Programs & Examples On #Array key

array-key refers to key portion of array holding key and value pair. In PHP array_keys() returns the keys, numeric and string, from the input array.

PHP - Get key name of array value

Yes you can infact php is one of the few languages who provide such support..

foreach($arr as $key=>$value)


How To Set Text In An EditText

This is the solution in Kotlin

val editText: EditText = findViewById(
    editText.setText("This is a text.")

Python using enumerate inside list comprehension

Be explicit about the tuples.

[(i, j) for (i, j) in enumerate(mylist)]

What is the equivalent of "none" in django templates?

You can also use another built-in template default_if_none

{{ profile.user.first_name|default_if_none:"--" }}

Is it possible to view RabbitMQ message contents directly from the command line?

a bit late to this, but yes rabbitmq has a build in tracer that allows you to see the incomming messages in a log. When enabled, you can just tail -f /var/tmp/rabbitmq-tracing/.log (on mac) to watch the messages.

the detailed discription is here

How do I test a private function or a class that has private methods, fields or inner classes?

Another approach I have used is to change a private method to package private or protected then complement it with the @VisibleForTesting annotation of the Google Guava library.

This will tell anybody using this method to take caution and not access it directly even in a package. Also a test class need not be in same package physically, but in the same package under the test folder.

For example, if a method to be tested is in src/main/java/mypackage/ then your test call should be placed in src/test/java/mypackage/ That way, you got access to the test method in your test class.

How do you get the currently selected <option> in a <select> via JavaScript?

var payeeCountry = document.getElementById( "payeeCountry" );
alert( payeeCountry.options[ yourSelect.selectedIndex ].value );

Deleting folders in python recursively

Try shutil.rmtree:

import shutil

How can I view an old version of a file with Git?

You can use a script like this to dump all the versions of a file to separate files:

e.g. path/to/somefile.txt

Get the script here as an answer to another similar question

How to parse a CSV file using PHP

A bit shorter answer since PHP >= 5.3.0:

    $csvFile = file('../somefile.csv');
    $data = [];
    foreach ($csvFile as $line) {
        $data[] = str_getcsv($line);

remove attribute display:none; so the item will be visible

For this particular purpose, $("span").show() should be good enough.

Is there any difference between DECIMAL and NUMERIC in SQL Server?

Joakim Backman's answer is specific, but this may bring additional clarity to it.

There is a minor difference. As per SQL For Dummies, 8th Edition (2013):

The DECIMAL data type is similar to NUMERIC. ... The difference is that your implementation may specify a precision greater than what you specify — if so, the implementation uses the greater precision. If you do not specify precision or scale, the implementation uses default values, as it does with the NUMERIC type.

It seems that the difference on some implementations of SQL is in data integrity. DECIMAL allows overflow from what is defined based on some system defaults, where as NUMERIC does not.

Method Call Chaining; returning a pointer vs a reference?

It's canonical to use references for this; precedence: ostream::operator<<. Pointers and references here are, for all ordinary purposes, the same speed/size/safety.

Need to list all triggers in SQL Server database with table name and table's schema

I had the same task recently and I used the following for sql server 2012 db. Use management studio and connect to the database you want to search. Then execute the following script.

[tgr].[name] as [trigger name], 
[tbl].[name] as [table name]

from sysobjects tgr 

join sysobjects tbl
on tgr.parent_obj =

WHERE tgr.xtype = 'TR'

How to do a GitHub pull request

To learn how to make a pull request I just followed two separate help pages on Github (linked below as bullet points). The following command line commands are for Part 1. Part 2, the actual pull request, is done entirely on Github's website.

$ git clone
$ cd dwolla-php
$ git remote add upstream
$ git fetch upstream
// make your changes to this newly cloned, local repo 
$ git add .
$ git commit -m '1st commit to dwolla'
$ git push origin master
  • Part 1: fork someone's repo:

    1. click the 'fork' button on the repo you want to contribute to, in this case: Dwolla's PHP repo (Dwolla/dwolla-php)
    2. get the URL for your newly created fork, in this case: (tim-peterson/dwolla-php)
    3. type the git clone->cd dwolla-php->git remote->git fetch sequence above to clone your fork somewhere in your computer (i.e., "copy/paste" it to, in this case: third_party TimPeterson$) and sync it with the master repo (Dwolla/dwolla-php)
    4. make your changes to your local repo
    5. type the git add->git commit->git push sequence above to push your changes to the remote repo, i.e., your fork on Github (tim-peterson/dwolla-php)
  • Part 2: make pull-request:

    1. go to your fork's webpage on Github (
    2. click 'pull-request' button
    3. give pull-request a name, fill in details of what changes you made, click submit button.
    4. you're done!!

private constructor

One common use is for template-typedef workaround classes like following:

template <class TObj>
class MyLibrariesSmartPointer
    typedef smart_ptr<TObj> type;

Obviously a public non-implemented constructor would work aswell, but a private construtor raises a compile time error instead of a link time error, if anyone tries to instatiate MyLibrariesSmartPointer<SomeType> instead of MyLibrariesSmartPointer<SomeType>::type, which is desireable.

Disable and enable buttons in C#

In your button1_click function you are using '==' for button2.Enabled == true;

This should be button2.Enabled = true;

How to get .pem file from .key and .crt files?

  1. Download certificate from provisional portal by appleId,
  2. Export certificate  from Key chain and  give name (Certificates.p12),
  3. Open terminal and goto folder where you save above Certificates.p12 file,
  4. Run below commands:

    a) openssl pkcs12 -in Certificates.p12 -out CertificateName.pem -nodes,

    b) openssl pkcs12 -in Certificates.p12 -out pushcert.pem -nodes -clcerts

  5. Your .pem file ready "pushcert.pem".

How can I get the Windows last reboot reason

Take a look at the Event Log API. Case a) (bluescreen, user cut the power cord or system hang) causes a note ('system did not shutdown correctly' or something like that) to be left in the 'System' event log the next time the system is rebooted properly. You should be able to access it programmatically using the above API (honestly, I've never used it but it should work).

How to send a simple email from a Windows batch file?

If you can't follow Max's suggestion of installing Blat (or any other utility) on your server, then perhaps your server already has software installed that can send emails.

I know that both Oracle and SqlServer have the capability to send email. You might have to work with your DBA to get that feature enabled and/or get the privilege to use it. Of course I can see how that might present its own set of problems and red tape. Assuming you can access the feature, it is fairly simple to have a batch file login to a database and send mail.

A batch file can easily run a VBScript via CSCRIPT. A quick google search finds many links showing how to send email with VBScript. The first one I happened to look at was It looks straight forward.

NSCameraUsageDescription in iOS 10.0 runtime crash?

Alternatively open Info.plist as source code and add this:

<string>Camera usage description</string>

Datatables warning(table id = 'example'): cannot reinitialise data table

You can add destroy:true to the configuration to make sure data table already present is removed before being reinitialized.

    destroy: true,

Rest-assured. Is it possible to extract value from request json?

I found the answer :)

Use JsonPath or XmlPath (in case you have XML) to get data from the response body.

In my case:

JsonPath jsonPath = new JsonPath(responseBody);
int user_id = jsonPath.getInt("user_id");

What is the path that Django uses for locating and loading templates?

For Django 1.6.6:

BASE_DIR = os.path.dirname(os.path.dirname(__file__))
TEMPLATE_DIRS = os.path.join(BASE_DIR, 'templates')

Also static and media for debug and production mode:

STATIC_URL = '/static/'
MEDIA_URL = '/media/'
    STATIC_ROOT = os.path.join(BASE_DIR, 'static')
    MEDIA_ROOT = os.path.join(BASE_DIR, 'media')

Into you must add:

from django.conf.urls import patterns, include, url
from django.contrib import admin
from django.conf.urls.static import static
from django.conf import settings

from news.views import Index


urlpatterns = patterns('',
    url(r'^admin/', include(,

urlpatterns += static(settings.STATIC_URL, document_root=settings.STATIC_ROOT)

In Django 1.8 you can set template paths, backend and other parameters for templates in one dictionary (

        'BACKEND': 'django.template.backends.django.DjangoTemplates',
        'DIRS': [
            path.join(BASE_DIR, 'templates')
        'APP_DIRS': True,
        'OPTIONS': {
            'context_processors': [

Official docs.

How to check if type of a variable is string?

Lots of good suggestions provided by others here, but I don't see a good cross-platform summary. The following should be a good drop in for any Python program:

def isstring(s):
    # if we use Python 3
    if (sys.version_info[0] >= 3):
        return isinstance(s, str)
    # we use Python 2
    return isinstance(s, basestring)

In this function, we use isinstance(object, classinfo) to see if our input is a str in Python 3 or a basestring in Python 2.

"Submit is not a function" error in JavaScript

submit is not a function

means that you named your submit button or some other element submit. Rename the button to btnSubmit and your call will magically work.

When you name the button submit, you override the submit() function on the form.

Multiple left-hand assignment with JavaScript

a = (b = 'string is truthy'); // b gets string; a gets b, which is a primitive (copy)
a = (b = { c: 'yes' }); // they point to the same object; a === b (not a copy)

(a && b) is logically (a ? b : a) and behaves like multiplication (eg. !!a * !!b)

(a || b) is logically (a ? a : b) and behaves like addition (eg. !!a + !!b)

(a = 0, b) is short for not caring if a is truthy, implicitly return b

a = (b = 0) && "nope, but a is 0 and b is 0"; // b is falsey + order of operations
a = (b = "b is this string") && "a gets this string"; // b is truthy + order of ops

JavaScript Operator Precedence (Order of Operations)

Note that the comma operator is actually the least privileged operator, but parenthesis are the most privileged, and they go hand-in-hand when constructing one-line expressions.

Eventually, you may need 'thunks' rather than hardcoded values, and to me, a thunk is both the function and the resultant value (the same 'thing').

const windowInnerHeight = () => 0.8 * window.innerHeight; // a thunk

windowInnerHeight(); // a thunk

need to test if sql query was successful


I understand that by saying "successful" you want to know if any rows have been updated. You can check it with this function.

If you use PDO ->

SQL providerName in web.config


Using Ansible set_fact to create a dictionary from register results

Thank you Phil for your solution; in case someone ever gets in the same situation as me, here is a (more complex) variant:

# this is just to avoid a call to |default on each iteration
- set_fact:
    postconf_d: {}

- name: 'get postfix default configuration'
  command: 'postconf -d'
  register: command

# the answer of the command give a list of lines such as:
# "key = value" or "key =" when the value is null
- name: 'set postfix default configuration as fact'
    postconf_d: >
        postconf_d |
          dict([ item.partition('=')[::2]|map('trim') ])
  with_items: command.stdout_lines

This will give the following output (stripped for the example):

"postconf_d": {
    "alias_database": "hash:/etc/aliases", 
    "alias_maps": "hash:/etc/aliases, nis:mail.aliases",
    "allow_min_user": "no", 
    "allow_percent_hack": "yes"

Going even further, parse the lists in the 'value':

- name: 'set postfix default configuration as fact'
    postconf_d: >-
      {% set key, val = item.partition('=')[::2]|map('trim') -%}
      {% if ',' in val -%}
        {% set val = val.split(',')|map('trim')|list -%}
      {% endif -%}
      {{ postfix_default_main_cf | combine({key: val}) }}
  with_items: command.stdout_lines
"postconf_d": {
    "alias_database": "hash:/etc/aliases", 
    "alias_maps": [
    "allow_min_user": "no", 
    "allow_percent_hack": "yes"

A few things to notice:

  • in this case it's needed to "trim" everything (using the >- in YAML and -%} in Jinja), otherwise you'll get an error like:

    FAILED! => {"failed": true, "msg": "|combine expects dictionaries, got u\"  {u'...
  • obviously the {% if .. is far from bullet-proof

  • in the postfix case, val.split(',')|map('trim')|list could have been simplified to val.split(', '), but I wanted to point out the fact you will need to |list otherwise you'll get an error like:

    "|combine expects dictionaries, got u\"{u'...': <generator object do_map at ...

Hope this can help.

How can I set response header on express.js assets

There is at least one middleware on npm for handling CORS in Express: cors. [see @mscdex answer]

This is how to set custom response headers, from the ExpressJS DOC

res.set(field, [value])

Set header field to value

res.set('Content-Type', 'text/plain');

or pass an object to set multiple fields at once.

  'Content-Type': 'text/plain',
  'Content-Length': '123',
  'ETag': '12345'

Aliased as

res.header(field, [value])

Android camera intent

try this code

Intent photo= new Intent("");
                    startActivityForResult(photo, CAMERA_PIC_REQUEST);

How to change the default docker registry from to my private registry?

I tried to add the following options in the /etc/docker/daemon.json. (I used CentOS7)

"add-registry": [""],
"block-registry": [""],

after that, restarted docker daemon. And it's working without I hope this someone will be helpful.

Find an item in List by LINQ?

Here is one way to rewrite your method to use LINQ:

public static int GetItemIndex(string search)
    List<string> _list = new List<string>() { "one", "two", "three" };

    var result = _list.Select((Value, Index) => new { Value, Index })
            .SingleOrDefault(l => l.Value == search);

    return result == null ? -1 : result.Index;

Thus, calling it with

GetItemIndex("two") will return 1,


GetItemIndex("notthere") will return -1.


php codeigniter count rows

Use this code:

$this->db->where(['id'=>2])->from("table name")->count_all_results();


$this->db->from("table name")->count_all_results();

Purge or recreate a Ruby on Rails database

I think the best way to run this command:

**rake db:reset** it does db:drop, db:setup
 rake db:setup does db:create, db:schema:load, db:seed

Difference between modes a, a+, w, w+, and r+ in built-in open function?

I think this is important to consider for cross-platform execution, i.e. as a CYA. :)

On Windows, 'b' appended to the mode opens the file in binary mode, so there are also modes like 'rb', 'wb', and 'r+b'. Python on Windows makes a distinction between text and binary files; the end-of-line characters in text files are automatically altered slightly when data is read or written. This behind-the-scenes modification to file data is fine for ASCII text files, but it’ll corrupt binary data like that in JPEG or EXE files. Be very careful to use binary mode when reading and writing such files. On Unix, it doesn’t hurt to append a 'b' to the mode, so you can use it platform-independently for all binary files.

This is directly quoted from Python Software Foundation 2.7.x.

Add a duration to a moment (moment.js)

For people having a startTime (like 12h:30:30) and a duration (value in minutes like 120), you can guess the endTime like so:

const startTime = '12:30:00';
const durationInMinutes = '120';

const endTime = moment(startTime, 'HH:mm:ss').add(durationInMinutes, 'minutes').format('HH:mm');

// endTime is equal to "14:30"

How to update SQLAlchemy row entry?

There are several ways to UPDATE using sqlalchemy

1) user.no_of_logins += 1

2) session.query().\
       filter(User.username ==\
       update({"no_of_logins": (User.no_of_logins +1)})

3) conn = engine.connect()
   stmt = User.update().\
       values(no_of_logins=(User.no_of_logins + 1)).\
       where(User.username ==

4) setattr(user, 'no_of_logins', user.no_of_logins+1)

Is it possible to focus on a <div> using JavaScript focus() function?

<div id="inner" tabindex="0">
    this div can now have focus and receive keyboard events

strange error in my Animation Drawable

Looks like whatever is in your Animation Drawable definition is too much memory to decode and sequence. The idea is that it loads up all the items and make them in an array and swaps them in and out of the scene according to the timing specified for each frame.

If this all can't fit into memory, it's probably better to either do this on your own with some sort of handler or better yet just encode a movie with the specified frames at the corresponding images and play the animation through a video codec.

How to keep two folders automatically synchronized?

You can take advantage of fschange. It’s a Linux filesystem change notification. The source code is downloadable from the above link, you can compile it yourself. fschange can be used to keep track of file changes by reading data from a proc file (/proc/fschange). When data is written to a file, fschange reports the exact interval that has been modified instead of just saying that the file has been changed. If you are looking for the more advanced solution, I would suggest checking Resilio Connect. It is cross-platform, provides extended options for use and monitoring. Since it’s BitTorrent-based, it is faster than any other existing sync tool. It was written on their behalf.

col align right

For Bootstrap 4 I find the following very handy because:

  • the column on the right takes exactly the space it needs and will pull right
  • while the left col always gets the maximum amount of space!.

It is the combination of col and col-auto which does the magic. So you don't have to define a col width (like col-2,...)

<div class="row">
    <div class="col">Left</div>
    <div class="col-auto">Right</div>

Ideal for aligning words, icons, buttons,... to the right.

An example to have this responsive on small devices:

<div class="row">
    <div class="col">Left</div>
    <div class="col-12 col-sm-auto">Right (Left on small)</div>

Check this Fiddle

How to have image and text side by side

Use following code :


<div class='container2'>
        <div class="left">
            <img src='' class='iconDetails'>
    <div   class="right" >
    <div style="font-size:.7em;width:160px;float:left;">fine location, GPS, coarse location</div>
    <div style="float:right;font-size:.7em">0 mins ago</div>


.iconDetails {

.container2 {
.left {float:left;width:45px;}
.right {float:left;margin:0 0 0 5px;width:215px;}

Aggregate a dataframe on a given column and display another column

A late answer, but and approach using data.table

DT <- data.table(dat)

DT[, .SD[which.max(Score),], by = Group]

Or, if it is possible to have more than one equally highest score

DT[, .SD[which(Score == max(Score)),], by = Group]

Noting that (from ?data.table

.SD is a data.table containing the Subset of x's Data for each group, excluding the group column(s)

Error: Generic Array Creation

The following will give you an array of the type you want while preserving type safety.

PCB[] getAll(Class<PCB[]> arrayType) {  
    PCB[] res = arrayType.cast(java.lang.reflect.Array.newInstance(arrayType.getComponentType(), list.size()));  
    for (int i = 0; i < res.length; i++)  {  
        res[i] = list.get(i);  
    return res;  

How this works is explained in depth in my answer to the question that Kirk Woll linked as a duplicate.

Execute PHP function with onclick

Try to do something like this:

<!--Include jQuery-->
<script type="text/javascript" src="jquery.min.js"></script> 

<script type="text/javascript"> 
function doSomething() { 
    return false; 

<a href="#" onclick="doSomething();">Click Me!</a>

Why this line xmlns:android="" must be the first in the layout xml file?

In XML, element names are defined by the developer. This often results in a conflict when trying to mix XML documents from different XML applications. A user or an XML application will not know how to handle these differences. Name conflicts in XML can easily be avoided using a name prefix. When using prefixes in XML, a namespace for the prefix must be defined.The namespace can be defined by an xmlns attribute in the start tag of an element.The namespace declaration has the following syntax. xmlns:prefix="URI".

How do I set a JLabel's background color?

You must set the setOpaque(true) to true other wise the background will not be painted to the form. I think from reading that if it is not set to true that it will paint some or not any of its pixels to the form. The background is transparent by default which seems odd to me at least but in the way of programming you have to set it to true as shown below.

      JLabel lb = new JLabel("Test");
      lb.setOpaque(true); <--This line of code must be set to true or otherwise the 

From the JavaDocs


public void setOpaque(boolean isOpaque)
  If true the component paints every pixel within its bounds. Otherwise, 
  the component may not paint some or all of its pixels, allowing the underlying 
  pixels to show through.
  The default value of this property is false for JComponent. However, 
  the default value for this property on most standard JComponent subclasses 
   (such as JButton and JTree) is look-and-feel dependent.

isOpaque - true if this component should be opaque
See Also:

CMD: Export all the screen content to a text file

If you want to append a file instead of constantly making a new one/deleting the old one's content, use double > marks. A single > mark will overwrite all the file's content.

Overwrite file


^This will open file.txt if it already exists and overwrite the data, or create a new file and fill it with your output

Append file from its end-point


^This will append file.txt from its current end of file if it already exists, or create a new file and fill it with your output.

Update #1 (advanced):

My batch-fu has improved over time, so here's some minor updates.

If you want to differentiate between error output and normal output for a program that correctly uses Standard streams, STDOUT/STDERR, you can do this with minor changes to the syntax. I'll just use > for overwriting for these examples, but they work perfectly fine with >> for append, in regards to file-piping output re-direction.

The 1 before the >> or > is the flag for STDOUT. If you need to actually output the number one or two before the re-direction symbols, this can lead to strange, unintuitive errors if you don't know about this mechanism. That's especially relevant when outputting a single result number into a file. 2 before the re-direction symbols is for STDERR.

Now that you know that you have more than one stream available, this is a good time to show the benefits of outputting to nul. Now, outputting to nul works the same way conceptually as outputting to a file. You don't see the content in your console. Instead of it going to file or your console output, it goes into the void.

STDERR to file and suppress STDOUT

MyCommand.exe 1>nul 2>errors.txt

STDERR to file to only log errors. Will keep STDOUT in console

MyCommand.exe 2>errors.txt

STDOUT to file and suppress STDERR

MyCommand.exe 1>file.txt 2>nul

STDOUT only to file. Will keep STDERR in console

MyCommand.exe 1>file.txt

STDOUT to one file and STDERR to another file

MyCommand.exe 1>stdout.txt 2>errors.txt

The only caveat I have here is that it can create a 0-byte file for an unused stream if one of the streams never gets used. Basically, if no errors occurred, you might end up with a 0-byte errors.txt file.

Update #2

I started noticing weird behavior when writing console apps that wrote directly to STDERR, and realized that if I wanted my error output to go to the same file when using basic piping, I either had to combine streams 1 and 2 or just use STDOUT. The problem with that problem is I didn't know about the correct way to combine streams, which is this:

%command% > outputfile 2>&1

Therefore, if you want all STDOUT and STDERR piped into the same stream, make sure to use that like so:

MyCommand.exe > file.txt 2>&1

The redirector actually defaults to 1> or 1>>, even if you don't explicitly use 1 in front of it if you don't use a number in front of it, and the 2>&1 combines the streams.

Update #3 (simple)

Null for Everything

If you want to completely suppress STDOUT and STDERR you can do it this way. As a warning not all text pipes use STDOUT and STDERR but it will work for a vast majority of use cases.

STD* to null MyCommand.exe>nul 2>&1

Copying a CMD or Powershell session's command output

If all you want is the command output from a CMD or Powershell session that you just finished up, or any other shell for that matter you can usually just select that console from that session, CTRL + A to select all content, then CTRL + C to copy the content. Then you can do whatever you like with the copied content while it's in your clipboard.

Now() function with time trim

Dates in VBA are just floating point numbers, where the integer part represents the date and the fraction part represents the time. So in addition to using the Date function as tlayton says (to get the current date) you can also cast a date value to a integer to get the date-part from an arbitrary date: Int(myDateValue).

Type.GetType("namespace.a.b.ClassName") returns null

You can also get the type without assembly qualified name but with the dll name also, for example:

Type myClassType = Type.GetType("TypeName,DllName");

I had the same situation and it worked for me. I needed an object of type "DataModel.QueueObject" and had a reference to "DataModel" so I got the type as follows:

Type type = Type.GetType("DataModel.QueueObject,DataModel");

The second string after the comma is the reference name (dll name).

list.clear() vs list = new ArrayList<Integer>();

It's hard to know without a benchmark, but if you have lots of items in your ArrayList and the average size is lower, it might be faster to make a new ArrayList.

public void clear() {

    // Let gc do its work
    for (int i = 0; i < size; i++)
        elementData[i] = null;

    size = 0;

Why can't I initialize non-const static member or static array in class?

Why I can't initialize static data members in class?

The C++ standard allows only static constant integral or enumeration types to be initialized inside the class. This is the reason a is allowed to be initialized while others are not.

C++03 9.4.2 Static data members

If a static data member is of const integral or const enumeration type, its declaration in the class definition can specify a constant-initializer which shall be an integral constant expression (5.19). In that case, the member can appear in integral constant expressions. The member shall still be defined in a namespace scope if it is used in the program and the namespace scope definition shall not contain an initializer.

What are integral types?

C++03 3.9.1 Fundamental types

Types bool, char, wchar_t, and the signed and unsigned integer types are collectively called integral types.43) A synonym for integral type is integer type.


43) Therefore, enumerations (7.2) are not integral; however, enumerations can be promoted to int, unsigned int, long, or unsigned long, as specified in 4.5.


You could use the enum trick to initialize an array inside your class definition.

class A 
    static const int a = 3;
    enum { arrsize = 2 };

    static const int c[arrsize] = { 1, 2 };


Why does the Standard does not allow this?

Bjarne explains this aptly here:

A class is typically declared in a header file and a header file is typically included into many translation units. However, to avoid complicated linker rules, C++ requires that every object has a unique definition. That rule would be broken if C++ allowed in-class definition of entities that needed to be stored in memory as objects.

Why are only static const integral types & enums allowed In-class Initialization?

The answer is hidden in Bjarne's quote read it closely,
"C++ requires that every object has a unique definition. That rule would be broken if C++ allowed in-class definition of entities that needed to be stored in memory as objects."

Note that only static const integers can be treated as compile time constants. The compiler knows that the integer value will not change anytime and hence it can apply its own magic and apply optimizations, the compiler simply inlines such class members i.e, they are not stored in memory anymore, As the need of being stored in memory is removed, it gives such variables the exception to rule mentioned by Bjarne.

It is noteworthy to note here that even if static const integral values can have In-Class Initialization, taking address of such variables is not allowed. One can take the address of a static member if (and only if) it has an out-of-class definition.This further validates the reasoning above.

enums are allowed this because values of an enumerated type can be used where ints are expected.see citation above

How does this change in C++11?

C++11 relaxes the restriction to certain extent.

C++11 9.4.2 Static data members

If a static data member is of const literal type, its declaration in the class definition can specify a brace-or-equal-initializer in which every initializer-clause that is an assignment-expression is a constant expression. A static data member of literal type can be declared in the class definition with the constexpr specifier; if so, its declaration shall specify a brace-or-equal-initializer in which every initializer-clause that is an assignment-expression is a constant expression. [ Note: In both these cases, the member may appear in constant expressions. —end note ] The member shall still be defined in a namespace scope if it is used in the program and the namespace scope definition shall not contain an initializer.

Also, C++11 will allow(§ a non-static data member to be initialized where it is declared(in its class). This will mean much easy user semantics.

Note that these features have not yet been implemented in latest gcc 4.7, So you might still get compilation errors.

What is the best way to return different types of ResponseEntity in Spring MVC or Spring-Boot

Here is a way that I would do it:

public ResponseEntity < ? extends BaseResponse > message(@PathVariable String player) { //REST Endpoint.

 try {
  return new ResponseEntity < ErrorResponse > (new ErrorResponse("111", "player is not found"), HttpStatus.BAD_REQUEST);
 } catch (Exception e) {

 Message msg = new Message(player, "Hello " + player);
 return new ResponseEntity < Message > (msg, HttpStatus.OK);


@RequestMapping(value = "/getAll/{player}", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity < List < ? extends BaseResponse >> messageAll(@PathVariable String player) { //REST Endpoint.

 try {
  List < ErrorResponse > errs = new ArrayList < ErrorResponse > ();
  errs.add(new ErrorResponse("111", "player is not found"));
  return new ResponseEntity < List < ? extends BaseResponse >> (errs, HttpStatus.BAD_REQUEST);
 } catch (Exception e) {

 Message msg = new Message(player, "Hello " + player);
 List < Message > msgList = new ArrayList < Message > ();
 return new ResponseEntity < List < ? extends BaseResponse >> (msgList, HttpStatus.OK);


LaTeX beamer: way to change the bullet indentation?

I use the package enumitem. You may then set such margins when you declare your lists (enumerate, description, itemize):

    \item Foo
    \item Bar

Naturally, the package provides lots of other nice customizations for lists (use 'label=' to change the bullet, use 'itemsep=' to change the spacing between items, etc...)

How can I check for IsPostBack in JavaScript?

Server-side, write:

   // NOTE: the following uses an overload of RegisterClientScriptBlock() 
   // that will surround our string with the needed script tags 
   ClientScript.RegisterClientScriptBlock(GetType(), "IsPostBack", "var isPostBack = true;", true);

Then, in your script which runs for the onLoad, check for the existence of that variable:

if(isPostBack) {
   // do your thing

You don't really need to set the variable otherwise, like Jonathan's solution. The client-side if statement will work fine because the "isPostBack" variable will be undefined, which evaluates as false in that if statement.

Error retrieving parent for item: No resource found that matches the given name 'android:TextAppearance.Material.Widget.Button.Borderless.Colored'

I found it, I was trying to compile my app which is using facebook sdk. I was made that like augst 2016. When I try to open it today i got same error. I had that line in my gradle " compile '' " and I went this page and i found the sdk version while i was running this app succesfully and it was 4.14.1 then I changed that line to " compile '' " and it worked.

Creating a constant Dictionary in C#

Creating a truly compile-time generated constant dictionary in C# is not really a straightforward task. Actually, none of the answers here really achieve that.

There is one solution though which meets your requirements, although not necessarily a nice one; remember that according to the C# specification, switch-case tables are compiled to constant hash jump tables. That is, they are constant dictionaries, not a series of if-else statements. So consider a switch-case statement like this:

switch (myString)
   case "cat": return 0;
   case "dog": return 1;
   case "elephant": return 3;

This is exactly what you want. And yes, I know, it's ugly.

How to uninstall Ruby from /usr/local?

do this way :

sudo apt purge ruby

ant warning: "'includeantruntime' was not set"

Use <property name="build.sysclasspath" value="last"/> in your build.xml file

For more details search includeAntRuntime in Ant javac

Other possible values could be found here

Break a previous commit into multiple commits

It's been more than 8 years, but maybe someone will find it helpful anyway. I was able to do the trick without rebase -i. The idea is to lead git to the same state it was before you did git commit:

# first rewind back (mind the dot,
# though it can be any valid path,
# for instance if you want to apply only a subset of the commit)
git reset --hard <previous-commit> .

# apply the changes
git checkout <commit-you-want-to-split>

# we're almost there, but the changes are in the index at the moment,
# hence one more step (exactly as git gently suggests):
# (use "git reset HEAD <file>..." to unstage)
git reset

After this you'll see this shiny Unstaged changes after reset: and your repo is in a state like you're about to commit all these files. From now on you can easily commit it again like you usually do. Hope it helps.

How to customize the configuration file of the official PostgreSQL Docker image?

I looked through all answers and there is another option left. You can change your CMD value in docker file (it is not the best one, but still possible way to achieve your goal).

Basically we need to

  • Copy config file in docker container
  • Override postgres start options

Docker file example:

FROM postgres:9.6
USER postgres

# Copy postgres config file into container
COPY postgresql.conf /etc/postgresql

# Override default postgres config file
CMD ["postgres", "-c", "config_file=/etc/postgresql/postgresql.conf"]

Though I think using command: postgres -c config_file=/etc/postgresql/postgresql.confin your docker-compose.yml file proposed by Matthias Braun is the best option.

How to show DatePickerDialog on Button click?

it works for me. if you want to enable future time for choose, you have to delete maximum date. You need to to do like followings.

 btnDate.setOnClickListener(new View.OnClickListener() {
                       public void onClick(View v) {
                              DialogFragment newFragment = new DatePickerFragment();
                          , "datePicker");

            public static class DatePickerFragment extends DialogFragment
                        implements DatePickerDialog.OnDateSetListener {

                    public Dialog onCreateDialog(Bundle savedInstanceState) {
                        final Calendar c = Calendar.getInstance();
                        int year = c.get(Calendar.YEAR);
                        int month = c.get(Calendar.MONTH);
                        int day = c.get(Calendar.DAY_OF_MONTH);
                        DatePickerDialog dialog = new DatePickerDialog(getActivity(), this, year, month, day);
                        return  dialog;

                    public void onDateSet(DatePicker view, int year, int month, int day) {
                       btnDate.setText(ConverterDate.ConvertDate(year, month + 1, day));

What is the difference between FragmentPagerAdapter and FragmentStatePagerAdapter?

Like the docs say, think about it this way. If you were to do an application like a book reader, you will not want to load all the fragments into memory at once. You would like to load and destroy Fragments as the user reads. In this case you will use FragmentStatePagerAdapter. If you are just displaying 3 "tabs" that do not contain a lot of heavy data (like Bitmaps), then FragmentPagerAdapter might suit you well. Also, keep in mind that ViewPager by default will load 3 fragments into memory. The first Adapter you mention might destroy View hierarchy and re load it when needed, the second Adapter only saves the state of the Fragment and completely destroys it, if the user then comes back to that page, the state is retrieved.

String concatenation of two pandas columns

df.astype(str).apply(lambda x: ' is '.join(x), axis=1)

0    1 is a
1    2 is b
2    3 is c
dtype: object

Export specific rows from a PostgreSQL table as INSERT SQL script

Create a table with the set you want to export and then use the command line utility pg_dump to export to a file:

create table export_table as 
select id, name, city
from nyummy.cimory
where city = 'tokyo'
$ pg_dump --table=export_table --data-only --column-inserts my_database > data.sql

--column-inserts will dump as insert commands with column names.

--data-only do not dump schema.

As commented below, creating a view in instead of a table will obviate the table creation whenever a new export is necessary.

How to add button in ActionBar(Android)?

An activity populates the ActionBar in its onCreateOptionsMenu() method.

Instead of using setcustomview(), just override onCreateOptionsMenu like this:

public boolean onCreateOptionsMenu(Menu menu) {
  MenuInflater inflater = getMenuInflater();
  inflater.inflate(, menu);
  return true;

If an actions in the ActionBar is selected, the onOptionsItemSelected() method is called. It receives the selected action as parameter. Based on this information you code can decide what to do for example:

public boolean onOptionsItemSelected(MenuItem item) {
  switch (item.getItemId()) {
      Toast.makeText(this, "Menu Item 1 selected", Toast.LENGTH_SHORT).show();
      Toast.makeText(this, "Menu item 2 selected", Toast.LENGTH_SHORT).show();
  return true;

How to format DateTime in Flutter , How to get current time in flutter?

With this approach, there is no need to import any library.

DateTime now =;

String convertedDateTime = "${now.year.toString()}-${now.month.toString().padLeft(2,'0')}-${,'0')} ${now.hour.toString()}-${now.minute.toString()}";


2020-12-05 14:57

creating a table in ionic

In Ionic 2 there's a easier way to do that. See the Ionic Docs.

It is more or less like the following:

      1 of 3
      2 of 3
      3 of 3

Play sound on button click android

Tested and working 100%

public class MainActivity extends ActionBarActivity {
    Context context = this;
    MediaPlayer mp;

    public void onCreate(Bundle savedInstanceState) {
        mp = MediaPlayer.create(context, R.raw.sound);
        final Button b = (Button) findViewById(;
        b.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {

                try {
                    if (mp.isPlaying()) {
                        mp = MediaPlayer.create(context, R.raw.sound);
                    } mp.start();
                } catch(Exception e) { e.printStackTrace(); }

This was all we had to do

if (mp.isPlaying()) {
    mp = MediaPlayer.create(context, R.raw.sound);

Connection reset by peer: mod_fcgid: error reading data from FastCGI server

I got the same problem (with Plesk 12 installed). However, when i switched from execute PHP as FastCGI to Apache Module the website worked.

Checked my suexec log:

$ cd /var/log/apache2/
$ less suexec.log

When you find something like this:

[2015-03-22 10:49:00]: directory is writable by others: (/var/www/cgi-bin/cgi_wrapper)
[2015-03-22 10:49:05]: uid: (10004/gb) gid: (1005/1005) cmd: cgi_wrapper

try this commands

$ chown root:root /var/www/cgi-bin/cgi_wrapper
$ chmod 755 /var/www/cgi-bin/cgi_wrapper
$ shutdown -r now

as root.

I hope it can help you.

How to scroll up or down the page to an anchor using jQuery?

Ok simplest method is : -

Within the click function (Jquery) : -

$('html,body').animate({scrollTop: $("#resultsdiv").offset().top},'slow');


<div id="resultsdiv">Where I want to scroll to</div>

Relation between CommonJS, AMD and RequireJS?


  • introduced in JavaScript to scale JavaScript project into multiple files
  • mostly used in browser based application and libraries
  • popular implementation is RequireJS, Dojo Toolkit


  • it is specification to handle large number of functions, files and modules of big project
  • initial name ServerJS introduced in January, 2009 by Mozilla
  • renamed in August, 2009 to CommonJS to show the broader applicability of the APIs
  • initially implementation were server, nodejs, desktop based libraries


upper.js file

exports.uppercase = str => str.toUpperCase()

main.js file

const uppercaseModule = require('uppercase.js')


  • AMD – one of the most ancient module systems, initially implemented by the library require.js.
  • CommonJS – the module system created for Node.js server.
  • UMD – one more module system, suggested as a universal one, compatible with AMD and CommonJS.


Insert HTML from CSS

This can be done. For example with Firefox


#hlinks {
  -moz-binding: url(stackexchange.xml#hlinks);


<bindings xmlns=""
  <binding id="hlinks">
      <html:a href="/privileges">privileges</html:a>
      <html:span class="lsep"> | </html:span>
      <html:a href="/users/logout">log out</html:a>

ref 1

ref 2

How to implement a Boolean search with multiple columns in pandas

the query() method can do that very intuitively. Express your condition in a string to be evaluated like the following example :

df = df.query("columnNameA <= @x or columnNameB == @y")

with x and y are declared variables which you can refer to with @

How do I declare and use variables in PL/SQL like I do in T-SQL?

In Oracle PL/SQL, if you are running a query that may return multiple rows, you need a cursor to iterate over the results. The simplest way is with a for loop, e.g.:

  myname varchar2(20) := 'tom';
  for result_cursor in (select * from mytable where first_name = myname) loop
  end loop;

If you have a query that returns exactly one row, then you can use the select...into... syntax, e.g.:

  myname varchar2(20);
  select first_name into myname 
    from mytable 
    where person_id = 123;

How does Facebook Sharer select Images and other metadata when sharing my URL?

For secure HTTPS

<meta property="og:image:secure_url" content="https://image.path.png" />

Importing larger sql files into MySQL

On item 1.16 of phpMyAdmin they say:

1.16 I cannot upload big dump files (memory, HTTP or timeout problems).

Starting with version 2.7.0, the import engine has been re–written and these problems should not occur. If possible, upgrade your phpMyAdmin to the latest version to take advantage of the new import features.

The first things to check (or ask your host provider to check) are the values of upload_max_filesize, memory_limit and post_max_size in the php.ini configuration file. All of these three settings limit the maximum size of data that can be submitted and handled by PHP. One user also said that post_max_size and memory_limit need to be larger than upload_max_filesize. There exist several workarounds if your upload is too big or your hosting provider is unwilling to change the settings:

Look at the $cfg['UploadDir'] feature. This allows one to upload a file to the server via scp, ftp, or your favorite file transfer method. PhpMyAdmin is then able to import the files from the temporary directory. More information is available in the Configuration of this document.

Using a utility (such as BigDump) to split the files before uploading. We cannot support this or any third party applications, but are aware of users having success with it.

If you have shell (command line) access, use MySQL to import the files directly. You can do this by issuing the “source” command from within MySQL:

source filename.sql;

Get element from within an iFrame

Do not forget to access iframe after it is loaded. Old but reliable way without jQuery:

<iframe src="" id="iframe" onload="access()"></iframe>

function access() {
   var iframe = document.getElementById("iframe");
   var innerDoc = iframe.contentDocument || iframe.contentWindow.document;

ERROR 2003 (HY000): Can't connect to MySQL server (111)

Not sure as cant see it in steps you mentioned.

Please try FLUSH PRIVILEGES [Reloads the privileges from the grant tables in the mysql database]:

flush privileges;

You need to execute it after GRANT

Hope this help!

How to send file contents as body entity using cURL

I know the question has been answered, but in my case I was trying to send the content of a text file to the Slack Webhook api and for some reason the above answer did not work. Anywho, this is what finally did the trick for me:

curl -X POST -H --silent --data-urlencode "payload={\"text\": \"$(cat file.txt | sed "s/\"/'/g")\"}"

Array[n] vs Array[10] - Initializing array with variable vs real number

In C++, variable length arrays are not legal. G++ allows this as an "extension" (because C allows it), so in G++ (without being -pedantic about following the C++ standard), you can do:

int n = 10;
double a[n]; // Legal in g++ (with extensions), illegal in proper C++

If you want a "variable length array" (better called a "dynamically sized array" in C++, since proper variable length arrays aren't allowed), you either have to dynamically allocate memory yourself:

int n = 10;
double* a = new double[n]; // Don't forget to delete [] a; when you're done!

Or, better yet, use a standard container:

int n = 10;
std::vector<double> a(n); // Don't forget to #include <vector>

If you still want a proper array, you can use a constant, not a variable, when creating it:

const int n = 10;
double a[n]; // now valid, since n isn't a variable (it's a compile time constant)

Similarly, if you want to get the size from a function in C++11, you can use a constexpr:

constexpr int n()
    return 10;

double a[n()]; // n() is a compile time constant expression

unix - count of columns in file

This is usually what I use for counting the number of fields:

head -n 1 | awk -F'|' '{print NF; exit}'

Big-oh vs big-theta

I have seen Big Theta, and I'm pretty sure I was taught the difference in school. I had to look it up though. This is what Wikipedia says:

Big O is the most commonly used asymptotic notation for comparing functions, although in many cases Big O may be replaced with Big Theta T for asymptotically tighter bounds.

Source: Big O Notation#Related asymptotic notation

I don't know why people use Big-O when talking formally. Maybe it's because most people are more familiar with Big-O than Big-Theta? I had forgotten that Big-Theta even existed until you reminded me. Although now that my memory is refreshed, I may end up using it in conversation. :)

Text to speech(TTS)-Android

    package com.example.text_to_speech;


import android.os.Bundle;
import android.speech.tts.TextToSpeech;
import android.view.View;
import android.widget.Toast;

import com.example.fyp.R;

import java.util.Locale;

import cn.pedant.SweetAlert.SweetAlertDialog;

public class textTospeech_class extends AppCompatActivity {
    TextToSpeech textToSpeech;
    String text;
    int result;
    protected void onCreate(Bundle savedInstanceState) {
        textToSpeech = new TextToSpeech(textTospeech_class.this, new TextToSpeech.OnInitListener() {
            public void onInit(int i) {
                if (i == TextToSpeech.SUCCESS) {
                    result = textToSpeech.setLanguage(Locale.ENGLISH);
                } else {
                    Toast.makeText(textTospeech_class.this, "Not Support in your device", Toast.LENGTH_SHORT).show();

    public void tts(View view)
        switch (view.getId()) {
                if (result == TextToSpeech.LANG_MISSING_DATA || result == TextToSpeech.LANG_NOT_SUPPORTED) {
                    Toast.makeText(textTospeech_class.this, "Not Support in your device", Toast.LENGTH_SHORT).show();

                } else {
                    textToSpeech.speak("a for apple", TextToSpeech.QUEUE_FLUSH, null);
                if(result==TextToSpeech.LANG_MISSING_DATA || result== TextToSpeech.LANG_NOT_SUPPORTED)
                    Toast.makeText(textTospeech_class.this, "Not Support in your device", Toast.LENGTH_SHORT).show();

                    textToSpeech.speak("b for ball",TextToSpeech.QUEUE_FLUSH,null);

List all column except for one in R

In addition to tcash21's numeric indexing if OP may have been looking for negative indexing by name. Here's a few ways I know, some are risky than others to use:

mtcars[, -which(names(mtcars) == "carb")]  #only works on a single column
mtcars[, names(mtcars) != "carb"]          #only works on a single column
mtcars[, !names(mtcars) %in% c("carb", "mpg")] 
mtcars[, -match(c("carb", "mpg"), names(mtcars))] 
mtcars2 <- mtcars; mtcars2$hp <- NULL         #lost column (risky)

remove.vars(mtcars2, names=c("mpg", "carb"), info=TRUE) 

Generally I use:

mtcars[, !names(mtcars) %in% c("carb", "mpg")] 

because I feel it's safe and efficient.

check for null date in CASE statement, where have I gone wrong?


    THEN 'Awaiting'
    ELSE 'Approved' END AS StartDateStatus
FROM myTable

You code would have been doing a When StartDate = NULL, I think.

NULL is never equal to NULL (as NULL is the absence of a value). NULL is also never not equal to NULL. The syntax noted above is ANSI SQL standard and the converse would be StartDate IS NOT NULL.

You can run the following:


And this returns:

EqualityCheck = 0
InEqualityCheck = 0
NullComparison = 1

For completeness, in SQL Server you can:


Which would result in your equals comparisons working differently:



Which returns:

EqualityCheck = 1
InEqualityCheck = 0
NullComparison = 1

But I would highly recommend against doing this. People subsequently maintaining your code might be compelled to hunt you down and hurt you...

Also, it will no longer work in upcoming versions of SQL server:

Going through a text file line by line in C

So many problems in so few lines. I probably forget some:

  • argv[0] is the program name, not the first argument;
  • if you want to read in a variable, you have to allocate its memory
  • one never loops on feof, one loops on an IO function until it fails, feof then serves to determinate the reason of failure,
  • sscanf is there to parse a line, if you want to parse a file, use fscanf,
  • "%s" will stop at the first space as a format for the ?scanf family
  • to read a line, the standard function is fgets,
  • returning 1 from main means failure


#include <stdio.h>

int main(int argc, char* argv[])
    char const* const fileName = argv[1]; /* should check that argc > 1 */
    FILE* file = fopen(fileName, "r"); /* should check the result */
    char line[256];

    while (fgets(line, sizeof(line), file)) {
        /* note that fgets don't strip the terminating \n, checking its
           presence would allow to handle lines longer that sizeof(line) */
        printf("%s", line); 
    /* may check feof here to make a difference between eof and io failure -- network
       timeout for instance */


    return 0;

How to use placeholder as default value in select2 framework

Put this in your script file:

    minimumResultsForSearch: -1,
    placeholder: function(){

And then in HTML, add the following code:

<select data-placeholder="Your Placeholder" multiple>
    <option></option> <------ this is where your placeholder data will appear
    <option>Value 1</option>
    <option>Value 2</option>
    <option>Value 3</option>
    <option>Value 4</option>
    <option>Value 5</option>

Get the Selected value from the Drop down box in PHP

Posting it from my project.

<select name="parent" id="parent"><option value="0">None</option>
 $allparent=mysql_query("select * from tbl_page_content where parent='0'");
   <option value="<?= $parent['id']; ?>" <?php if( $pageDetail['parent']==$parent['id'] ) { echo($select); }?>><?= $parent['name']; ?></option>

Executing multi-line statements in the one-line command-line?

(answered Nov 23 '10 at 19:48) I'm not really a big Pythoner - but I found this syntax once, forgot where from, so I thought I'd document it:

if you use sys.stdout.write instead of print (the difference being, sys.stdout.write takes arguments as a function, in parenthesis - whereas print doesn't), then for a one-liner, you can get away with inverting the order of the command and the for, removing the semicolon, and enclosing the command in square brackets, i.e.:

python -c "import sys; [sys.stdout.write('rob\n') for r in range(10)]"

Have no idea how this syntax would be called in Python :)

Hope this helps,


(EDIT Tue Apr 9 20:57:30 2013) Well, I think I finally found what these square brackets in one-liners are about; they are "list comprehensions" (apparently); first note this in Python 2.7:

$ STR=abc
$ echo $STR | python -c "import sys,re; a=(sys.stdout.write(line) for line in sys.stdin); print a"
<generator object <genexpr> at 0xb771461c>

So the command in round brackets/parenthesis is seen as a "generator object"; if we "iterate" through it by calling next() - then the command inside the parenthesis will be executed (note the "abc" in the output):

$ echo $STR | python -c "import sys,re; a=(sys.stdout.write(line) for line in sys.stdin); ; print a"
<generator object <genexpr> at 0xb777b734>

If we now use square brackets - note that we don't need to call next() to have the command execute, it executes immediately upon assignment; however, later inspection reveals that a is None:

$ echo $STR | python -c "import sys,re; a=[sys.stdout.write(line) for line in sys.stdin]; print a"

This doesn't leave much info to look for, for the square brackets case - but I stumbled upon this page which I think explains:

Python Tips And Tricks – First Edition - Python Tutorials | Dream.In.Code:

If you recall, the standard format of a single line generator is a kind of one line 'for' loop inside brackets. This will produce a 'one-shot' iterable object which is an object you can iterate over in only one direction and which you can't re-use once you reach the end.

A 'list comprehension' looks almost the same as a regular one-line generator, except that the regular brackets - ( ) - are replaced by square brackets - [ ]. The major advanatge of alist comprehension is that produces a 'list', rather than a 'one-shot' iterable object, so that you can go back and forth through it, add elements, sort, etc.

And indeed it is a list - it's just its first element becomes none as soon as it is executed:

$ echo $STR | python -c "import sys,re; print [sys.stdout.write(line) for line in sys.stdin].__class__"
<type 'list'>
$ echo $STR | python -c "import sys,re; print [sys.stdout.write(line) for line in sys.stdin][0]"

List comprehensions are otherwise documented in 5. Data Structures: 5.1.4. List Comprehensions — Python v2.7.4 documentation as "List comprehensions provide a concise way to create lists"; presumably, that's where the limited "executability" of lists comes into play in one-liners.

Well, hope I'm not terribly too off the mark here ...

EDIT2: and here is a one-liner command line with two non-nested for-loops; both enclosed within "list comprehension" square brackets:

$ echo $STR | python -c "import sys,re; a=[sys.stdout.write(line) for line in sys.stdin]; b=[sys.stdout.write(str(x)) for x in range(2)] ; print a ; print b"
[None, None]

Notice that the second "list" b now has two elements, since its for loop explicitly ran twice; however, the result of sys.stdout.write() in both cases was (apparently) None.

MS Access DB Engine (32-bit) with Office 64-bit

A similar approach to @Peter Coppins answer. This, I think, is a bit easier and doesn't require the use of the Orca utility:

  1. Check the "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\14.0\Common\FilesPaths" registry key and make sure the value "mso.dll" is NOT present. If it is present, then Office 64-bit seems to be installed and you should not need this workaround.

  2. Download the Microsoft Access Database Engine 2010 Redistributable.

  3. From the command line, run: AccessDatabaseEngine_x64.exe /passive

(Note: this installer silently crashed or failed for me, so I unzipped the components and ran: AceRedist.msi /passive and that installed fine. Maybe a Windows 10 thing.)

  1. Delete or rename the "mso.dll" value in the "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\14.0\Common\FilesPaths" key.

Source: How to install 64-bit Microsoft Database Drivers alongside 32-bit Microsoft Office

how to concat two columns into one with the existing column name in mysql?

Just Remove * from your select clause, and mention all column names explicitly and omit the FIRSTNAME column. After this write CONCAT(FIRSTNAME, ',', LASTNAME) AS FIRSTNAME. The above query will give you the only one FIRSTNAME column.

Not equal string

Try this:

if(myString != "-1")

The opperand is != and not =!

You can also use Equals


Note the ! before myString

How to set cursor position in EditText?

I want to set cursor position in edittext which contains no data

There is only one position in an empty EditText, it's setSelection(0).

Or did you mean you want to get focus to your EditText when your activity opens? In that case its requestFocus()

How to use basic authorization in PHP curl

Try the following code :


$ch = curl_init();
curl_setopt($ch, CURLOPT_URL,$URL);
curl_setopt($ch, CURLOPT_TIMEOUT, 30); //timeout after 30 seconds
curl_setopt($ch, CURLOPT_RETURNTRANSFER,1);
curl_setopt($ch, CURLOPT_USERPWD, "$username:$password");
$result=curl_exec ($ch);
$status_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);   //get status code
curl_close ($ch);

Get yesterday's date using Date

Calendar cal = Calendar.getInstance();
   DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
   System.out.println("Today's date is "+dateFormat.format(cal.getTime()));

   cal.add(Calendar.DATE, -1);
   System.out.println("Yesterday's date was "+dateFormat.format(cal.getTime())); 

Create File If File Does Not Exist

This works as well for me

string path = TextFile + ".txt";

if (!File.Exists(HttpContext.Current.Server.MapPath(path)))
using (StreamWriter w = File.AppendText(HttpContext.Current.Server.MapPath(path)))
    w.WriteLine("{0}", "Hello World");

How to append text to an existing file in Java?

Better to use try-with-resources then all that pre-java 7 finally business

static void appendStringToFile(Path file, String s) throws IOException  {
    try (BufferedWriter out = Files.newBufferedWriter(file, StandardCharsets.UTF_8, StandardOpenOption.APPEND)) {

Neither BindingResult nor plain target object for bean name available as request attr

We faced the same issue and changed commandname="" to modelAttribute="" in jsp page to solve this issue.

In Perl, how can I concisely check if a $variable is defined and contains a non zero length string?

It isn't always possible to do repetitive things in a simple and elegant way.

Just do what you always do when you have common code that gets replicated across many projects:

Search CPAN, someone may have already the code for you. For this issue I found Scalar::MoreUtils.

If you don't find something you like on CPAN, make a module and put the code in a subroutine:

package My::String::Util;
use strict;
use warnings;
our @ISA = qw( Exporter );
our @EXPORT = ();
our @EXPORT_OK = qw( is_nonempty);

use Carp  qw(croak);

sub is_nonempty ($) {
    croak "is_nonempty() requires an argument" 
        unless @_ == 1;

    no warnings 'uninitialized';

    return( defined $_[0] and length $_[0] != 0 );



blah blah blah

=head3 is_nonempty

Returns true if the argument is defined and has non-zero length.    

More boilerplate POD.


Then in your code call it:

use My::String::Util qw( is_nonempty );

if ( is_nonempty $name ) {
    # do something with $name

Or if you object to prototypes and don't object to the extra parens, skip the prototype in the module, and call it like: is_nonempty($name).

Append values to a set in Python

For me, in Python 3, it's working simply in this way:

keep = keep.union((0,1,2,3,4,5,6,7,8,9,10))

I don't know if it may be correct...

How do I know which version of Javascript I'm using?

Rather than finding which version you are using you can rephrase your question to "which version of ECMA script does my browser's JavaScript/JSscript engine conform to".

For IE :

alert(@_jscript_version);      //IE

Refer Squeegy's answer for non-IE versions :)

Process.start: how to get the output?

The standard .NET way of doing this is to read from the Process' StandardOutput stream. There is an example in the linked MSDN docs. Similar, you can read from StandardError, and write to StandardInput.

unbound method f() must be called with fibo_ instance as first argument (got classobj instance instead)

fibo = f.fibo references the class itself. You probably wanted fibo = f.fibo() (note the parentheses) to make an instance of the class, after which fibo.f() should succeed correctly.

f.fibo.f() fails because you are essentially calling f(self, a=0) without supplying self; self is "bound" automatically when you have an instance of the class.

Warning: The method assertEquals from the type Assert is deprecated

You're using junit.framework.Assert instead of org.junit.Assert.


ENABLEDELAYEDEXPANSION is a parameter passed to the SETLOCAL command (look at setlocal /?)

Its effect lives for the duration of the script, or an ENDLOCAL:

When the end of a batch script is reached, an implied ENDLOCAL is executed for any outstanding SETLOCAL commands issued by that batch script.

In particular, this means that if you use SETLOCAL ENABLEDELAYEDEXPANSION in a script, any environment variable changes are lost at the end of it unless you take special measures.

How can I call a method in Objective-C?

syntax is of objective c is

returnObj = [object functionName: parameters];

Where object is the object which has the method you're calling. If you're calling it from the same object, you'll use 'self'. This tutorial might help you out in learning Obj-C.

In your case it is simply

[self score];

If you want to pass a parameter then it is like that

- (void)score(int x) {
    // some code

and I have tried to call it in an other method like this:

- (void)score2 {
    [self score:x];

Where can I set path to make.exe on Windows?

The path is in the registry but usually you edit through this interface:

  1. Go to Control Panel -> System -> System settings -> Environment Variables.
  2. Scroll down in system variables until you find PATH.
  3. Click edit and change accordingly.
  4. BE SURE to include a semicolon at the end of the previous as that is the delimiter, i.e. c:\path;c:\path2
  5. Launch a new console for the settings to take effect.

How to find the parent element using javascript

Use the change event of the select:

   $(this).parents('td').css('background', '#000000');

iOS 7 App Icons, Launch images And Naming Convention While Keeping iOS 6 Icons

Okay adding to @null's awesome post about using the Asset Catalog.

You may need to do the following to get the App's Icon linked and working for Ad-Hoc distributions / production to be seen in Organiser, Test flight and possibly unknown AppStore locations.

After creating the Asset Catalog, take note of the name of the Launch Images and App Icon names listed in the .xassets in Xcode.

By Default this should be

  • AppIcon
  • LaunchImage

[To see this click on your .xassets folder/icon in Xcode.] (this can be changed, so just take note of this variable for later)

What is created now each build is the following data structures in your .app:

For App Icons:


  • AppIcon57x57.png (iPhone non retina) [Notice the Icon name prefix]
  • [email protected] (iPhone retina)

And the same format for each of the other icon resolutions.


  • AppIcon72x72~ipad.png (iPad non retina)
  • AppIcon72x72@2x~ipad.png (iPad retina)

(For iPad it is slightly different postfix)

Main Problem

Now I noticed that in my Info.plist in Xcode 5.0.1 it automatically attempted and failed to create a key for "Icon files (iOS 5)" after completing the creation of the Asset Catalog.

If it did create a reference successfully / this may have been patched by Apple or just worked, then all you have to do is review the image names to validate the format listed above.

Final Solution:

Add the following key to you main .plist

I suggest you open your main .plist with a external text editor such as TextWrangler rather than in Xcode to copy and paste the following key in.

            <string>[email protected]</string>

Please Note I have only included my example resolutions, you will need to add them all.

If you want to add this Key in Xcode without an external editor, Use the following:

  • Icon files (iOS 5) - Dictionary
  • Primary Icon - Dictionary
  • Icon files - Array
  • Item 0 - String = AppIcon57x57.png And for each other item / app icon.

Now when you finally archive your project the final .xcarchive payload .plist will now include the above stated icon locations to build and use.

Do not add the following to any .plist: Just an example of what Xcode will now generate for your final payload

    <string>Applications/[email protected]</string>

c# datagridview doubleclick on row with FullRowSelect

You get the index number of the row in the datagridview using northwind database employees tables as an example:

using System;
using System.Windows.Forms;

namespace WindowsFormsApplication5
    public partial class Form1 : Form
        public Form1()

        private void Form1_Load(object sender, EventArgs e)
            // TODO: This line of code loads data into the 'nORTHWNDDataSet.Employees' table. You can move, or remove it, as needed.


        private void dataGridView1_CellDoubleClick(object sender, DataGridViewCellEventArgs e)
            var dataIndexNo = dataGridView1.Rows[e.RowIndex].Index.ToString();
            string cellValue = dataGridView1.Rows[e.RowIndex].Cells[1].Value.ToString();

            MessageBox.Show("The row index = " + dataIndexNo.ToString() + " and the row data in second column is: "
                + cellValue.ToString());

the result will show you index number of record and the contents of the second table column in datagridview:

enter image description here

What is the proper way to comment functions in Python?

The correct way to do it is to provide a docstring. That way, help(add) will also spit out your comment.

def add(self):
    """Create a new user.
    Line 2 of comment...
    And so on... 

That's three double quotes to open the comment and another three double quotes to end it. You can also use any valid Python string. It doesn't need to be multiline and double quotes can be replaced by single quotes.

See: PEP 257

PostgreSQL unnest() with element number

Postgres 9.4 or later

Use WITH ORDINALITY for set-returning functions:

When a function in the FROM clause is suffixed by WITH ORDINALITY, a bigint column is appended to the output which starts from 1 and increments by 1 for each row of the function's output. This is most useful in the case of set returning functions such as unnest().

In combination with the LATERAL feature in pg 9.3+, and according to this thread on pgsql-hackers, the above query can now be written as:

SELECT, a.elem,
FROM   tbl AS t
LEFT   JOIN LATERAL unnest(string_to_array(t.elements, ','))
                    WITH ORDINALITY AS a(elem, nr) ON TRUE;

LEFT JOIN ... ON TRUE preserves all rows in the left table, even if the table expression to the right returns no rows. If that's of no concern you can use this otherwise equivalent, less verbose form with an implicit CROSS JOIN LATERAL:

SELECT, a.elem,
FROM   tbl t, unnest(string_to_array(t.elements, ',')) WITH ORDINALITY a(elem, nr);

Or simpler if based off an actual array (arr being an array column):

SELECT, a.elem,
FROM   tbl t, unnest(t.arr) WITH ORDINALITY a(elem, nr);

Or even, with minimal syntax:

SELECT id, a, ordinality
FROM   tbl, unnest(arr) WITH ORDINALITY a;

a is automatically table and column alias. The default name of the added ordinality column is ordinality. But it's better (safer, cleaner) to add explicit column aliases and table-qualify columns.

Postgres 8.4 - 9.3

With row_number() OVER (PARTITION BY id ORDER BY elem) you get numbers according to the sort order, not the ordinal number of the original ordinal position in the string.

You can simply omit ORDER BY:

SELECT *, row_number() OVER (PARTITION by id) AS nr
FROM  (SELECT id, regexp_split_to_table(elements, ',') AS elem FROM tbl) t;

While this normally works and I have never seen it fail in simple queries, PostgreSQL asserts nothing concerning the order of rows without ORDER BY. It happens to work due to an implementation detail.

To guarantee ordinal numbers of elements in the blank-separated string:

SELECT id, arr[nr] AS elem, nr
   SELECT *, generate_subscripts(arr, 1) AS nr
   FROM  (SELECT id, string_to_array(elements, ' ') AS arr FROM tbl) t
   ) sub;

Or simpler if based off an actual array:

SELECT id, arr[nr] AS elem, nr
FROM  (SELECT *, generate_subscripts(arr, 1) AS nr FROM tbl) t;

Related answer on dba.SE:

Postgres 8.1 - 8.4

None of these features are available, yet: RETURNS TABLE, generate_subscripts(), unnest(), array_length(). But this works:

CREATE FUNCTION f_unnest_ord(anyarray, OUT val anyelement, OUT ordinality integer)
'SELECT $1[i], i - array_lower($1,1) + 1
 FROM   generate_series(array_lower($1,1), array_upper($1,1)) i';

Note in particular, that the array index can differ from ordinal positions of elements. Consider this demo with an extended function:

CREATE FUNCTION f_unnest_ord_idx(anyarray, OUT val anyelement, OUT ordinality int, OUT idx int)
'SELECT $1[i], i - array_lower($1,1) + 1, i
 FROM   generate_series(array_lower($1,1), array_upper($1,1)) i';

SELECT id, arr, (rec).*
   SELECT *, f_unnest_ord_idx(arr) AS rec
   FROM  (VALUES (1, '{a,b,c}'::text[])  --  short for: '[1:3]={a,b,c}'
               , (2, '[5:7]={a,b,c}')
               , (3, '[-9:-7]={a,b,c}')
      ) t(id, arr)
   ) sub;

 id |       arr       | val | ordinality | idx
  1 | {a,b,c}         | a   |          1 |   1
  1 | {a,b,c}         | b   |          2 |   2
  1 | {a,b,c}         | c   |          3 |   3
  2 | [5:7]={a,b,c}   | a   |          1 |   5
  2 | [5:7]={a,b,c}   | b   |          2 |   6
  2 | [5:7]={a,b,c}   | c   |          3 |   7
  3 | [-9:-7]={a,b,c} | a   |          1 |  -9
  3 | [-9:-7]={a,b,c} | b   |          2 |  -8
  3 | [-9:-7]={a,b,c} | c   |          3 |  -7


How to check String in response body with mockMvc

Here is an example how to parse JSON response and even how to send a request with a bean in JSON form:

  protected MockMvc mvc;

  private static final ObjectMapper MAPPER = new ObjectMapper()
    .configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false)
    .configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false)
    .registerModule(new JavaTimeModule());

  public static String requestBody(Object request) {
    try {
      return MAPPER.writeValueAsString(request);
    } catch (JsonProcessingException e) {
      throw new RuntimeException(e);

  public static <T> T parseResponse(MvcResult result, Class<T> responseClass) {
    try {
      String contentAsString = result.getResponse().getContentAsString();
      return MAPPER.readValue(contentAsString, responseClass);
    } catch (IOException e) {
      throw new RuntimeException(e);

  public void testUpdate() {
    Book book = new Book();
    MvcResult requestResult = mvc.perform(post("")
    UpdateBookResponse updateBookResponse = parseResponse(requestResult, UpdateBookResponse.class);
    assertEquals("1984", updateBookResponse.getTitle());
    assertEquals("Orwell", updateBookResponse.getAuthor());

As you can see here the Book is a request DTO and the UpdateBookResponse is a response object parsed from JSON. You may want to change the Jackson's ObjectMapper configuration.

JSON.parse unexpected character error

You can make sure that the object in question is stringified before passing it to parse function by simply using JSON.stringify() .

Updated your line below,


or if you have JSON stored in some variable:


How to get a enum value from string in C#?

baseKey choice;
if (Enum.TryParse("HKEY_LOCAL_MACHINE", out choice)) {
     uint value = (uint)choice;

     // `value` is what you're looking for

} else { /* error: the string was not an enum member */ }

Before .NET 4.5, you had to do the following, which is more error-prone and throws an exception when an invalid string is passed:

(uint)Enum.Parse(typeof(baseKey), "HKEY_LOCAL_MACHINE")

Comparing two dictionaries and checking how many (key, value) pairs are equal

Below code will help you to compare list of dict in python

def compate_generic_types(object1, object2):
    if isinstance(object1, str) and isinstance(object2, str):
        return object1 == object2
    elif isinstance(object1, unicode) and isinstance(object2, unicode):
        return object1 == object2
    elif isinstance(object1, bool) and isinstance(object2, bool):
        return object1 == object2
    elif isinstance(object1, int) and isinstance(object2, int):
        return object1 == object2
    elif isinstance(object1, float) and isinstance(object2, float):
        return object1 == object2
    elif isinstance(object1, float) and isinstance(object2, int):
        return object1 == float(object2)
    elif isinstance(object1, int) and isinstance(object2, float):
        return float(object1) == object2

    return True

def deep_list_compare(object1, object2):
    retval = True
    count = len(object1)
    object1 = sorted(object1)
    object2 = sorted(object2)
    for x in range(count):
        if isinstance(object1[x], dict) and isinstance(object2[x], dict):
            retval = deep_dict_compare(object1[x], object2[x])
            if retval is False:
                print "Unable to match [{0}] element in list".format(x)
                return False
        elif isinstance(object1[x], list) and isinstance(object2[x], list):
            retval = deep_list_compare(object1[x], object2[x])
            if retval is False:
                print "Unable to match [{0}] element in list".format(x)
                return False
            retval = compate_generic_types(object1[x], object2[x])
            if retval is False:
                print "Unable to match [{0}] element in list".format(x)
                return False

    return retval

def deep_dict_compare(object1, object2):
    retval = True

    if len(object1) != len(object2):
        return False

    for k in object1.iterkeys():
        obj1 = object1[k]
        obj2 = object2[k]
        if isinstance(obj1, list) and isinstance(obj2, list):
            retval = deep_list_compare(obj1, obj2)
            if retval is False:
                print "Unable to match [{0}]".format(k)
                return False

        elif isinstance(obj1, dict) and isinstance(obj2, dict):
            retval = deep_dict_compare(obj1, obj2)
            if retval is False:
                print "Unable to match [{0}]".format(k)
                return False
            retval = compate_generic_types(obj1, obj2)
            if retval is False:
                print "Unable to match [{0}]".format(k)
                return False

    return retval

C# Linq Group By on multiple columns

var consolidatedChildren =
    from c in children
    group c by new
    } into gcs
    select new ConsolidatedChild()
        School = gcs.Key.School,
        Friend = gcs.Key.Friend,
        FavoriteColor = gcs.Key.FavoriteColor,
        Children = gcs.ToList(),

var consolidatedChildren =
        .GroupBy(c => new
        .Select(gcs => new ConsolidatedChild()
            School = gcs.Key.School,
            Friend = gcs.Key.Friend,
            FavoriteColor = gcs.Key.FavoriteColor,
            Children = gcs.ToList(),

How to align title at center of ActionBar in default theme(Theme.Holo.Light)

solution is based on these things:

  • you need to use your own class that extends Toolbar (support.v7.widget.toolbar)
  • you need to override one method Toolbar#addView

what does it do:

when first time toolbar is executing #setTitle, it creates AppCompatTextView and uses it to display title text.

when the AppCompatTextView is created, toolbar (as ViewGroup), adds it into it's own hierarchy with #addView method.

also, while trying to find solution i noticed that the textview has layout width set to "wrap_content", so i decided to make it "match_parent" and assign textalignment to "center".

MyToolbar.kt, skipping unrelated stuff (constructors/imports):

class MyToolbar : Toolbar {

  override fun addView(child: View, params: ViewGroup.LayoutParams) {
    if (child is TextView) {
        params.width = ViewGroup.LayoutParams.MATCH_PARENT
        child.textAlignment= View.TEXT_ALIGNMENT_CENTER
    super.addView(child, params)

possible "side effects" - this will apply to "subtitle" too

How to check if a file exists before creating a new file

Try this (copied-ish from Erik Garrison:

#include <sys/stat.h>

bool FileExists(char* filename) 
    struct stat fileInfo;
    return stat(filename, &fileInfo) == 0;

stat returns 0 if the file exists and -1 if not.

Item frequency count in Python

The answer below takes some extra cycles, but it is another method

def func(tup):
    return tup[-1]

def print_words(filename):
    f = open("small.txt",'r')
    whole_content = (
    print whole_content
    list_content = whole_content.split()
    dict = {}
    for one_word in list_content:
        dict[one_word] = 0
    for one_word in list_content:
        dict[one_word] += 1
    print dict.items()
    print sorted(dict.items(),key=func)

How to check if a variable exists in a FreeMarker template?

I think a lot of people are wanting to be able to check to see if their variable is not empty as well as if it exists. I think that checking for existence and emptiness is a good idea in a lot of cases, and makes your template more robust and less prone to silly errors. In other words, if you check to make sure your variable is not null AND not empty before using it, then your template becomes more flexible, because you can throw either a null variable or an empty string into it, and it will work the same in either case.

<#if p?? && p?has_content>1</#if>

Let's say you want to make sure that p is more than just whitespace. Then you could trim it before checking to see if it has_content.

<#if p?? && p?trim?has_content>1</#if>


Please ignore my suggestion -- has_content is all that is needed, as it does a null check along with the empty check. Doing p?? && p?has_content is equivalent to p?has_content, so you may as well just use has_content.

Do we have router.reload in vue-router?

Here's a solution if you just want to update certain components on a page:

In template

<Component1 :key="forceReload" />
<Component2 :key="forceReload" />

In data

data() {
  return {
    forceReload: 0

In methods:

   Methods: {
     reload() {
        this.forceReload += 1

Use a unique key and bind it to a data property for each one you want to update (I typically only need this for a single component, two at the most. If you need more, I suggest just refreshing the full page using the other answers.

I learned this from Michael Thiessen's post:

Disable sorting for a particular column in jQuery DataTables

This is what you're looking for:

$('#example').dataTable( {
      "aoColumnDefs": [
          { 'bSortable': false, 'aTargets': [ 1 ] }

How can I check if a string contains a character in C#?

The following should work:

var abc = "sAb";
bool exists = abc.IndexOf("ab", StringComparison.CurrentCultureIgnoreCase) > -1;

CSS Child vs Descendant selectors

Bascailly, "a b" selects all b's inside a, while "a>b" selects b's what are only children to the a, it will not select b what is child of b what is child of a.

This example illustrates the difference:

div span{background:red}


Background color of abc and def will be green, but ghi will have red background color.

IMPORTANT: If you change order of the rules to:

div span{background:red}

All letters will have red background, because descendant selector selects child's too.

How to print a dictionary line by line in Python?

I prefer the clean formatting of yaml:

import yaml


  color: 2
  speed: 70
  color: 3
  speed: 60

HTML input type=file, get the image before submitting the form

I found This simpler yet powerful tutorial which uses the fileReader Object. It simply creates an img element and, using the fileReader object, assigns its source attribute as the value of the form input

function previewFile() {_x000D_
  var preview = document.querySelector('img');_x000D_
  var file    = document.querySelector('input[type=file]').files[0];_x000D_
  var reader  = new FileReader();_x000D_
  reader.onloadend = function () {_x000D_
    preview.src = reader.result;_x000D_
  if (file) {_x000D_
  } else {_x000D_
    preview.src = "";_x000D_
<input type="file" onchange="previewFile()"><br>_x000D_
<img src="" height="200" alt="Image preview...">

What is the .idea folder?

As of year 2020, JetBrains suggests to commit the .idea folder.
The JetBrains IDEs (webstorm, intellij, android studio, pycharm, clion, etc.) automatically add that folder to your git repository (if there's one).
Inside the folder .idea, has been already created a .gitignore, updated by the IDE itself to avoid to commit user related settings that may contains privacy/password data.

It is safe (and usually useful) to commit the .idea folder.

how to save canvas as png image?

Try this:

jQuery('body').after('<a id="Download" target="_blank">Click Here</a>');

var canvas = document.getElementById('canvasID');
var ctx = canvas.getContext('2d');

document.getElementById('Download').addEventListener('click', function() {
    downloadCanvas(this, 'canvas', 'test.png');
}, false);

function downloadCanvas(link, canvasId, filename) {
    link.href = document.getElementById(canvasId).toDataURL();
    link.Download = filename;

You can just put this code in console in firefox or chrom and after changed your canvas tag ID in this above script and run this script in console.

After the execute this code you will see the link as text "click here" at bottom of the html page. click on this link and open the canvas drawing as a PNG image in new window save the image.

AngularJS - Create a directive that uses ng-model

Creating an isolate scope is undesirable. I would avoid using the scope attribute and do something like this. scope:true gives you a new child scope but not isolate. Then use parse to point a local scope variable to the same object the user has supplied to the ngModel attribute.

app.directive('myDir', ['$parse', function ($parse) {
    return {
        restrict: 'EA',
        scope: true,
        link: function (scope, elem, attrs) {
            if(!attrs.ngModel) {return;}
            var model = $parse(attrs.ngModel);
            scope.model = model(scope);

Regex in JavaScript for validating decimal numbers

I found that I could use


for more than two decimal places.

How to check postgres user and password?

You will not be able to find out the password he chose. However, you may create a new user or set a new password to the existing user.

Usually, you can login as the postgres user:

Open a Terminal and do sudo su postgres. Now, after entering your admin password, you are able to launch psql and do


This creates a new admin user. If you want to list the existing users, you could also do


to list all users and then

ALTER USER yourusername WITH PASSWORD 'yournewpass';

Ajax call Into MVC Controller- Url Issue

A good way to do it without getting the view involved may be:

    type: "POST",
    url: '/Controller/Search',
    data: { queryString: searchVal },
    success: function (data) {
      alert("here" + data.d.toString());

This will try to POST to the URL:

"http://domain/Controller/Search (which is the correct URL for the action you want to use)"

How to set a variable to current date and date-1 in linux?

you should man date first

date +%Y-%m-%d
date +%Y-%m-%d -d yesterday

How do I show a "Loading . . . please wait" message in Winforms for a long loading form?

or if you don't want anything fancy like animation etc. you can create a label and dock it to form then change it's z-index from document outline window to 0 and give it a background color so other controls wont be visible than run Application.DoEvents() once in form load event and do all your coding in form shown event and at the and of shown event set your label visible property to false then run Application.DoEvents() again.

How do I create a link using javascript?

      var a = document.createElement('a');
      var linkText = document.createTextNode("my title text");
      a.title = "my title text";
      a.href = "";

getFilesDir() vs Environment.getDataDirectory()

Environment returns user data directory. And getFilesDir returns application data directory.

Vue.js - How to properly watch for nested data

Personally I prefer this clean implementation:

watch: {
  myVariable: {
     handler(newVal, oldVal){  // here having access to the new and old value
       // do stuff
     deep: true,
     immediate: true //  Also very important the immediate in case you need it, the callback will be called immediately after the start of the observation


How to Publish Web with msbuild?

For generating the publish output provide one more parameter. msbuild example.sln /p:publishprofile=profilename /p:deployonbuild=true /p:configuration=debug/or any

How to escape strings in SQL Server using PHP?

I have been using this as an alternative of mysql_real_escape_string():

function htmlsan($htmlsanitize){
    return $htmlsanitize = htmlspecialchars($htmlsanitize, ENT_QUOTES, 'UTF-8');
$data = "Whatever the value's is";
$data = stripslashes(htmlsan($data));

How can I force Python's file.write() to use the same newline format in Windows as in Linux ("\r\n" vs. "\n")?

You can still use the textmode and force the linefeed-newline with the keyword argument newline

f = open("./foo",'w',newline='\n')

Tested with Python 3.4.2.

Edit: This does not work in Python 2.7.

Get HTML5 localStorage keys

Since the question mentioned finding the keys, I figured I'd mention that to show every key and value pair, you could do it like this (based on Kevin's answer):

for ( var i = 0, len = localStorage.length; i < len; ++i ) {
  console.log( localStorage.key( i ) + ": " + localStorage.getItem( localStorage.key( i ) ) );

This will log the data in the format "key: value"

(Kevin: feel free to just take this info into the your answer if you want!)

Quicker way to get all unique values of a column in VBA?

Try this

Option Explicit

Sub UniqueValues()
Dim ws As Worksheet
Dim uniqueRng As Range
Dim myCol As Long

myCol = 5 '<== set it as per your needs
Set ws = ThisWorkbook.Worksheets("unique") '<== set it as per your needs

Set uniqueRng = GetUniqueValues(ws, myCol)

End Sub

Function GetUniqueValues(ws As Worksheet, col As Long) As Range
Dim firstRow As Long

With ws
    .Columns(col).RemoveDuplicates Columns:=Array(1), header:=xlNo

    firstRow = 1
    If IsEmpty(.Cells(1, col)) Then firstRow = .Cells(1, col).End(xlDown).row

    Set GetUniqueValues = Range(.Cells(firstRow, col), .Cells(.Rows.Count, col).End(xlUp))
End With

End Function

it should be quite fast and without the drawback NeepNeepNeep told about

How can I get a List from some class properties with Java 8 Stream?

You can use map :

List<String> names =


In order to combine the Lists of friend names, you need to use flatMap :

List<String> friendNames =

How can I convert my Java program to an .exe file?


The Java Packager tool compiles, packages, and prepares Java and JavaFX applications for distribution. The javapackager command is the command-line version.

– Oracle's documentation

The javapackager utility ships with the JDK. It can generate .exe files with the -native exe flag, among many other things.


WinRun4j is a java launcher for windows. It is an alternative to javaw.exe and provides the following benefits:

  • Uses an INI file for specifying classpath, main class, vm args, program args.
  • Custom executable name that appears in task manager.
  • Additional JVM args for more flexible memory use.
  • Built-in icon replacer for custom icon.
  • [more bullet points follow]

– WinRun4J's webpage

WinRun4J is an open source utility. It has many features.


Packages your JAR, assets and a JVM for distribution on Windows, Linux and Mac OS X, adding a native executable file to make it appear like a native app. Packr is most suitable for GUI applications.

– packr README

packr is another open source tool.


JSmooth is a Java Executable Wrapper. It creates native Windows launchers (standard .exe) for your java applications. It makes java deployment much smoother and user-friendly, as it is able to find any installed Java VM by itself.

– JSmooth's website

JSmooth is open source and has features, but it is very old. The last release was in 2007.


JexePack is a command line tool (great for automated scripting) that allows you to package your Java application (class files), optionally along with its resources (like GIF/JPG/TXT/etc), into a single compressed 32-bit Windows EXE, which runs using Sun's Java Runtime Environment. Both console and windowed applications are supported.

– JexePack's website

JexePack is trialware. Payment is required for production use, and exe files created with this tool will display "reminders" without payment. Also, the last release was in 2013.


InstallAnywhere makes it easy for developers to create professional installation software for any platform. With InstallAnywhere, you’ll adapt to industry changes quickly, get to market faster and deliver an engaging customer experience. And know the vulnerability of your project’s OSS components before you ship.

– InstallAnywhere's website

InstallAnywhere is a commercial/enterprise package that generates installers for Java-based programs. It's probably capable of creating .exe files.

Executable JAR files

As an alternative to .exe files, you can create a JAR file that automatically runs when double-clicked, by adding an entry point to the JAR manifest.

For more information

An excellent source of information on this topic is Excelsior's article "Convert Java to EXE – Why, When, When Not and How".

See also the companion article "Best JAR to EXE Conversion Tools, Free and Commercial".

How can I initialize a C# List in the same line I declare it. (IEnumerable string Collection Example)

Change the code to

List<string> nameslist = new List<string> {"one", "two", "three"};


List<string> nameslist = new List<string>(new[] {"one", "two", "three"});

How to set space between listView Items in Android

Simplest solution with OP's existing code (list items already have got padding) is to add following code:

listView.setDivider(new ColorDrawable(Color.TRANSPARENT));  //hide the divider
listView.setClipToPadding(false);   // list items won't clip, so padding stays

This SO answer helped me.

Note: You may face a bug of the list item recycling too soon on older platforms, as has been asked here.

Best practices for styling HTML emails

In addition to the answers posted here, make sure you read this article:

Appending a list to a list of lists in R

The purrr package has a lot of handy functions for working on lists. The flatten command can clean up unwanted nesting.

resultsa <- list(1,2,3,4,5)
resultsb <- list(6,7,8,9,10)
resultsc <- list(11,12,13,14,15)

nested_outlist <- list(resultsa, resultsb, resultsc)
outlist <- purrr::flatten(nested_outlist)

How to check if a float value is a whole number

To check if a float value is a whole number, use the float.is_integer() method:

>>> (1.0).is_integer()
>>> (1.555).is_integer()

The method was added to the float type in Python 2.6.

Take into account that in Python 2, 1/3 is 0 (floor division for integer operands!), and that floating point arithmetic can be imprecise (a float is an approximation using binary fractions, not a precise real number). But adjusting your loop a little this gives:

>>> for n in range(12000, -1, -1):
...     if (n ** (1.0/3)).is_integer():
...         print n

which means that anything over 3 cubed, (including 10648) was missed out due to the aforementioned imprecision:

>>> (4**3) ** (1.0/3)
>>> 10648 ** (1.0/3)

You'd have to check for numbers close to the whole number instead, or not use float() to find your number. Like rounding down the cube root of 12000:

>>> int(12000 ** (1.0/3))
>>> 22 ** 3

If you are using Python 3.5 or newer, you can use the math.isclose() function to see if a floating point value is within a configurable margin:

>>> from math import isclose
>>> isclose((4**3) ** (1.0/3), 4)
>>> isclose(10648 ** (1.0/3), 22)

For older versions, the naive implementation of that function (skipping error checking and ignoring infinity and NaN) as mentioned in PEP485:

def isclose(a, b, rel_tol=1e-9, abs_tol=0.0):
    return abs(a - b) <= max(rel_tol * max(abs(a), abs(b)), abs_tol)

Inserting a PDF file in LaTeX

Use the pdfpages package.


To include all the pages in the PDF file:


To include just the first page of a PDF:


Run texdoc pdfpages in a shell to see the complete manual for pdfpages.

How to present UIActionSheet iOS Swift?

Action Sheet in iOS10 with Swift3.0. Follow this link.

 @IBAction func ShowActionSheet(_ sender: UIButton) {
    // Create An UIAlertController with Action Sheet

    let optionMenuController = UIAlertController(title: nil, message: "Choose Option from Action Sheet", preferredStyle: .actionSheet)

    // Create UIAlertAction for UIAlertController

    let addAction = UIAlertAction(title: "Add", style: .default, handler: {
        (alert: UIAlertAction!) -> Void in
        print("File has been Add")
    let saveAction = UIAlertAction(title: "Edit", style: .default, handler: {
        (alert: UIAlertAction!) -> Void in
        print("File has been Edit")

    let deleteAction = UIAlertAction(title: "Delete", style: .default, handler: {
        (alert: UIAlertAction!) -> Void in
        print("File has been Delete")
    let cancelAction = UIAlertAction(title: "Cancel", style: .cancel, handler: {
        (alert: UIAlertAction!) -> Void in

    // Add UIAlertAction in UIAlertController


    // Present UIAlertController with Action Sheet

    self.present(optionMenuController, animated: true, completion: nil)


PHP equivalent of .NET/Java's toString()

Putting it in double quotes should work:

$myText = "$myVar";

WordPress - Check if user is logged in

This problem is from the lazy update data request of Chrome. At the first time you go to homepage. Chrome request with empty data. Then you go to the login page and logged in. When you back home page Chrome lazy to update the cookie data request because this domain is the same with the first time you access. Solution: Add parameter for home url. That helps Chrome realizes that this request need to update cookie to call to the server.

add at dashboard page

$track = '?track='.uniqid();
<a href="<?= get_home_url(). $track ?>"> <img src="/img/logo.svg"></a>

How do I draw a shadow under a UIView?

Swift 3

self.paddingView.layer.masksToBounds = false
self.paddingView.layer.shadowOffset = CGSize(width: -15, height: 10)
self.paddingView.layer.shadowRadius = 5
self.paddingView.layer.shadowOpacity = 0.5

Failed to resolve:

Go to SDK path: SDK\extras\android\m2repository\com\android\support\appcompat-v7 to see correct dependency name, then change name if your dependency is alpha version:

dependencies {
  compile fileTree(dir: 'libs', include: ['*.jar'])
  compile ''

to :

dependencies {
  compile fileTree(dir: 'libs', include: ['*.jar'])
  compile ''

Cycles in an Undirected Graph

DFS APPROACH WITH A CONDITION(parent != next node) Let's see the code and then understand what's going on :

bool Graph::isCyclicUtil(int v, bool visited[], int parent) 
    // Mark the current node as visited 
    visited[v] = true; 

    // Recur for all the vertices adjacent to this vertex 
    list<int>::iterator i; 
    for (i = adj[v].begin(); i != adj[v].end(); ++i) 
        // If an adjacent is not visited, then recur for that adjacent 
        if (!visited[*i]) 
           if (isCyclicUtil(*i, visited, v)) 
              return true; 

        // If an adjacent is visited and not parent of current vertex, 
        // then there is a cycle. 
        else if (*i != parent) 
           return true; 
    return false; 

The above code explains itself but I will try to explain one condition i.e *i != parent Here if suppose graph is


Then when we are at 1 and goes to 2, the parent for 2 becomes 1 and when we go back to 1 as 1 is in adj matrix of 2 then since next vertex 1 is also the parent of 2 Therefore cycle will not be detected for the immediate parent in this DFS approach. Hence Code works fine

How do I commit case-sensitive only filename changes in Git?

You can use git mv:

git mv -f OldFileNameCase newfilenamecase

jQuery same click event for multiple elements

$('.class1, .class2').on('click', some_function);


$('.class1').add('.class2').on('click', some_function);

This also works with existing objects:

const $class1 = $('.class1');
const $class2 = $('.class2');
$class1.add($class2).on('click', some_function);

The type is defined in an assembly that is not referenced, how to find the cause?

It just happened to me that different projects were referencing different copies of the same dll. I made sure all referenced the same file on disk, and the error disappeared as I expected.

Convert a JSON String to a HashMap

Using json-simple you can convert data JSON to Map and Map to JSON.

    JSONObject obj11 = new JSONObject();
    obj11.put(1, "Kishan");
    obj11.put(2, "Radhesh");
    obj11.put(3, "Sonal");
    obj11.put(4, "Madhu");

    Map map = new  HashMap();


    map = obj11;


    JSONObject obj12 = new JSONObject();

    obj12 = (JSONObject) map;

catch(Exception e)
    System.err.println("EROR : 01 :"+e);

How to submit a form on enter when the textarea has focus?

You can't do this without JavaScript. Stackoverflow is using the jQuery JavaScript library which attachs functions to HTML elements on page load.

Here's how you could do it with vanilla JavaScript:

<textarea onkeydown="if (event.keyCode == 13) { this.form.submit(); return false; }"></textarea>

Keycode 13 is the enter key.

Here's how you could do it with jQuery like as Stackoverflow does:

<textarea class="commentarea"></textarea>


$(document).ready(function() {
    $('.commentarea').keydown(function(event) {
        if (event.which == 13) {

How should I set the default proxy to use default credentials?

For those who, unlike Brian Genisio, are able to set the contents of their application's config file:- don't do anything in code. Instead add this to your app.config / web.config.

  <defaultProxy useDefaultCredentials="true" />

Really and truly the default for using the default credentials should be "true"; I've seen this issue confuse so many people - developers, users, IT guys.

For more info see here:-

UPDATE: I've created this issue/idea for Microsoft to change the default of useDefaultCredentials from false to true so that this whole problem goes away and .NET apps "just work"; please vote it up if you agree:

How to Parse a JSON Object In Android

In your JSON format, it do not have starting JSON object

Like :

    "info" :       <!-- this is starting JSON object -->

Above Json starts with info as JSON object. So while executing :

JSONObject json = new JSONObject(result);    // create JSON obj from string
JSONObject json2 = json.getJSONObject("info");    // this will return correct

Now, we can access result field :

JSONObject jsonResult = json2.getJSONObject("results");
test = json2.getString("name"); // returns "Marina Rasche Werft GmbH & Co. KG"

I think this was missing and so the problem was solved while we use JSONTokener like answer of yours.

Your answer is very fine. Just i think i add this information so i answered

Thank you

How to hide action bar before activity is created, and then show it again?

The best way to do this is two make the first activity as blank activity and the content you want to put and then after some time fire another activity. By following this way you can make the first activity as your splash screen without action bar or anything. Heres my first activity

package com.superoriginal.rootashadnasim.syllabus;

import android.content.Intent;
import android.os.Handler;
import android.os.Bundle;

public class first_screen extends AppCompatActivity {

protected void onCreate(Bundle savedInstanceState) {

    final Handler h=new Handler();
    h.postDelayed(new Runnable() {
        public void run() {
            Intent intent=new     Intent(getApplicationContext(),DrawerChooseBranchMainActivity.class);


After that you can put any of your activity as first activity If you want no action bar in any screen then just add this in your styles

    <item name="windowActionBar">false</item>
    <item name="windowNoTitle">true</item>

How do I tokenize a string sentence in NLTK?

This is actually on the main page of

>>> import nltk
>>> sentence = """At eight o'clock on Thursday morning
... Arthur didn't feel very good."""
>>> tokens = nltk.word_tokenize(sentence)
>>> tokens
['At', 'eight', "o'clock", 'on', 'Thursday', 'morning',
'Arthur', 'did', "n't", 'feel', 'very', 'good', '.']

How to restore the menu bar in Visual Studio Code

In version 1.36.1 I tried to follow the steps mentioned in the previous answers and noticed that the Toggle Menu Bar has moved to a different location and has been renamed to Show Menu Bar. Follow these steps:

  1. Press Alt to make menu visible
  2. Click on the View menu, navigate to the Appearance option and choose Show Menu Bar

SQL 'LIKE' query using '%' where the search criteria contains '%'

Select * from table where name like search_criteria

if you are expecting the user to add their own wildcards...

Round up double to 2 decimal places

Just single line of code:

 let obj = self.arrayResult[indexPath.row]
 let str = String(format: "%.2f", arguments: [Double((obj.mainWeight)!)!])

$(document).ready(function(){ Uncaught ReferenceError: $ is not defined

many other people answered your question above. This problen arises when your script don't find the jQuery script and if you are using other framework or cms then maybe there is a conflict between jQuery and other libraries. In my case i used as following- `

<script src="js_directory/jquery.1.7.min.js"></script>
    //your other code here


here might be some syntax error. Please forgive me because i'm writing from my cell phone. Thanks

React router nav bar example

Yes, Daniel is correct, but to expand upon his answer, your primary app component would need to have a navbar component within it. That way, when you render the primary app (any page under the '/' path), it would also display the navbar. I am guessing that you wouldn't want your login page to display the navbar, so that shouldn't be a nested component, and should instead be by itself. So your routes would end up looking something like this:

  <Route path="/" component={App}>
    <Route path="page1" component={Page1} />
    <Route path="page2" component={Page2} />
  <Route path="/login" component={Login} />

And the other components would look something like this:

var NavBar = React.createClass({
  render() {
    return (
          <a onClick={() => history.push('page1') }>Page 1</a>
          <a onClick={() => history.push('page2') }>Page 2</a>

var App = React.createClass({
  render() {
    return (
        <NavBar />
        <div>Other Content</div>

How to set TLS version on apache HttpClient

You could just specify the following property -Dhttps.protocols=TLSv1.1,TLSv1.2 at your server which configures the JVM to specify which TLS protocol version should be used during all https connections from client.

The client and server cannot communicate, because they do not possess a common algorithm - ASP.NET C# IIS TLS 1.0 / 1.1 / 1.2 - Win32Exception

There are several other posts about this now and they all point to enabling TLS 1.2. Anything less is unsafe.

You can do this in .NET 3.5 with a patch.
You can do this in .NET 4.0 and 4.5 with a single line of code

ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12; // .NET 4.5
ServicePointManager.SecurityProtocol = (SecurityProtocolType)3072; // .NET 4.0

In .NET 4.6, it automatically uses TLS 1.2.

See here for more details: .NET support for TLS

How can I center an image in Bootstrap?

Image by default is displayed as inline-block, you need to display it as block in order to center it with .mx-auto. This can be done with built-in .d-block:

<div class="container">
    <div class="row">
        <div class="col-4">
            <img class="mx-auto d-block" src="...">  

Or leave it as inline-block and wrapped it in a div with .text-center:

<div class="container">
    <div class="row">
        <div class="col-4">
          <div class="text-center">
            <img src="..."> 

I made a fiddle showing both ways. They are documented here as well.

Unsetting array values in a foreach loop

foreach($images as $key => $image)
    if(in_array($image, array(

How to download dependencies in gradle

I have found this answer also very helpful:

gradle dependencies will list the dependencies and download them as a side-effect.

Code for printf function in C

Here's the GNU version of printf... you can see it passing in stdout to vfprintf:

__printf (const char *format, ...)
   va_list arg;
   int done;

   va_start (arg, format);
   done = vfprintf (stdout, format, arg);
   va_end (arg);

   return done;

See here.

Here's a link to vfprintf... all the formatting 'magic' happens here.

The only thing that's truly 'different' about these functions is that they use varargs to get at arguments in a variable length argument list. Other than that, they're just traditional C. (This is in contrast to Pascal's printf equivalent, which is implemented with specific support in the compiler... at least it was back in the day.)

counting number of directories in a specific directory

Get a count of only the directories in the current directory

echo */ | wc

you will get out put like 1 309 4594

2nd digit represents no. of directories.


tree -L 1 | tail -1

Why am I suddenly getting a "Blocked loading mixed active content" issue in Firefox?

Simply changing HTTP to HTTPS solved this issue for me.


<script src=""></script>


<script src=""></script>

running php script (php function) in linux bash

php -f test.php

See the manual for full details of running PHP from the command line

const to Non-const Conversion in C++

Leaving this here for myself,

If I get this error, I probably used const char* when I should be using char* const.

This makes the pointer constant, and not the contents of the string.

const char* const makes it so the value and the pointer is constant also.

calling parent class method from child class object in java

Use the keyword super within the overridden method in the child class to use the parent class method. You can only use the keyword within the overridden method though. The example below will help.

public class Parent {
    public int add(int m, int n){
        return m+n;

public class Child extends Parent{
    public int add(int m,int n,int o){
        return super.add(super.add(m, n),0);


public class SimpleInheritanceTest {
    public static void main(String[] a){
        Child child = new Child();
        child.add(10, 11);

The add method in the Child class calls super.add to reuse the addition logic.

How to convert map to url query string?

You can use a Stream for this, but instead of appending query parameters myself I'd use a Uri.Builder. For example:

final Map<String, String> map = new HashMap<>();
map.put("param1", "cat");
map.put("param2", "12");

final Uri uri = 
        () -> Uri.parse("relativeUrl").buildUpon(),
        (builder, e) -> builder.appendQueryParameter(e.getKey(), e.getValue()),
        (b1, b2) -> { throw new UnsupportedOperationException(); }

//Or, if you consider it more readable...
final Uri.Builder builder = Uri.parse("relativeUrl").buildUpon();
map.entrySet().forEach(e -> builder.appendQueryParameter(e.getKey(), e.getValue())
final Uri uri =;


assertEquals(Uri.parse("relativeUrl?param1=cat&param2=12"), uri);

addClass and removeClass in jQuery - not removing class

I would recomend to cache the jQuery objects you use more than once. For Instance:

    $(document).on("click", ".clickable", function () {

would be:

    var doc = $(document);
    doc.on('click', '.clickable', function(){
       var currentClickedObject = $(this);

its actually more code, BUT it is muuuuuuch faster because you dont have to "walk" through the whole jQuery library in order to get the $(this) object.

How to get child element by ID in JavaScript?

Here is a pure JavaScript solution (without jQuery)

var _Utils = function ()
    this.findChildById = function (element, childID, isSearchInnerDescendant) // isSearchInnerDescendant <= true for search in inner childern 
        var retElement = null;
        var lstChildren = isSearchInnerDescendant ? Utils.getAllDescendant(element) : element.childNodes;

        for (var i = 0; i < lstChildren.length; i++)
            if (lstChildren[i].id == childID)
                retElement = lstChildren[i];

        return retElement;

    this.getAllDescendant = function (element, lstChildrenNodes)
        lstChildrenNodes = lstChildrenNodes ? lstChildrenNodes : [];

        var lstChildren = element.childNodes;

        for (var i = 0; i < lstChildren.length; i++) 
            if (lstChildren[i].nodeType == 1) // 1 is 'ELEMENT_NODE'
                lstChildrenNodes = Utils.getAllDescendant(lstChildren[i], lstChildrenNodes);

        return lstChildrenNodes;
var Utils = new _Utils;

Example of use:

var myDiv = document.createElement("div");
myDiv.innerHTML = "<table id='tableToolbar'>" +
                        "<tr>" +
                            "<td>" +
                                "<div id='divIdToSearch'>" +
                                "</div>" +
                            "</td>" +
                        "</tr>" +

var divToSearch = Utils.findChildById(myDiv, "divIdToSearch", true);

Cannot simply use PostgreSQL table name ("relation does not exist")

Easiest workaround is Just change the table name and all column names to lowercase and your issue will be resolved.

For example:

  • Change Table_Name to table_name and
  • Change ColumnName to columnname

Make Bootstrap's Carousel both center AND responsive?

Add a class to each image in the carousel html code, then with css apply margin: 0 auto.

FileNotFoundException while getting the InputStream object from HttpURLConnection

The solution:
just change localhost for the IP of your PC
if you want to know this: Windows+r > cmd > ipconfig
just replace for your own IP (don't try because it's same as localhost)

Python: can't assign to literal

This is taken from the Python docs:

Identifiers (also referred to as names) are described by the following lexical definitions:

identifier ::=  (letter|"_") (letter | digit | "_")*

letter     ::=  lowercase | uppercase

lowercase  ::=  "a"..."z"

uppercase  ::=  "A"..."Z"

digit      ::=  "0"..."9"

Identifiers are unlimited in length. Case is significant.

That should explain how to name your variables.

SQL Server reports 'Invalid column name', but the column is present and the query works through management studio

I suspect that you have two tables with the same name. One is owned by the schema 'dbo' (dbo.PerfDiag), and the other is owned by the default schema of the account used to connect to SQL Server (something like userid.PerfDiag).

When you have an unqualified reference to a schema object (such as a table) — one not qualified by schema name — the object reference must be resolved. Name resolution occurs by searching in the following sequence for an object of the appropriate type (table) with the specified name. The name resolves to the first match:

  • Under the default schema of the user.
  • Under the schema 'dbo'.

The unqualified reference is bound to the first match in the above sequence.

As a general recommended practice, one should always qualify references to schema objects, for performance reasons:

  • An unqualified reference may invalidate a cached execution plan for the stored procedure or query, since the schema to which the reference was bound may change depending on the credentials executing the stored procedure or query. This results in recompilation of the query/stored procedure, a performance hit. Recompilations cause compile locks to be taken out, blocking others from accessing the needed resource(s).

  • Name resolution slows down query execution as two probes must be made to resolve to the likely version of the object (that owned by 'dbo'). This is the usual case. The only time a single probe will resolve the name is if the current user owns an object of the specified name and type.

[Edited to further note]

The other possibilities are (in no particular order):

  • You aren't connected to the database you think you are.
  • You aren't connected to the SQL Server instance you think you are.

Double check your connect strings and ensure that they explicitly specify the SQL Server instance name and the database name.

What is the usefulness of PUT and DELETE HTTP request methods?

Although I take the risk of not being popular I say they are not useful nowadays.

I think they were well intended and useful in the past when for example DELETE told the server to delete the resource found at supplied URL and PUT (with its sibling PATCH) told the server to do update in an idempotent manner.

Things evolved and URLs became virtual (see url rewriting for example) making resources lose their initial meaning of real folder/subforder/file and so, CRUD action verbs covered by HTTP protocol methods (GET, POST, PUT/PATCH, DELETE) lost track.

Let's take an example:

  • /api/entity/list/{id} vs GET /api/entity/{id}
  • /api/entity/add/{id} vs POST /api/entity
  • /api/entity/edit/{id} vs PUT /api/entity/{id}
  • /api/entity/delete/{id} vs DELETE /api/entity/{id}

On the left side is not written the HTTP method, essentially it doesn't matter (POST and GET are enough) and on the right side appropriate HTTP methods are used.

Right side looks elegant, clean and professional. Imagine now you have to maintain a code that's been using the elegant API and you have to search where deletion call is done. You'll search for "api/entity" and among results you'll have to see which one is doing DELETE. Or even worse, you have a junior programmer which by mistake switched PUT with DELETE and as URL is the same shit happened.

In my opinion putting the action verb in the URL has advantages over using the appropriate HTTP method for that action even if it's not so elegant. If you want to see where delete call is made you just have to search for "api/entity/delete" and you'll find it straight away.

Building an API without the whole HTTP array of methods makes it easier to be consumed and maintained afterwards

Read lines from a file into a Bash array

One alternate way if file contains strings without spaces with 1string each line:

fileItemString=$(cat  filename |tr "\n" " ")



Print whole Array: