How to properly override clone method?

There are two cases in which the CloneNotSupportedException will be thrown:

The class being cloned does not implemented Cloneable (assuming that the actual cloning eventually defers to Object's clone method). If the class you are writing this method in implements Cloneable, this will never happen (since any sub-classes will inherit it appropriately).
The exception is explicitly thrown by an implementation - this is the recommended way to prevent clonability in a subclass when the superclass is Cloneable.

The latter case cannot occur in your class (as you're directly calling the superclass' method in the try block, even if invoked from a subclass calling super.clone()) and the former should not since your class clearly should implement Cloneable.

Basically, you should log the error for sure, but in this particular instance it will only happen if you mess up your class' definition. Thus treat it like a checked version of NullPointerException (or similar) - it will never be thrown if your code is functional.

In other situations you would need to be prepared for this eventuality - there is no guarantee that a given object is cloneable, so when catching the exception you should take appropriate action depending on this condition (continue with the existing object, take an alternative cloning strategy e.g. serialize-deserialize, throw an IllegalParameterException if your method requires the parameter by cloneable, etc. etc.).

Edit: Though overall I should point out that yes, clone() really is difficult to implement correctly and difficult for callers to know whether the return value will be what they want, doubly so when you consider deep vs shallow clones. It's often better just to avoid the whole thing entirely and use another mechanism.

"insufficient memory for the Java Runtime Environment " message in eclipse

If you are on ec2 and wanted to do mvn build then use -T option which tells maven to use number of threads while doing build

eg:mvn -T 10 clean package

Detecting the onload event of a window opened with window.open

onload event handler must be inside popup's HTML <body> markup.

How to set null to a GUID property

Choose your poison - if you can't change the type of the property to be nullable then you're going to have to use a "magic" value to represent NULL. Guid.Empty seems as good as any unless you have some specific reason for not wanting to use it. A second choice would be Guid.Parse("ffffffff-ffff-ffff-ffff-ffffffffffff") but that's a lot uglier IMHO.

How do you check whether a number is divisible by another number (Python)?

You can use % operator to check divisiblity of a given number

The code to check whether given no. is divisible by 3 or 5 when no. less than 1000 is given below:

n=0
while n<1000:
    if n%3==0 or n%5==0:
        print n,'is multiple of 3 or 5'
    n=n+1

C++11 rvalues and move semantics confusion (return statement)

As already mentioned in comments to the first answer, the return std::move(...); construct can make a difference in cases other than returning of local variables. Here's a runnable example that documents what happens when you return a member object with and without std::move():

#include <iostream>
#include <utility>

struct A {
  A() = default;
  A(const A&) { std::cout << "A copied\n"; }
  A(A&&) { std::cout << "A moved\n"; }
};

class B {
  A a;
 public:
  operator A() const & { std::cout << "B C-value: "; return a; }
  operator A() & { std::cout << "B L-value: "; return a; }
  operator A() && { std::cout << "B R-value: "; return a; }
};

class C {
  A a;
 public:
  operator A() const & { std::cout << "C C-value: "; return std::move(a); }
  operator A() & { std::cout << "C L-value: "; return std::move(a); }
  operator A() && { std::cout << "C R-value: "; return std::move(a); }
};

int main() {
  // Non-constant L-values
  B b;
  C c;
  A{b};    // B L-value: A copied
  A{c};    // C L-value: A moved

  // R-values
  A{B{}};  // B R-value: A copied
  A{C{}};  // C R-value: A moved

  // Constant L-values
  const B bc;
  const C cc;
  A{bc};   // B C-value: A copied
  A{cc};   // C C-value: A copied

  return 0;
}

Presumably, return std::move(some_member); only makes sense if you actually want to move the particular class member, e.g. in a case where class C represents short-lived adapter objects with the sole purpose of creating instances of struct A.

Notice how struct A always gets copied out of class B, even when the class B object is an R-value. This is because the compiler has no way to tell that class B's instance of struct A won't be used any more. In class C, the compiler does have this information from std::move(), which is why struct A gets moved, unless the instance of class C is constant.

Jquery DatePicker Set default date

Today date:

$( ".selector" ).datepicker( "setDate", new Date());
// Or on the init
$( ".selector" ).datepicker({ defaultDate: new Date() });

15 days from today:

$( ".selector" ).datepicker( "setDate", 15);
// Or on the init
$( ".selector" ).datepicker({ defaultDate: 15 });

jQuery ui docs

Check if MySQL table exists or not

Use this query and then check the results.

$query = 'show tables like "test1"';

How to change the remote repository for a git submodule?

These commands will do the work on command prompt without altering any files on local repository

git config --file=.gitmodules submodule.Submod.url https://github.com/username/ABC.git
git config --file=.gitmodules submodule.Submod.branch Development
git submodule sync
git submodule update --init --recursive --remote

Please look at the blog for screenshots: Changing GIT submodules URL/Branch to other URL/branch of same repository

VS2010 How to include files in project, to copy them to build output directory automatically during build or publish

Just so my fellow neuronically impaired comrades might chance upon it here, I had assumed that, for web projects, if the linked file was an external .config file that the "output directory" would be the same directory that web.config lives in, i.e. your web project's root. In retrospect, it is entirely unsurprising that it copies the linked file into the root/bin folder.

So, if it's an appSettings include file, your web.config's open tag would be

<appSettings file=".\bin\includedAppSettingsFile.config">

Duh.

How can I select and upload multiple files with HTML and PHP, using HTTP POST?

Full solution in Firefox 5:

<html>
<head>
</head>
<body>
 <form name="uploader" id="uploader" action="multifile.php" method="POST" enctype="multipart/form-data" >
  <input id="infile" name="infile[]" type="file" onBlur="submit();" multiple="true" ></input> 
 </form>

<?php
echo "No. files uploaded : ".count($_FILES['infile']['name'])."<br>"; 


$uploadDir = "images/";
for ($i = 0; $i < count($_FILES['infile']['name']); $i++) {

 echo "File names : ".$_FILES['infile']['name'][$i]."<br>";
 $ext = substr(strrchr($_FILES['infile']['name'][$i], "."), 1); 

 // generate a random new file name to avoid name conflict
 $fPath = md5(rand() * time()) . ".$ext";

 echo "File paths : ".$_FILES['infile']['tmp_name'][$i]."<br>";
 $result = move_uploaded_file($_FILES['infile']['tmp_name'][$i], $uploadDir . $fPath);

 if (strlen($ext) > 0){
  echo "Uploaded ". $fPath ." succefully. <br>";
 }
}
echo "Upload complete.<br>";
?>

</body>
</html>

Android Intent Cannot resolve constructor

Or you can simply start the activity as shown below;

startActivity( new Intent(currentactivity.this, Tostartactivity.class));

Is it possible to clone html element objects in JavaScript / JQuery?

You need to select "#foo2" as your selector. Then, get it with html().

Here is the html:

<div id="foo1">

</div>
<div id="foo2">
    <div>Foo Here</div>
</div>?

Here is the javascript:

$("#foo2").click(function() {
    //alert("clicked");
    var value=$(this).html();
    $("#foo1").html(value);
});?

Here is the jsfiddle: http://jsfiddle.net/fritzdenim/DhCjf/

How can I pass selected row to commandLink inside dataTable or ui:repeat?

In JSF 1.2 this was done by <f:setPropertyActionListener> (within the command component). In JSF 2.0 (EL 2.2 to be precise, thanks to BalusC) it's possible to do it like this: action="${filterList.insert(f.id)}

What is the proper way to comment functions in Python?

I would go for a documentation practice that integrates with a documentation tool such as Sphinx.

The first step is to use a docstring:

def add(self):
 """ Method which adds stuff
 """

Highlight Anchor Links when user manually scrolls?

You can use Jquery's on method and listen for the scroll event.

How to keep a VMWare VM's clock in sync?

Something to note here. We had the same issue with Windows VM's running on an ESXi host. The time sync was turned on in VMWare Tools on the guest, but the guest clocks were consistently off (by about 30 seconds) from the host clock. The ESXi host was configured to get time updates from an internal time server.

It turns out we had the Internet Time setting turned on in the Windows VM's (Control Panel > Date and Time > Internet Time tab) so the guest was getting time updates from two places and the internet time was winning. We turned that off and now the guest clocks are good, getting their time exclusively from the ESXi host.

How to remove non UTF-8 characters from text file

Your method must read byte by byte and fully understand and appreciate the byte wise construction of characters. The simplest method is to use an editor which will read anything but only output UTF-8 characters. Textpad is one choice.

jQuery Set Select Index

Select the item based on the value in the select list (especially if the option values have a space or weird character in it) by simply doing this:

$("#SelectList option").each(function () {
    if ($(this).val() == "1:00 PM")
        $(this).attr('selected', 'selected');
});

Also, if you have a dropdown (as opposed to a multi-select) you may want to do a break; so you don't get the first-value-found to be overwritten.

Angularjs - ng-cloak/ng-show elements blink

I personally decided to use the ng-class attribute rather than the ng-show. I've had a lot more success going this route especially for pop-up windows that are always not shown by default.

What used to be <div class="options-modal" ng-show="showOptions"></div>

is now: <div class="options-modal" ng-class="{'show': isPrintModalShown}">

with the CSS for the options-modal class being display: none by default. The show class contains the display:block CSS.

How to Get a Specific Column Value from a DataTable?

string countryName = "USA";
DataTable dt = new DataTable();
int id = (from DataRow dr in dt.Rows
              where (string)dr["CountryName"] == countryName
              select (int)dr["id"]).FirstOrDefault();

Jump into interface implementation in Eclipse IDE

Here's what I do:

In the interface, move the cursor to the method name. Press F4. => Type Hierarchy view appears
In the lower part of the view, the method should already be selected. In its toolbar, click "Lock view and show members in hierarchy" (should be the leftmost toolbar icon).
In the upper part of the view, you can browse through all implementations of the method.

The procedure isn't very quick, but it gives you a good overview.

ping: google.com: Temporary failure in name resolution

If you get the IP address from a DHCP server, you can also set the server to send a DNS server. Or add the nameserver 8.8.8.8 into /etc/resolvconf/resolv.conf.d/base file. The information in this file is included in the resolver configuration file even when no interfaces are configured.

How to try convert a string to a Guid

Unfortunately, there isn't a TryParse() equivalent. If you create a new instance of a System.Guid and pass the string value in, you can catch the three possible exceptions it would throw if it is invalid.

Those are:

ArgumentNullException
FormatException
OverflowException

I have seen some implementations where you can do a regex on the string prior to creating the instance, if you are just trying to validate it and not create it.

How do I use Assert to verify that an exception has been thrown?

if you use NUNIT, you can do something like this:

Assert.Throws<ExpectedException>(() => methodToTest());

It is also possible to store the thrown exception in order to validate it further:

ExpectedException ex = Assert.Throws<ExpectedException>(() => methodToTest());
Assert.AreEqual( "Expected message text.", ex.Message );
Assert.AreEqual( 5, ex.SomeNumber);

See: http://nunit.org/docs/2.5/exceptionAsserts.html

addID in jQuery?

Like this :

var id = $('div.foo').attr('id');
$('div.foo').attr('id', id + ' id_adding');

get actual ID
put actuel ID and add the new one

How to disable compiler optimizations in gcc?

You can disable optimizations if you pass -O0 with the gcc command-line.

E.g. to turn a .C file into a .S file call:

gcc -O0 -S test.c

How can I access "static" class variables within class methods in Python?

Define class method:

class Foo(object):
    bar = 1
    @classmethod
    def bah(cls):    
        print cls.bar

Now if bah() has to be instance method (i.e. have access to self), you can still directly access the class variable.

class Foo(object):
    bar = 1
    def bah(self):    
        print self.bar

Capturing window.onbeforeunload

To pop a message when the user is leaving the page to confirm leaving, you just do:

<script>
    window.onbeforeunload = function(e) {
      return 'Are you sure you want to leave this page?  You will lose any unsaved data.';
    };
</script>

To call a function:

<script>
    window.onbeforeunload = function(e) {
       callSomeFunction();
       return null;
    };
</script>

Not able to pip install pickle in python 3.6

$ pip install pickle5

import pickle5 as pickle

pb = pickle.PickleBuffer(b"foo")
data = pickle.dumps(pb, protocol=5)
assert pickle.loads(data) == b"foo"

This package backports all features and APIs added in the pickle module in Python 3.8.3, including the PEP 574 additions. It should work with Python 3.5, 3.6 and 3.7.

Basic usage is similar to the pickle module, except that the module to be imported is pickle5:

https://pypi.org/project/pickle5/

Converting data frame column from character to numeric

If we need only one column to be numeric

yyz$b <- as.numeric(as.character(yyz$b))

But, if all the columns needs to changed to numeric, use lapply to loop over the columns and convert to numeric by first converting it to character class as the columns were factor.

yyz[] <- lapply(yyz, function(x) as.numeric(as.character(x)))

Both the columns in the OP's post are factor because of the string "n/a". This could be easily avoided while reading the file using na.strings = "n/a" in the read.table/read.csv or if we are using data.frame, we can have character columns with stringsAsFactors=FALSE (the default is stringsAsFactors=TRUE)

Regarding the usage of apply, it converts the dataset to matrix and matrix can hold only a single class. To check the class, we need

lapply(yyz, class)

sapply(yyz, class)

Or check

str(yyz)

How to check permissions of a specific directory?

To check the permission configuration of a file, use the command:

ls –l [file_name]

To check the permission configuration of a directory, use the command:

ls –l [Directory-name]

nodejs get file name from absolute path?

So Nodejs comes with the default global variable called '__fileName' that holds the current file being executed My advice is to pass the __fileName to a service from any file , so that the retrieval of the fileName is made dynamic

Below, I make use of the fileName string and then split it based on the path.sep. Note path.sep avoids issues with posix file seperators and windows file seperators (issues with '/' and '\'). It is much cleaner. Getting the substring and getting only the last seperated name and subtracting it with the actulal length by 3 speaks for itself.

You can write a service like this (Note this is in typescript , but you can very well write it in js )

export class AppLoggingConstants {

    constructor(){

    }
      // Here make sure the fileName param is actually '__fileName'
    getDefaultMedata(fileName: string, methodName: string) {
        const appName = APP_NAME;
        const actualFileName = fileName.substring(fileName.lastIndexOf(path.sep)+1, fileName.length - 3);
        //const actualFileName = fileName;
     return appName+ ' -- '+actualFileName;
    }


}

export const AppLoggingConstantsInstance = new AppLoggingConstants();

Image Processing: Algorithm Improvement for 'Coca-Cola Can' Recognition

Maybe too many years late, but nevertheless a theory to try.

The ratio of bounding rectangle of red logo region to the overall dimension of the bottle/can is different. In the case of Can, should be 1:1, whereas will be different in that of bottle (with or without cap). This should make it easy to distinguish between the two.

Update: The horizontal curvature of the logo region will be different between the Can and Bottle due their respective size difference. This could be specifically useful if your robot needs to pick up can/bottle, and you decide the grip accordingly.

How to compile and run C in sublime text 3?

Instruction is base on the "icemelon" post. Link to the post:

how-do-i-compile-and-run-a-c-program-in-sublime-text-2

Use the link below to find out how to setup enviroment variable on your OS:

c_environment_setup

The instruction below was tested on the Windows 8.1 system and Sublime Text 3 - build 3065.

1) Install MinGW. 2) Add path to the "MinGW\bin" in the "PATH environment variable".

"System Properties -> Advanced -> Environment" variables and there update "PATH' variable.

3) Then check your PATH environment variable by the command below in the "Command Prompt":

echo %path%

4) Add new Build System to the Sublime Text.

My version of the code below ("C.sublime-build").

link to the code:

C.sublime-build

// Put this file here:
// "C:\Users\[User Name]\AppData\Roaming\Sublime Text 3\Packages\User"
// Use "Ctrl+B" to Build and "Crtl+Shift+B" to Run the project.
// OR use "Tools -> Build System -> New Build System..." and put the code there.

{
    "cmd" : ["gcc", "$file_name", "-o", "${file_base_name}.exe"],

    // Doesn't work, sublime text 3, Windows 8.1    
    // "cmd" : ["gcc $file_name -o ${file_base_name}"],

    "selector" : "source.c",
    "shell": true,
    "working_dir" : "$file_path",

    // You could add path to your gcc compiler this and don't add path to your "PATH environment variable"
    // "path" : "C:\\MinGW\\bin"

    "variants" : [

        { "name": "Run",
          "cmd" : ["${file_base_name}.exe"]
        }
    ]
}

Html code as IFRAME source rather than a URL

You can do this with a data URL. This includes the entire document in a single string of HTML. For example, the following HTML:

<html><body>foo</body></html>

can be encoded as this:

data:text/html;charset=utf-8,%3Chtml%3E%3Cbody%3Efoo%3C/body%3E%3C/html%3E

and then set as the src attribute of the iframe. Example.

Edit: The other alternative is to do this with Javascript. This is almost certainly the technique I'd choose. You can't guarantee how long a data URL the browser will accept. The Javascript technique would look something like this:

var iframe = document.getElementById('foo'),
    iframedoc = iframe.contentDocument || iframe.contentWindow.document;

iframedoc.body.innerHTML = 'Hello world';

Example

Edit 2 (December 2017): use the Html5's srcdoc attribute, just like in Saurabh Chandra Patel's answer, who now should be the accepted answer! If you can detect IE/Edge efficiently, a tip is to use srcdoc-polyfill library only for them and the "pure" srcdoc attribute in all non-IE/Edge browsers (check caniuse.com to be sure).

<iframe srcdoc="<html><body>Hello, <b>world</b>.</body></html>"></iframe>

Reading a key from the Web.Config using ConfigurationManager

I found this solution to be quite helpful. It uses C# 4.0 DynamicObject to wrap the ConfigurationManager. So instead of accessing values like this:

 WebConfigurationManager.AppSettings["PFUserName"]

you access them as a property:

dynamic appSettings = new AppSettingsWrapper();
Console.WriteLine(appSettings.PFUserName);

EDIT: Adding code snippet in case link becomes stale:

public class AppSettingsWrapper : DynamicObject
{
     private NameValueCollection _items;

    public AppSettingsWrapper()
    {
        _items = ConfigurationManager.AppSettings;
    }

     public override bool TryGetMember(GetMemberBinder binder, out object result)
    {
        result = _items[binder.Name];
        return result != null;
    }
}

javascript create array from for loop

even shorter if you can lose the yearStart value:

var yearStart = 2000;
var yearEnd = 2040;

var arr = [];

while(yearStart < yearEnd+1){
  arr.push(yearStart++);
}

UPDATE: If you can use the ES6 syntax you can do it the way proposed here:

let yearStart = 2000;
let yearEnd = 2040;
let years = Array(yearEnd-yearStart+1)
    .fill()
    .map(() => yearStart++);

How do I use LINQ Contains(string[]) instead of Contains(string)

If you are truly looking to replicate Contains, but for an array, here is an extension method and sample code for usage:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ContainsAnyThingy
{
    class Program
    {
        static void Main(string[] args)
        {
            string testValue = "123345789";

            //will print true
            Console.WriteLine(testValue.ContainsAny("123", "987", "554")); 

            //but so will this also print true
            Console.WriteLine(testValue.ContainsAny("1", "987", "554"));
            Console.ReadKey();

        }
    }

    public static class StringExtensions
    {
        public static bool ContainsAny(this string str, params string[] values)
        {
            if (!string.IsNullOrEmpty(str) || values.Length > 0)
            {
                foreach (string value in values)
                {
                    if(str.Contains(value))
                        return true;
                }
            }

            return false;
        }
    }
}

How do I initialize Kotlin's MutableList to empty MutableList?

I do like below to :

var book: MutableList<Books> = mutableListOf()

/** Returns a new [MutableList] with the given elements. */

public fun <T> mutableListOf(vararg elements: T): MutableList<T>
    = if (elements.size == 0) ArrayList() else ArrayList(ArrayAsCollection(elements, isVarargs = true))

Cycles in an Undirected Graph

A connected, undirected graph G that has no cycles is a tree! Any tree has exactly n - 1 edges, so we can simply traverse the edge list of the graph and count the edges. If we count n - 1 edges then we return “yes” but if we reach the nth edge then we return “no”. This takes O (n) time because we look at at most n edges.

But if the graph is not connected,then we would have to use DFS. We can traverse through the edges and if any unexplored edges lead to the visited vertex then it has cycle.

Selenium and xPath - locating a link by containing text

Use this

//*[@id='popover-search']/div/div/ul/li[1]/a/span[contains(text(),'Some text')]

//*[@id='popover-search']/div/div/ul/li[1]/a/span[contains(.,'Some text')]

ORA-12516, TNS:listener could not find available handler

I fixed this problem with sql command line:

connect system/<password>
alter system set processes=300 scope=spfile;
alter system set sessions=300 scope=spfile;

Restart database.

How to use Scanner to accept only valid int as input

What you could do is also to take the next token as a String, converts this string to a char array and test that each character in the array is a digit.

I think that's correct, if you don't want to deal with the exceptions.

Convert A String (like testing123) To Binary In Java

This is my implementation.

public class Test {
    public String toBinary(String text) {
        StringBuilder sb = new StringBuilder();

        for (char character : text.toCharArray()) {
            sb.append(Integer.toBinaryString(character) + "\n");
        }

        return sb.toString();

    }
}

Lining up labels with radio buttons in bootstrap

Best is to just Apply margin-top: 2px on the input element.

Bootstrap adds a margin-top: 4px to input element causing radio button to move down than the content.

SQL to Entity Framework Count Group-By

Here is a simple example of group by in .net core 2.1

var query = this.DbContext.Notifications.
            Where(n=> n.Sent == false).
            GroupBy(n => new { n.AppUserId })
            .Select(g => new { AppUserId = g.Key, Count =  g.Count() });

var query2 = from n in this.DbContext.Notifications
            where n.Sent == false
            group n by n.AppUserId into g
            select new { id = g.Key,  Count = g.Count()};

Which translates to:

SELECT [n].[AppUserId], COUNT(*) AS [Count]
FROM [Notifications] AS [n]
WHERE [n].[Sent] = 0
GROUP BY [n].[AppUserId]

Getting error: Peer authentication failed for user "postgres", when trying to get pgsql working with rails

If you have an issue, you need to locate your pg_hba.conf. The command is:

find / -name 'pg_hba.conf' 2>/dev/null

and after that change the configuration file:

Postgresql 9.3

Postgresql 9.4

The next step is: Restarting your db instance:

service postgresql-9.3 restart

If you have any problems, you need to set password again:

ALTER USER db_user with password 'db_password';

Update label from another thread

Use MethodInvoker for updating label text in other thread.

private void AggiornaContatore()
{
    MethodInvoker inv = delegate 
    {
      this.lblCounter.Text = this.index.ToString(); 
    }

 this.Invoke(inv);
}

You are getting the error because your UI thread is holding the label, and since you are trying to update it through another thread you are getting cross thread exception.

You may also see: Threading in Windows Forms

PostgreSQL delete all content

The content of the table/tables in PostgreSQL database can be deleted in several ways.

Deleting table content using sql:

Deleting content of one table:

TRUNCATE table_name;
DELETE FROM table_name;

Deleting content of all named tables:

TRUNCATE table_a, table_b, …, table_z;

Deleting content of named tables and tables that reference to them (I will explain it in more details later in this answer):

TRUNCATE table_a, table_b CASCADE;

Deleting table content using pgAdmin:

Deleting content of one table:

Right click on the table -> Truncate

Deleting content of table and tables that reference to it:

Right click on the table -> Truncate Cascaded

Difference between delete and truncate:

From the documentation:

DELETE deletes rows that satisfy the WHERE clause from the specified table. If the WHERE clause is absent, the effect is to delete all rows in the table. http://www.postgresql.org/docs/9.3/static/sql-delete.html

TRUNCATE is a PostgreSQL extension that provides a faster mechanism to remove all rows from a table. TRUNCATE quickly removes all rows from a set of tables. It has the same effect as an unqualified DELETE on each table, but since it does not actually scan the tables it is faster. Furthermore, it reclaims disk space immediately, rather than requiring a subsequent VACUUM operation. This is most useful on large tables. http://www.postgresql.org/docs/9.1/static/sql-truncate.html

Working with table that is referenced from other table:

When you have database that has more than one table the tables have probably relationship. As an example there are three tables:

create table customers (
customer_id int not null,
name varchar(20),
surname varchar(30),
constraint pk_customer primary key (customer_id)
);

create table orders (
order_id int not null,
number int not null,
customer_id int not null,
constraint pk_order primary key (order_id),
constraint fk_customer foreign key (customer_id) references customers(customer_id)
);

create table loyalty_cards (
card_id int not null,
card_number varchar(10) not null,
customer_id int not null,
constraint pk_card primary key (card_id),
constraint fk_customer foreign key (customer_id) references customers(customer_id)
);

And some prepared data for these tables:

insert into customers values (1, 'John', 'Smith');

insert into orders values 
(10, 1000, 1),
(11, 1009, 1),
(12, 1010, 1);        

insert into loyalty_cards values (100, 'A123456789', 1);

Table orders references table customers and table loyalty_cards references table customers. When you try to TRUNCATE / DELETE FROM the table that is referenced by other table/s (the other table/s has foreign key constraint to the named table) you get an error. To delete content from all three tables you have to name all these tables (the order is not important)

TRUNCATE customers, loyalty_cards, orders;

or just the table that is referenced with CASCADE key word (you can name more tables than just one)

TRUNCATE customers CASCADE;

The same applies for pgAdmin. Right click on customers table and choose Truncate Cascaded.

How to find file accessed/created just few minutes ago

To find files accessed 1, 2, or 3 minutes ago use -3

find . -cmin -3

Javascript - check array for value

If you don't care about legacy browsers:

if ( bank_holidays.indexOf( '06/04/2012' ) > -1 )

if you do care about legacy browsers, there is a shim available on MDN. Otherwise, jQuery provides an equivalent function:

if ( $.inArray( '06/04/2012', bank_holidays ) > -1 )

How to remove old Docker containers

You can use the following command to remove the exited containers:

docker rm $(sudo docker ps -a | grep Exit | cut -d ' ' -f 1)

Here is the full gist to also remove the old images on docker: Gist to remove old Docker containers and images.

Best way to list files in Java, sorted by Date Modified?

Elegant solution since Java 8:

File[] files = directory.listFiles();
Arrays.sort(files, Comparator.comparingLong(File::lastModified));

Or, if you want it in descending order, just reverse it:

File[] files = directory.listFiles();
Arrays.sort(files, Comparator.comparingLong(File::lastModified).reversed());

Calculate relative time in C#

Here's how I do it

var ts = new TimeSpan(DateTime.UtcNow.Ticks - dt.Ticks);
double delta = Math.Abs(ts.TotalSeconds);

if (delta < 60)
{
  return ts.Seconds == 1 ? "one second ago" : ts.Seconds + " seconds ago";
}
if (delta < 60 * 2)
{
  return "a minute ago";
}
if (delta < 45 * 60)
{
  return ts.Minutes + " minutes ago";
}
if (delta < 90 * 60)
{
  return "an hour ago";
}
if (delta < 24 * 60 * 60)
{
  return ts.Hours + " hours ago";
}
if (delta < 48 * 60 * 60)
{
  return "yesterday";
}
if (delta < 30 * 24 * 60 * 60)
{
  return ts.Days + " days ago";
}
if (delta < 12 * 30 * 24 * 60 * 60)
{
  int months = Convert.ToInt32(Math.Floor((double)ts.Days / 30));
  return months <= 1 ? "one month ago" : months + " months ago";
}
int years = Convert.ToInt32(Math.Floor((double)ts.Days / 365));
return years <= 1 ? "one year ago" : years + " years ago";

Suggestions? Comments? Ways to improve this algorithm?

How to put table in the center of the page using CSS?

How to detect when facebook's FB.init is complete

Here is a solution in case you use jquery and Facebook Asynchronous Lazy Loading:

// listen to an Event
$(document).bind('fbInit',function(){
    console.log('fbInit complete; FB Object is Available');
});

// FB Async
window.fbAsyncInit = function() {
    FB.init({appId: 'app_id', 
         status: true, 
         cookie: true,
         oauth:true,
         xfbml: true});

    $(document).trigger('fbInit'); // trigger event
};

How to create a GUID in Excel?

As of modern version of Excel, there's the syntax with commas, not semicolons. I'm posting this answer for convenience of others so they don't have to replace the strings- We're all lazy... hrmp... human, right?

=CONCATENATE(DEC2HEX(RANDBETWEEN(0,4294967295),8),"-",DEC2HEX(RANDBETWEEN(0,42949),4),"-",DEC2HEX(RANDBETWEEN(0,42949),4),"-",DEC2HEX(RANDBETWEEN(0,42949),4),"-",DEC2HEX(RANDBETWEEN(0,4294967295),8),DEC2HEX(RANDBETWEEN(0,42949),4))

Or, if you like me dislike when a guid screams and shouts and you, we can go lower-cased like this.

=LOWER(CONCATENATE(DEC2HEX(RANDBETWEEN(0,4294967295),8),"-",DEC2HEX(RANDBETWEEN(0,42949),4),"-",DEC2HEX(RANDBETWEEN(0,42949),4),"-",DEC2HEX(RANDBETWEEN(0,42949),4),"-",DEC2HEX(RANDBETWEEN(0,4294967295),8),DEC2HEX(RANDBETWEEN(0,42949),4)))

How can I install a local gem?

If you create your gems with bundler:

# do this in the proper directory
bundle gem foobar

You can install them with rake after they are written:

# cd into your gem directory
rake install

Chances are, that your downloaded gem will know rake install, too.

<button> background image

Delete "button" before # rock:

button #rock {
    background: url(img/rock.png) no-repeat;
}

Worked for me in Google Chrome.

What Regex would capture everything from ' mark to the end of a line?

In your example I'd go for the following pattern:

'([^\n]+)$

use multiline and global options to match all occurences.

To include the linefeed in the match you could use:

'[^\n]+\n

But this might miss the last line if it has no linefeed.

For a single line, if you don't need to match the linefeed I'd prefer to use:

'[^$]+$

Can't clone a github repo on Linux via HTTPS

As JERC said, make sure you have an updated version of git. If you are only using the default settings, when you try to install git you will get version 1.7.1. Other than manually downloading and installing the latest version of get, you can also accomplish this by adding a new repository to yum.

From tecadmin.net:

Download and install the rpmforge repository:

# use this for 64-bit
rpm -i 'http://pkgs.repoforge.org/rpmforge-release/rpmforge-release-0.5.3-1.el6.rf.x86_64.rpm'
# use this for 32-bit
rpm -i 'http://pkgs.repoforge.org/rpmforge-release/rpmforge-release-0.5.3-1.el6.rf.i686.rpm'

# then run this in either case
rpm --import http://apt.sw.be/RPM-GPG-KEY.dag.txt

Then you need to enable the rpmforge-extras. Edit /etc/yum.repos.d/rpmforge.repo and change enabled = 0 to enabled = 1 under [rpmforge-extras]. The file looks like this:

### Name: RPMforge RPM Repository for RHEL 6 - dag
### URL: http://rpmforge.net/
[rpmforge]
name = RHEL $releasever - RPMforge.net - dag
baseurl = http://apt.sw.be/redhat/el6/en/$basearch/rpmforge
mirrorlist = http://mirrorlist.repoforge.org/el6/mirrors-rpmforge
#mirrorlist = file:///etc/yum.repos.d/mirrors-rpmforge
enabled = 1
protect = 0
gpgkey = file:///etc/pki/rpm-gpg/RPM-GPG-KEY-rpmforge-dag
gpgcheck = 1

[rpmforge-extras]
name = RHEL $releasever - RPMforge.net - extras
baseurl = http://apt.sw.be/redhat/el6/en/$basearch/extras
mirrorlist = http://mirrorlist.repoforge.org/el6/mirrors-rpmforge-extras
#mirrorlist = file:///etc/yum.repos.d/mirrors-rpmforge-extras
enabled = 0 ####### CHANGE THIS LINE TO "enabled = 1" #############
protect = 0
gpgkey = file:///etc/pki/rpm-gpg/RPM-GPG-KEY-rpmforge-dag
gpgcheck = 1

[rpmforge-testing]
name = RHEL $releasever - RPMforge.net - testing
baseurl = http://apt.sw.be/redhat/el6/en/$basearch/testing
mirrorlist = http://mirrorlist.repoforge.org/el6/mirrors-rpmforge-testing
#mirrorlist = file:///etc/yum.repos.d/mirrors-rpmforge-testing
enabled = 0
protect = 0
gpgkey = file:///etc/pki/rpm-gpg/RPM-GPG-KEY-rpmforge-dag
gpgcheck = 1

Once you've done this, then you can update git with

yum update git

I'm not sure why, but they then suggest disabling rpmforge-extras (change back to enabled = 0) and then running yum clean all.

Most likely you'll need to use sudo for these commands.

When to use Comparable and Comparator

There had been a similar question here: When should a class be Comparable and/or Comparator?

I would say the following: Implement Comparable for something like a natural ordering, e.g. based on an internal ID

Implement a Comparator if you have a more complex comparing algorithm, e.g. multiple fields and so on.

C++ String Declaring

C++ supplies a string class that can be used like this:

#include <string>
#include <iostream>

int main() {
    std::string Something = "Some text";
    std::cout << Something << std::endl;
}

How can I create a copy of an object in Python?

Shallow copy with copy.copy()

#!/usr/bin/env python3

import copy

class C():
    def __init__(self):
        self.x = [1]
        self.y = [2]

# It copies.
c = C()
d = copy.copy(c)
d.x = [3]
assert c.x == [1]
assert d.x == [3]

# It's shallow.
c = C()
d = copy.copy(c)
d.x[0] = 3
assert c.x == [3]
assert d.x == [3]

Deep copy with copy.deepcopy()

#!/usr/bin/env python3
import copy
class C():
    def __init__(self):
        self.x = [1]
        self.y = [2]
c = C()
d = copy.deepcopy(c)
d.x[0] = 3
assert c.x == [1]
assert d.x == [3]

Documentation: https://docs.python.org/3/library/copy.html

Tested on Python 3.6.5.

What is the default value for Guid?

You can use these methods to get an empty guid. The result will be a guid with all it's digits being 0's - "00000000-0000-0000-0000-000000000000".

new Guid()

default(Guid)

Guid.Empty

.NET console application as Windows service

So here's the complete walkthrough:

Create new Console Application project (e.g. MyService)
Add two library references: System.ServiceProcess and System.Configuration.Install
Add the three files printed below
Build the project and run "InstallUtil.exe c:\path\to\MyService.exe"
Now you should see MyService on the service list (run services.msc)

*InstallUtil.exe can be usually found here: C:\windows\Microsoft.NET\Framework\v4.0.30319\InstallUtil.ex??e

Program.cs

using System;
using System.IO;
using System.ServiceProcess;

namespace MyService
{
    class Program
    {
        public const string ServiceName = "MyService";

        static void Main(string[] args)
        {
            if (Environment.UserInteractive)
            {
                // running as console app
                Start(args);

                Console.WriteLine("Press any key to stop...");
                Console.ReadKey(true);

                Stop();
            }
            else
            {
                // running as service
                using (var service = new Service())
                {
                    ServiceBase.Run(service);
                }
            }
        }

        public static void Start(string[] args)
        {
            File.AppendAllText(@"c:\temp\MyService.txt", String.Format("{0} started{1}", DateTime.Now, Environment.NewLine));
        }

        public static void Stop()
        {
            File.AppendAllText(@"c:\temp\MyService.txt", String.Format("{0} stopped{1}", DateTime.Now, Environment.NewLine));
        }
    }
}

MyService.cs

using System.ServiceProcess;

namespace MyService
{
    class Service : ServiceBase
    {
        public Service()
        {
            ServiceName = Program.ServiceName;
        }

        protected override void OnStart(string[] args)
        {
            Program.Start(args);
        }

        protected override void OnStop()
        {
            Program.Stop();
        }
    }
}

MyServiceInstaller.cs

using System.ComponentModel;
using System.Configuration.Install;
using System.ServiceProcess;

namespace MyService
{
    [RunInstaller(true)]
    public class MyServiceInstaller : Installer
    {
        public MyServiceInstaller()
        {
            var spi = new ServiceProcessInstaller();
            var si = new ServiceInstaller();

            spi.Account = ServiceAccount.LocalSystem;
            spi.Username = null;
            spi.Password = null;

            si.DisplayName = Program.ServiceName;
            si.ServiceName = Program.ServiceName;
            si.StartType = ServiceStartMode.Automatic;

            Installers.Add(spi);
            Installers.Add(si);
        }
    }
}

Unable to simultaneously satisfy constraints, will attempt to recover by breaking constraint

Basically, you just have to remove that constraint from the associated view. For instance, if is the height constraint giving warning, just remove it from your view; it will not affect the view.

Android load from URL to Bitmap

public Drawable loadImageFromURL(String url, String name) {
    try {
        InputStream is = (InputStream) new URL(url).getContent();
        Drawable d = Drawable.createFromStream(is, name);
        return d;
    } catch (Exception e) {
        return null;
    }
}

C++ IDE for Macs

Xcode is free and good, which is lucky because it's pretty much the only option on the Mac.

Can I call a base class's virtual function if I'm overriding it?

If there are multiple levels of inheritance, you can specify the direct base class, even if the actual implementation is at a lower level.

class Foo
{
public:
  virtual void DoStuff ()
  {
  }
};

class Bar : public Foo
{
};

class Baz : public Bar
{
public:
  void DoStuff ()
  {
    Bar::DoStuff() ;
  }
};

In this example, the class Baz specifies Bar::DoStuff() although the class Bar does not contain an implementation of DoStuff. That is a detail, which Baz does not need to know.

It is clearly a better practice to call Bar::DoStuff than Foo::DoStuff, in case a later version of Bar also overrides this method.

How to find the type of an object in Go?

I found 3 ways to return a variable's type at runtime:

Using string formatting

func typeof(v interface{}) string {
    return fmt.Sprintf("%T", v)
}

Using reflect package

func typeof(v interface{}) string {
    return reflect.TypeOf(v).String()
}

Using type assertions

func typeof(v interface{}) string {
    switch v.(type) {
    case int:
        return "int"
    case float64:
        return "float64"
    //... etc
    default:
        return "unknown"
    }
}

Every method has a different best use case:

string formatting - short and low footprint (not necessary to import reflect package)
reflect package - when need more details about the type we have access to the full reflection capabilities
type assertions - allows grouping types, for example recognize all int32, int64, uint32, uint64 types as "int"

Verify ImageMagick installation

If your ISP/hosting service has installed ImageMagick and put its location in the PATH environment variable, you can find what versions are installed and where using:

<?php
echo "<pre>";
system("type -a convert");  
echo "</pre>";
?>

npm WARN notsup SKIPPING OPTIONAL DEPENDENCY: Unsupported platform for [email protected]

This is fixed in npm 7. See npm/cli#PR169

How to return a html page from a restful controller in spring boot?

When using @RestController like this:

@RestController
public class HomeController {

    @RequestMapping("/")
    public String welcome() {
        return "login";
    }
}

This is the same as you do like this in a normal controller:

@Controller
public class HomeController {

    @RequestMapping("/")
    @ResponseBody
    public String welcome() {
        return "login";
    }
}

Using @ResponseBody returns return "login"; as a String object. Any object you return will be attached as payload in the HTTP body as JSON.

This is why you are getting just login in the response.

Warning: Cannot modify header information - headers already sent by ERROR

You are trying to send headers information after outputing content.

If you want to do this, look for output buffering.

Therefore, look to use ob_start();

How do I retrieve my MySQL username and password?

Do it without down time

Run following command in the Terminal to connect to the DBMS (you need root access):

sudo mysql -u root -p;

run update password of the target user (for my example username is mousavi and it's password must be 123456):

UPDATE mysql.user SET authentication_string=PASSWORD('123456') WHERE user='mousavi';

at this point you need to do a flush to apply changes:

FLUSH PRIVILEGES;

Done! You did it without any stop or restart mysql service.

What's the difference between setWebViewClient vs. setWebChromeClient?

I feel this question need a bit more details. My answer is inspired from the Android Programming, The Big Nerd Ranch Guide (2nd edition).

By default, JavaScript is off in WebView. You do not always need to have it on, but for some apps, might do require it.

Loading the URL has to be done after configuring the WebView, so you do that last. Before that, you turn JavaScript on by calling getSettings() to get an instance of WebSettings and calling WebSettings.setJavaScriptEnabled(true). WebSettings is the first of the three ways you can modify your WebView. It has various properties you can set, like the user agent string and text size.

After that, you configure your WebViewClient. WebViewClient is an event interface. By providing your own implementation of WebViewClient, you can respond to rendering events. For example, you could detect when the renderer starts loading an image from a particular URL or decide whether to resubmit a POST request to the server.

WebViewClient has many methods you can override, most of which you will not deal with. However, you do need to replace the default WebViewClient’s implementation of shouldOverrideUrlLoading(WebView, String). This method determines what will happen when a new URL is loaded in the WebView, like by pressing a link. If you return true, you are saying, “Do not handle this URL, I am handling it myself.” If you return false, you are saying, “Go ahead and load this URL, WebView, I’m not doing anything with it.”

The default implementation fires an implicit intent with the URL, just like you did earlier. Now, though, this would be a severe problem. The first thing some Web Applications does is redirect you to the mobile version of the website. With the default WebViewClient, that means that you are immediately sent to the user’s default web browser. This is just what you are trying to avoid. The fix is simple – just override the default implementation and return false.

Use WebChromeClient to spruce things up Since you are taking the time to create your own WebView, let’s spruce it up a bit by adding a progress bar and updating the toolbar’s subtitle with the title of the loaded page.

To hook up the ProgressBar, you will use the second callback on WebView: WebChromeClient.

WebViewClient is an interface for responding to rendering events; WebChromeClient is an event interface for reacting to events that should change elements of chrome around the browser. This includes JavaScript alerts, favicons, and of course updates for loading progress and the title of the current page.

Hook it up in onCreateView(…). Using WebChromeClient to spruce things up Progress updates and title updates each have their own callback method, onProgressChanged(WebView, int) and onReceivedTitle(WebView, String). The progress you receive from onProgressChanged(WebView, int) is an integer from 0 to 100. If it is 100, you know that the page is done loading, so you hide the ProgressBar by setting its visibility to View.GONE.

Disclaimer: This information was taken from Android Programming: The Big Nerd Ranch Guide with permission from the authors. For more information on this book or to purchase a copy, please visit bignerdranch.com.

Why does Oracle not find oci.dll?

if you use 64-bit pc, oracle doesn't compatible with it. Oracle doesn't find oci.dll file in 64-bit.

Therefore, you can try to change oracle home on the top. As a result of that, home path will change.

At least, I solved that error with changing path.

Check if element found in array c++

Here is a simple generic C++11 function contains which works for both arrays and containers:

using namespace std;

template<class C, typename T>
bool contains(C&& c, T e) { return find(begin(c), end(c), e) != end(c); };

Simple usage contains(arr, el) is somewhat similar to in keyword semantics in Python.

Here is a complete demo:

#include <algorithm>
#include <array>
#include <string>
#include <vector>
#include <iostream>

template<typename C, typename T>
bool contains(C&& c, T e) { 
    return std::find(std::begin(c), std::end(c), e) != std::end(c);
};

template<typename C, typename T>
void check(C&& c, T e) {
    std::cout << e << (contains(c,e) ? "" : " not") <<  " found\n";
}

int main() {
    int a[] = { 10, 15, 20 };
    std::array<int, 3> b { 10, 10, 10 };
    std::vector<int> v { 10, 20, 30 };
    std::string s { "Hello, Stack Overflow" };
    
    check(a, 10);
    check(b, 15);
    check(v, 20);
    check(s, 'Z');

    return 0;
}

Output:

10 found
15 not found
20 found
Z not found

How does System.out.print() work?

The scenarios that you have mentioned are not of overloading, you are just concatenating different variables with a String.

System.out.print("Hello World");

System.out.print("My name is" + foo);

System.out.print("Sum of " + a + "and " + b + "is " + c); 

System.out.print("Total USD is " + usd);

in all of these cases, you are only calling print(String s) because when something is concatenated with a string it gets converted to a String by calling the toString() of that object, and primitives are directly concatenated. However if you want to know of different signatures then yes print() is overloaded for various arguments.

Destroy or remove a view in Backbone.js

This is what I've been using. Haven't seen any issues.

destroy: function(){
  this.remove();
  this.unbind();
}

How can I compare strings in C using a `switch` statement?

We cannot escape if-else ladder in order to compare a string with others. Even regular switch-case is also an if-else ladder (for integers) internally. We might only want to simulate the switch-case for string, but can never replace if-else ladder. The best of the algorithms for string comparison cannot escape from using strcmp function. Means to compare character by character until an unmatch is found. So using if-else ladder and strcmp are inevitable.

DEMO

And here are simplest macros to simulate the switch-case for strings.

#ifndef SWITCH_CASE_INIT
#define SWITCH_CASE_INIT
    #define SWITCH(X)   for (char* __switch_p__ = X, int __switch_next__=1 ; __switch_p__ ; __switch_p__=0, __switch_next__=1) { {
    #define CASE(X)         } if (!__switch_next__ || !(__switch_next__ = strcmp(__switch_p__, X))) {
    #define DEFAULT         } {
    #define END         }}
#endif

And you can use them as

char* str = "def";

SWITCH (str)
    CASE ("abc")
        printf ("in abc\n");
        break;
    CASE ("def")              // Notice: 'break;' statement missing so the control rolls through subsequent CASE's until DEFAULT 
        printf("in def\n");
    CASE ("ghi")
        printf ("in ghi\n");
    DEFAULT
        printf("in DEFAULT\n");
END

Output:

in def
in ghi
in DEFAULT

Below is nested SWITCH usage:

char* str = "def";
char* str1 = "xyz";

SWITCH (str)
    CASE ("abc")
        printf ("in abc\n");
        break;
    CASE ("def")                                
        printf("in def\n");
        SWITCH (str1)                           // <== Notice: Nested SWITCH
            CASE ("uvw")
                printf("in def => uvw\n");
                break;
            CASE ("xyz")
                printf("in def => xyz\n");
                break;
            DEFAULT
                printf("in def => DEFAULT\n");
        END
    CASE ("ghi")
        printf ("in ghi\n");
    DEFAULT
        printf("in DEFAULT\n");
END

Output:

in def
in def => xyz
in ghi
in DEFAULT

Here is reverse string SWITCH, where in you can use a variable (rather than a constant) in CASE clause:

char* str2 = "def";
char* str3 = "ghi";

SWITCH ("ghi")                      // <== Notice: Use of variables and reverse string SWITCH.
    CASE (str1)
        printf ("in str1\n");
        break;
    CASE (str2)                     
        printf ("in str2\n");
        break;
    CASE (str3)                     
        printf ("in str3\n");
        break;
    DEFAULT
        printf("in DEFAULT\n");
END

Output:

in str3

MIT vs GPL license

Can I include GPL licensed code in a MIT licensed product?

You can. GPL is free software as well as MIT is, both licenses do not restrict you to bring together the code where as "include" is always two-way.

In copyright for a combined work (that is two or more works form together a work), it does not make much of a difference if the one work is "larger" than the other or not.

So if you include GPL licensed code in a MIT licensed product you will at the same time include a MIT licensed product in GPL licensed code as well.

As a second opinion, the OSI listed the following criteria (in more detail) for both licenses (MIT and GPL):

Free Redistribution
Source Code
Derived Works
Integrity of The Author's Source Code
No Discrimination Against Persons or Groups
No Discrimination Against Fields of Endeavor
Distribution of License
License Must Not Be Specific to a Product
License Must Not Restrict Other Software
License Must Be Technology-Neutral

Both allow the creation of combined works, which is what you've been asking for.

If combining the two works is considered being a derivate, then this is not restricted as well by both licenses.

And both licenses do not restrict to distribute the software.

It seems to me that the chief difference between the MIT license and GPL is that the MIT doesn't require modifications be open sourced whereas the GPL does.

The GPL doesn't require you to release your modifications only because you made them. That's not precise.

You might mix this with distribiution of software under GPL which is not what you've asked about directly.

Is that correct - is the GPL is more restrictive than the MIT license?

This is how I understand it:

As far as distribution counts, you need to put the whole package under GPL. MIT code inside of the package will still be available under MIT whereas the GPL applies to the package as a whole if not limited by higher rights.

"Restrictive" or "more restrictive" / "less restrictive" depends a lot on the point of view. For a software-user the MIT might result in software that is more restricted than the one available under GPL even some call the GPL more restrictive nowadays. That user in specific will call the MIT more restrictive. It's just subjective to say so and different people will give you different answers to that.

As it's just subjective to talk about restrictions of different licenses, you should think about what you would like to achieve instead:

If you want to restrict the use of your modifications, then MIT is able to be more restrictive than the GPL for distribution and that might be what you're looking for.
In case you want to ensure that the freedom of your software does not get restricted that much by the users you distribute it to, then you might want to release under GPL instead of MIT.

As long as you're the author it's you who can decide.

So the most restrictive person ever is the author, regardless of which license anybody is opting for ;)

strdup() - what does it do in C?

Exactly what it sounds like, assuming you're used to the abbreviated way in which C and UNIX assigns words, it duplicates strings :-)

Keeping in mind it's actually not part of the ISO C standard itself^(a) (it's a POSIX thing), it's effectively doing the same as the following code:

char *strdup(const char *src) {
    char *dst = malloc(strlen (src) + 1);  // Space for length plus nul
    if (dst == NULL) return NULL;          // No memory
    strcpy(dst, src);                      // Copy the characters
    return dst;                            // Return the new string
}

In other words:

It tries to allocate enough memory to hold the old string (plus a '\0' character to mark the end of the string).
If the allocation failed, it sets errno to ENOMEM and returns NULL immediately. Setting of errno to ENOMEM is something malloc does in POSIX so we don't need to explicitly do it in our strdup. If you're not POSIX compliant, ISO C doesn't actually mandate the existence of ENOMEM so I haven't included that here^(b).
Otherwise the allocation worked so we copy the old string to the new string^(c) and return the new address (which the caller is responsible for freeing at some point).

Keep in mind that's the conceptual definition. Any library writer worth their salary may have provided heavily optimised code targeting the particular processor being used.

^(a) However, functions starting with str and a lower case letter are reserved by the standard for future directions. From C11 7.1.3 Reserved identifiers:

Each header declares or defines all identifiers listed in its associated sub-clause, and *optionally declares or defines identifiers listed in its associated future library directions sub-clause.**

The future directions for string.h can be found in C11 7.31.13 String handling <string.h>:

Function names that begin with str, mem, or wcs and a lowercase letter may be added to the declarations in the <string.h> header.

So you should probably call it something else if you want to be safe.

^(b) The change would basically be replacing if (d == NULL) return NULL; with:

if (d == NULL) {
    errno = ENOMEM;
    return NULL;
}

^(c) Note that I use strcpy for that since that clearly shows the intent. In some implementations, it may be faster (since you already know the length) to use memcpy, as they may allow for transferring the data in larger chunks, or in parallel. Or it may not :-) Optimisation mantra #1: "measure, don't guess".

In any case, should you decide to go that route, you would do something like:

char *strdup(const char *src) {
    size_t len = strlen(src) + 1;       // String plus '\0'
    char *dst = malloc(len);            // Allocate space
    if (dst == NULL) return NULL;       // No memory
    memcpy (dst, src, len);             // Copy the block
    return dst;                         // Return the new string
}

How to insert DECIMAL into MySQL database

Yes, 4,2 means "4 digits total, 2 of which are after the decimal place". That translates to a number in the format of 00.00. Beyond that, you'll have to show us your SQL query. PHP won't translate 3.80 into 99.99 without good reason. Perhaps you've misaligned your fields/values in the query and are trying to insert a larger number that belongs in another field.

Java 8 Lambda function that throws exception?

You'll need to do one of the following.

If it's your code, then define your own functional interface that declares the checked exception:

@FunctionalInterface
public interface CheckedFunction<T, R> {
   R apply(T t) throws IOException;
}

and use it:

void foo (CheckedFunction f) { ... }

Otherwise, wrap Integer myMethod(String s) in a method that doesn't declare a checked exception:

public Integer myWrappedMethod(String s) {
    try {
        return myMethod(s);
    }
    catch(IOException e) {
        throw new UncheckedIOException(e);
    }
}

and then:

Function<String, Integer> f = (String t) -> myWrappedMethod(t);

or:

Function<String, Integer> f =
    (String t) -> {
        try {
           return myMethod(t);
        }
        catch(IOException e) {
            throw new UncheckedIOException(e);
        }
    };

How can I create a copy of an Oracle table without copying the data?

Just use a where clause that won't select any rows:

create table xyz_new as select * from xyz where 1=0;

Limitations

The following things will not be copied to the new table:

sequences
triggers
indexes
some constraints may not be copied
materialized view logs

This also does not handle partitions

Possible to access MVC ViewBag object from Javascript file?

For CoreMVC 3.1, that would be,

@using Newtonsoft.Json
var listInJs =  @Html.Raw(JsonConvert.SerializeObject(ViewBag.SomeGenericList));

Linux command to list all available commands and aliases

The problem is that the tab-completion is searching your path, but all commands are not in your path.

To find the commands in your path using bash you could do something like :

for x in echo $PATH | cut -d":" -f1; do ls $x; done

Run chrome in fullscreen mode on Windows

You can also add --disable-session-crashed-bubble to eliminate the errors that come up after a crash or improper shutdown.

PDF files do not open in Internet Explorer with Adobe Reader 10.0 - users get an empty gray screen. How can I fix this for my users?

I had this problem. Reinstalling the latest version of Adobe Reader did nothing. Adobe Reader worked in Chrome but not in IE. This worked for me ...

1) Go to IE's Tools-->Compatibility View menu.
2) Enter a website that has the PDF you wish to see. Click OK.
3) Restart IE 4) Go to the website you entered and select the PDF. It should come up.
5) Go back to Compatibility View and delete the entry you made.
6) Adobe Reader works OK now in IE on all websites.

It's a strange fix, but it worked for me. I needed to go through an Adobe acceptance screen after reinstall that only appeared after I did the Compatibility View trick. Once accepted, it seemed to work everywhere. Pretty flaky stuff. Hope this helps someone.

What is a "method" in Python?

Sorry, but--in my opinion--RichieHindle is completely right about saying that method...

It's a function which is a member of a class.

Here is the example of a function that becomes the member of the class. Since then it behaves as a method of the class. Let's start with the empty class and the normal function with one argument:

>>> class C:
...     pass
...
>>> def func(self):
...     print 'func called'
...
>>> func('whatever')
func called

Now we add a member to the C class, which is the reference to the function. After that we can create the instance of the class and call its method as if it was defined inside the class:

>>> C.func = func
>>> o = C()
>>> o.func()
func called

We can use also the alternative way of calling the method:

>>> C.func(o)
func called

The o.func even manifests the same way as the class method:

>>> o.func
<bound method C.func of <__main__.C instance at 0x000000000229ACC8>>

And we can try the reversed approach. Let's define a class and steal its method as a function:

>>> class A:
...     def func(self):
...         print 'aaa'
...
>>> a = A()
>>> a.func
<bound method A.func of <__main__.A instance at 0x000000000229AD08>>
>>> a.func()
aaa

So far, it looks the same. Now the function stealing:

>>> afunc = A.func
>>> afunc(a)
aaa

The truth is that the method does not accept 'whatever' argument:

>>> afunc('whatever')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unbound method func() must be called with A instance as first 
  argument (got str instance instead)

IMHO, this is not the argument against method is a function that is a member of a class.

Later found the Alex Martelli's answer that basically says the same. Sorry if you consider it duplication :)

YouTube URL in Video Tag

Video tag supports only video formats (like mp4 etc). Youtube does not expose its raw video files - it only exposes the unique id of the video. Since that id does not correspond to the actual file, video tag cannot be used.

If you do get hold of the actual source file using one of the youtube download sites or soft wares, you will be able to use the video tag. But even then, the url of the actual source will cease to work after a set time. So your video also will work only till then.

Best way to incorporate Volley (or other library) into Android Studio project

For incorporate volley in android studio,

paste the following command in terminal (
git clone https://android.googlesource.com/platform/frameworks/volley ) and run it.

Refer android developer tutorial for this.

It will create a folder name volley in the src directory.
Then go to android studio and right click on the project.
choose New -> Module from the list.
Then click on import existing Project from the below list.
you will see a text input area namely source directory, browse the folder you downloaded (volley) and then click on finish.
you will see a folder volley in your project view.
the switch to android view and open the build:gradle(Module:app) file and append the following line in the dependency area:

compile 'com.mcxiaoke.volley:library-aar:1.0.0'
Now synchronise your project and also build your project.

In Java, how can I determine if a char array contains a particular character?

You can also define these chars as list of string. Then you can check if the characters is valid for accepted characters with list.Contains(x) method.

What is the best way to calculate a checksum for a file that is on my machine?

On MySQL.com, MD5s are listed alongside each file that you can download. For instance, MySQL "Windows Essentials" 5.1 is 528c89c37b3a6f0bd34480000a56c372.

You can download md5 (md5.exe), a command line tool that will calculate the MD5 of any file that you have locally. MD5 is just like any other cryptographic hash function, which means that a given array of bytes will always produce the same hash. That means if your downloaded MySQL zip file (or whatever) has the same MD5 as they post on their site, you have the exact same file.

How to correctly save instance state of Fragments in back stack?

This is the way I am using at this moment... it's very complicated but at least it handles all the possible situations. In case anyone is interested.

public final class MyFragment extends Fragment {
    private TextView vstup;
    private Bundle savedState = null;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.whatever, null);
        vstup = (TextView)v.findViewById(R.id.whatever);

        /* (...) */

        /* If the Fragment was destroyed inbetween (screen rotation), we need to recover the savedState first */
        /* However, if it was not, it stays in the instance from the last onDestroyView() and we don't want to overwrite it */
        if(savedInstanceState != null && savedState == null) {
            savedState = savedInstanceState.getBundle(App.STAV);
        }
        if(savedState != null) {
            vstup.setText(savedState.getCharSequence(App.VSTUP));
        }
        savedState = null;

        return v;
    }

    @Override
    public void onDestroyView() {
        super.onDestroyView();
        savedState = saveState(); /* vstup defined here for sure */
        vstup = null;
    }

    private Bundle saveState() { /* called either from onDestroyView() or onSaveInstanceState() */
        Bundle state = new Bundle();
        state.putCharSequence(App.VSTUP, vstup.getText());
        return state;
    }

    @Override
    public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        /* If onDestroyView() is called first, we can use the previously savedState but we can't call saveState() anymore */
        /* If onSaveInstanceState() is called first, we don't have savedState, so we need to call saveState() */
        /* => (?:) operator inevitable! */
        outState.putBundle(App.STAV, (savedState != null) ? savedState : saveState());
    }

    /* (...) */

}

Alternatively, it is always a possibility to keep the data displayed in passive Views in variables and using the Views only for displaying them, keeping the two things in sync. I don't consider the last part very clean, though.

How to put space character into a string name in XML?

Insert \u0020 directly in the XML for a blank you would like to preserve.

<string name="spelatonertext3">-4, \u00205, \u0020\u0020-5, \u00206, \u0020-6,</string>

The 'packages' element is not declared

Use <packages xmlns="urn:packages">in the place of <packages>

Is it possible to hide the cursor in a webpage using CSS or Javascript?

Pointer Lock API

While the cursor: none CSS solution is definitely a solid and easy workaround, if your actual goal is to remove the default cursor while your web application is being used, or implement your own interpretation of raw mouse movement (for FPS games, for example), you might want to consider using the Pointer Lock API instead.

You can use requestPointerLock on an element to remove the cursor, and redirect all mousemove events to that element (which you may or may not handle):

document.body.requestPointerLock();

To release the lock, you can use exitPointerLock:

document.exitPointerLock();

Additional notes

No cursor, for real

This is a very powerful API call. It not only renders your cursor invisible, but it actually removes your operating system's native cursor. You won't be able to select text, or do anything with your mouse (except listening to some mouse events in your code) until the pointer lock is released (either by using exitPointerLock or pressing ESC in some browsers).

That is, you cannot leave the window with your cursor for it to show again, as there is no cursor.

Restrictions

As mentioned above, this is a very powerful API call, and is thus only allowed to be made in response to some direct user-interaction on the web, such as a click; for example:

document.addEventListener("click", function () {
    document.body.requestPointerLock();
});

Also, requestPointerLock won't work from a sandboxed iframe unless the allow-pointer-lock permission is set.

User-notifications

Some browsers will prompt the user for a confirmation before the lock is engaged, some will simply display a message. This means pointer lock might not activate right away after the call. However, the actual activation of pointer locking can be listened to by listening to the pointerchange event on the element on which requestPointerLock was called:

document.body.addEventListener("pointerlockchange", function () {
    if (document.pointerLockElement === document.body) {
        // Pointer is now locked to <body>.
    }
});

Most browsers will only display the message once, but Firefox will occasionally spam the message on every single call. AFAIK, this can only be worked around by user-settings, see Disable pointer-lock notification in Firefox.

Listening to raw mouse movement

The Pointer Lock API not only removes the mouse, but instead redirects raw mouse movement data to the element requestPointerLock was called on. This can be listened to simply by using the mousemove event, then accessing the movementX and movementY properties on the event object:

document.body.addEventListener("mousemove", function (e) {
    console.log("Moved by " + e.movementX + ", " + e.movementY);
});

Is there an embeddable Webkit component for Windows / C# development?

There's a WebKit-Sharp component on Mono's GitHub Repository. I can't find any web-viewable documentation on it, and I'm not even sure if it's WinForms or GTK# (can't grab the source from here to check at the moment), but it's probably your best bet, either way.

Error message "Forbidden You don't have permission to access / on this server"

If you are using MAMP Pro the way to fix this is by checking the Indexes checkbox under the Hosts - Extended tab.

In MAMP Pro v3.0.3 this is what that looks like: enter image description here

Field 'browser' doesn't contain a valid alias configuration

In my case, it was due to a broken symlink when trying to npm link a custom angular library to consuming app. After running npm link @authoring/canvas

"@authoring/canvas": "path/to/ui-authoring-canvas/dist"

It appear everything was OK but the module still couldn't be found:

When I corrected the import statement to something that the editor could find Link:

import {CirclePackComponent} from '@authoring/canvas/lib/circle-pack/circle-pack.component';

I received this which is mention in the overflow thread:

To fix this I had to:

cd /usr/local/lib/node_modules/packageName
cd ..
rm -rf packageName
In the root directory of the library, run:

a) rm -rf dist
b) npm run build
c) cd dist 
d) npm link

In the consuming app, update the package.json with:

"packageName": "file:/path/to/local/node_module/packageName""

In the root directory of the consuming app run npm link packageName

Laravel - Eloquent "Has", "With", "WhereHas" - What do they mean?

Document has already explain the usage. So I am using SQL to explain these methods

Example:

Assuming there is an Order (orders) has many OrderItem (order_items).

And you have already build the relationship between them.

// App\Models\Order:
public function orderItems() {
    return $this->hasMany('App\Models\OrderItem', 'order_id', 'id');
}

These three methods are all based on a relationship.

With

Result: with() return the model object and its related results.

Advantage: It is eager-loading which can prevent the N+1 problem.

When you are using the following Eloquent Builder:

Order::with('orderItems')->get();

Laravel change this code to only two SQL:

// get all orders:
SELECT * FROM orders; 

// get the order_items based on the orders' id above
SELECT * FROM order_items WHERE order_items.order_id IN (1,2,3,4...);

And then laravel merge the results of the second SQL as different from the results of the first SQL by foreign key. At last return the collection results.

So if you selected columns without the foreign_key in closure, the relationship result will be empty:

Order::with(['orderItems' => function($query) { 
           // $query->sum('quantity');
           $query->select('quantity'); // without `order_id`
       }
])->get();

#=> result:
[{  id: 1,
    code: '00001',
    orderItems: [],    // <== is empty
  },{
    id: 2,
    code: '00002',
    orderItems: [],    // <== is empty
  }...
}]

Has

Has will return the model's object that its relationship is not empty.

Order::has('orderItems')->get();

Laravel change this code to one SQL:

select * from `orders` where exists (
    select * from `order_items` where `order`.`id` = `order_item`.`order_id`
)

whereHas

whereHas and orWhereHas methods to put where conditions on your has queries. These methods allow you to add customized constraints to a relationship constraint.

Order::whereHas('orderItems', function($query) {
   $query->where('status', 1);
})->get();

Laravel change this code to one SQL:

select * from `orders` where exists (
    select * 
    from `order_items` 
    where `orders`.`id` = `order_items`.`order_id` and `status` = 1
)

Angular 2 Date Input not binding to date value

you can use a workaround, like this:

<input type='date' (keyup)="0" #myDate [(ngModel)]='demoUser.date'/><br>

on your component :

 @Input public date: Date,

How do I reverse a commit in git?

git push -f maybe?

man git-push will tell more.

How to get current moment in ISO 8601 format with date, hour, and minute?

I do believe the easiest way is to first go to instant and then to string like:

String d = new Date().toInstant().toString();

Which will result in:

2017-09-08T12:56:45.331Z

How to use _CRT_SECURE_NO_WARNINGS

I was getting the same error in Visual Studio 2017 and to fix it just added #define _CRT_SECURE_NO_WARNINGS after #include "pch.h"

#include "pch.h"
#define _CRT_SECURE_NO_WARNINGS
....

Why doesn't RecyclerView have onItemClickListener()?

I use this method to start an Intent from RecyclerView:

@Override
 public void onBindViewHolder(ViewHolder viewHolder, int i) {

    final MyClass myClass = mList.get(i);
    viewHolder.txtViewTitle.setText(myclass.name);
   ...
    viewHolder.itemView.setOnClickListener(new View.OnClickListener() {
      @Override
       public void onClick(View v){
             Intent detailIntent = new Intent(mContext, type.class);                                                            
             detailIntent.putExtra("MyClass", myclass);
             mContext.startActivity(detailIntent);
       }
}
);

Defining and using a variable in batch file

The space before the = is interpreted as part of the name, and the space after it (as well as the quotation marks) are interpreted as part of the value. So the variable you’ve created can be referenced with %location %. If that’s not what you want, remove the extra space(s) in the definition.

Add CSS3 transition expand/collapse

This is my solution that adjusts the height automatically:

_x000D_

function growDiv() {_x000D_
  var growDiv = document.getElementById('grow');_x000D_
  if (growDiv.clientHeight) {_x000D_
    growDiv.style.height = 0;_x000D_
  } else {_x000D_
    var wrapper = document.querySelector('.measuringWrapper');_x000D_
    growDiv.style.height = wrapper.clientHeight + "px";_x000D_
  }_x000D_
  document.getElementById("more-button").value = document.getElementById("more-button").value == 'Read more' ? 'Read less' : 'Read more';_x000D_
}

_x000D_

#more-button {_x000D_
  border-style: none;_x000D_
  background: none;_x000D_
  font: 16px Serif;_x000D_
  color: blue;_x000D_
  margin: 0 0 10px 0;_x000D_
}_x000D_
_x000D_
#grow input:checked {_x000D_
  color: red;_x000D_
}_x000D_
_x000D_
#more-button:hover {_x000D_
  color: black;_x000D_
}_x000D_
_x000D_
#grow {_x000D_
  -moz-transition: height .5s;_x000D_
  -ms-transition: height .5s;_x000D_
  -o-transition: height .5s;_x000D_
  -webkit-transition: height .5s;_x000D_
  transition: height .5s;_x000D_
  height: 0;_x000D_
  overflow: hidden;_x000D_
}

_x000D_

<input type="button" onclick="growDiv()" value="Read more" id="more-button">_x000D_
_x000D_
<div id='grow'>_x000D_
  <div class='measuringWrapper'>_x000D_
    <div class="text">Here is some more text: Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vestibulum vitae urna nulla. Vivamus a purus mi. In hac habitasse platea dictumst. In ac tempor quam. Vestibulum eleifend vehicula ligula, et cursus nisl gravida sit_x000D_
      amet. Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas.</div>_x000D_
  </div>_x000D_
</div>

_x000D_

I used the workaround that r3bel posted: Can you use CSS3 to transition from height:0 to the variable height of content?

Scripting Language vs Programming Language

If we see logically programming language and scripting language so this is 99.09% same . because we use same concept like loop , control condition ,variable and all so we can say yes both are same but there is only one thing is different between them that is in C/C++ and other programming language we compile the code before execution . but in the PHP , JavaScript and other scripting language we don't need to compile we directly execute in the browser.

Thanks Nitish K. Jha

Parsing a comma-delimited std::string

simple structure, easily adaptable, easy maintenance.

std::string stringIn = "my,csv,,is 10233478,separated,by commas";
std::vector<std::string> commaSeparated(1);
int commaCounter = 0;
for (int i=0; i<stringIn.size(); i++) {
    if (stringIn[i] == ",") {
        commaSeparated.push_back("");
        commaCounter++;
    } else {
        commaSeparated.at(commaCounter) += stringIn[i];
    }
}

in the end you will have a vector of strings with every element in the sentence separated by spaces. empty strings are saved as separate items.

How to import set of icons into Android Studio project

Edit : After Android Studios 1.5 android support Vector Asset Studio.

Follow this, which says:

To start Vector Asset Studio:

In Android Studio, open an Android app project.

In the Project window, select the Android view.

Right-click the res folder and select New > Vector Asset.

Old Answer

Go to Settings > Plugin > Browse Repository > Search Android Drawable Import

This plugin consists of 4 main features.

AndroidIcons Drawable Import
Material Icons Drawable Import
Scaled Drawable
Multisource-Drawable

How to Use Material Icons Drawable Import : (Android Studio 1.2)

Go to File > Setting > Other Settings > Android Drawable Import

enter image description here

Download Material Icon and select your downloaded path.

enter image description here

Now right click on project , New > Material Icon Import

enter image description here

Use your favorite drawable in your project.

enter image description here

embedding image in html email

Using Base64 to embed images in html is awesome. Nonetheless, please notice that base64 strings can make your email size big.

Therefore,

1) If you have many images, uploading your images to a server and loading those images from the server can make your email size smaller. (You can get a lot of free services via Google)

2) If there are just a few images in your mail, using base64 strings is definitely an awesome option.

Besides the choices provided by existing answers, you can also use a command to generate a base64 string on linux:

base64 test.jpg

HTML - Arabic Support

As mentioned above, by default text editors will not use UTF-8 as the standard encoding for documents. However most editors will allow you to change that in the settings. Even for each specific document.

How to convert a DataTable to a string in C#?

public static string DataTable2String(DataTable dataTable)
{
    StringBuilder sb = new StringBuilder();
    if (dataTable != null)
    {
        string seperator = " | ";

        #region get min length for columns
        Hashtable hash = new Hashtable();
        foreach (DataColumn col in dataTable.Columns)
            hash[col.ColumnName] = col.ColumnName.Length;
        foreach (DataRow row in dataTable.Rows)
            for (int i = 0; i < row.ItemArray.Length; i++)
                if (row[i] != null)
                    if (((string)row[i]).Length > (int)hash[dataTable.Columns[i].ColumnName])
                        hash[dataTable.Columns[i].ColumnName] = ((string)row[i]).Length;
        int rowLength = (hash.Values.Count + 1) * seperator.Length;
        foreach (object o in hash.Values)
            rowLength += (int)o;
        #endregion get min length for columns

        sb.Append(new string('=', (rowLength - " DataTable ".Length) / 2));
        sb.Append(" DataTable ");
        sb.AppendLine(new string('=', (rowLength - " DataTable ".Length) / 2));
        if (!string.IsNullOrEmpty(dataTable.TableName))
            sb.AppendLine(String.Format("{0,-" + rowLength + "}", String.Format("{0," + ((rowLength + dataTable.TableName.Length) / 2).ToString() + "}", dataTable.TableName)));

        #region write values
        foreach (DataColumn col in dataTable.Columns)
            sb.Append(seperator + String.Format("{0,-" + hash[col.ColumnName] + "}", col.ColumnName));
        sb.AppendLine(seperator);
        sb.AppendLine(new string('-', rowLength));
        foreach (DataRow row in dataTable.Rows)
        {
            for (int i = 0; i < row.ItemArray.Length; i++)
            {
                sb.Append(seperator + String.Format("{0," + hash[dataTable.Columns[i].ColumnName] + "}", row[i]));
                if (i == row.ItemArray.Length - 1)
                    sb.AppendLine(seperator);
            }
        }
        #endregion write values

        sb.AppendLine(new string('=', rowLength));
    }
    else
        sb.AppendLine("================ DataTable is NULL ================");

    return sb.ToString();
}

output:

======================= DataTable =======================
                         MyTable                          
 | COL1 | COL2                    | COL3 1000000ng name | 
----------------------------------------------------------
 |    1 |                       2 |                   3 | 
 |  abc | Dienstag, 12. März 2013 |                 xyz | 
 | Have |                  a nice |                day! | 
==========================================================

Declaring & Setting Variables in a Select Statement

I have tried this and it worked:

define PROPp_START_DT = TO_DATE('01-SEP-1999')

select * from proposal where prop_start_dt = &PROPp_START_DT

How do I remove/delete a virtualenv?

1. Remove the Python environment

There is no command to remove a virtualenv so you need to do that by hand, you will need to deactivate if you have it on and remove the folder:

deactivate
rm -rf <env name>

2. Create an env. with another Python version

When you create an environment the python uses the current version by default, so if you want another one you will need to specify at the moment you are creating it. To make and env. with Python 3.7 called MyEnv just type:

python3.7 -m venv MyEnv

Now to make with Python 2.X use virtualenv instead of venv:

python2.7 -m virtualenv MyEnv

3. List all Python versions on my machine

If any of the previous lines of code didn't worked you probably don't have the specific version installed. First list all your versions with:

ls -ls /usr/bin/python*

If you didn't find it, install Python 3.7 using apt-get:

sudo apt-get install python3.7

And with yum:

sudo yum install python3

4. Best practice: upgrade you pip (weekly)

pip install --upgrade pip

How to cast an object in Objective-C

Sure, the syntax is exactly the same as C - NewObj* pNew = (NewObj*)oldObj;

In this situation you may wish to consider supplying this list as a parameter to the constructor, something like:

// SelectionListViewController
-(id) initWith:(SomeListClass*)anItemList
{
  self = [super init];

  if ( self ) {
    [self setList: anItemList];
  }

  return self;
}

Then use it like this:

myEditController = [[SelectionListViewController alloc] initWith: listOfItems];

Setting focus to iframe contents

document.getElementsByName("iframe_name")[0].contentWindow.document.body.focus();

C# declare empty string array

Your syntax is wrong:

string[] arr = new string[]{};

string[] arr = new string[0];

How to avoid pressing Enter with getchar() for reading a single character only?

Since you are working on a Unix derivative (Ubuntu), here is one way to do it - not recommended, but it will work (as long as you can type commands accurately):

echo "stty -g $(stty -g)" > restore-sanity
stty cbreak
./your_program

Use interrupt to stop the program when you are bored with it.

sh restore-sanity

The 'echo' line saves the current terminal settings as a shell script that will restore them.
The 'stty' line turns off most of the special processing (so Control-D has no effect, for example) and sends characters to the program as soon as they are available. It means you cannot edit your typing any more.
The 'sh' line reinstates your original terminal settings.

You can economize if 'stty sane' restores your settings sufficiently accurately for your purposes. The format of '-g' is not portable across versions of 'stty' (so what is generated on Solaris 10 won't work on Linux, or vice versa), but the concept works everywhere. The 'stty sane' option is not universally available, AFAIK (but is on Linux).

Using Exit button to close a winform program

Remove the method, I suspect you might also need to remove it from your Form.Designer.

Otherwise: Application.Exit();

Should work.

That's why the designer is bad for you. :)

Left padding a String with Zeros

I have used this:

DecimalFormat numFormat = new DecimalFormat("00000");
System.out.println("Code format: "+numFormat.format(123));

Result: 00123

I hope you find it useful!

Open file with associated application

In .Net Core (as of v2.2) it should be:

new Process
{
    StartInfo = new ProcessStartInfo(@"file path")
    {
        UseShellExecute = true
    }
}.Start();

Related github issue can be found here

Detect if user is scrolling

Use an interval to check

You can setup an interval to keep checking if the user has scrolled then do something accordingly.

Borrowing from the great John Resig in his article.

Example:

    let didScroll = false;

    window.onscroll = () => didScroll = true;

    setInterval(() => {
        if ( didScroll ) {
            didScroll = false;
            console.log('Someone scrolled me!')
        }
    }, 250);

See live example

Maven with Eclipse Juno

From Eclipse

Go to Help
Eclipse Marketplace
Search for m2e or maven integration for eclipse
click on Install against - 'Maven Integration for Eclipse (Juno and newer) 1.4'
Restart and Enjoy!!!

Git push requires username and password

For the uninitiated who are confused by the previous answers, you can do:

git remote -v

Which will respond with something like

origin    https://[email protected]/yourname/yourrepo.git (fetch)
origin    https://[email protected]/yourname/yourrepo.git (push)

Then you can run the command many other have suggested, but now you know yourname and yourrepo from above, so you can just cut and paste yourname/yourrepo.git from the above into:

git remote set-url origin [email protected]:yourname/yourrepo.git

Round up double to 2 decimal places

Consider using NumberFormatter for this purpose, it provides more flexibility if you want to print the percentage sign of the ratio or if you have things like currency and large numbers.

let amount = 10.000001
let formatter = NumberFormatter()
formatter.numberStyle = .decimal
formatter.maximumFractionDigits = 2
let formattedAmount = formatter.string(from: amount as NSNumber)! 
print(formattedAmount) // 10

How to find the size of a table in SQL?

And in PostgreSQL:

SELECT pg_size_pretty(pg_relation_size('tablename'));

Oracle query to fetch column names

SELECT * FROM <SCHEMA_NAME.TABLE_NAME> WHERE ROWNUM = 0; --> Note that, this is Query Result, a ResultSet. This is exportable to other formats. And, you can export the Query Result to Text format. Export looks like below when I did SELECT * FROM SATURN.SPRIDEN WHERE ROWNUM = 0; :

"SPRTELE_PIDM" "SPRTELE_SEQNO" "SPRTELE_TELE_CODE" "SPRTELE_ACTIVITY_DATE" "SPRTELE_PHONE_AREA" "SPRTELE_PHONE_NUMBER" "SPRTELE_PHONE_EXT" "SPRTELE_STATUS_IND" "SPRTELE_ATYP_CODE" "SPRTELE_ADDR_SEQNO" "SPRTELE_PRIMARY_IND" "SPRTELE_UNLIST_IND" "SPRTELE_COMMENT" "SPRTELE_INTL_ACCESS" "SPRTELE_DATA_ORIGIN" "SPRTELE_USER_ID" "SPRTELE_CTRY_CODE_PHONE" "SPRTELE_SURROGATE_ID" "SPRTELE_VERSION" "SPRTELE_VPDI_CODE"
DESCRIBE <TABLE_NAME> --> Note: This is script output.

npm - how to show the latest version of a package

You can see all the version of a module with npm view. eg: To list all versions of bootstrap including beta.

npm view bootstrap versions

But if the version list is very big it will truncate. An --json option will print all version including beta versions as well.

npm view bootstrap versions --json

If you want to list only the stable versions not the beta then use singular version

npm view bootstrap@* versions

npm view bootstrap@* versions --json

And, if you want to see only latest version then here you go.

npm view bootstrap version

Hidden Features of C#?

Everything else, plus

1) implicit generics (why only on methods and not on classes?)

void GenericMethod<T>( T input ) { ... }

//Infer type, so
GenericMethod<int>(23); //You don't need the <>.
GenericMethod(23);      //Is enough.

2) simple lambdas with one parameter:

x => x.ToString() //simplify so many calls

3) anonymous types and initialisers:

//Duck-typed: works with any .Add method.
var colours = new Dictionary<string, string> {
    { "red", "#ff0000" },
    { "green", "#00ff00" },
    { "blue", "#0000ff" }
};

int[] arrayOfInt = { 1, 2, 3, 4, 5 };

Another one:

4) Auto properties can have different scopes:

public int MyId { get; private set; }

Thanks @pzycoman for reminding me:

5) Namespace aliases (not that you're likely to need this particular distinction):

using web = System.Web.UI.WebControls;
using win = System.Windows.Forms;

web::Control aWebControl = new web::Control();
win::Control aFormControl = new win::Control();

Understanding Spring @Autowired usage

TL;DR

The @Autowired annotation spares you the need to do the wiring by yourself in the XML file (or any other way) and just finds for you what needs to be injected where and does that for you.

Full explanation

The @Autowired annotation allows you to skip configurations elsewhere of what to inject and just does it for you. Assuming your package is com.mycompany.movies you have to put this tag in your XML (application context file):

<context:component-scan base-package="com.mycompany.movies" />

This tag will do an auto-scanning. Assuming each class that has to become a bean is annotated with a correct annotation like @Component (for simple bean) or @Controller (for a servlet control) or @Repository (for DAO classes) and these classes are somewhere under the package com.mycompany.movies, Spring will find all of these and create a bean for each one. This is done in 2 scans of the classes - the first time it just searches for classes that need to become a bean and maps the injections it needs to be doing, and on the second scan it injects the beans. Of course, you can define your beans in the more traditional XML file or with an @Configuration class (or any combination of the three).

The @Autowired annotation tells Spring where an injection needs to occur. If you put it on a method setMovieFinder it understands (by the prefix set + the @Autowired annotation) that a bean needs to be injected. In the second scan, Spring searches for a bean of type MovieFinder, and if it finds such bean, it injects it to this method. If it finds two such beans you will get an Exception. To avoid the Exception, you can use the @Qualifier annotation and tell it which of the two beans to inject in the following manner:

@Qualifier("redBean")
class Red implements Color {
   // Class code here
}

@Qualifier("blueBean")
class Blue implements Color {
   // Class code here
}

Or if you prefer to declare the beans in your XML, it would look something like this:

<bean id="redBean" class="com.mycompany.movies.Red"/>

<bean id="blueBean" class="com.mycompany.movies.Blue"/>

In the @Autowired declaration, you need to also add the @Qualifier to tell which of the two color beans to inject:

@Autowired
@Qualifier("redBean")
public void setColor(Color color) {
  this.color = color;
}

If you don't want to use two annotations (the @Autowired and @Qualifier) you can use @Resource to combine these two:

@Resource(name="redBean")
public void setColor(Color color) {
  this.color = color;
}

The @Resource (you can read some extra data about it in the first comment on this answer) spares you the use of two annotations and instead, you only use one.

I'll just add two more comments:

Good practice would be to use @Inject instead of @Autowired because it is not Spring-specific and is part of the JSR-330 standard.
Another good practice would be to put the @Inject / @Autowired on a constructor instead of a method. If you put it on a constructor, you can validate that the injected beans are not null and fail fast when you try to start the application and avoid a NullPointerException when you need to actually use the bean.

Update: To complete the picture, I created a new question about the @Configuration class.

Calculating time difference between 2 dates in minutes

I think you could use TIMESTAMPDIFF(unit,datetime_expr1,datetime_expr2) something like

select * from MyTab T where
TIMESTAMPDIFF(MINUTE,T.runTime,NOW()) > 20

C++ Array Of Pointers

If you don't use the STL, then the code looks a ~~lot~~ bit like C.

#include <cstdlib>
#include <new>

template< class T >
void append_to_array( T *&arr, size_t &n, T const &obj ) {
    T *tmp = static_cast<T*>( std::realloc( arr, sizeof(T) * (n+1) ) );
    if ( tmp == NULL ) throw std::bad_alloc( __FUNCTION__ );
       // assign things now that there is no exception
    arr = tmp;
    new( &arr[ n ] ) T( obj ); // placement new
    ++ n;
}

T can be any POD type, including pointers.

Note that arr must be allocated by malloc, not new[].

How to change the background colour's opacity in CSS

Use rgba as most of the commonly used browsers supports it..

.social img:hover {
 background-color: rgba(0, 0, 0, .5)
}

Class file for com.google.android.gms.internal.zzaja not found

I had such a similar error when i was recently upgrading my play service dependency. It seems to occur when you leave out updating the firebase dependencies that correspond to the version of play services you use. I beleive this is the most recent update of these dependencies

Here is what the two versions of my dependencies were:

Error version of dependencies

compile 'com.google.firebase:firebase-appindexing:10.0.1'
compile 'com.google.android.gms:play-services-maps:10.0.1'
compile 'com.google.android.gms:play-services-places:10.0.1'
compile 'com.google.android.gms:play-services-location:10.0.1'
compile 'com.google.firebase:firebase-auth:9.8.0'
compile 'com.google.firebase:firebase-database:9.8.0'
compile 'com.firebaseui:firebase-ui-database:1.0.1'
compile 'com.google.firebase:firebase-storage:9.8.0'

Working version of dependencies ``

compile 'com.google.firebase:firebase-appindexing:10.0.1'
compile 'com.google.android.gms:play-services-maps:10.0.1'
compile 'com.google.android.gms:play-services-places:10.0.1'
compile 'com.google.android.gms:play-services-location:10.0.1'
compile 'com.google.firebase:firebase-auth:10.0.0'
compile 'com.google.firebase:firebase-database:10.0.0'
compile 'com.firebaseui:firebase-ui-database:1.0.1'
compile 'com.google.firebase:firebase-storage:10.0.0'

`` Google seems to move play service updates along with firebase updates these days. Hopes this saves a few souls out there.

RelativeLayout center vertical

If View's height/width = wrap_content

use:

android:layout_centerHorizontal="true"
android:layout_centerVertical="true"

If View's height/width = match_parent

use:

android:gravity="center_vertical|center_horizontal"

What is the Gradle artifact dependency graph command?

Ah, since I had no dependencies in my master project, "gradle dependencies" only lists those and not subproject dependencies so the correct command ended up being

 gradle :<subproject>:dependencies

so for me this was

 gradle :master:dependencies

Convert audio files to mp3 using ffmpeg

https://trac.ffmpeg.org/wiki/Encode/MP3

VBR Encoding:

ffmpeg -vn -ar 44100 -ac 2 -q:a 1 -codec:a libmp3lame output.mp3

Convert time in HH:MM:SS format to seconds only?

In pseudocode:

split it by colon
seconds = 3600 * HH + 60 * MM + SS

Transparent control over PictureBox

How to search for a string in cell array in MATLAB?

Other answers are probably simpler for this case, but for completeness I thought I would add the use of cellfun with an anonymous function

indices = find(cellfun(@(x) strcmp(x,'KU'), strs))

which has the advantage that you can easily make it case insensitive or use it in cases where you have cell array of structures:

indices = find(cellfun(@(x) strcmpi(x.stringfield,'KU'), strs))

Nested lists python

Try this setup:

a = [["a","b","c",],["d","e"],["f","g","h"]]

To print the 2nd element in the 1st list ("b"), use print a[0][1] - For the 2nd element in 3rd list ("g"): print a[2][1]

The first brackets reference which nested list you're accessing, the second pair references the item in that list.

Read a HTML file into a string variable in memory

You can do it the simple way:

string pathToHTMLFile = @"C:\temp\someFile.html";
string htmlString = File.ReadAllText(pathToHTMLFile);

Or you could stream it in with FileStream/StreamReader:

using (FileStream fs = File.Open(pathToHTMLFile, FileMode.Open, FileAccess.ReadWrite))
{
    using (StreamReader sr = new StreamReader(fs))
    {
        htmlString = sr.ReadToEnd();
    }
}

This latter method allows you to open the file while still permitting others to perform Read/Write operations on the file. I can't imagine an HTML file being very big, but it has the added benefit of streaming the file instead of capturing it as one large chunk like the first method.

What's the quickest way to multiply multiple cells by another number?

Put the number you want to multiply by in a cell that is not in your range. Select the cell and "Copy" it to the clipboard. Next, select the Range A1:D5, and from the menu choose Edit|Paste Special. A dialog box will appear. In the "Operation" area, select "Multiply" and click "OK".

Unsigned values in C

Assign a int -1 to an unsigned: As -1 does not fit in the range [0...UINT_MAX], multiples of UINT_MAX+1 are added until the answer is in range. Evidently UINT_MAX is pow(2,32)-1 or 429496725 on OP's machine so a has the value of 4294967295.

    unsigned int a = -1;

The "%x", "%u" specifier expects a matching unsigned. Since these do not match, "If a conversion specification is invalid, the behavior is undefined. If any argument is not the correct type for the corresponding conversion specification, the behavior is undefined." C11 §7.21.6.1 9. The printf specifier does not change b.

    printf("%x\n", b);  // UB
    printf("%u\n", b);  // UB

The "%d" specifier expects a matching int. Since these do not match, more UB.

    printf("%d\n", a);  // UB

Given undefined behavior, the conclusions are not supported.

both cases, the bytes are the same (ffffffff).

Even with the same bit pattern, different types may have different values. ffffffff as an unsigned has the value of 4294967295. As an int, depending signed integer encoding, it has the value of -1, -2147483647 or TBD. As a float it may be a NAN.

what is unsigned word for?

unsigned stores a whole number in the range [0 ... UINT_MAX]. It never has a negative value. If code needs a non-negative number, use unsigned. If code needs a counting number that may be +, - or 0, use int.

Update: to avoid a compiler warning about assigning a signed int to unsigned, use the below. This is an unsigned 1u being negated - which is well defined as above. The effect is the same as a -1, but conveys to the compiler direct intentions.

unsigned int a = -1u;

In c# what does 'where T : class' mean?

It is a generic type constraint. In this case it means that the generic type T has to be a reference type (class, interface, delegate, or array type).

Getting the SQL from a Django QuerySet

This middleware will output every SQL query to your console, with color highlighting and execution time, it's been invaluable for me in optimizing some tricky requests

http://djangosnippets.org/snippets/290/

How to align footer (div) to the bottom of the page?

This will make the div fixed at the bottom of the page but in case the page is long it will only be visible when you scroll down.

<style type="text/css">
  #footer {
    position : absolute;
    bottom : 0;
    height : 40px;
    margin-top : 40px;
  }
</style>
<div id="footer">I am footer</div>

The height and margin-top should be the same so that the footer doesnt show over the content.

How to declare array of zeros in python (or an array of a certain size)

Just for completeness: To declare a multidimensional list of zeros in python you have to use a list comprehension like this:

buckets = [[0 for col in range(5)] for row in range(10)]

to avoid reference sharing between the rows.

This looks more clumsy than chester1000's code, but is essential if the values are supposed to be changed later. See the Python FAQ for more details.

Can I change the Android startActivity() transition animation?

Most of the answers are pretty correct, but some of them are deprecated such as when using R.anim.hold and some of them are just elaboratig the process.

So, you can use:

startActivity(intent);
overridePendingTransition(android.R.anim.fade_in, android.R.anim.fade_out);

Difference between clean, gradlew clean

You should use this one too:

./gradlew :app:dependencies (Mac and Linux) -With ./

gradlew :app:dependencies (Windows) -Without ./

The libs you are using internally using any other versions of google play service.If yes then remove or update those libs.

Eclipse HotKey: how to switch between tabs?

On a SLES12 machine you can use Ctrl+PageUp and Ctrl+PageDown to navigate between tabs by default. You can always change these keys from Preferences window by browsing through "keys" section under "General" category. This process is well explained by Victor and VonC above.

Add column with constant value to pandas dataframe

With modern pandas you can just do:

df['new'] = 0

How to print Unicode character in Python?

This fixes UTF-8 printing in python:

UTF8Writer = codecs.getwriter('utf8')
sys.stdout = UTF8Writer(sys.stdout)

How to make a page redirect using JavaScript?

You can achieve this using the location object.

location.href = "http://someurl";

"cannot be used as a function error"

This line is the problem:

int estimatedPopulation (int currentPopulation,
                         float growthRate (birthRate, deathRate))

Make it:

int estimatedPopulation (int currentPopulation, float birthRate, float deathRate)

instead and invoke the function with three arguments like

estimatePopulation( currentPopulation, birthRate, deathRate );

OR declare it with two arguments like:

int estimatedPopulation (int currentPopulation, float growthrt ) { ... }

and call it as

estimatedPopulation( currentPopulation, growthRate (birthRate, deathRate));

Edit:

Probably more important here - C++ (and C) names have scope. You can have two things named the same but not at the same time. In your particular case your grouthRate variable in the main() hides the function with the same name. So within main() you can only access grouthRate as float. On the other hand, outside of the main() you can only access that name as a function, since that automatic variable is only visible within the scope of main().

Just hope I didn't confuse you further :)

Javascript + Regex = Nothing to repeat error?

for example I faced this in express node.js when trying to create route for paths not starting with /internal

app.get(`\/(?!internal).*`, (req, res)=>{

and after long trying it just worked when passing it as a RegExp Object using new RegExp()

app.get(new RegExp("\/(?!internal).*"), (req, res)=>{

this may help if you are getting this common issue in routing

Java and SQLite

sqlitejdbc code can be downloaded using git from https://github.com/crawshaw/sqlitejdbc.

# git clone https://github.com/crawshaw/sqlitejdbc.git sqlitejdbc
...
# cd sqlitejdbc
# make

Note: Makefile requires curl binary to download sqlite libraries/deps.

What JSON library to use in Scala?

@AlaxDean's #7 answer, Argonaut is the only one that I was able to get working quickly with sbt and intellij. Actually json4s also took little time but dealing with a raw AST is not what I wanted. I got argonaut to work by putting in a single line into my build.st:

libraryDependencies += "io.argonaut" %% "argonaut" % "6.0.1"

And then a simple test to see if it I could get JSON:

package mytest


import scalaz._, Scalaz._
import argonaut._, Argonaut._

object Mytest extends App {

  val requestJson  =
    """
    {
      "userid": "1"
    }
    """.stripMargin

  val updatedJson: Option[Json] = for {
    parsed <- requestJson.parseOption
  } yield ("name", jString("testuser")) ->: parsed

  val obj = updatedJson.get.obj
  printf("Updated user: %s\n", updatedJson.toString())
  printf("obj : %s\n", obj.toString())
  printf("userid: %s\n", obj.get.toMap("userid"))
}

And then

$ sbt
> run
Updated user: Some({"userid":"1","name":"testuser"})
obj : Some(object[("userid","1"),("name","testuser")])
userid: "1"

Make sure you are familiar with Option which is just a value that can also be null (null safe I guess). Argonaut makes use of Scalaz so if you see something you don't understand like the symbol \/ (an or operation) it's probably Scalaz.

How to install Jdk in centos

Here is something that might help. Use the root privileges. if you have .bin then simply add the execution permission to the bin file.

chmod a+x jdk*.bin

next step is to run the .bin file which is simply

./jdk*.bin in the location you want to install.

you are done.

CSS: Set Div height to 100% - Pixels

Negative margins of course!

HTML

<div id="header">
    <h1>Header Text</h1>
</div>
<div id="wrapper">
    <div id="content">
        Lorem ipsum dolor sit amet, consectetur adipiscing elit. Curabitur 
        ullamcorper velit aliquam dolor dapibus interdum sed in dolor. Phasellus 
        vel quam et quam congue sodales.
    </div>
</div>

CSS

#header
{
    height: 111px;
    margin-top: 0px;
}
#wrapper
{
    margin-bottom: 0px;
    margin-top: -111px;
    height: 100%;
    position:relative;
    z-index:-1;
}
#content
{
    margin-top: 111px;
    padding: 0.5em;
}

PHP: merge two arrays while keeping keys instead of reindexing?

You can simply 'add' the arrays:

>> $a = array(1, 2, 3);
array (
  0 => 1,
  1 => 2,
  2 => 3,
)
>> $b = array("a" => 1, "b" => 2, "c" => 3)
array (
  'a' => 1,
  'b' => 2,
  'c' => 3,
)
>> $a + $b
array (
  0 => 1,
  1 => 2,
  2 => 3,
  'a' => 1,
  'b' => 2,
  'c' => 3,
)

How to add a new object (key-value pair) to an array in javascript?

.push() will add elements to the end of an array.

Use .unshift() if need to add some element to the beginning of array i.e:

items.unshift({'id':5});

Demo:

_x000D_

items = [{'id': 1}, {'id': 2}, {'id': 3}, {'id': 4}];_x000D_
items.unshift({'id': 0});_x000D_
console.log(items);

_x000D_

And use .splice() in case you want to add object at a particular index i.e:

items.splice(2, 0, {'id':5});
           // ^ Given object will be placed at index 2...

Demo:

_x000D_

items = [{'id': 1}, {'id': 2}, {'id': 3}, {'id': 4}];_x000D_
items.splice(2, 0, {'id': 2.5});_x000D_
console.log(items);

_x000D_

Twitter Bootstrap scrollable table rows and fixed header

Just stack two bootstrap tables; one for columns, the other for content. No plugins, just pure bootstrap (and that ain't no bs, haha!)

  <table id="tableHeader" class="table" style="table-layout:fixed">
        <thead>
            <tr>
                <th>Col1</th>
                ...
            </tr>
        </thead>
  </table>
  <div style="overflow-y:auto;">
    <table id="tableData" class="table table-condensed" style="table-layout:fixed">
        <tbody>
            <tr>
                <td>data</td>
                ...
            </tr>
        </tbody>
    </table>
 </div>

Demo JSFiddle

The content table div needs overflow-y:auto, for vertical scroll bars. Had to use table-layout:fixed, otherwise, columns did not line up. Also, had to put the whole thing inside a bootstrap panel to eliminate space between the tables.

Have not tested with custom column widths, but provided you keep the widths consistent between the tables, it should work.

    // ADD THIS JS FUNCTION TO MATCH UP COL WIDTHS
    $(function () {

        //copy width of header cells to match width of cells with data
        //so they line up properly
        var tdHeader = document.getElementById("tableHeader").rows[0].cells;
        var tdData = document.getElementById("tableData").rows[0].cells;

        for (var i = 0; i < tdData.length; i++)
            tdHeader[i].style.width = tdData[i].offsetWidth + 'px';

    });

Unable to resolve host "<insert URL here>" No address associated with hostname

Are you able to reach that url from within the built-in browser?

If not, it means that your network setup is not correct. If you are in the emulator, you may have a look at the networking section of the docs.

If you are on OS/X, the emulator is using "the first" interface, en0 even if you are on wireless (en1), as en0 without a cable is still marked as up. You can issue ifconfig en0 down and restart the emulator. I think I have read about similar behavior on Windows.

If you are on Wifi/3G, call your network provider for the correct DNS settings.

Why am I seeing net::ERR_CLEARTEXT_NOT_PERMITTED errors after upgrading to Cordova Android 8?

Old ionic cli (4.2) was causing issue in my case, update to 5 solve the problem

Java 8 LocalDate Jackson format

annotation in Pojo without using additional dependencies

@DateTimeFormat (pattern = "yyyy/MM/dd", iso = DateTimeFormat.ISO.DATE)
private LocalDate enddate;

Receiver not registered exception error?

Unregister broadcast receiver in Try Catch

    try {
        unregisterReceiver(receiver);
    } catch (IllegalArgumentException e) {
        System.out.printf(e.getMessage());
    }

How to get the file ID so I can perform a download of a file from Google Drive API on Android?

If you know the the name of the file and if you always want to download that specific file, then you can easily get the ID and other attributes for your desired file from: https://developers.google.com/drive/v2/reference/files/list (towards the bottom you will find a way to run queries). In the q field enter title = 'your_file_name' and run it. You should see some result show up right below and within it should be an "id" field. That is the id you are looking for.

You can also play around with additional parameters from: https://developers.google.com/drive/search-parameters

jQuery: Check if div with certain class name exists

$('div').hasClass('mydivclass')// Returns true if the class exist.

PHP Regex to check date is in YYYY-MM-DD format

Check and validate YYYY-MM-DD date in one line statement

function isValidDate($date) {
    return preg_match("/^(\d{4})-(\d{1,2})-(\d{1,2})$/", $date, $m)
        ? checkdate(intval($m[2]), intval($m[3]), intval($m[1]))
        : false;
}

The output will be:

var_dump(isValidDate("2018-01-01")); // bool(true)
var_dump(isValidDate("2018-1-1"));   // bool(true)
var_dump(isValidDate("2018-02-28")); // bool(true)
var_dump(isValidDate("2018-02-30")); // bool(false)

Day and month without leading zero are allowed. If you don't want to allow this, the regexp should be:

"/^(\d{4})-(\d{2})-(\d{2})$/"

Conditional Replace Pandas

I would use lambda function on a Series of a DataFrame like this:

f = lambda x: 0 if x>100 else 1
df['my_column'] = df['my_column'].map(f)

I do not assert that this is an efficient way, but it works fine.

How do I clone a subdirectory only of a Git repository?

If you're actually ony interested in the latest revision files of a directory, Github lets you download a repository as Zip file, which does not contain history. So downloading is very much faster.

Convert Date/Time for given Timezone - java

As always, I recommend reading this article about date and time in Java so that you understand it.

The basic idea is that 'under the hood' everything is done in UTC milliseconds since the epoch. This means it is easiest if you operate without using time zones at all, with the exception of String formatting for the user.

Therefore I would skip most of the steps you have suggested.

Set the time on an object (Date, Calendar etc).
Set the time zone on a formatter object.
Return a String from the formatter.

Alternatively, you can use Joda time. I have heard it is a much more intuitive datetime API.

Cannot GET / Nodejs Error

Have you checked your folder structure? It seems to me like Express can't find your root directory, which should be a a folder named "site" right under your default directory. Here is how it should look like, according to the tutorial:

node_modules/
  .bin/
  express/
  mongoose/
  path/
site/
  css/
  img/
  js/
  index.html
package.json

For example on my machine, I started getting the same error as you when I renamed my "site" folder as something else. So I would suggest you check that you have the index.html page inside a "site" folder that sits on the same path as your server.js file.

Hope that helps!

nginx: [emerg] "server" directive is not allowed here

The path to the nginx.conf file which is the primary Configuration file for Nginx - which is also the file which shall INCLUDE the Path for other Nginx Config files as and when required is /etc/nginx/nginx.conf.

You may access and edit this file by typing this at the terminal

cd /etc/nginx

/etc/nginx$ sudo nano nginx.conf

Further in this file you may Include other files - which can have a SERVER directive as an independent SERVER BLOCK - which need not be within the HTTP or HTTPS blocks, as is clarified in the accepted answer above.

I repeat - if you need a SERVER BLOCK to be defined within the PRIMARY Config file itself than that SERVER BLOCK will have to be defined within an enclosing HTTP or HTTPS block in the /etc/nginx/nginx.conf file which is the primary Configuration file for Nginx.

Also note -its OK if you define , a SERVER BLOCK directly not enclosing it within a HTTP or HTTPS block , in a file located at path /etc/nginx/conf.d . Also to make this work you will need to include the path of this file in the PRIMARY Config file as seen below :-

http{
    include /etc/nginx/conf.d/*.conf; #includes all files of file type.conf
}

Further to this you may comment out from the PRIMARY Config file , the line

http{
    #include /etc/nginx/sites-available/some_file.conf; # Comment Out 
    include /etc/nginx/conf.d/*.conf; #includes all files of file type.conf
}

and need not keep any Config Files in /etc/nginx/sites-available/ and also no need to SYMBOLIC Link them to /etc/nginx/sites-enabled/ , kindly note this works for me - in case anyone think it doesnt for them or this kind of config is illegal etc etc , pls do leave a comment so that i may correct myself - thanks .

EDIT :- According to the latest version of the Official Nginx CookBook , we need not create any Configs within - /etc/nginx/sites-enabled/ , this was the older practice and is DEPRECIATED now .

Thus No need for the INCLUDE DIRECTIVE include /etc/nginx/sites-available/some_file.conf; .

Quote from Nginx CookBook page - 5 .

"In some package repositories, this folder is named sites-enabled, and configuration files are linked from a folder named site-available; this convention is depre- cated."

Android 8: Cleartext HTTP traffic not permitted

You might only want to allow cleartext while debugging, but keep the security benefits of rejecting cleartext in production. This is useful for me because I test my app against a development server that does not support https. Here is how to enforce https in production, but allow cleartext in debug mode:

In build.gradle:

// Put this in your buildtypes debug section:
manifestPlaceholders = [usesCleartextTraffic:"true"]

// Put this in your buildtypes release section
manifestPlaceholders = [usesCleartextTraffic:"false"]

In the application tag in AndroidManifest.xml

android:usesCleartextTraffic="${usesCleartextTraffic}"

Check if a key exists inside a json object

Try this,

if(thisSession.hasOwnProperty('merchant_id')){

}

the JS Object thisSession should be like

{
amt: "10.00",
email: "[email protected]",
merchant_id: "sam",
mobileNo: "9874563210",
orderID: "123456",
passkey: "1234"
}

you can find the details here

Drag and drop elements from list into separate blocks

Also check it

jQuery: Customizable layout using drag and drop (examples)

http://devheart.org/examples/jquery-customizable-layout-using-drag-and-drop/1-getting-started-with-sortable-lists/

Update elements in a JSONObject

Hello I can suggest you universal method. use recursion.

    public static JSONObject function(JSONObject obj, String keyMain,String valueMain, String newValue) throws Exception {
    // We need to know keys of Jsonobject
    JSONObject json = new JSONObject()
    Iterator iterator = obj.keys();
    String key = null;
    while (iterator.hasNext()) {
        key = (String) iterator.next();
        // if object is just string we change value in key
        if ((obj.optJSONArray(key)==null) && (obj.optJSONObject(key)==null)) {
            if ((key.equals(keyMain)) && (obj.get(key).toString().equals(valueMain))) {
                // put new value
                obj.put(key, newValue);
                return obj;
            }
        }

        // if it's jsonobject
        if (obj.optJSONObject(key) != null) {
            function(obj.getJSONObject(key), keyMain, valueMain, newValue);
        }

        // if it's jsonarray
        if (obj.optJSONArray(key) != null) {
            JSONArray jArray = obj.getJSONArray(key);
            for (int i=0;i<jArray.length();i++) {
                    function(jArray.getJSONObject(i), keyMain, valueMain, newValue);
            }
        }
    }
    return obj;
}

It should work. If you have questions, go ahead.. I'm ready.

Format XML string to print friendly XML string

Use XmlTextWriter...

public static string PrintXML(string xml)
{
    string result = "";

    MemoryStream mStream = new MemoryStream();
    XmlTextWriter writer = new XmlTextWriter(mStream, Encoding.Unicode);
    XmlDocument document = new XmlDocument();

    try
    {
        // Load the XmlDocument with the XML.
        document.LoadXml(xml);

        writer.Formatting = Formatting.Indented;

        // Write the XML into a formatting XmlTextWriter
        document.WriteContentTo(writer);
        writer.Flush();
        mStream.Flush();

        // Have to rewind the MemoryStream in order to read
        // its contents.
        mStream.Position = 0;

        // Read MemoryStream contents into a StreamReader.
        StreamReader sReader = new StreamReader(mStream);

        // Extract the text from the StreamReader.
        string formattedXml = sReader.ReadToEnd();

        result = formattedXml;
    }
    catch (XmlException)
    {
        // Handle the exception
    }

    mStream.Close();
    writer.Close();

    return result;
}

read.csv warning 'EOF within quoted string' prevents complete reading of file

The readr package will fix this issue.

install.packages('readr')
library(readr)
readr::read_csv('yourfile.csv')

How to implement if-else statement in XSLT?

You have to reimplement it using <xsl:choose> tag:

       <xsl:choose>
         <xsl:when test="$CreatedDate > $IDAppendedDate">
           <h2> mooooooooooooo </h2>
         </xsl:when>
         <xsl:otherwise>
          <h2> dooooooooooooo </h2>
         </xsl:otherwise>
       </xsl:choose>

How to append multiple values to a list in Python

letter = ["a", "b", "c", "d"]
letter.extend(["e", "f", "g", "h"])
letter.extend(("e", "f", "g", "h"))
print(letter)
... 
['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'e', 'f', 'g', 'h']

Forcing a postback

No, not from code behind. A postback is a request initiated from a page on the client back to itself on the server using the Http POST method. On the server side you can request a redirect but the will be Http GET request.

Select rows having 2 columns equal value

Select * from tablename t1, tablename t2, tablename t3 
where t1.C1 = t2.c2 and t2.c2 = t3.c3

Seems like this will work. Though does not seems like an efficient way.

How do I trim whitespace from a string?

You want strip():

myphrases = [" Hello ", " Hello", "Hello ", "Bob has a cat"]

for phrase in myphrases:
    print(phrase.strip())

Get checkbox list values with jQuery

Not tested but should work:

$("#MyDiv td input:checked").each(function()
{
    alert($(this).attr("id"));
});

How do I force detach Screen from another SSH session?

Short answer

Reattach without ejecting others: screen -x
Get list of displays: ^A *, select the one to disconnect, press d

Explained answer

Background: When I was looking for the solution with same problem description, I have always landed on this answer. I would like to provide more sensible solution. (For example: the other attached screen has a different size and a I cannot force resize it in my terminal.)

Note: PREFIX is usually ^A = ctrl+a

Note: the display may also be called:

"user front-end" (in at command manual in screen)

"client" (tmux vocabulary where this functionality is detach-client)

"terminal" (as we call the window in our user interface) /depending on

1. Reattach a session: screen -x

-x attach to a not detached screen session without detaching it

2. List displays of this session: PREFIX *

It is the default key binding for: PREFIX :displays. Performing it within the screen, identify the other display we want to disconnect (e.g. smaller size). (Your current display is displayed in brighter color/bold when not selected).

term-type   size         user interface           window       Perms
---------- ------- ---------- ----------------- ----------     -----
 screen     240x60         you@/dev/pts/2      nb  0(zsh)        rwx
 screen      78x40         you@/dev/pts/0      nb  0(zsh)        rwx

Using arrows ? ?, select the targeted display, press d If nothing happens, you tried to detach your own display and screen will not detach it. If it was another one, within a second or two, the entry will disappear.

Press ENTER to quit the listing.

Optionally: in order to make the content fit your screen, reflow: PREFIX F (uppercase F)

Excerpt from man page of screen:

displays

Shows a tabular listing of all currently connected user front-ends (displays). This is most useful for multiuser sessions. The following keys can be used in displays list:

mouseclick Move to the selected line. Available when "mousetrack" is set to on.

space Refresh the list

d Detach that display

D Power detach that display

C-g, enter, or escape Exit the list

change image opacity using javascript

You could use jQuery's animate or fadeTo.

Error Code: 1290. The MySQL server is running with the --secure-file-priv option so it cannot execute this statement

The code above exports data without the heading columns which is weird. Here's how to do it. You have to merge the two files later though using text a editor.

SELECT column_name FROM information_schema.columns WHERE table_schema = 'my_app_db' AND table_name = 'customers' INTO OUTFILE 'C:/ProgramData/MySQL/MySQL Server 5.6/Uploads/customers_heading_cols.csv' FIELDS TERMINATED BY '' OPTIONALLY ENCLOSED BY '"' LINES TERMINATED BY ',';

When to use cla(), clf() or close() for clearing a plot in matplotlib?

They all do different things, since matplotlib uses a hierarchical order in which a figure window contains a figure which may consist of many axes. Additionally, there are functions from the pyplot interface and there are methods on the Figure class. I will discuss both cases below.

pyplot interface

pyplot is a module that collects a couple of functions that allow matplotlib to be used in a functional manner. I here assume that pyplot has been imported as import matplotlib.pyplot as plt. In this case, there are three different commands that remove stuff:

plt.cla() clears an axes, i.e. the currently active axes in the current figure. It leaves the other axes untouched.

plt.clf() clears the entire current figure with all its axes, but leaves the window opened, such that it may be reused for other plots.

plt.close() closes a window, which will be the current window, if not specified otherwise.

Which functions suits you best depends thus on your use-case.

The close() function furthermore allows one to specify which window should be closed. The argument can either be a number or name given to a window when it was created using figure(number_or_name) or it can be a figure instance fig obtained, i.e., usingfig = figure(). If no argument is given to close(), the currently active window will be closed. Furthermore, there is the syntax close('all'), which closes all figures.

methods of the Figure class

Additionally, the Figure class provides methods for clearing figures. I'll assume in the following that fig is an instance of a Figure:

fig.clf() clears the entire figure. This call is equivalent to plt.clf() only if fig is the current figure.

fig.clear() is a synonym for fig.clf()

Note that even del fig will not close the associated figure window. As far as I know the only way to close a figure window is using plt.close(fig) as described above.

Difference between DOM parentNode and parentElement

Use .parentElement and you can't go wrong as long as you aren't using document fragments.

If you use document fragments, then you need .parentNode:

let div = document.createDocumentFragment().appendChild(document.createElement('div'));
div.parentElement // null
div.parentNode // document fragment

Also:

_x000D_

let div = document.getElementById('t').content.firstChild_x000D_
div.parentElement // null_x000D_
div.parentNode // document fragment

_x000D_

<template id="t"><div></div></template>

_x000D_

Apparently the <html>'s .parentNode links to the Document. This should be considered a decision phail as documents aren't nodes since nodes are defined to be containable by documents and documents can't be contained by documents.

How to move a file?

Based on the answer described here, using subprocess is another option.

Something like this:

subprocess.call("mv %s %s" % (source_files, destination_folder), shell=True)

I am curious to know the pro's and con's of this method compared to shutil. Since in my case I am already using subprocess for other reasons and it seems to work I am inclined to stick with it.

Is it system dependent maybe?

Convert string to date in Swift

In swift4,

    var Msg_Date_ = "2019-03-30T05:30:00+0000"

    let dateFormatterGet = DateFormatter()
    dateFormatterGet.dateFormat = "yyyy-MM-dd'T'HH:mm:ss"
    let dateFormatterPrint = DateFormatter()
    dateFormatterPrint.dateFormat = "MMM dd yyyy h:mm a"  //"MMM d, h:mm a" for  Sep 12, 2:11 PM
    let datee = dateFormatterGet.date(from: Msg_Date_)
    Msg_Date_ =  dateFormatterPrint.string(from: datee ?? Date())

    print(Msg_Date_)

//output :- Mar 30 2019 05:30 PM

How to check if an object is a list or tuple (but not string)?

Generally speaking, the fact that a function which iterates over an object works on strings as well as tuples and lists is more feature than bug. You certainly can use isinstance or duck typing to check an argument, but why should you?

That sounds like a rhetorical question, but it isn't. The answer to "why should I check the argument's type?" is probably going to suggest a solution to the real problem, not the perceived problem. Why is it a bug when a string is passed to the function? Also: if it's a bug when a string is passed to this function, is it also a bug if some other non-list/tuple iterable is passed to it? Why, or why not?

I think that the most common answer to the question is likely to be that developers who write f("abc") are expecting the function to behave as though they'd written f(["abc"]). There are probably circumstances where it makes more sense to protect developers from themselves than it does to support the use case of iterating across the characters in a string. But I'd think long and hard about it first.

Programs & Examples On #Cloneable

How to properly override clone method?

"insufficient memory for the Java Runtime Environment " message in eclipse

Detecting the onload event of a window opened with window.open

How to set null to a GUID property

How do you check whether a number is divisible by another number (Python)?

C++11 rvalues and move semantics confusion (return statement)

Jquery DatePicker Set default date

Check if MySQL table exists or not

How to change the remote repository for a git submodule?

VS2010 How to include files in project, to copy them to build output directory automatically during build or publish

How can I select and upload multiple files with HTML and PHP, using HTTP POST?

Android Intent Cannot resolve constructor

Is it possible to clone html element objects in JavaScript / JQuery?

How can I pass selected row to commandLink inside dataTable or ui:repeat?

What is the proper way to comment functions in Python?

Highlight Anchor Links when user manually scrolls?

How to keep a VMWare VM's clock in sync?

How to remove non UTF-8 characters from text file

jQuery Set Select Index

Angularjs - ng-cloak/ng-show elements blink

How to Get a Specific Column Value from a DataTable?

Jump into interface implementation in Eclipse IDE

ping: google.com: Temporary failure in name resolution

How to try convert a string to a Guid

How do I use Assert to verify that an exception has been thrown?

addID in jQuery?

How to disable compiler optimizations in gcc?

How can I access "static" class variables within class methods in Python?

Capturing window.onbeforeunload

Not able to pip install pickle in python 3.6

Converting data frame column from character to numeric

How to check permissions of a specific directory?

nodejs get file name from absolute path?

Image Processing: Algorithm Improvement for 'Coca-Cola Can' Recognition

How to compile and run C in sublime text 3?

Html code as IFRAME source rather than a URL

Reading a key from the Web.Config using ConfigurationManager

javascript create array from for loop

How do I use LINQ Contains(string[]) instead of Contains(string)

How do I initialize Kotlin's MutableList to empty MutableList?

Cycles in an Undirected Graph

Selenium and xPath - locating a link by containing text

ORA-12516, TNS:listener could not find available handler

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Convert A String (like testing123) To Binary In Java

Lining up labels with radio buttons in bootstrap

SQL to Entity Framework Count Group-By

Getting error: Peer authentication failed for user "postgres", when trying to get pgsql working with rails

Update label from another thread

PostgreSQL delete all content

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How to remove old Docker containers

Best way to list files in Java, sorted by Date Modified?

Calculate relative time in C#

How to put table in the center of the page using CSS?

How to detect when facebook's FB.init is complete

How to create a GUID in Excel?

How can I install a local gem?

<button> background image

What Regex would capture everything from ' mark to the end of a line?

Can't clone a github repo on Linux via HTTPS

When to use Comparable and Comparator

C++ String Declaring

How can I create a copy of an object in Python?

What is the default value for Guid?

.NET console application as Windows service

Unable to simultaneously satisfy constraints, will attempt to recover by breaking constraint

Android load from URL to Bitmap

C++ IDE for Macs

Can I call a base class's virtual function if I'm overriding it?

How to find the type of an object in Go?

Verify ImageMagick installation

npm WARN notsup SKIPPING OPTIONAL DEPENDENCY: Unsupported platform for [email protected]

How to return a html page from a restful controller in spring boot?

Warning: Cannot modify header information - headers already sent by ERROR

How do I retrieve my MySQL username and password?

Do it without down time

What's the difference between setWebViewClient vs. setWebChromeClient?