server;

     listen 444 ssl default_server;
     listen [::]:444 ssl default_server;

    root /srv/nodejs/echantillonnage1;

    # Add index.php to the list if you are using PHP
    index index.html index.htm index.nginx-debian.html;

    server_name dev.echantillonnage.app;
    ssl_certificate /srv/nodejs/certificatSsl/dev/dev.echantillonnage.app.chained.crt;
    ssl_certificate_key /srv/nodejs/certificatSsl/dev/dev.echantillonnage.app.key;

    location / {
            # First attempt to serve request as file, then
            # as directory, then fall back to displaying a 404.
            proxy_pass http://127.0.0.1:8091;
            proxy_http_version 1.1;
            proxy_set_header Upgrade $http_upgrade;
            proxy_set_header Connection 'upgrade';
            proxy_set_header Host $host;
            proxy_cache_bypass $http_upgrade;
    #try_files $uri $uri/ =404;
    }
 }

When I was launching https://dev.echantillonnage.app , I was getting

    Fix CURL (51) SSL error: no alternative certificate subject name matches

My mistake was the two lines bellow

    listen 444 ssl default_server;
     listen [::]:444 ssl default_server;

I had to change this to:

     listen 443 ssl;
     listen [::]:443 ssl;

Simple Android grid example using RecyclerView with GridLayoutManager (like the old GridView)

Short answer

For those who are already familiar with setting up a RecyclerView to make a list, the good news is that making a grid is largely the same. You just use a GridLayoutManager instead of a LinearLayoutManager when you set the RecyclerView up.

recyclerView.setLayoutManager(new GridLayoutManager(this, numberOfColumns));

If you need more help than that, then check out the following example.

Full example

The following is a minimal example that will look like the image below.

enter image description here

Start with an empty activity. You will perform the following tasks to add the RecyclerView grid. All you need to do is copy and paste the code in each section. Later you can customize it to fit your needs.

  • Add dependencies to gradle
  • Add the xml layout files for the activity and for the grid cell
  • Make the RecyclerView adapter
  • Initialize the RecyclerView in your activity

Update Gradle dependencies

Make sure the following dependencies are in your app gradle.build file:

compile 'com.android.support:appcompat-v7:27.1.1'
compile 'com.android.support:recyclerview-v7:27.1.1'

You can update the version numbers to whatever is the most current.

Create activity layout

Add the RecyclerView to your xml layout.

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/rvNumbers"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

</RelativeLayout>

Create grid cell layout

Each cell in our RecyclerView grid is only going to have a single TextView. Create a new layout resource file.

recyclerview_item.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal"
    android:padding="5dp"
    android:layout_width="50dp"
    android:layout_height="50dp">

        <TextView
            android:id="@+id/info_text"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:gravity="center"
            android:background="@color/colorAccent"/>

</LinearLayout>

Create the adapter

The RecyclerView needs an adapter to populate the views in each cell with your data. Create a new java file.

MyRecyclerViewAdapter.java

public class MyRecyclerViewAdapter extends RecyclerView.Adapter<MyRecyclerViewAdapter.ViewHolder> {

    private String[] mData;
    private LayoutInflater mInflater;
    private ItemClickListener mClickListener;

    // data is passed into the constructor
    MyRecyclerViewAdapter(Context context, String[] data) {
        this.mInflater = LayoutInflater.from(context);
        this.mData = data;
    }

    // inflates the cell layout from xml when needed
    @Override
    @NonNull 
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = mInflater.inflate(R.layout.recyclerview_item, parent, false);
        return new ViewHolder(view);
    }

    // binds the data to the TextView in each cell
    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
        holder.myTextView.setText(mData[position]);
    }

    // total number of cells
    @Override
    public int getItemCount() {
        return mData.length;
    }


    // stores and recycles views as they are scrolled off screen
    public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
        TextView myTextView;

        ViewHolder(View itemView) {
            super(itemView);
            myTextView = itemView.findViewById(R.id.info_text);
            itemView.setOnClickListener(this);
        }

        @Override
        public void onClick(View view) {
            if (mClickListener != null) mClickListener.onItemClick(view, getAdapterPosition());
        }
    }

    // convenience method for getting data at click position
    String getItem(int id) {
        return mData[id];
    }

    // allows clicks events to be caught
    void setClickListener(ItemClickListener itemClickListener) {
        this.mClickListener = itemClickListener;
    }

    // parent activity will implement this method to respond to click events
    public interface ItemClickListener {
        void onItemClick(View view, int position);
    }
}

Notes

  • Although not strictly necessary, I included the functionality for listening for click events on the cells. This was available in the old GridView and is a common need. You can remove this code if you don't need it.

Initialize RecyclerView in Activity

Add the following code to your main activity.

MainActivity.java

public class MainActivity extends AppCompatActivity implements MyRecyclerViewAdapter.ItemClickListener {

    MyRecyclerViewAdapter adapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // data to populate the RecyclerView with
        String[] data = {"1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13", "14", "15", "16", "17", "18", "19", "20", "21", "22", "23", "24", "25", "26", "27", "28", "29", "30", "31", "32", "33", "34", "35", "36", "37", "38", "39", "40", "41", "42", "43", "44", "45", "46", "47", "48"};

        // set up the RecyclerView
        RecyclerView recyclerView = findViewById(R.id.rvNumbers);
        int numberOfColumns = 6;
        recyclerView.setLayoutManager(new GridLayoutManager(this, numberOfColumns));
        adapter = new MyRecyclerViewAdapter(this, data);
        adapter.setClickListener(this);
        recyclerView.setAdapter(adapter);
    }

    @Override
    public void onItemClick(View view, int position) {
        Log.i("TAG", "You clicked number " + adapter.getItem(position) + ", which is at cell position " + position);
    }
}

Notes

  • Notice that the activity implements the ItemClickListener that we defined in our adapter. This allows us to handle cell click events in onItemClick.

Finished

That's it. You should be able to run your project now and get something similar to the image at the top.

Going on

Rounded corners

Auto-fitting columns

Further study

Razor-based view doesn't see referenced assemblies

In my case, the separate project that contained the namespace was a Console Application. Changing it to a Class Library fixed the problem.

What is the purpose of shuffling and sorting phase in the reducer in Map Reduce Programming?

I've always assumed this was necessary as the output from the mapper is the input for the reducer, so it was sorted based on the keyspace and then split into buckets for each reducer input. You want to ensure all the same values of a Key end up in the same bucket going to the reducer so they are reduced together. There is no point sending K1,V2 and K1,V4 to different reducers as they need to be together in order to be reduced.

Tried explaining it as simply as possible

Split string with PowerShell and do something with each token

To complement Justus Thane's helpful answer:

  • As Joey notes in a comment, PowerShell has a powerful, regex-based -split operator.

    • In its unary form (-split '...'), -split behaves like awk's default field splitting, which means that:
      • Leading and trailing whitespace is ignored.
      • Any run of whitespace (e.g., multiple adjacent spaces) is treated as a single separator.
  • In PowerShell v4+ an expression-based - and therefore faster - alternative to the ForEach-Object cmdlet became available: the .ForEach() array (collection) method, as described in this blog post (alongside the .Where() method, a more powerful, expression-based alternative to Where-Object).

Here's a solution based on these features:

PS> (-split '   One      for the money   ').ForEach({ "token: [$_]" })
token: [One]
token: [for]
token: [the]
token: [money]

Note that the leading and trailing whitespace was ignored, and that the multiple spaces between One and for were treated as a single separator.

jquery remove "selected" attribute of option?

Another alternative:

$('option:selected', $('#mySelectParent')).removeAttr("selected");

Hope it helps

How to find the php.ini file used by the command line?

You can use get_cfg_var('cfg_file_path') for that:

To check whether the system is using a configuration file, try retrieving the value of the cfg_file_path configuration setting. If this is available, a configuration file is being used.
Unlike phpinfo() it will tell if it didn't find/use a php.ini at all.

var_dump( get_cfg_var('cfg_file_path') );

And you can simply set the location of the php.ini. You're using the command line version, so using the -c parameter you can specifiy the location, e.g.

php -c /home/me/php.ini -f /home/me/test.php

What is the simplest way to get indented XML with line breaks from XmlDocument?

A more simplified approach based on the accepted answer:

static public string Beautify(this XmlDocument doc) {
    StringBuilder sb = new StringBuilder();
    XmlWriterSettings settings = new XmlWriterSettings
    {
        Indent = true
    };

    using (XmlWriter writer = XmlWriter.Create(sb, settings)) {
        doc.Save(writer);
    }

    return sb.ToString(); 
}

Setting the new line is not necessary. Indent characters also has the default two spaces so I preferred not to set it as well.

Test for multiple cases in a switch, like an OR (||)

You need to make two case labels.

Control will fall through from the first label to the second, so they'll both execute the same code.

How do I replace whitespaces with underscore?

OP is using python, but in javascript (something to be careful of since the syntaxes are similar.

// only replaces the first instance of ' ' with '_'
"one two three".replace(' ', '_'); 
=> "one_two three"

// replaces all instances of ' ' with '_'
"one two three".replace(/\s/g, '_');
=> "one_two_three"

How can I dismiss the on screen keyboard?

To dismiss the keyboard (1.7.8+hotfix.2 and above) just call the method below:

FocusScope.of(context).unfocus();

Once the FocusScope.of(context).unfocus() method already check if there is focus before dismiss the keyboard it's not needed to check it. But in case you need it just call another context method: FocusScope.of(context).hasPrimaryFocus

SQL Server SELECT INTO @variable?

You cannot SELECT .. INTO .. a TABLE VARIABLE. The best you can do is create it first, then insert into it. Your 2nd snippet has to be

DECLARE @TempCustomer TABLE
(
   CustomerId uniqueidentifier,
   FirstName nvarchar(100),
   LastName nvarchar(100),
   Email nvarchar(100)
);
INSERT INTO 
    @TempCustomer 
SELECT 
    CustomerId, 
    FirstName, 
    LastName, 
    Email 
FROM 
    Customer
WHERE 
    CustomerId = @CustomerId

Delay/Wait in a test case of Xcode UI testing

Based on @Ted's answer, I've used this extension:

extension XCTestCase {

    // Based on https://stackoverflow.com/a/33855219
    func waitFor<T>(object: T, timeout: TimeInterval = 5, file: String = #file, line: UInt = #line, expectationPredicate: @escaping (T) -> Bool) {
        let predicate = NSPredicate { obj, _ in
            expectationPredicate(obj as! T)
        }
        expectation(for: predicate, evaluatedWith: object, handler: nil)

        waitForExpectations(timeout: timeout) { error in
            if (error != nil) {
                let message = "Failed to fulful expectation block for \(object) after \(timeout) seconds."
                let location = XCTSourceCodeLocation(filePath: file, lineNumber: line)
                let issue = XCTIssue(type: .assertionFailure, compactDescription: message, detailedDescription: nil, sourceCodeContext: .init(location: location), associatedError: nil, attachments: [])
                self.record(issue)
            }
        }
    }

}

You can use it like this

let element = app.staticTexts["Name of your element"]
waitFor(object: element) { $0.exists }

It also allows for waiting for an element to disappear, or any other property to change (by using the appropriate block)

waitFor(object: element) { !$0.exists } // Wait for it to disappear

How to remove gem from Ruby on Rails application?

If you're using Rails 3+, remove the gem from the Gemfile and run bundle install.

If you're using Rails 2, hopefully you've put the declaration in config/environment.rb. If so, removing it from there and running rake gems:install should do the trick.

Maximum number of rows in an MS Access database engine table?

Practical = 'useful in practice' - so the best you're going to get is anecdotal. Everything else is just prototyping and testing results.

I agree with others - determining 'a max quantity of records' is completely dependent on schema - # tables, # fields, # indexes.

Another anecdote for you: I recently hit 1.6GB file size with 2 primary data stores (tables), of 36 and 85 fields respectively, with some subset copies in 3 additional tables.

Who cares if data is unique or not - only material if context says it is. Data is data is data, unless duplication affects handling by the indexer.

The total row counts making up that 1.6GB is 1.72M.

How to use mongoose findOne

Mongoose basically wraps mongodb's api to give you a pseudo relational db api so queries are not going to be exactly like mongodb queries. Mongoose findOne query returns a query object, not a document. You can either use a callback as the solution suggests or as of v4+ findOne returns a thenable so you can use .then or await/async to retrieve the document.

// thenables
Auth.findOne({nick: 'noname'}).then(err, result) {console.log(result)};
Auth.findOne({nick: 'noname'}).then(function (doc) {console.log(doc)});

// To use a full fledge promise you will need to use .exec()
var auth = Auth.findOne({nick: 'noname'}).exec();
auth.then(function (doc) {console.log(doc)});

// async/await
async function auth() {
  const doc = await Auth.findOne({nick: 'noname'}).exec();
  return doc;
}
auth();

See the docs if you would like to use a third party promise library.

Error: " 'dict' object has no attribute 'iteritems' "

In Python2, we had .items() and .iteritems() in dictionaries. dict.items() returned list of tuples in dictionary [(k1,v1),(k2,v2),...]. It copied all tuples in dictionary and created new list. If dictionary is very big, there is very big memory impact.

So they created dict.iteritems() in later versions of Python2. This returned iterator object. Whole dictionary was not copied so there is lesser memory consumption. People using Python2 are taught to use dict.iteritems() instead of .items() for efficiency as explained in following code.

import timeit

d = {i:i*2 for i in xrange(10000000)}  
start = timeit.default_timer()
for key,value in d.items():
    tmp = key + value #do something like print
t1 = timeit.default_timer() - start

start = timeit.default_timer()
for key,value in d.iteritems():
    tmp = key + value
t2 = timeit.default_timer() - start

Output:

Time with d.items(): 9.04773592949
Time with d.iteritems(): 2.17707300186

In Python3, they wanted to make it more efficient, so moved dictionary.iteritems() to dict.items(), and removed .iteritems() as it was no longer needed.

You have used dict.iteritems() in Python3 so it has failed. Try using dict.items() which has the same functionality as dict.iteritems() of Python2. This is a tiny bit migration issue from Python2 to Python3.

Compiler error: memset was not declared in this scope

Whevever you get a problem like this just go to the man page for the function in question and it will tell you what header you are missing, e.g.

$ man memset

MEMSET(3)                BSD Library Functions Manual                MEMSET(3)

NAME
     memset -- fill a byte string with a byte value

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <string.h>

     void *
     memset(void *b, int c, size_t len);

Note that for C++ it's generally preferable to use the proper equivalent C++ headers, <cstring>/<cstdio>/<cstdlib>/etc, rather than C's <string.h>/<stdio.h>/<stdlib.h>/etc.

Remove last item from array

var arr = [1,0,2];
arr.length--; 

// removes the last element // need to check if arr.length > 0

Error message: (provider: Shared Memory Provider, error: 0 - No process is on the other end of the pipe.)

In C# and SQL SERVER, we can fix the error by adding Integrated Security = true to the connection string.

Please find the full connection string:

constr = @"Data Source=<Data-Source-Server-Name>;Initial Catalog=<DB-Name>;Integrated Security=true";

Is there a way to make a DIV unselectable?

Use

onselectstart="return false"

it prevents copying your content.

Executing command line programs from within python

I am not familiar with sox, but instead of making repeated calls to the program as a command line, is it possible to set it up as a service and connect to it for requests? You can take a look at the connection interface such as sqlite for inspiration.

HTTP status code 0 - Error Domain=NSURLErrorDomain?

The Response was Empty. Most of the case the codes will stats with 1xx, 2xx, 3xx, 4xx, 5xx.

List of HTTP status codes

Class name does not name a type in C++

Aren't you missing the #include "B.h" in A.h?

How to edit incorrect commit message in Mercurial?

Well, I used to do this way:

Imagine, you have 500 commits, and your erroneous commit message is in r.498.

hg qimport -r 498:tip
hg qpop -a
joe .hg/patches/498.diff
(change the comment, after the mercurial header)
hg qpush -a
hg qdelete -r qbase:qtip

How to SELECT by MAX(date)?

This should do it:

SELECT report_id, computer_id, date_entered
FROM reports AS a
WHERE date_entered = (
    SELECT MAX(date_entered)
    FROM reports AS b
    WHERE a.report_id = b.report_id
      AND a.computer_id = b.computer_id
)

Python send UDP packet

Manoj answer above is correct, but another option is to use MESSAGE.encode() or encode('utf-8') to convert to bytes. bytes and encode are mostly the same, encode is compatible with python 2. see here for more

full code:

import socket

UDP_IP = "127.0.0.1"
UDP_PORT = 5005
MESSAGE = "Hello, World!"

print("UDP target IP: %s" % UDP_IP)
print("UDP target port: %s" % UDP_PORT)
print("message: %s" % MESSAGE)

sock = socket.socket(socket.AF_INET, # Internet
                     socket.SOCK_DGRAM) # UDP
sock.sendto(MESSAGE.encode(), (UDP_IP, UDP_PORT))

Type definition in object literal in TypeScript

Update 2019-05-15 (Improved Code Pattern as Alternative)

After many years of using const and benefiting from more functional code, I would recommend against using the below in most cases. (When building objects, forcing the type system into a specific type instead of letting it infer types is often an indication that something is wrong).

Instead I would recommend using const variables as much as possible and then compose the object as the final step:

const id = GetId();
const hasStarted = true;
...
const hasFinished = false;
...
return {hasStarted, hasFinished, id};
  • This will properly type everything without any need for explicit typing.
  • There is no need to retype the field names.
  • This leads to the cleanest code from my experience.
  • This allows the compiler to provide more state verification (for example, if you return in multiple locations, the compiler will ensure the same type of object is always returned - which encourages you to declare the whole return value at each position - giving a perfectly clear intention of that value).

Addition 2020-02-26

If you do actually need a type that you can be lazily initialized: Mark it is a nullable union type (null or Type). The type system will prevent you from using it without first ensuring it has a value.

In tsconfig.json, make sure you enable strict null checks:

"strictNullChecks": true

Then use this pattern and allow the type system to protect you from accidental null/undefined access:



const state = {
    instance: null as null | ApiService,
    // OR
    // instance: undefined as undefined | ApiService,

};

const useApi = () => {
    // If I try to use it here, the type system requires a safe way to access it

    // Simple lazy-initialization 
    const api = state?.instance ?? (state.instance = new ApiService());
    api.fun();

    // Also here are some ways to only access it if it has value:

    // The 'right' way: Typescript 3.7 required
    state.instance?.fun();

    // Or the old way: If you are stuck before Typescript 3.7
    state.instance && state.instance.fun();

    // Or the long winded way because the above just feels weird
    if (state.instance) { state.instance.fun(); }

    // Or the I came from C and can't check for nulls like they are booleans way
    if (state.instance != null) { state.instance.fun(); }

    // Or the I came from C and can't check for nulls like they are booleans 
    // AND I was told to always use triple === in javascript even with null checks way
    if (state.instance !== null && state.instance !== undefined) { state.instance.fun(); }
};

class ApiService {
    fun() {
        // Do something useful here
    }
}

Do not do the below in 99% of cases:

Update 2016-02-10 - To Handle TSX (Thanks @Josh)

Use the as operator for TSX.

var obj = {
    property: null as string
};

A longer example:

var call = {
    hasStarted: null as boolean,
    hasFinished: null as boolean,
    id: null as number,
};

Original Answer

Use the cast operator to make this succinct (by casting null to the desired type).

var obj = {
    property: <string> null
};

A longer example:

var call = {
    hasStarted: <boolean> null,
    hasFinished: <boolean> null,
    id: <number> null,
};

This is much better than having two parts (one to declare types, the second to declare defaults):

var callVerbose: {
    hasStarted: boolean;
    hasFinished: boolean;
    id: number;
} = {
    hasStarted: null,
    hasFinished: null,
    id: null,
};

Using number_format method in Laravel

Here's another way of doing it, add in app\Providers\AppServiceProvider.php

use Illuminate\Support\Str;

...

public function boot()
{
    // add Str::currency macro
    Str::macro('currency', function ($price)
    {
        return number_format($price, 2, '.', '\'');
    });
}

Then use Str::currency() in the blade templates or directly in the Expense model.

@foreach ($Expenses as $Expense)
    <tr>
        <td>{{{ $Expense->type }}}</td>
        <td>{{{ $Expense->narration }}}</td>
        <td>{{{ Str::currency($Expense->price) }}}</td>
        <td>{{{ $Expense->quantity }}}</td>
        <td>{{{ Str::currency($Expense->amount) }}}</td>                                                            
    </tr>
@endforeach

Why does flexbox stretch my image rather than retaining aspect ratio?

Adding margin to align images:

Since we wanted the image to be left-aligned, we added:

img {
  margin-right: auto;
}

Similarly for image to be right-aligned, we can add margin-right: auto;. The snippet shows a demo for both types of alignment.

Good Luck...

_x000D_
_x000D_
div {_x000D_
  display:flex; _x000D_
  flex-direction:column;_x000D_
  border: 2px black solid;_x000D_
}_x000D_
_x000D_
h1 {_x000D_
  text-align: center;_x000D_
}_x000D_
hr {_x000D_
  border: 1px black solid;_x000D_
  width: 100%_x000D_
}_x000D_
img.one {_x000D_
  margin-right: auto;_x000D_
}_x000D_
_x000D_
img.two {_x000D_
  margin-left: auto;_x000D_
}
_x000D_
<div>_x000D_
  <h1>Flex Box</h1>_x000D_
  _x000D_
  <hr />_x000D_
  _x000D_
  <img src="https://via.placeholder.com/80x80" class="one" _x000D_
  />_x000D_
  _x000D_
  _x000D_
  <img src="https://via.placeholder.com/80x80" class="two" _x000D_
  />_x000D_
  _x000D_
  <hr />_x000D_
</div>
_x000D_
_x000D_
_x000D_

How can I declare optional function parameters in JavaScript?

Update

With ES6, this is possible in exactly the manner you have described; a detailed description can be found in the documentation.

Old answer

Default parameters in JavaScript can be implemented in mainly two ways:

function myfunc(a, b)
{
    // use this if you specifically want to know if b was passed
    if (b === undefined) {
        // b was not passed
    }
    // use this if you know that a truthy value comparison will be enough
    if (b) {
        // b was passed and has truthy value
    } else {
        // b was not passed or has falsy value
    }
    // use this to set b to a default value (using truthy comparison)
    b = b || "default value";
}

The expression b || "default value" evaluates the value AND existence of b and returns the value of "default value" if b either doesn't exist or is falsy.

Alternative declaration:

function myfunc(a)
{
    var b;

    // use this to determine whether b was passed or not
    if (arguments.length == 1) {
        // b was not passed
    } else {
        b = arguments[1]; // take second argument
    }
}

The special "array" arguments is available inside the function; it contains all the arguments, starting from index 0 to N - 1 (where N is the number of arguments passed).

This is typically used to support an unknown number of optional parameters (of the same type); however, stating the expected arguments is preferred!

Further considerations

Although undefined is not writable since ES5, some browsers are known to not enforce this. There are two alternatives you could use if you're worried about this:

b === void 0;
typeof b === 'undefined'; // also works for undeclared variables

Eclipse HotKey: how to switch between tabs?

Right to left : ctrl+ shift + 9 or ctrl + shift + Page Up or ctrl + Page Up

Left to right : ctrl + shift + 3 or ctrl + shift + Page Down or ctrl + Page Down

Check if a Bash array contains a value

This approach has the advantage of not needing to loop over all the elements (at least not explicitly). But since array_to_string_internal() in array.c still loops over array elements and concatenates them into a string, it's probably not more efficient than the looping solutions proposed, but it's more readable.

if [[ " ${array[@]} " =~ " ${value} " ]]; then
    # whatever you want to do when array contains value
fi

if [[ ! " ${array[@]} " =~ " ${value} " ]]; then
    # whatever you want to do when array doesn't contain value
fi

Note that in cases where the value you are searching for is one of the words in an array element with spaces, it will give false positives. For example

array=("Jack Brown")
value="Jack"

The regex will see "Jack" as being in the array even though it isn't. So you'll have to change IFS and the separator characters on your regex if you want still to use this solution, like this

IFS=$'\t'
array=("Jack Brown\tJack Smith")
unset IFS
value="Jack"

if [[ "\t${array[@]}\t" =~ "\t${value}\t" ]]; then
    echo "true"
else
    echo "false"
fi

This will print "false".

Obviously this can also be used as a test statement, allowing it to be expressed as a one-liner

[[ " ${array[@]} " =~ " ${value} " ]] && echo "true" || echo "false"

Scroll Automatically to the Bottom of the Page

So many answers trying to calculate the height of the document. But it wasn't calculating correctly for me. However, both of these worked:

jquery

    $('html,body').animate({scrollTop: 9999});

or just js

    window.scrollTo(0,9999);

How can I display a messagebox in ASP.NET?

The best solution is a minimal use of java directly in the visualstudio GUI

here it is: On a button go to the "OnClientClick" property (its not into events*) overthere type:

return confirm('are you sure?')

it will put a dialog with cancel ok buttons transparent over current page if cancel is pressed no postback will ocure. However if you want only ok button type:

alert ('i told you so')

The events like onclick work server side they execute your code, while OnClientClick runs in the browser side. the come most close to a basic dialog

PHP Call to undefined function

Your function is probably in a different namespace than the one you're calling it from.

http://php.net/manual/en/language.namespaces.basics.php

Git status ignore line endings / identical files / windows & linux environment / dropbox / mled

I created a script to ignore differences in line endings:

It will display the files which are not added to the commit list and were modified (after ignoring differences in line endings). You can add the argument "add" to add those files to your commit.

#!/usr/bin/perl

# Usage: ./gitdiff.pl [add]
#    add : add modified files to git

use warnings;
use strict;

my ($auto_add) = @ARGV;
if(!defined $auto_add) {
    $auto_add = "";
}

my @mods = `git status --porcelain 2>/dev/null | grep '^ M ' | cut -c4-`;
chomp(@mods);
for my $mod (@mods) {
    my $diff = `git diff -b $mod 2>/dev/null`;
    if($diff) {
        print $mod."\n";
        if($auto_add eq "add") {
            `git add $mod 2>/dev/null`;
        }
    }
}

Source code: https://github.com/lepe/scripts/blob/master/gitdiff.pl

Updates:

  • fix by evandro777 : When the file has space in filename or directory

How to Alter a table for Identity Specification is identity SQL Server

You cannot "convert" an existing column into an IDENTITY column - you will have to create a new column as INT IDENTITY:

ALTER TABLE ProductInProduct 
ADD NewId INT IDENTITY (1, 1);

Update:

OK, so there is a way of converting an existing column to IDENTITY. If you absolutely need this - check out this response by Martin Smith with all the gory details.

Invert match with regexp

Okay, I have refined my regular expression based on the solution you came up with (which erroneously matches strings that start with 'test').

^((?!foo).)*$

This regular expression will match only strings that do not contain foo. The first lookahead will deny strings beginning with 'foo', and the second will make sure that foo isn't found elsewhere in the string.

How to set border on jPanel?

An empty border is transparent. You need to specify a Line Border or some other visible border when you set the border in order to see it.

Based on Edit to question:

The painting does not honor the border. Add this line of code to your test and you will see the border:

    jboard.setBorder(BorderFactory.createEmptyBorder(0,10,10,10)); 
    jboard.add(new JButton("Test"));  //Add this line
    frame.add(jboard);

How to use sed to replace only the first occurrence in a file?

Just add the number of occurrence at the end:

sed s/#include/#include "newfile.h"\n#include/1

Print current call stack from a method in Python code

Here's an example of getting the stack via the traceback module, and printing it:

import traceback

def f():
    g()

def g():
    for line in traceback.format_stack():
        print(line.strip())

f()

# Prints:
# File "so-stack.py", line 10, in <module>
#     f()
# File "so-stack.py", line 4, in f
#     g()
# File "so-stack.py", line 7, in g
#     for line in traceback.format_stack():

If you really only want to print the stack to stderr, you can use:

traceback.print_stack()

Or to print to stdout (useful if want to keep redirected output together), use:

traceback.print_stack(file=sys.stdout)

But getting it via traceback.format_stack() lets you do whatever you like with it.

text-align: right on <select> or <option>

I was facing the same issue in which I need to align selected placeholder value to the right of the select box & also need to align options to right but when I have used direction: rtl; to select & applied some right padding to select then all options also getting shift to the right by padding as I only want to apply padding to selected placeholder.

I have fixed the issue by the following the style:

select:first-child{
  text-indent: 24%;
  direction: rtl;
  padding-right: 7px;
}

select option{
  direction: rtl;
}

You can change text-indent as per your requirement. Hope it will help you.

What are .tpl files? PHP, web design

Other possibilities for .tpl: HTML::SimpleTemplate, example:

Hello $name

, and Template Toolkit, example:

Hello [% world %]!

How to write the code for the back button?

<a href="javascript:history.back(1)">Back</a>

this one (by Eiko) is perfect, use css to make a button of <a>... eg you can use this css class in <a> as `

<a class=".back_button" href="javascript:history.back(1)">Back</a>`

.back_button {
display:block;
width:100px;
height:30px;
text-align:center;
background-color:yellow;
border:1px solid #000000;
}

how do you insert null values into sql server

INSERT INTO atable (x,y,z) VALUES ( NULL,NULL,NULL)

Updating property value in properties file without deleting other values

Properties prop = new Properties();
prop.load(...); // FileInputStream 
prop.setProperty("key", "value");
prop.store(...); // FileOutputStream 

What is JSON and why would I use it?

In short - JSON is a way of serializing in such a way, that it becomes JavaScript code. When executed (with eval or otherwise), this code creates and returns a JavaScript object which contains the data you serialized. This is available because JavaScript allows the following syntax:

var MyArray = [ 1, 2, 3, 4]; // MyArray is now an array with 4 elements
var MyObject = {
    'StringProperty' : 'Value',
    'IntProperty' : 12,
    'ArrayProperty' : [ 1, 2, 3],
    'ObjectProperty' : { 'SubObjectProperty': 'SomeValue' }
}; // MyObject is now an object with property values set.

You can use this for several purposes. For one, it's a comfortable way to pass data from your server backend to your JavaScript code. Thus, this is often used in AJAX.

You can also use it as a standalone serialization mechanism, which is simpler and takes up less space than XML. Many libraries exists that allow you to serialize and deserialize objects in JSON for various programming languages.

Oracle date "Between" Query

You need to convert those to actual dates instead of strings, try this:

SELECT *
FROM <TABLENAME>
WHERE start_date BETWEEN TO_DATE('2010-01-15','YYYY-MM-DD') AND TO_DATE('2010-01-17', 'YYYY-MM-DD');

Edited to deal with format as specified:

SELECT *
FROM <TABLENAME>
WHERE start_date BETWEEN TO_DATE('15-JAN-10','DD-MON-YY') AND TO_DATE('17-JAN-10','DD-MON-YY');

PuTTY Connection Manager download?

Try SuperPuTTY. It is similar to puttycm.

You can also try mobaxterm or mremoteng

Using find to locate files that match one of multiple patterns

Braces within the pattern \(\) is required for name pattern with or

find Documents -type f \( -name "*.py" -or -name "*.html" \)

While for the name pattern with and operator it is not required

find Documents -type f ! -name "*.py" -and ! -name "*.html" 

One liner to check if element is in the list

There is a boolean contains(Object obj) method within the List interface.

You should be able to say:

if (list.contains("a")) {
    System.out.println("It's there");
}

According to the javadoc:

boolean contains(Object o)

Returns true if this list contains the specified element. More formally, returns true if and only if this list contains at least one element e such that (o==null ? e==null : o.equals(e)).

How to parse XML using shellscript?

There's also xmlstarlet (which is available for Windows as well).

http://xmlstar.sourceforge.net/doc/xmlstarlet.txt

How do I create a singleton service in Angular 2?

I know angular has hierarchical injectors like Thierry said.

But I have another option here in case you find a use-case where you don't really want to inject it at the parent.

We can achieve that by creating an instance of the service, and on provide always return that.

import { provide, Injectable } from '@angular/core';
import { Http } from '@angular/core'; //Dummy example of dependencies

@Injectable()
export class YourService {
  private static instance: YourService = null;

  // Return the instance of the service
  public static getInstance(http: Http): YourService {
    if (YourService.instance === null) {
       YourService.instance = new YourService(http);
    }
    return YourService.instance;
  }

  constructor(private http: Http) {}
}

export const YOUR_SERVICE_PROVIDER = [
  provide(YourService, {
    deps: [Http],
    useFactory: (http: Http): YourService => {
      return YourService.getInstance(http);
    }
  })
];

And then on your component you use your custom provide method.

@Component({
  providers: [YOUR_SERVICE_PROVIDER]
})

And you should have a singleton service without depending on the hierarchical injectors.

I'm not saying this is a better way, is just in case someone has a problem where hierarchical injectors aren't possible.

Getting individual colors from a color map in matplotlib

I had precisely this problem, but I needed sequential plots to have highly contrasting color. I was also doing plots with a common sub-plot containing reference data, so I wanted the color sequence to be consistently repeatable.

I initially tried simply generating colors randomly, reseeding the RNG before each plot. This worked OK (commented-out in code below), but could generate nearly indistinguishable colors. I wanted highly contrasting colors, ideally sampled from a colormap containing all colors.

I could have as many as 31 data series in a single plot, so I chopped the colormap into that many steps. Then I walked the steps in an order that ensured I wouldn't return to the neighborhood of a given color very soon.

My data is in a highly irregular time series, so I wanted to see the points and the lines, with the point having the 'opposite' color of the line.

Given all the above, it was easiest to generate a dictionary with the relevant parameters for plotting the individual series, then expand it as part of the call.

Here's my code. Perhaps not pretty, but functional.

from matplotlib import cm
cmap = cm.get_cmap('gist_rainbow')  #('hsv') #('nipy_spectral')

max_colors = 31   # Constant, max mumber of series in any plot.  Ideally prime.
color_number = 0  # Variable, incremented for each series.

def restart_colors():
    global color_number
    color_number = 0
    #np.random.seed(1)

def next_color():
    global color_number
    color_number += 1
    #color = tuple(np.random.uniform(0.0, 0.5, 3))
    color = cmap( ((5 * color_number) % max_colors) / max_colors )
    return color

def plot_args():  # Invoked for each plot in a series as: '**(plot_args())'
    mkr = next_color()
    clr = (1 - mkr[0], 1 - mkr[1], 1 - mkr[2], mkr[3])  # Give line inverse of marker color
    return {
        "marker": "o",
        "color": clr,
        "mfc": mkr,
        "mec": mkr,
        "markersize": 0.5,
        "linewidth": 1,
    }

My context is JupyterLab and Pandas, so here's sample plot code:

restart_colors()  # Repeatable color sequence for every plot

fig, axs = plt.subplots(figsize=(15, 8))
plt.title("%s + T-meter"%name)

# Plot reference temperatures:
axs.set_ylabel("°C", rotation=0)
for s in ["T1", "T2", "T3", "T4"]:
    df_tmeter.plot(ax=axs, x="Timestamp", y=s, label="T-meter:%s" % s, **(plot_args()))

# Other series gets their own axis labels
ax2 = axs.twinx()
ax2.set_ylabel(units)

for c in df_uptime_sensors:
    df_uptime[df_uptime["UUID"] == c].plot(
        ax=ax2, x="Timestamp", y=units, label="%s - %s" % (units, c), **(plot_args())
    )

fig.tight_layout()
plt.show()

The resulting plot may not be the best example, but it becomes more relevant when interactively zoomed in. uptime + T-meter

Fatal error: Call to a member function bind_param() on boolean

Any time you get the...

"Fatal error: Call to a member function bind_param() on boolean"

...it is likely because there is an issue with your query. The prepare() might return FALSE (a Boolean), but this generic failure message doesn't leave you much in the way of clues. How do you find out what is wrong with your query? You ask!

First of all, make sure error reporting is turned on and visible: add these two lines to the top of your file(s) right after your opening <?php tag:

error_reporting(E_ALL);
ini_set('display_errors', 1);

If your error reporting has been set in the php.ini you won't have to worry about this. Just make sure you handle errors gracefully and never reveal the true cause of any issues to your users. Revealing the true cause to the public can be a gold engraved invitation for those wanting to harm your sites and servers. If you do not want to send errors to the browser you can always monitor your web server error logs. Log locations will vary from server to server e.g., on Ubuntu the error log is typically located at /var/log/apache2/error.log. If you're examining error logs in a Linux environment you can use tail -f /path/to/log in a console window to see errors as they occur in real-time....or as you make them.

Once you're squared away on standard error reporting adding error checking on your database connection and queries will give you much more detail about the problems going on. Have a look at this example where the column name is incorrect. First, the code which returns the generic fatal error message:

$sql = "SELECT `foo` FROM `weird_words` WHERE `definition` = ?";
$query = $mysqli->prepare($sql)); // assuming $mysqli is the connection
$query->bind_param('s', $definition);
$query->execute();

The error is generic and not very helpful to you in solving what is going on.

With a couple of more lines of code you can get very detailed information which you can use to solve the issue immediately. Check the prepare() statement for truthiness and if it is good you can proceed on to binding and executing.

$sql = "SELECT `foo` FROM `weird_words` WHERE `definition` = ?";
if($query = $mysqli->prepare($sql)) { // assuming $mysqli is the connection
    $query->bind_param('s', $definition);
    $query->execute();
    // any additional code you need would go here.
} else {
    $error = $mysqli->errno . ' ' . $mysqli->error;
    echo $error; // 1054 Unknown column 'foo' in 'field list'
}

If something is wrong you can spit out an error message which takes you directly to the issue. In this case there is no foo column in the table, solving the problem is trivial.

If you choose, you can include this checking in a function or class and extend it by handling the errors gracefully as mentioned previously.

How do I use InputFilter to limit characters in an EditText in Android?

In addition to the accepted answer, it is also possible to use e.g.: android:inputType="textCapCharacters" as an attribute of <EditText> in order to only accept upper case characters (and numbers).

Boolean.parseBoolean("1") = false...?

As a note ,
for those who need to have null value for things other than "true" or "false" strings , you can use the function below

public Boolean tryParseBoolean(String inputBoolean)
{    
    if(!inputBoolean.equals("true")&&!inputBoolean.equals("false")) return null;
    return Boolean.valueOf(inputBoolean);
}

R - argument is of length zero in if statement

You can use isTRUE for such cases. isTRUE is the same as { is.logical(x) && length(x) == 1 && !is.na(x) && x }

If you use shiny there you could use isTruthy which covers the following cases:

  • FALSE

  • NULL

  • ""

  • An empty atomic vector

  • An atomic vector that contains only missing values

  • A logical vector that contains all FALSE or missing values

  • An object of class "try-error"

  • A value that represents an unclicked actionButton()

How do I run Redis on Windows?

The Redis download page now has links to some unofficial Windows ports. The dmajkic one seems to be the most popular/complete.

More detailed answer: How to run Redis as a service under Windows