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Some Of The Best Answers From Latest Asked Questions

first-child and last-child with IE8

Since :last-child is a CSS3 pseudo-class, it is not supported in IE8. I believe :first-child is supported, as it's defined in the CSS2.1 specification.

One possible solution is to simply give the last child a class name and style that class.

Another would be to use JavaScript. jQuery makes this particularly easy as it provides a :last-child pseudo-class which should work in IE8. Unfortunately, that could result in a flash of unstyled content while the DOM loads.

Force DOM redraw/refresh on Chrome/Mac

This solution without timeouts! Real force redraw! For Android and iOS.

var forceRedraw = function(element){
  var disp = element.style.display;
  element.style.display = 'none';
  var trick = element.offsetHeight;
  element.style.display = disp;
};

Configuring user and password with Git Bash

Make sure you are using the SSH URL for the GitHub repository rather than the HTTPS URL. It will ask for username and password when you are using HTTPS and not SSH. You can check the file .git/config or run git config -e or git remote show origin to verify the URL and change it if needed.

jQuery.ajax handling continue responses: "success:" vs ".done"?

If you need async: false in your ajax, you should use success instead of .done. Else you better to use .done. This is from jQuery official site:

As of jQuery 1.8, the use of async: false with jqXHR ($.Deferred) is deprecated; you must use the success/error/complete callback options instead of the corresponding methods of the jqXHR object such as jqXHR.done().

Install msi with msiexec in a Specific Directory

Use APPLICATIONFOLDER="path" for latest msiexec

How does origin/HEAD get set?

Note first that your question shows a bit of misunderstanding. origin/HEAD represents the default branch on the remote, i.e. the HEAD that's in that remote repository you're calling origin. When you switch branches in your repo, you're not affecting that. The same is true for remote branches; you might have master and origin/master in your repo, where origin/master represents a local copy of the master branch in the remote repository.

origin's HEAD will only change if you or someone else actually changes it in the remote repository, which should basically never happen - you want the default branch a public repo to stay constant, on the stable branch (probably master). origin/HEAD is a local ref representing a local copy of the HEAD in the remote repository. (Its full name is refs/remotes/origin/HEAD.)

I think the above answers what you actually wanted to know, but to go ahead and answer the question you explicitly asked... origin/HEAD is set automatically when you clone a repository, and that's about it. Bizarrely, that it's not set by commands like git remote update - I believe the only way it will change is if you manually change it. (By change I mean point to a different branch; obviously the commit it points to changes if that branch changes, which might happen on fetch/pull/remote update.)


Edit: The problem discussed below was corrected in Git 1.8.4.3; see this update.


There is a tiny caveat, though. HEAD is a symbolic ref, pointing to a branch instead of directly to a commit, but the git remote transfer protocols only report commits for refs. So Git knows the SHA1 of the commit pointed to by HEAD and all other refs; it then has to deduce the value of HEAD by finding a branch that points to the same commit. This means that if two branches happen to point there, it's ambiguous. (I believe it picks master if possible, then falls back to first alphabetically.) You'll see this reported in the output of git remote show origin:

$ git remote show origin
* remote origin
  Fetch URL: ...
  Push  URL: ...
  HEAD branch (remote HEAD is ambiguous, may be one of the following):
    foo
    master

Oddly, although the notion of HEAD printed this way will change if things change on the remote (e.g. if foo is removed), it doesn't actually update refs/remotes/origin/HEAD. This can lead to really odd situations. Say that in the above example origin/HEAD actually pointed to foo, and origin's foo branch was then removed. We can then do this:

$ git remote show origin
...
HEAD branch: master
$ git symbolic-ref refs/remotes/origin/HEAD
refs/remotes/origin/foo
$ git remote update --prune origin
Fetching origin
 x [deleted]         (none)     -> origin/foo
   (refs/remotes/origin/HEAD has become dangling)

So even though remote show knows HEAD is master, it doesn't update anything. The stale foo branch is correctly pruned, and HEAD becomes dangling (pointing to a nonexistent branch), and it still doesn't update it to point to master. If you want to fix this, use git remote set-head origin -a, which automatically determines origin's HEAD as above, and then actually sets origin/HEAD to point to the appropriate remote branch.

How do I reformat HTML code using Sublime Text 2?

The only package I've been able to find is Tag.

You can install it using the package control. https://sublime.wbond.net

After installing package control. Go to package control (Preferences -> Package Control) then type install, hit enter. Then type tag and hit enter.

After installing Tag, highlight the text and press the shortcut Ctrl+Alt+F.

Oracle: How to filter by date and time in a where clause

In the example that you have provided there is nothing that would throw a SQL command not properly formed error. How are you executing this query? What are you not showing us?

This example script works fine:

create table tableName
(session_start_date_time DATE);

insert into tableName (session_start_date_time) 
values (sysdate+1);

select * from tableName
where session_start_date_time > to_date('12-Jan-2012 16:00', 'DD-MON-YYYY hh24:mi');

As does this example:

create table tableName2
(session_start_date_time TIMESTAMP);

insert into tableName2 (session_start_date_time) 
values (to_timestamp('01/12/2012 16:01:02.345678','mm/dd/yyyy hh24:mi:ss.ff'));

select * from tableName2
where session_start_date_time > to_date('12-Jan-2012 16:00', 'DD-MON-YYYY hh24:mi');

select * from tableName2
where session_start_date_time > to_timestamp('01/12/2012 14:01:02.345678','mm/dd/yyyy hh24:mi:ss.ff');

So there must be something else that is wrong.

ERROR 1044 (42000): Access denied for user ''@'localhost' to database 'db'

This is something to do with user permissions. Giving proper grants will solve this issue.

Step [1]: Open terminal and run this command

$ mysql -uroot -p

Output [1]: This should give you mysql prompt shown below

enter image description here

Step [2]:

mysql> CREATE USER 'parsa'@'localhost' IDENTIFIED BY 'your_password';
mysql> grant all privileges on *.* to 'parsa'@'localhost';

Syntax:

mysql> grant all privileges on `database_name`.`table_name` to 'user_name'@'hostname';

Note:

  • hostname can be IP address, localhost, 127.0.0.1
  • In database_name/table_name, * means all databases
  • In hostname, to specify all hosts use '%'

Step [3]: Get out of current mysql prompt by either entering quit / exit command or press Ctrl+D.

Step [4]: Login to your new user

$ mysql -uparsa -pyour_password

Step [5]: Create the database

mysql> create database `database_name`;

OnChange event handler for radio button (INPUT type="radio") doesn't work as one value

You can add the following JS script

<script>
    function myfunction(event) {
        alert('Checked radio with ID = ' + event.target.id);
    }
    document.querySelectorAll("input[name='gun']").forEach((input) => {
        input.addEventListener('change', myfunction);
    });
</script>

Setting Remote Webdriver to run tests in a remote computer using Java

This is how I got rid of the error:

WebDriverException: Error forwarding the new session cannot find : {platform=WINDOWS, ensureCleanSession=true, browserName=internet explorer, version=11}

In your nodeconfig.json, the version must be a String, not an integer.

So instead of using "version": 11 use "version": "11" (note the double quotes).

A full example of a working nodecondig.json file for a RemoteWebDriver:

{
  "capabilities":
  [
    {
      "platform": "WIN8_1",
      "browserName": "internet explorer",
      "maxInstances": 1,
      "seleniumProtocol": "WebDriver"
      "version": "11"
    }
    ,{
      "platform": "WIN7",
      "browserName": "chrome",
      "maxInstances": 4,
      "seleniumProtocol": "WebDriver"
      "version": "40"
    }
    ,{
      "platform": "LINUX",
      "browserName": "firefox",
      "maxInstances": 4,
      "seleniumProtocol": "WebDriver"
      "version": "33"
    }
  ],
  "configuration":
  {
    "proxy": "org.openqa.grid.selenium.proxy.DefaultRemoteProxy",
    "maxSession": 3,
    "port": 5555,
    "host": ip,
    "register": true,
    "registerCycle": 5000,
    "hubPort": 4444,
    "hubHost": {your-ip-address}
  }
}

Sort array of objects by single key with date value

I face with same thing, so i handle this with a generic why and i build a function for this:

//example:
//array: [{name: 'idan', workerType: '3'}, {name: 'stas', workerType: '5'}, {name: 'kirill', workerType: '2'}]
//keyField: 'workerType'
// keysArray: ['4', '3', '2', '5', '6']
sortByArrayOfKeys = (array, keyField, keysArray) => {
    array.sort((a, b) => {
        const aIndex = keysArray.indexOf(a[keyField])
        const bIndex = keysArray.indexOf(b[keyField])
        if (aIndex < bIndex) return -1;
        if (aIndex > bIndex) return 1;
        return 0;
    })
}

How can I specify a [DllImport] path at runtime?

Contrary to the suggestions by some of the other answers, using the DllImport attribute is still the correct approach.

I honestly don't understand why you can't do just like everyone else in the world and specify a relative path to your DLL. Yes, the path in which your application will be installed differs on different people's computers, but that's basically a universal rule when it comes to deployment. The DllImport mechanism is designed with this in mind.

In fact, it isn't even DllImport that handles it. It's the native Win32 DLL loading rules that govern things, regardless of whether you're using the handy managed wrappers (the P/Invoke marshaller just calls LoadLibrary). Those rules are enumerated in great detail here, but the important ones are excerpted here:

Before the system searches for a DLL, it checks the following:

  • If a DLL with the same module name is already loaded in memory, the system uses the loaded DLL, no matter which directory it is in. The system does not search for the DLL.
  • If the DLL is on the list of known DLLs for the version of Windows on which the application is running, the system uses its copy of the known DLL (and the known DLL's dependent DLLs, if any). The system does not search for the DLL.

If SafeDllSearchMode is enabled (the default), the search order is as follows:

  1. The directory from which the application loaded.
  2. The system directory. Use the GetSystemDirectory function to get the path of this directory.
  3. The 16-bit system directory. There is no function that obtains the path of this directory, but it is searched.
  4. The Windows directory. Use the GetWindowsDirectory function to get the path of this directory.
  5. The current directory.
  6. The directories that are listed in the PATH environment variable. Note that this does not include the per-application path specified by the App Paths registry key. The App Paths key is not used when computing the DLL search path.

So, unless you're naming your DLL the same thing as a system DLL (which you should obviously not be doing, ever, under any circumstances), the default search order will start looking in the directory from which your application was loaded. If you place the DLL there during the install, it will be found. All of the complicated problems go away if you just use relative paths.

Just write:

[DllImport("MyAppDll.dll")] // relative path; just give the DLL's name
static extern bool MyGreatFunction(int myFirstParam, int mySecondParam);

But if that doesn't work for whatever reason, and you need to force the application to look in a different directory for the DLL, you can modify the default search path using the SetDllDirectory function.
Note that, as per the documentation:

After calling SetDllDirectory, the standard DLL search path is:

  1. The directory from which the application loaded.
  2. The directory specified by the lpPathName parameter.
  3. The system directory. Use the GetSystemDirectory function to get the path of this directory.
  4. The 16-bit system directory. There is no function that obtains the path of this directory, but it is searched.
  5. The Windows directory. Use the GetWindowsDirectory function to get the path of this directory.
  6. The directories that are listed in the PATH environment variable.

So as long as you call this function before you call the function imported from the DLL for the first time, you can modify the default search path used to locate DLLs. The benefit, of course, is that you can pass a dynamic value to this function that is computed at run-time. That isn't possible with the DllImport attribute, so you will still use a relative path (the name of the DLL only) there, and rely on the new search order to find it for you.

You'll have to P/Invoke this function. The declaration looks like this:

[DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
static extern bool SetDllDirectory(string lpPathName);

return query based on date

You can also try:

{
    "dateProp": { $gt: new Date('06/15/2016').getTime() }
}

Insert data using Entity Framework model

[HttpPost] // it use when you write logic on button click event

public ActionResult DemoInsert(EmployeeModel emp)
{
    Employee emptbl = new Employee();    // make object of table
    emptbl.EmpName = emp.EmpName;
    emptbl.EmpAddress = emp.EmpAddress;  // add if any field you want insert
    dbc.Employees.Add(emptbl);           // pass the table object 
    dbc.SaveChanges();

    return View();
}

How to specify non-default shared-library path in GCC Linux? Getting "error while loading shared libraries" when running

Should it be LIBRARY_PATH instead of LD_LIBRARY_PATH. gcc checks for LIBRARY_PATH which can be seen with -v option

What is the purpose of Android's <merge> tag in XML layouts?

To have a more in-depth knowledge of what's happening, I created the following example. Have a look at the activity_main.xml and content_profile.xml files.

activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <include layout="@layout/content_profile" />

</LinearLayout>

content_profile.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Howdy" />

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Hi there" />

</LinearLayout>

In here, the entire layout file when inflated looks like this.

<LinearLayout>
    <LinearLayout>
        <TextView />
        <TextView />
    </LinearLayout>
</LinearLayout>

See that there is a LinearLayout inside the parent LinearLayout which doesn't serve any purpose and is redundant. A look at the layout through Layout Inspector tool clearly explains this.

enter image description here

content_profile.xml after updating the code to use merge instead of a ViewGroup like LinearLayout.

<merge xmlns:android="http://schemas.android.com/apk/res/android">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Howdy" />

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Hi there" />

</merge>

Now our layout looks like this

<LinearLayout>
    <TextView />
    <TextView />
</LinearLayout>

Here we see that the redundant LinearLayout ViewGroup is removed. Now Layout Inspector tool gives the following layout hierarchy.

enter image description here

So always try to use merge when your parent layout can position your child layouts, or more precisely use merge when you understand that there is going to be a redundant view group in the hierarchy.

m2eclipse error

I had same problem with Eclipse 3.7.2 (Indigo) and maven 3.0.4.

In my case, the problem was caused by missing maven-resources-plugin-2.4.3.jar in {user.home}\.m2\repository\org\apache\maven\plugins\maven-resources-plugin\2.4.3 folder. (no idea why maven didn't update it)

Solution:

1.) add dependency to pom.xml

<dependency>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-resources-plugin</artifactId>
    <version>2.4.3</version>
</dependency>

2.) run mvn install from Eclipse or from command line

3.) refresh the project in eclipse (F5)

4.) run Maven > Update Project Configuration... on project (right click)

JAR file is downloaded to local repository and there are no errors in WS.

Oracle 11g Express Edition for Windows 64bit?

Some of more advanced Oracle database features such as session trace do not work properly in Oracle 11g XE 32-bit if installed on Windows 64-bit system. I needed session trace on Windows 7 64-bit.

Apart from that it works well for me in multiple production MS Windows 64-bit systems: Windows Server 2008 R2 and Windows Server 2003 R2.

Add a column to a table, if it does not already exist

You can use a similar construct by using the sys.columns table io sys.objects.

IF NOT EXISTS (
  SELECT * 
  FROM   sys.columns 
  WHERE  object_id = OBJECT_ID(N'[dbo].[Person]') 
         AND name = 'ColumnName'
)

How to quickly test some javascript code?

If you want to edit some complex javascript I suggest you use JsFiddle. Alternatively, for smaller pieces of javascript you can just run it through your browser URL bar, here's an example:

javascript:alert("hello world");

And, as it was already suggested both Firebug and Chrome developer tools have Javascript console, in which you can type in your javascript to execute. So do Internet Explorer 8+, Opera, Safari and potentially other modern browsers.

how much memory can be accessed by a 32 bit machine?

basically 32bit architecture can address 4GB as you expected. There are some techniques which allows processor to address more data like AWE or PAE.

How do I automatically play a Youtube video (IFrame API) muted?

The accepted answer works pretty good. I wanted more control so I added a couple of functions more to the script:

function unmuteVideo() {
    player.unMute();
    return false;
  }
  function muteVideo() {
    player.mute();
    return false;
  }
  function setVolumeVideo(volume) {
    player.setVolume(volume);
    return false;
  }

And here is the HTML:

<br>
<button type="button" onclick="unmuteVideo();">Unmute Video</button>
<button type="button" onclick="muteVideo();">Mute Video</button>
<br>
<br>
<button type="button" onclick="setVolumeVideo(100);">Volume 100%</button>
<button type="button" onclick="setVolumeVideo(75);">Volume 75%</button>
<button type="button" onclick="setVolumeVideo(50);">Volume 50%</button>
<button type="button" onclick="setVolumeVideo(25);">Volume 25%</button>

Now you have more control of the sound... Check the reference URL for more:

YouTube IFrame Player API

How can I find out if an .EXE has Command-Line Options?

Just use IDA PRO (https://www.hex-rays.com/products/ida/index.shtml) to disassemble the file, and search for some known command line option (using Search...Text) - in that section you will then typically see all the command line options - for the program (LIB2NIST.exe) in the screenshot below, for example, it shows a documented command line option (/COM2TAG) but also some undocumented ones, like /L. Hope this helps?

enter image description here

Why is the console window closing immediately once displayed my output?

Add The Read method to show the output.

Console.WriteLine("Hello, World!");
Console.Read();
return 0;

XMLHttpRequest (Ajax) Error

I see 2 possible problems:

Problem 1

  • the XMLHTTPRequest object has not finished loading the data at the time you are trying to use it

Solution: assign a callback function to the objects "onreadystatechange" -event and handle the data in that function

xmlhttp.onreadystatechange = callbackFunctionName;

Once the state has reached DONE (4), the response content is ready to be read.

Problem 2

  • the XMLHTTPRequest object does not exist in all browsers (by that name)

Solution: Either use a try-catch for creating the correct object for correct browser ( ActiveXObject in IE) or use a framework, for example jQuery ajax-method

Note: if you decide to use jQuery ajax-method, you assign the callback-function with jqXHR.done()

Determine if 2 lists have the same elements, regardless of order?

As mentioned in comments above, the general case is a pain. It is fairly easy if all items are hashable or all items are sortable. However I have recently had to try solve the general case. Here is my solution. I realised after posting that this is a duplicate to a solution above that I missed on the first pass. Anyway, if you use slices rather than list.remove() you can compare immutable sequences.

def sequences_contain_same_items(a, b):
    for item in a:
        try:
            i = b.index(item)
        except ValueError:
            return False
        b = b[:i] + b[i+1:]
    return not b

How to change the current URL in javascript?

What you're doing is appending a "1" (the string) to your URL. If you want page 1.html link to page 2.html you need to take the 1 out of the string, add one to it, then reassemble the string.

Why not do something like this:

var url = 'http://mywebsite.com/1.html';
var pageNum = parseInt( url.split("/").pop(),10 );
var nextPage = 'http://mywebsite.com/'+(pageNum+1)+'.html';

nextPage will contain the url http://mywebsite.com/2.html in this case. Should be easy to put in a function if needed.

How can I list all collections in the MongoDB shell?

The command used for displaying all the collections in the MongoDB database is

show collections

Before running the show collections command you have to select the database:

use mydb // mydb is the name of the database being selected

To see all the databases, you can use the command

show dbs // Shows all the database names present

For more information, visit see Getting Started.

Comments in .gitignore?

Do git help gitignore

You will get the help page with following line:

A line starting with # serves as a comment.

How do I vertically center text with CSS?

Wherever you want vertically center style means you can try display:table-cell and vertical-align:middle.

Example:

_x000D_
_x000D_
#box_x000D_
{_x000D_
  display: table-cell;_x000D_
  vertical-align: middle;_x000D_
  height: 90px;_x000D_
  width: 270px;_x000D_
  background: #000;_x000D_
  font-size: 48px;_x000D_
  font-style: oblique;_x000D_
  color: #FFF;_x000D_
  text-align: center;_x000D_
  margin-top: 20px;_x000D_
  margin-left: 5px;_x000D_
}
_x000D_
<div Id="box">_x000D_
  Lorem ipsum dolor sit amet, consectetur adipiscing elit._x000D_
</div>
_x000D_
_x000D_
_x000D_

Using routes in Express-js

Seems that only index.js get loaded when you require("./routes") . I used the following code in index.js to load the rest of the routes:

var fs = require('fs')
  , path = require('path');

fs.readdirSync(__dirname).forEach(function(file){
  var route_fname = __dirname + '/' + file;
  var route_name = path.basename(route_fname, '.js');
  if(route_name !== 'index' && route_name[0] !== "."){ 
    exports[route_name] = require(route_fname)[route_name];
  }
});

ImportError: No module named PIL

I used:

pip install Pillow 

and pip installed PIL in Lib\site-packages. When I moved PIL to Lib everything worked fine. I'm on Windows 10.

How to programmatically turn off WiFi on Android device?

You need the following permissions in your manifest file:

<uses-permission android:name="android.permission.ACCESS_WIFI_STATE"></uses-permission>
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE"></uses-permission>

Then you can use the following in your activity class:

WifiManager wifiManager = (WifiManager) this.getApplicationContext().getSystemService(Context.WIFI_SERVICE); 
wifiManager.setWifiEnabled(true);
wifiManager.setWifiEnabled(false);

Use the following to check if it's enabled or not

boolean wifiEnabled = wifiManager.isWifiEnabled()

You'll find a nice tutorial on the subject on this site.

Simple file write function in C++

You need to declare the prototype of your writeFile function, before actually using it:

int writeFile( void );

int main( void )
{
   ...

Unexpected end of file error

Change the Platform of your C++ project to "x64" (or whichever platform you are targeting) instead of "Win32". This can be found in Visual Studio under Build -> Configuration Manager. Find your project in the list and change the Platform column. Don't forget to do this for all solution configurations.

Clear all fields in a form upon going back with browser back button

I came across this post while searching for a way to clear the entire form related to the BFCache (back/forward button cache) in Chrome.

In addition to what Sim supplied, my use case required that the details needed to be combined with Clear Form on Back Button?.

I found that the best way to do this is in allow the form to behave as it expects, and to trigger an event:

$(window).bind("pageshow", function() {
    var form = $('form'); 
    // let the browser natively reset defaults
    form[0].reset();
});

If you are not handling the input events to generate an object in JavaScript, or something else for that matter, then you are done. However, if you are listening to the events, then at least in Chrome you need to trigger a change event yourself (or whatever event you care to handle, including a custom one):

form.find(':input').not(':button,:submit,:reset,:hidden').trigger('change');

That must be added after the reset to do any good.

JavaScript single line 'if' statement - best syntax, this alternative?

As has already been stated, you can use:

&& style

lemons && document.write("foo gave me a bar");  

or

bracket-less style

if (lemons) document.write("foo gave me a bar");

short-circuit return

If, however, you wish to use the one line if statement to short-circuit a function though, you'd need to go with the bracket-less version like so:

if (lemons) return "foo gave me a bar";

as

lemons && return "foo gave me a bar"; // does not work!

will give you a SyntaxError: Unexpected keyword 'return'

ALTER TABLE to add a composite primary key

It`s definitely better to use COMPOSITE UNIQUE KEY, as @GranadaCoder offered, a little bit tricky example though:

ALTER IGNORE TABLE table_name ADD UNIQUES INDEX idx_name(some_id, another_id, one_more_id);

PHP read and write JSON from file

The clue is in the error message - if you look at the documentation for json_decode note that it can take a second param, which controls whether it returns an array or an object - it defaults to object.

So change your call to

$json = json_decode(file_get_contents($file), true);

And it'll return an associative array and your code should work fine.

Tomcat is not running even though JAVA_HOME path is correct

I deleted the Tomcat and unzipped it again and it worked.

Calling stored procedure from another stored procedure SQL Server

You could add an OUTPUT parameter to test2, and set it to the new id straight after the INSERT using:

SELECT @NewIdOutputParam = SCOPE_IDENTITY()

Then in test1, retrieve it like so:

DECLARE @NewId INTEGER
EXECUTE test2 @NewId OUTPUT
-- Now use @NewId as needed

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?

Compiler error "archive for required library could not be read" - Spring Tool Suite

I faced this problem. I had "Archive for required library spring-boot-devtools cannot be read or is not a valid ZIP file" and the solution was like that:- 1- determine the dependencies names that have problems(for may case it is spring-boot-devtools). 2- close eclipse. 3- search in your .m2 file on these dependencies(by name). 4- delete these folders. 5- reopen eclipse and let maven rebuild your dependencies again.

How do I drop a MongoDB database from the command line?

Start MongoDB

Command for Database drop is :

1. first select the database which you want to delete

use < database name >

2. Then use this..

db.dropDatabase()

Get all messages from Whatsapp

Edit

As WhatsApp put some effort into improving their encryption system, getting the data is not that easy anymore. With newer versions of WhatsApp it is no longer possible to use adb backup. Apps can deny backups and the WhatsApp client does that. If you happen to have a rooted phone, you can use a root shell to get the unencrypted database file.

If you do not have root, you can still decrypt the data if you have an old WhatsApp APK. Find a version that still allows backups. Then you can make a backup of the app's data folder, which will contain an encryption key named, well, key.

Now you'll need the encrypted database. Use a file explorer of your choice or, if you like the command line more, use adb:

adb pull /sdcard/WhatsApp/Databases/msgstore.db.crypt12

Using the two files, you could now use https://gitlab.com/digitalinternals/whatsapp-crypt12 to get the plain text database. It is no longer possible to use Linux board tools like openssl because WhatsApp seems to use a modified version of the Spongy Castle API for cryptography that openssl does not understand.

Original Answer (only for the old crypt7)

As whatsapp is now using the crypt7 format, it is not that easy to get and decrypt the database anymore. There is a working approach using ADB and USB debugging.

You can either get the encryption keys via ADB and decrypt the message database stored on /sdcard, or you just get the plain version of the database via ADB backup, what seems to be the easier option.

To get the database, do the following:

Connect your Android phone to your computer. Now run

adb backup -f whatsapp_backup.ab -noapk com.whatsapp

to backup all files WhatsApp has created in its private folder.
You will get a zlib compressed file using tar format with some ADB headers. We need to get rid of those headers first as they confuse the decompression command:

dd if=whatsapp_backup.ab ibs=1 skip=24 of=whatsapp_backup.ab.nohdr

The file can now be decompressed:

cat whatsapp_backup.ab.nohdr | python -c "import zlib,sys;sys.stdout.write(zlib.decompress(sys.stdin.read()))" 1> whatsapp_backup.tar

This command runs Python and decompresses the file using zlib to whatsapp_backup.tar
Now we can unTAR the file:

tar xf whatsapp_backup.tar

The archive is now extracted to your current working directory and you can find the databases (msgstore.db and wa.db) in apps/com.whatsapp/db/

ValueError: unsupported format character while forming strings

For anyone checking this using python 3:

If you want to print the following output "100% correct":

python 3.8: print("100% correct")
python 3.7 and less: print("100%% correct")


A neat programming workaround for compatibility across diff versions of python is shown below:

Note: If you have to use this, you're probably experiencing many other errors... I'd encourage you to upgrade / downgrade python in relevant machines so that they are all compatible.

DevOps is a notable exception to the above -- implementing the following code would indeed be appropriate for specific DevOps / Debugging scenarios.

import sys

if version_info.major==3:
    if version_info.minor>=8:
        my_string = "100% correct"
    else:
        my_string = "100%% correct"

# Finally
print(my_string)

How to send email to multiple recipients using python smtplib?

I tried the below and it worked like a charm :)

rec_list =  ['[email protected]', '[email protected]']
rec =  ', '.join(rec_list)

msg['To'] = rec

send_out = smtplib.SMTP('localhost')
send_out.sendmail(me, rec_list, msg.as_string())

How to create standard Borderless buttons (like in the design guideline mentioned)?

Look into the theme attributes buttonBarStyle, buttonBarButtonStyle, and borderlessButtonStyle.

Secure random token in Node.js

0. Using nanoid third party library [NEW!]

A tiny, secure, URL-friendly, unique string ID generator for JavaScript

https://github.com/ai/nanoid

import { nanoid } from "nanoid";
const id = nanoid(48);


1. Base 64 Encoding with URL and Filename Safe Alphabet

Page 7 of RCF 4648 describes how to encode in base 64 with URL safety. You can use an existing library like base64url to do the job.

The function will be:

var crypto = require('crypto');
var base64url = require('base64url');

/** Sync */
function randomStringAsBase64Url(size) {
  return base64url(crypto.randomBytes(size));
}

Usage example:

randomStringAsBase64Url(20);
// Returns 'AXSGpLVjne_f7w5Xg-fWdoBwbfs' which is 27 characters length.

Note that the returned string length will not match with the size argument (size != final length).


2. Crypto random values from limited set of characters

Beware that with this solution the generated random string is not uniformly distributed.

You can also build a strong random string from a limited set of characters like that:

var crypto = require('crypto');

/** Sync */
function randomString(length, chars) {
  if (!chars) {
    throw new Error('Argument \'chars\' is undefined');
  }

  var charsLength = chars.length;
  if (charsLength > 256) {
    throw new Error('Argument \'chars\' should not have more than 256 characters'
      + ', otherwise unpredictability will be broken');
  }

  var randomBytes = crypto.randomBytes(length);
  var result = new Array(length);

  var cursor = 0;
  for (var i = 0; i < length; i++) {
    cursor += randomBytes[i];
    result[i] = chars[cursor % charsLength];
  }

  return result.join('');
}

/** Sync */
function randomAsciiString(length) {
  return randomString(length,
    'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789');
}

Usage example:

randomAsciiString(20);
// Returns 'rmRptK5niTSey7NlDk5y' which is 20 characters length.

randomString(20, 'ABCDEFG');
// Returns 'CCBAAGDGBBEGBDBECDCE' which is 20 characters length.

Convert ndarray from float64 to integer

Use .astype.

>>> a = numpy.array([1, 2, 3, 4], dtype=numpy.float64)
>>> a
array([ 1.,  2.,  3.,  4.])
>>> a.astype(numpy.int64)
array([1, 2, 3, 4])

See the documentation for more options.

Oracle SQL : timestamps in where clause

For everyone coming to this thread with fractional seconds in your timestamp use:

to_timestamp('2018-11-03 12:35:20.419000', 'YYYY-MM-DD HH24:MI:SS.FF')

FB OpenGraph og:image not pulling images (possibly https?)

For me this worked:

<meta property="og:url" content="http://yoursiteurl" />
    <meta property="og:image" content="link_to_first_image_if_you_want" />
    <meta property="og:image" content="link_to_second_image_if_you_want" />
    <meta property="og:image:type" content="image/jpeg" /> 
    <meta property="og:image:width" content="400" /> 
    <meta property="og:image:height" content="300" />
    <meta property="og:title" content="your title" />
    <meta property="og:description"  content="your text about homepage"/> 

Append text using StreamWriter

Also look at log4net, which makes logging to 1 or more event stores — whether it's the console, the Windows event log, a text file, a network pipe, a SQL database, etc. — pretty trivial. You can even filter stuff in its configuration, for instance, so that only log records of a particular severity (say ERROR or FATAL) from a single component or assembly are directed to a particular event store.

http://logging.apache.org/log4net/

Exception 'open failed: EACCES (Permission denied)' on Android

Solution for Android Q:

<application ...
    android:requestLegacyExternalStorage="true" ... >

val() vs. text() for textarea

The best way to set/get the value of a textarea is the .val(), .value method.

.text() internally uses the .textContent (or .innerText for IE) method to get the contents of a <textarea>. The following test cases illustrate how text() and .val() relate to each other:

var t = '<textarea>';
console.log($(t).text('test').val());             // Prints test
console.log($(t).val('too').text('test').val());  // Prints too
console.log($(t).val('too').text());              // Prints nothing
console.log($(t).text('test').val('too').val());  // Prints too

console.log($(t).text('test').val('too').text()); // Prints test

The value property, used by .val() always shows the current visible value, whereas text()'s return value can be wrong.

Java String encoding (UTF-8)

How is this different from the following?

This line of code here:

String newString = new String(oldString.getBytes("UTF-8"), "UTF-8"));

constructs a new String object (i.e. a copy of oldString), while this line of code:

String newString = oldString;

declares a new variable of type java.lang.String and initializes it to refer to the same String object as the variable oldString.

Is there any scenario in which the two lines will have different outputs?

Absolutely:

String newString = oldString;
boolean isSameInstance = newString == oldString; // isSameInstance == true

vs.

String newString = new String(oldString.getBytes("UTF-8"), "UTF-8"));
 // isSameInstance == false (in most cases)    
boolean isSameInstance = newString == oldString;

a_horse_with_no_name (see comment) is right of course. The equivalent of

String newString = new String(oldString.getBytes("UTF-8"), "UTF-8"));

is

String newString = new String(oldString);

minus the subtle difference wrt the encoding that Peter Lawrey explains in his answer.

duplicate 'row.names' are not allowed error

Another possible reason for this error is that you have entire rows duplicated. If that is the case, the problem is solved by removing the duplicate rows.

repaint() in Java

You may need to call frame.repaint() as well to force the frame to actually redraw itself. I've had issues before where I tried to repaint a component and it wasn't updating what was displayed until the parent's repaint() method was called.

Logical operator in a handlebars.js {{#if}} conditional

Handlebars supports nested operations. This provides a lot of flexibility (and cleaner code) if we write our logic a little differently.

{{#if (or section1 section2)}}
.. content
{{/if}}

In fact, we can add all sorts of logic:

{{#if (or 
        (eq section1 "foo")
        (ne section2 "bar"))}}
.. content
{{/if}}

Just register these helpers:

Handlebars.registerHelper({
    eq: (v1, v2) => v1 === v2,
    ne: (v1, v2) => v1 !== v2,
    lt: (v1, v2) => v1 < v2,
    gt: (v1, v2) => v1 > v2,
    lte: (v1, v2) => v1 <= v2,
    gte: (v1, v2) => v1 >= v2,
    and() {
        return Array.prototype.every.call(arguments, Boolean);
    },
    or() {
        return Array.prototype.slice.call(arguments, 0, -1).some(Boolean);
    }
});

JSHint and jQuery: '$' is not defined

All you need to do is set "jquery": true in your .jshintrc.

Per the JSHint options reference:

jquery

This option defines globals exposed by the jQuery JavaScript library.

Excel VBA - Range.Copy transpose paste

Here's an efficient option that doesn't use the clipboard.

Sub transposeAndPasteRow(rowToCopy As Range, pasteTarget As Range)
    pasteTarget.Resize(rowToCopy.Columns.Count) = Application.WorksheetFunction.Transpose(rowToCopy.Value)
End Sub

Use it like this.

Sub test()
    Call transposeAndPasteRow(Worksheets("Sheet1").Range("A1:A5"), Worksheets("Sheet2").Range("A1"))
End Sub

How can I get name of element with jQuery?

The method .attr() allows getting attribute value of the first element in a jQuery object:

$('#myelement').attr('name');

Populating VBA dynamic arrays

In addition to Cody's useful comments it is worth noting that at times you won't know how big your array should be. The two options in this situation are

  1. Creating an array big enough to handle anything you think will be thrown at it
  2. Sensible use of Redim Preserve

The code below provides an example of a routine that will dimension myArray in line with the lngSize variable, then add additional elements (equal to the initial array size) by use of a Mod test whenever the upper bound is about to be exceeded

Option Base 1

Sub ArraySample()
    Dim myArray() As String
    Dim lngCnt As Long
    Dim lngSize As Long

    lngSize = 10
    ReDim myArray(1 To lngSize)

    For lngCnt = 1 To lngSize*5
        If lngCnt Mod lngSize = 0 Then ReDim Preserve myArray(1 To UBound(myArray) + lngSize)
        myArray(lngCnt) = "I am record number " & lngCnt
    Next
End Sub

How to add a custom Ribbon tab using VBA?

I encountered difficulties with Roi-Kyi Bryant's solution when multiple add-ins tried to modify the ribbon. I also don't have admin access on my work-computer, which ruled out installing the Custom UI Editor. So, if you're in the same boat as me, here's an alternative example to customising the ribbon using only Excel. Note, my solution is derived from the Microsoft guide.


  1. Create Excel file/files whose ribbons you want to customise. In my case, I've created two .xlam files, Chart Tools.xlam and Priveleged UDFs.xlam, to demonstrate how multiple add-ins can interact with the Ribbon.
  2. Create a folder, with any folder name, for each file you just created.
  3. Inside each of the folders you've created, add a customUI and _rels folder.
  4. Inside each customUI folder, create a customUI.xml file. The customUI.xml file details how Excel files interact with the ribbon. Part 2 of the Microsoft guide covers the elements in the customUI.xml file.

My customUI.xml file for Chart Tools.xlam looks like this

<customUI xmlns="http://schemas.microsoft.com/office/2006/01/customui" xmlns:x="sao">
  <ribbon>
    <tabs>
      <tab idQ="x:chartToolsTab" label="Chart Tools">
        <group id="relativeChartMovementGroup" label="Relative Chart Movement" >
            <button id="moveChartWithRelativeLinksButton" label="Copy and Move" imageMso="ResultsPaneStartFindAndReplace" onAction="MoveChartWithRelativeLinksCallBack" visible="true" size="normal"/>
            <button id="moveChartToManySheetsWithRelativeLinksButton" label="Copy and Distribute" imageMso="OutlineDemoteToBodyText" onAction="MoveChartToManySheetsWithRelativeLinksCallBack" visible="true" size="normal"/>
        </group >
        <group id="chartDeletionGroup" label="Chart Deletion">
            <button id="deleteAllChartsInWorkbookSharingAnAddressButton" label="Delete Charts" imageMso="CancelRequest" onAction="DeleteAllChartsInWorkbookSharingAnAddressCallBack" visible="true" size="normal"/>
        </group>
      </tab>
    </tabs>
  </ribbon>
</customUI>

My customUI.xml file for Priveleged UDFs.xlam looks like this

<customUI xmlns="http://schemas.microsoft.com/office/2006/01/customui" xmlns:x="sao">
  <ribbon>
    <tabs>
      <tab idQ="x:privelgedUDFsTab" label="Privelged UDFs">
        <group id="privelgedUDFsGroup" label="Toggle" >
            <button id="initialisePrivelegedUDFsButton" label="Activate" imageMso="TagMarkComplete" onAction="InitialisePrivelegedUDFsCallBack" visible="true" size="normal"/>
            <button id="deInitialisePrivelegedUDFsButton" label="De-Activate" imageMso="CancelRequest" onAction="DeInitialisePrivelegedUDFsCallBack" visible="true" size="normal"/>
        </group >
      </tab>
    </tabs>
  </ribbon>
</customUI>
  1. For each file you created in Step 1, suffix a .zip to their file name. In my case, I renamed Chart Tools.xlam to Chart Tools.xlam.zip, and Privelged UDFs.xlam to Priveleged UDFs.xlam.zip.
  2. Open each .zip file, and navigate to the _rels folder. Copy the .rels file to the _rels folder you created in Step 3. Edit each .rels file with a text editor. From the Microsoft guide

Between the final <Relationship> element and the closing <Relationships> element, add a line that creates a relationship between the document file and the customization file. Ensure that you specify the folder and file names correctly.

<Relationship Type="http://schemas.microsoft.com/office/2006/
  relationships/ui/extensibility" Target="/customUI/customUI.xml" 
  Id="customUIRelID" />

My .rels file for Chart Tools.xlam looks like this

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
    <Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships">
        <Relationship Id="rId3" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/extended-properties" Target="docProps/app.xml"/><Relationship Id="rId2" Type="http://schemas.openxmlformats.org/package/2006/relationships/metadata/core-properties" Target="docProps/core.xml"/>
        <Relationship Id="rId1" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/officeDocument" Target="xl/workbook.xml"/>
        <Relationship Type="http://schemas.microsoft.com/office/2006/relationships/ui/extensibility" Target="/customUI/customUI.xml" Id="chartToolsCustomUIRel" />
    </Relationships>

My .rels file for Priveleged UDFs looks like this.

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
    <Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships">
        <Relationship Id="rId3" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/extended-properties" Target="docProps/app.xml"/><Relationship Id="rId2" Type="http://schemas.openxmlformats.org/package/2006/relationships/metadata/core-properties" Target="docProps/core.xml"/>
        <Relationship Id="rId1" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/officeDocument" Target="xl/workbook.xml"/>
        <Relationship Type="http://schemas.microsoft.com/office/2006/relationships/ui/extensibility" Target="/customUI/customUI.xml" Id="privelegedUDFsCustomUIRel" />
    </Relationships>
  1. Replace the .rels files in each .zip file with the .rels file/files you modified in the previous step.
  2. Copy and paste the .customUI folder you created into the home directory of the .zip file/files.
  3. Remove the .zip file extension from the Excel files you created.
  4. If you've created .xlam files, back in Excel, add them to your Excel add-ins.
  5. If applicable, create callbacks in each of your add-ins. In Step 4, there are onAction keywords in my buttons. The onAction keyword indicates that, when the containing element is triggered, the Excel application will trigger the sub-routine encased in quotation marks directly after the onAction keyword. This is known as a callback. In my .xlam files, I have a module called CallBacks where I've included my callback sub-routines.

CallBacks Module

My CallBacks module for Chart Tools.xlam looks like

Option Explicit

Public Sub MoveChartWithRelativeLinksCallBack(ByRef control As IRibbonControl)
  MoveChartWithRelativeLinks
End Sub

Public Sub MoveChartToManySheetsWithRelativeLinksCallBack(ByRef control As IRibbonControl)
  MoveChartToManySheetsWithRelativeLinks
End Sub

Public Sub DeleteAllChartsInWorkbookSharingAnAddressCallBack(ByRef control As IRibbonControl)
  DeleteAllChartsInWorkbookSharingAnAddress
End Sub

My CallBacks module for Priveleged UDFs.xlam looks like

Option Explicit

Public Sub InitialisePrivelegedUDFsCallBack(ByRef control As IRibbonControl)
  ThisWorkbook.InitialisePrivelegedUDFs
End Sub

Public Sub DeInitialisePrivelegedUDFsCallBack(ByRef control As IRibbonControl)
  ThisWorkbook.DeInitialisePrivelegedUDFs
End Sub

Different elements have a different callback sub-routine signature. For buttons, the required sub-routine parameter is ByRef control As IRibbonControl. If you don't conform to the required callback signature, you will receive an error while compiling your VBA project/projects. Part 3 of the Microsoft guide defines all the callback signatures.


Here's what my finished example looks like

Finished Product


Some closing tips

  1. If you want add-ins to share Ribbon elements, use the idQ and xlmns: keyword. In my example, the Chart Tools.xlam and Priveleged UDFs.xlam both have access to the elements with idQ's equal to x:chartToolsTab and x:privelgedUDFsTab. For this to work, the x: is required, and, I've defined its namespace in the first line of my customUI.xml file, <customUI xmlns="http://schemas.microsoft.com/office/2006/01/customui" xmlns:x="sao">. The section Two Ways to Customize the Fluent UI in the Microsoft guide gives some more details.
  2. If you want add-ins to access Ribbon elements shipped with Excel, use the isMSO keyword. The section Two Ways to Customize the Fluent UI in the Microsoft guide gives some more details.

Add quotation at the start and end of each line in Notepad++

You won't be able to do it in a single replacement; you'll have to perform a few steps. Here's how I'd do it:

  1. Find (in regular expression mode):

    (.+)
    

    Replace with:

    "\1"
    

    This adds the quotes:

    "AliceBlue"
    "AntiqueWhite"
    "Aqua"
    "Aquamarine"
    "Azure"
    "Beige"
    "Bisque"
    "Black"
    "BlanchedAlmond"
    
  2. Find (in extended mode):

    \r\n
    

    Replace with (with a space after the comma, not shown):

    , 
    

    This converts the lines into a comma-separated list:

    "AliceBlue", "AntiqueWhite", "Aqua", "Aquamarine", "Azure", "Beige", "Bisque", "Black", "BlanchedAlmond"
    

  3. Add the var myArray = assignment and braces manually:

    var myArray = ["AliceBlue", "AntiqueWhite", "Aqua", "Aquamarine", "Azure", "Beige", "Bisque", "Black", "BlanchedAlmond"];
    

Why when I transfer a file through SFTP, it takes longer than FTP?

I'm the author of HPN-SSH and I was asked by a commenter here to weigh in. I'd like to start with a couple of background items. First off, it's important to keep in mind that SSHv2 is a multiplexed protocol - multiple channels over a single TCP connection. As such, the SSH channels are essentially unaware of the underlying flow control algorithm used by TCP. This means that SSHv2 has to implement its own flow control algorithm. The most common implementation basically reimplements sliding windows. The means that you have the SSH sliding window riding on top of the TCP sliding window. The end results is that the effective size of the receive buffer is the minimum of the receive buffers of the two sliding windows. Stock OpenSSH has a maximum receive buffer size of 2MB but this really ends up being closer to ~1.2MB. Most modern OSes have a buffer that can grow (using auto-tuning receive buffers) up to an effective size of 4MB. Why does this matter? If the receive buffer size is less than the bandwidth delay product (BDP) then you will never be able to fully fill the pipe regardless of how fast your system is.

This is complicated by the fact that SFTP adds another layer of flow control onto of the TCP and SSH flow controls. SFTP uses a concept of outstanding messages. Each message may be a command, a result of a command, or bulk data flow. The outstanding messages may be up to a specific datagram size. So you end up with what you might as well think of as yet another receive buffer. The size of this receive buffer is datagram size * maximum outstanding messages (both of which may be set on the command line). The default is 32k * 64 (2MB). So when using SFTP you have to make sure that the TCP receive buffer, the SSH receive buffer, and the SFTP receive buffer are all of sufficient size (without being too large or you can have over buffering problems in interactive sessions).

HPN-SSH directly addresses the SSH buffer problem by having a maximum buffer size of around 16MB. More importantly, the buffer dynamically grows to the proper size by polling the proc entry for the TCP connection's buffer size (basically poking a hole between layers 3 and 4). This avoids overbuffering in almost all situations. In SFTP we raise the maximum number of outstanding requests to 256. At least we should be doing that - it looks like that change didn't propagate as expected to the 6.3 patch set (though it is in 6.2. I'll fix that soon). There isn't a 6.4 version because 6.3 patches cleanly against 6.4 (which is a 1 line security fix from 6.3). You can get the patch set from sourceforge.

I know this sounds odd but right sizing the buffers was the single most important change in terms of performance. In spite of what many people think the encryption is not the real source of poor performance in most cases. You can prove this to yourself by transferring data to sources that are increasingly far away (in terms of RTT). You'll notice that the longer the RTT the lower the throughput. That clearly indicates that this is an RTT dependent performance problem.

Anyway, with this change I started seeing improvements of up to 2 orders of magnitude. If you understand TCP you'll understand why this made such a difference. It's not about the size of the datagram or the number of packets or anything like that. It's entire because in order to make efficient use of the network path you must have a receive buffer equal to the amount of data that can be in transit between the two hosts. This also means that you may not see any improvement whatsoever if the path isn't sufficiently fast and long enough. If the BDP is less than 1.2MB HPN-SSH may be of no value to you.

The parallelized AES-CTR cipher is a performance boost on systems with multiple cores if you need to have full encryption end to end. Usually I suggest people (or have control over both the server and client) to use the NONE cipher switch (encrypted authentication, bulk data passed in clear) as most data isn't all that sensitive. However, this only works in non-interactive sessions like SCP. It doesn't work in SFTP.

There are some other performance improvements as well but nothing as important as the right sizing of the buffers and the encryption work. When I get some free time I'll probably pipeline the HMAC process (currently the biggest drag on performance) and do some more minor optimization work.

So if HPN-SSH is so awesome why hasn't OpenSSH adopted it? That's a long story and people who know the OpenBSD team probably already know the answer. I understand many of their reasons - it's a big patch which would require additional work on their end (and they are a small team), they don't care as much about performance as security (though there is no security implications to HPN-SSH), etc etc etc. However, even though OpenSSH doesn't use HPN-SSH Facebook does. So do Google, Yahoo, Apple, most ever large research data center, NASA, NOAA, the government, the military, and most financial institutions. It's pretty well vetted at this point.

If anyone has any questions feel free to ask but I may not be keeping up to date on this forum. You can always send me mail via the HPN-SSH email address (google it).

Adding a Scrollable JTextArea (Java)

A scroll pane is a container which contains another component. You can't add your text area to two different scroll panes. The scroll pane takes care of the horizontal and vertical scroll bars.

And if you never add the scroll pane to the frame, it will never be visible.

Read the swing tutorial about scroll panes.

How to get char from string by index?

Previous answers cover about ASCII character at a certain index.

It is a little bit troublesome to get a Unicode character at a certain index in Python 2.

E.g., with s = '????????' which is <type 'str'>,

__getitem__, e.g., s[i] , does not lead you to where you desire. It will spit out semething like ?. (Many Unicode characters are more than 1 byte but __getitem__ in Python 2 is incremented by 1 byte.)

In this Python 2 case, you can solve the problem by decoding:

s = '????????'
s = s.decode('utf-8')
for i in range(len(s)):
    print s[i]

How to draw text using only OpenGL methods?

enter image description here

Use glutStrokeCharacter(GLUT_STROKE_ROMAN, myCharString).

An example: A STAR WARS SCROLLER.

#include <windows.h>
#include <string.h>
#include <GL\glut.h>
#include <iostream.h>
#include <fstream.h>

GLfloat UpwardsScrollVelocity = -10.0;
float view=20.0;

char quote[6][80];
int numberOfQuotes=0,i;

//*********************************************
//*  glutIdleFunc(timeTick);                  *
//*********************************************

void timeTick(void)
{
    if (UpwardsScrollVelocity< -600)
        view-=0.000011;
    if(view < 0) {view=20; UpwardsScrollVelocity = -10.0;}
    //  exit(0);
    UpwardsScrollVelocity -= 0.015;
  glutPostRedisplay();

}


//*********************************************
//* printToConsoleWindow()                *
//*********************************************

void printToConsoleWindow()
{
    int l,lenghOfQuote, i;

    for(  l=0;l<numberOfQuotes;l++)
    {
        lenghOfQuote = (int)strlen(quote[l]);

        for (i = 0; i < lenghOfQuote; i++)
        {
          //cout<<quote[l][i];
        }
          //out<<endl;
    }

}

//*********************************************
//* RenderToDisplay()                       *
//*********************************************

void RenderToDisplay()
{
    int l,lenghOfQuote, i;

    glTranslatef(0.0, -100, UpwardsScrollVelocity);
    glRotatef(-20, 1.0, 0.0, 0.0);
    glScalef(0.1, 0.1, 0.1);



    for(  l=0;l<numberOfQuotes;l++)
    {
        lenghOfQuote = (int)strlen(quote[l]);
        glPushMatrix();
        glTranslatef(-(lenghOfQuote*37), -(l*200), 0.0);
        for (i = 0; i < lenghOfQuote; i++)
        {
            glColor3f((UpwardsScrollVelocity/10)+300+(l*10),(UpwardsScrollVelocity/10)+300+(l*10),0.0);
            glutStrokeCharacter(GLUT_STROKE_ROMAN, quote[l][i]);
        }
        glPopMatrix();
    }

}
//*********************************************
//* glutDisplayFunc(myDisplayFunction);       *
//*********************************************

void myDisplayFunction(void)
{
  glClear(GL_COLOR_BUFFER_BIT);
  glLoadIdentity();
  gluLookAt(0.0, 30.0, 100.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
  RenderToDisplay();
  glutSwapBuffers();
}
//*********************************************
//* glutReshapeFunc(reshape);               *
//*********************************************

void reshape(int w, int h)
{
  glViewport(0, 0, w, h);
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  gluPerspective(60, 1.0, 1.0, 3200);
  glMatrixMode(GL_MODELVIEW);
}

//*********************************************
//* int main()                                *
//*********************************************


int main()
{
    strcpy(quote[0],"Luke, I am your father!.");
    strcpy(quote[1],"Obi-Wan has taught you well. ");
    strcpy(quote[2],"The force is strong with this one. ");
    strcpy(quote[3],"Alert all commands. Calculate every possible destination along their last known trajectory. ");
    strcpy(quote[4],"The force is with you, young Skywalker, but you are not a Jedi yet.");
    numberOfQuotes=5;

    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
    glutInitWindowSize(800, 400);
    glutCreateWindow("StarWars scroller");
    glClearColor(0.0, 0.0, 0.0, 1.0);
    glLineWidth(3);

    glutDisplayFunc(myDisplayFunction);
    glutReshapeFunc(reshape);
    glutIdleFunc(timeTick);
    glutMainLoop();

    return 0;
}

what is difference between success and .done() method of $.ajax

success only fires if the AJAX call is successful, i.e. ultimately returns a HTTP 200 status. error fires if it fails and complete when the request finishes, regardless of success.

In jQuery 1.8 on the jqXHR object (returned by $.ajax) success was replaced with done, error with fail and complete with always.

However you should still be able to initialise the AJAX request with the old syntax. So these do similar things:

// set success action before making the request
$.ajax({
  url: '...',
  success: function(){
    alert('AJAX successful');
  }
});

// set success action just after starting the request
var jqxhr = $.ajax( "..." )
  .done(function() { alert("success"); });

This change is for compatibility with jQuery 1.5's deferred object. Deferred (and now Promise, which has full native browser support in Chrome and FX) allow you to chain asynchronous actions:

$.ajax("parent").
    done(function(p) { return $.ajax("child/" + p.id); }).
    done(someOtherDeferredFunction).
    done(function(c) { alert("success: " + c.name); });

This chain of functions is easier to maintain than a nested pyramid of callbacks you get with success.

However, please note that done is now deprecated in favour of the Promise syntax that uses then instead:

$.ajax("parent").
    then(function(p) { return $.ajax("child/" + p.id); }).
    then(someOtherDeferredFunction).
    then(function(c) { alert("success: " + c.name); }).
    catch(function(err) { alert("error: " + err.message); });

This is worth adopting because async and await extend promises improved syntax (and error handling):

try {
    var p = await $.ajax("parent");
    var x = await $.ajax("child/" + p.id);
    var c = await someOtherDeferredFunction(x);
    alert("success: " + c.name);
}
catch(err) { 
    alert("error: " + err.message); 
}

How to convert JSON to CSV format and store in a variable

Funny nothing complete nor working here (IE nor node.js). Answer on similar question, a bit structured JSON (suppose no need to copy it again), also demo snippet included. JSON To CSV conversion (JavaScript) : How to properly format CSV conversion Hope not only single type convertor, also on my Github (mentioned in profile) is similar used to analyze unknow JSON structure. I am author of code in this answer and all code on my Github (except some projects started as fork/+translation).

How to change xampp localhost to another folder ( outside xampp folder)?

just in case someone looks for this, the path to the file on Sourav answer (httpd.conf) in linux is /opt/lampp/etc/httpd.conf

how to implement a long click listener on a listview

or try this code:

listView.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {

            public boolean onItemLongClick(AdapterView<?> arg0, View v,
                    int index, long arg3) {

    Toast.makeText(list.this,myList.getItemAtPosition(index).toString(), Toast.LENGTH_LONG).show();
                return false;
            }
}); 

How to remove first and last character of a string?

In Kotlin

private fun removeLastChar(str: String?): String? {
    return if (str == null || str.isEmpty()) str else str.substring(0, str.length - 1)
}

CSS3 :unchecked pseudo-class

I think you are trying to over complicate things. A simple solution is to just style your checkbox by default with the unchecked styles and then add the checked state styles.

input[type="checkbox"] {
  // Unchecked Styles
}
input[type="checkbox"]:checked {
  // Checked Styles
}

I apologize for bringing up an old thread but felt like it could have used a better answer.

EDIT (3/3/2016):

W3C Specs state that :not(:checked) as their example for selecting the unchecked state. However, this is explicitly the unchecked state and will only apply those styles to the unchecked state. This is useful for adding styling that is only needed on the unchecked state and would need removed from the checked state if used on the input[type="checkbox"] selector. See example below for clarification.

input[type="checkbox"] {
  /* Base Styles aka unchecked */
  font-weight: 300; // Will be overwritten by :checked
  font-size: 16px; // Base styling
}
input[type="checkbox"]:not(:checked) {
  /* Explicit Unchecked Styles */
  border: 1px solid #FF0000; // Only apply border to unchecked state
}
input[type="checkbox"]:checked {
  /* Checked Styles */
  font-weight: 900; // Use a bold font when checked
}

Without using :not(:checked) in the example above the :checked selector would have needed to use a border: none; to achieve the same affect.

Use the input[type="checkbox"] for base styling to reduce duplication.

Use the input[type="checkbox"]:not(:checked) for explicit unchecked styles that you do not want to apply to the checked state.

What is the command for cut copy paste a file from one directory to other directory

use the xclip which is command line interface to X selections

install

apt-get install xclip

usage

echo "test xclip " > /tmp/test.xclip
xclip -i < /tmp/test.xclip
xclip -o > /tmp/test.xclip.out

cat /tmp/test.xclip.out   # "test xclip"

enjoy.

Gerrit error when Change-Id in commit messages are missing

under my .git/hooks folder, some sample files were missing. like commit-msg,post-commit.sample,post-update.sample...adding these files resolved my change id missing issue.

What exactly is Apache Camel?

Most "new" things in computing aren't really new at all, they're just a mystifying wrapper around something that already well-understood. When they're hard to understand, it's usually because someone decided to invent new language terms or colonise existing terms for a different purpose (a good example of that is the X developers' reversal of what "client" and "server" mean.)

Camel is a Java-based wrapper/API for inter-application middleware.

Middleware is a general term for software that provides interpretation services between entities that don't share a common language or data types.

That's what Camel is, at bottom. We can flesh out the description by noting that it provides for EIP-type middleware.

It doesn't provide the middleware itself, since it can't know the details of what the applications need to communicate. But it provides the API for creating the invariant parts of that middleware (create a start point, create an end point, create conditions for starting and ending, etc)

Hope that helps.

Remove ALL styling/formatting from hyperlinks

You can just use an a selector in your stylesheet to define all states of an anchor/hyperlink. For example:

a {
    color: blue;
}

Would override all link styles and make all the states the colour blue.

How to make a <svg> element expand or contract to its parent container?

Suppose I have an SVG which looks like this: pic1

And I want to put it in a div and make it fill the div responsively. My way of doing it is as follows:

First I open the SVG file in an application like inkscape. In File->Document Properties I set the width of the document to 800px and and the height to 600px (you can choose other sizes). Then I fit the SVG into this document.

pic2

Then I save this file as a new SVG file and get the path data from this file. Now in HTML the code that does the magic is as follows:

<div id="containerId">    
    <svg
    id="svgId" 
    xmlns:svg="http://www.w3.org/2000/svg"
    xmlns="http://www.w3.org/2000/svg"
    version="1.1"
    x="0"
    y="0"
    width="100%"
    height="100%"
    viewBox="0 0 800 600"
    preserveAspectRatio="none">
       <path d="m0 0v600h800v-600h-75.07031l-431 597.9707-292.445315-223.99609 269.548825-373.97461h-271.0332z" fill="#f00"/>
    </svg>
</div>

Note that width and height of SVG are both set to 100%, since we want it to fill the container vertically and horizontally ,but width and height of the viewBox are the same as the width and height of the document in inkscape which is 800px X 600px. The next thing you need to do is set the preserveAspectRatio to "none". If you need to have more information on this attribute here's a good link. And that's all there is to it.

One more thing is that this code works on almost all the major browsers even the old ones but on some versions of android and ios you need to use some javascrip/jQuery code to keep it consistent. I use the following in document ready and resize functions:

$('#svgId').css({
    'width': $('#containerId').width() + 'px',
    'height': $('#containerId').height() + 'px'
});

Hope it helps!

Ajax Success and Error function failure

You can implement error-specific logic as follows:

error: function (XMLHttpRequest, textStatus, errorThrown) {
    if (textStatus == 'Unauthorized') {
        alert('custom message. Error: ' + errorThrown);
    } else {
        alert('custom message. Error: ' + errorThrown);
    }
}

Cross browser JavaScript (not jQuery...) scroll to top animation

I modified the code of @TimWolla to add more options and a some movement functions. Also, added support to crossbrowser with document.body.scrollTop and document.documentElement.scrollTop

// scroll to top
scrollTo(0, 1000);

// Element to move, time in ms to animate
function scrollTo(element, duration) {
    var e = document.documentElement;
    if(e.scrollTop===0){
        var t = e.scrollTop;
        ++e.scrollTop;
        e = t+1===e.scrollTop--?e:document.body;
    }
    scrollToC(e, e.scrollTop, element, duration);
}

// Element to move, element or px from, element or px to, time in ms to animate
function scrollToC(element, from, to, duration) {
    if (duration <= 0) return;
    if(typeof from === "object")from=from.offsetTop;
    if(typeof to === "object")to=to.offsetTop;

    scrollToX(element, from, to, 0, 1/duration, 20, easeOutCuaic);
}

function scrollToX(element, xFrom, xTo, t01, speed, step, motion) {
    if (t01 < 0 || t01 > 1 || speed<= 0) {
        element.scrollTop = xTo;
        return;
    }
    element.scrollTop = xFrom - (xFrom - xTo) * motion(t01);
    t01 += speed * step;

    setTimeout(function() {
        scrollToX(element, xFrom, xTo, t01, speed, step, motion);
    }, step);
}
function easeOutCuaic(t){
    t--;
    return t*t*t+1;
}

http://jsfiddle.net/forestrf/tPQSv/

Minified version: http://jsfiddle.net/forestrf/tPQSv/139/

// c = element to scroll to or top position in pixels
// e = duration of the scroll in ms, time scrolling
// d = (optative) ease function. Default easeOutCuaic
function scrollTo(c,e,d){d||(d=easeOutCuaic);var a=document.documentElement;if(0===a.scrollTop){var b=a.scrollTop;++a.scrollTop;a=b+1===a.scrollTop--?a:document.body}b=a.scrollTop;0>=e||("object"===typeof b&&(b=b.offsetTop),"object"===typeof c&&(c=c.offsetTop),function(a,b,c,f,d,e,h){function g(){0>f||1<f||0>=d?a.scrollTop=c:(a.scrollTop=b-(b-c)*h(f),f+=d*e,setTimeout(g,e))}g()}(a,b,c,0,1/e,20,d))};
function easeOutCuaic(t){
    t--;
    return t*t*t+1;
}

Which version of Python do I have installed?

If you are already in a REPL window and don't see the welcome message with the version number, you can use help() to see the major and minor version:

>>>help()
Welcome to Python 3.6's help utility!
...

Disable arrow key scrolling in users browser

Summary

Simply prevent the default browser action:

window.addEventListener("keydown", function(e) {
    // space and arrow keys
    if([32, 37, 38, 39, 40].indexOf(e.code) > -1) {
        e.preventDefault();
    }
}, false);

If you need to support Internet Explorer or other older browsers, use e.keyCode instead of e.code, but keep in mind that keyCode is deprecated.

Original answer

I used the following function in my own game:

var keys = {};
window.addEventListener("keydown",
    function(e){
        keys[e.code] = true;
        switch(e.code){
            case 37: case 39: case 38:  case 40: // Arrow keys
            case 32: e.preventDefault(); break; // Space
            default: break; // do not block other keys
        }
    },
false);
window.addEventListener('keyup',
    function(e){
        keys[e.code] = false;
    },
false);

The magic happens in e.preventDefault();. This will block the default action of the event, in this case moving the viewpoint of the browser.

If you don't need the current button states you can simply drop keys and just discard the default action on the arrow keys:

var arrow_keys_handler = function(e) {
    switch(e.code){
        case 37: case 39: case 38:  case 40: // Arrow keys
        case 32: e.preventDefault(); break; // Space
        default: break; // do not block other keys
    }
};
window.addEventListener("keydown", arrow_keys_handler, false);

Note that this approach also enables you to remove the event handler later if you need to re-enable arrow key scrolling:

window.removeEventListener("keydown", arrow_keys_handler, false);

References

iOS - UIImageView - how to handle UIImage image orientation

Swift 3.1

func fixImageOrientation(_ image: UIImage)->UIImage {
    UIGraphicsBeginImageContext(image.size)
    image.draw(at: .zero)
    let newImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    return newImage ?? image
}

Python Image Library fails with message "decoder JPEG not available" - PIL

For those on OSX, I used the following binary to get libpng and libjpeg installed systemwide:

libpng & libjpeg for OSX

Because I already had PIL installed (via pip on a virtualenv), I ran:

pip uninstall PIL
pip install PIL --upgrade

This resolved the decoder JPEG not available error for me.

UPDATE (4/24/14):

Newer versions of pip require additional flags to download libraries (including PIL) from external sources. Try the following:

pip install PIL --allow-external PIL --allow-unverified PIL

See the following answer for additional info: pip install PIL dont install into virtualenv

UPDATE 2:

If on OSX Mavericks, you'll want to set the ARCHFLAGS flag as @RicardoGonzales comments below:

ARCHFLAGS=-Wno-error=unused-command-line-argument-hard-error-in-future pip install PIL --allow-external PIL --allow-unverified PIL

Invalid application of sizeof to incomplete type with a struct

I think that the problem is that you put #ifdef instead of #ifndef at the top of your header.h file.

C# Validating input for textbox on winforms

With WinForms you can use the ErrorProvider in conjunction with the Validating event to handle the validation of user input. The Validating event provides the hook to perform the validation and ErrorProvider gives a nice consistent approach to providing the user with feedback on any error conditions.

http://msdn.microsoft.com/en-us/library/system.windows.forms.errorprovider.aspx

How to return a class object by reference in C++?

You can only return non-local objects by reference. The destructor may have invalidated some internal pointer, or whatever.

Don't be afraid of returning values -- it's fast!

How to make a gui in python

If you're more into gaming you can use PyGame for GUIs.

Select * from subquery

You can select every column from that sub-query by aliasing it and adding the alias before the *:

SELECT t.*, a+b AS total_sum
FROM
(
   SELECT SUM(column1) AS a, SUM(column2) AS b
   FROM table
) t

What's the best practice to round a float to 2 decimals?

//by importing Decimal format we can do...

import java.util.Scanner;
import java.text.DecimalFormat;
public class Average
{
public static void main(String[] args)
{
int sub1,sub2,sub3,total;
Scanner in = new Scanner(System.in);
System.out.print("Enter Subject 1 Marks : ");
sub1 = in.nextInt();
System.out.print("Enter Subject 2 Marks : ");
sub2 = in.nextInt();
System.out.print("Enter Subject 3 Marks : ");
sub3 = in.nextInt();
total = sub1 + sub2 + sub3;
System.out.println("Total Marks of Subjects = " + total);
res = (float)total;
average = res/3;
System.out.println("Before Rounding Decimal.. Average = " +average +"%");
DecimalFormat df = new DecimalFormat("###.##");
System.out.println("After Rounding Decimal.. Average = " +df.format(average)+"%");
}
}
/* Output
Enter Subject 1 Marks : 72
Enter Subject 2 Marks : 42
Enter Subject 3 Marks : 52
Total Marks of Subjects = 166
Before Rounding Decimal.. Average = 55.333332%
After Rounding Decimal.. Average = 55.33%
*/

/* Output
Enter Subject 1 Marks : 98
Enter Subject 2 Marks : 88
Enter Subject 3 Marks : 78
Total Marks of Subjects = 264
Before Rounding Decimal.. Average = 88.0%
After Rounding Decimal.. Average = 88%
*/

/* You can Find Avrerage values in two ouputs before rounding average
And After rounding Average..*/

How can I reference a commit in an issue comment on GitHub?

If you are trying to reference a commit in another repo than the issue is in, you can prefix the commit short hash with reponame@.

Suppose your commit is in the repo named dev, and the GitLab issue is in the repo named test. You can leave a comment on the issue and reference the commit by dev@e9c11f0a (where e9c11f0a is the first 8 letters of the sha hash of the commit you want to link to) if that makes sense.

How to print all key and values from HashMap in Android?

    for (String entry : map.keySet()) {
      String value = map.get(entry);
      System.out.print(entry + "" + value + " ");
      // do stuff
    }