Programs & Examples On #Mencoder

MEncoder is a free command line video decoding, encoding and filtering tool released under the GNU General Public License. It is a close sibling to MPlayer and can convert all the formats that MPlayer understands into a variety of compressed and uncompressed formats using different codecs.

Using Python to execute a command on every file in a folder

To find all the filenames use os.listdir().

Then you loop over the filenames. Like so:

import os
for filename in os.listdir('dirname'):
     callthecommandhere(blablahbla, filename, foo)

If you prefer subprocess, use subprocess. :-)

Spring MVC Missing URI template variable

I got this error for a stupid mistake, the variable name in the @PathVariable wasn't matching the one in the @RequestMapping

For example

@RequestMapping(value = "/whatever/{**contentId**}", method = RequestMethod.POST)
public … method(@PathVariable Integer **contentID**){

It may help others

Storing images in SQL Server?

There's a really good paper by Microsoft Research called To Blob or Not To Blob.

Their conclusion after a large number of performance tests and analysis is this:

  • if your pictures or document are typically below 256KB in size, storing them in a database VARBINARY column is more efficient

  • if your pictures or document are typically over 1 MB in size, storing them in the filesystem is more efficient (and with SQL Server 2008's FILESTREAM attribute, they're still under transactional control and part of the database)

  • in between those two, it's a bit of a toss-up depending on your use

If you decide to put your pictures into a SQL Server table, I would strongly recommend using a separate table for storing those pictures - do not store the employee photo in the employee table - keep them in a separate table. That way, the Employee table can stay lean and mean and very efficient, assuming you don't always need to select the employee photo, too, as part of your queries.

For filegroups, check out Files and Filegroup Architecture for an intro. Basically, you would either create your database with a separate filegroup for large data structures right from the beginning, or add an additional filegroup later. Let's call it "LARGE_DATA".

Now, whenever you have a new table to create which needs to store VARCHAR(MAX) or VARBINARY(MAX) columns, you can specify this file group for the large data:

 CREATE TABLE dbo.YourTable
     (....... define the fields here ......)
     ON Data                   -- the basic "Data" filegroup for the regular data
     TEXTIMAGE_ON LARGE_DATA   -- the filegroup for large chunks of data

Check out the MSDN intro on filegroups, and play around with it!

How do I merge two dictionaries in a single expression (taking union of dictionaries)?

Another, more concise, option:

z = dict(x, **y)

Note: this has become a popular answer, but it is important to point out that if y has any non-string keys, the fact that this works at all is an abuse of a CPython implementation detail, and it does not work in Python 3, or in PyPy, IronPython, or Jython. Also, Guido is not a fan. So I can't recommend this technique for forward-compatible or cross-implementation portable code, which really means it should be avoided entirely.

How do I make jQuery wait for an Ajax call to finish before it returns?

Instead of setting async to false which is usually bad design, you may want to consider blocking the UI while the operation is pending.

This can be nicely achieved with jQuery promises as follows:

// same as $.ajax but settings can have a maskUI property
// if settings.maskUI==true, the UI will be blocked while ajax in progress
// if settings.maskUI is other than true, it's value will be used as the color value while bloking (i.e settings.maskUI='rgba(176,176,176,0.7)'
// in addition an hourglass is displayed while ajax in progress
function ajaxMaskUI(settings) {
    function maskPageOn(color) { // color can be ie. 'rgba(176,176,176,0.7)' or 'transparent'
        var div = $('#maskPageDiv');
        if (div.length === 0) {
            $(document.body).append('<div id="maskPageDiv" style="position:fixed;width:100%;height:100%;left:0;top:0;display:none"></div>'); // create it
            div = $('#maskPageDiv');
        if (div.length !== 0) {
            div[0].style.zIndex = 2147483647;
            div[0].style.display = 'inline';
    function maskPageOff() {
        var div = $('#maskPageDiv');
        if (div.length !== 0) {
            div[0].style.display = 'none';
            div[0].style.zIndex = 'auto';
    function hourglassOn() {
        if ($('style:contains("html.hourGlass")').length < 1) $('<style>').text('html.hourGlass, html.hourGlass * { cursor: wait !important; }').appendTo('head');
    function hourglassOff() {

    if (settings.maskUI===true) settings.maskUI='transparent';

    if (!!settings.maskUI) {

    var dfd = new $.Deferred();
        .fail(function(jqXHR, textStatus, errorThrown) {
            if (!!settings.maskUI) {
            dfd.reject(jqXHR, textStatus, errorThrown);
        }).done(function(data, textStatus, jqXHR) {
            if (!!settings.maskUI) {
            dfd.resolve(data, textStatus, jqXHR);

    return dfd.promise();

with this you can now do:

    url: url,
    maskUI: true // or try for example 'rgba(176,176,176,0.7)'
}).fail(function (jqXHR, textStatus, errorThrown) {
    console.log('error ' + textStatus);
}).done(function (data, textStatus, jqXHR) {
    console.log('success ' + JSON.stringify(data));

And the UI will block until the ajax command returns

see jsfiddle

How do I convert uint to int in C#?

Assuming you want to simply lift the 32bits from one type and dump them as-is into the other type:

uint asUint = unchecked((uint)myInt);
int asInt = unchecked((int)myUint);

The destination type will blindly pick the 32 bits and reinterpret them.

Conversely if you're more interested in keeping the decimal/numerical values within the range of the destination type itself:

uint asUint = checked((uint)myInt);
int asInt = checked((int)myUint);

In this case, you'll get overflow exceptions if:

  • casting a negative int (eg: -1) to an uint
  • casting a positive uint between 2,147,483,648 and 4,294,967,295 to an int

In our case, we wanted the unchecked solution to preserve the 32bits as-is, so here are some examples:


int => uint

int....: 0000000000 (00-00-00-00)
asUint.: 0000000000 (00-00-00-00)
int....: 0000000001 (01-00-00-00)
asUint.: 0000000001 (01-00-00-00)
int....: -0000000001 (FF-FF-FF-FF)
asUint.: 4294967295 (FF-FF-FF-FF)
int....: 2147483647 (FF-FF-FF-7F)
asUint.: 2147483647 (FF-FF-FF-7F)
int....: -2147483648 (00-00-00-80)
asUint.: 2147483648 (00-00-00-80)

uint => int

uint...: 0000000000 (00-00-00-00)
asInt..: 0000000000 (00-00-00-00)
uint...: 0000000001 (01-00-00-00)
asInt..: 0000000001 (01-00-00-00)
uint...: 2147483647 (FF-FF-FF-7F)
asInt..: 2147483647 (FF-FF-FF-7F)
uint...: 4294967295 (FF-FF-FF-FF)
asInt..: -0000000001 (FF-FF-FF-FF)


int[] testInts = { 0, 1, -1, int.MaxValue, int.MinValue };
uint[] testUints = { uint.MinValue, 1, uint.MaxValue / 2, uint.MaxValue };

foreach (var Int in testInts)
    uint asUint = unchecked((uint)Int);
    Console.WriteLine("int....: {0:D10} ({1})", Int, BitConverter.ToString(BitConverter.GetBytes(Int)));
    Console.WriteLine("asUint.: {0:D10} ({1})", asUint, BitConverter.ToString(BitConverter.GetBytes(asUint)));
    Console.WriteLine(new string('-',30));
Console.WriteLine(new string('=', 30));
foreach (var Uint in testUints)
    int asInt = unchecked((int)Uint);
    Console.WriteLine("uint...: {0:D10} ({1})", Uint, BitConverter.ToString(BitConverter.GetBytes(Uint)));
    Console.WriteLine("asInt..: {0:D10} ({1})", asInt, BitConverter.ToString(BitConverter.GetBytes(asInt)));
    Console.WriteLine(new string('-', 30));

Convert Map<String,Object> to Map<String,String>

As you are casting from Object to String I recommend you catch and report (in some way, here I just print a message, which is generally bad) the exception.

    Map<String,Object> map = new HashMap<String,Object>(); //Object is containing String
    Map<String,String> newMap =new HashMap<String,String>();

    for (Map.Entry<String, Object> entry : map.entrySet()) {
            newMap.put(entry.getKey(), (String) entry.getValue());
        catch(ClassCastException e){
            System.out.println("ERROR: "+entry.getKey()+" -> "+entry.getValue()+
                               " not added, as "+entry.getValue()+" is not a String");

SQL 'like' vs '=' performance

It's a measureable difference.

Run the following:

Create Table #TempTester (id int, col1 varchar(20), value varchar(20))

INSERT INTO #TempTester (id, col1, value)
(1, 'this is #1', 'abcdefghij')

INSERT INTO #TempTester (id, col1, value)
(2, 'this is #2', 'foob'),
(3, 'this is #3', 'abdefghic'),
(4, 'this is #4', 'other'),
(5, 'this is #5', 'zyx'),
(6, 'this is #6', 'zyx'),
(7, 'this is #7', 'zyx'),
(8, 'this is #8', 'klm'),
(9, 'this is #9', 'klm'),
(10, 'this is #10', 'zyx')
GO 10000


CREATE NONCLUSTERED INDEX ixTesting ON #TempTester(value)




SELECT * FROM #TempTester WHERE value LIKE 'abc%'

SELECT * FROM #TempTester WHERE value = 'abcdefghij'

The resulting execution plan shows you that the cost of the first operation, the LIKE comparison, is about 10 times more expensive than the = comparison.

If you can use an = comparison, please do so.

How to check if a line has one of the strings in a list?

This still loops through the cartesian product of the two lists, but it does it one line:

>>> lines1 = ['soup', 'butter', 'venison']
>>> lines2 = ['prune', 'rye', 'turkey']
>>> search_strings = ['a', 'b', 'c']
>>> any(s in l for l in lines1 for s in search_strings)
>>> any(s in l for l in lines2 for s in search_strings)

This also have the advantage that any short-circuits, and so the looping stops as soon as a match is found. Also, this only finds the first occurrence of a string from search_strings in linesX. If you want to find multiple occurrences you could do something like this:

>>> lines3 = ['corn', 'butter', 'apples']
>>> [(s, l) for l in lines3 for s in search_strings if s in l]
[('c', 'corn'), ('b', 'butter'), ('a', 'apples')]

If you feel like coding something more complex, it seems the Aho-Corasick algorithm can test for the presence of multiple substrings in a given input string. (Thanks to Niklas B. for pointing that out.) I still think it would result in quadratic performance for your use-case since you'll still have to call it multiple times to search multiple lines. However, it would beat the above (cubic, on average) algorithm.

Converting a Java Keystore into PEM Format

Converting a Java Keystore into PEM Format

The most precise answer of all must be that this is NOT possible.

A Java keystore is merely a storage facility for cryptographic keys and certificates while PEM is a file format for X.509 certificates only.

Razor view engine - How can I add Partial Views

If you don't want to duplicate code, and like me you just want to show stats, in your view model, you could just pass in the models you want to get data from like so:

public class GameViewModel
    public virtual Ship Ship { get; set; }
    public virtual GamePlayer GamePlayer { get; set; }     

Then, in your controller just run your queries on the respective models, pass them to the view model and return it, example:

GameViewModel PlayerStats = new GameViewModel();

GamePlayer currentPlayer = (from c in db.GamePlayer [more queries]).FirstOrDefault();

[code to check if results]

//pass current player into custom view model
PlayerStats.GamePlayer = currentPlayer;

Like I said, you should only really do this if you want to display stats from the relevant tables, and there's no other part of the CRUD process happening, for security reasons other people have mentioned above.

CSS: auto height on containing div, 100% height on background div inside containing div

You shouldn't have to set height: 100% at any point if you want your container to fill the page. Chances are, your problem is rooted in the fact that you haven't cleared the floats in the container's children. There are quite a few ways to solve this problem, mainly adding overflow: hidden to the container.

#container { overflow: hidden; }

Should be enough to solve whatever height problem you're having.

How can I create a correlation matrix in R?

An example,

 d <- data.frame(x1=rnorm(10),
cor(d) # get correlations (returns matrix)

What is the ultimate postal code and zip regex?

As others have pointed out, one regex to rule them all is unlikely. However, you can craft regular expressions for as many countries as you need using the address formatting info from the Universal Postal Union -- a little-known UN agency.

For example, here are the address formatting rules, including postal code, for a handful of countries (PDF format):

Find the server name for an Oracle database

SELECT  host_name
FROM    v$instance

What is the optimal way to compare dates in Microsoft SQL server?

Here is an example:

I've an Order table with a DateTime field called OrderDate. I want to retrieve all orders where the order date is equals to 01/01/2006. there are next ways to do it:

1) WHERE DateDiff(dd, OrderDate, '01/01/2006') = 0
2) WHERE Convert(varchar(20), OrderDate, 101) = '01/01/2006'
3) WHERE Year(OrderDate) = 2006 AND Month(OrderDate) = 1 and Day(OrderDate)=1
4) WHERE OrderDate LIKE '01/01/2006%'
5) WHERE OrderDate >= '01/01/2006'  AND OrderDate < '01/02/2006'

Is found here

How to compare two maps by their values

If you want to compare two Maps then, below code may help you

(new TreeMap<String, Object>(map1).toString().hashCode()) == new TreeMap<String, Object>(map2).toString().hashCode()

PostgreSQL: how to convert from Unix epoch to date?

On Postgres 10:

SELECT to_timestamp(CAST(epoch_ms as bigint)/1000)

Bring a window to the front in WPF

In case you need the window to be in front the first time it loads then you should use the following:

private void Window_ContentRendered(object sender, EventArgs e)
    this.Topmost = false;

private void Window_Initialized(object sender, EventArgs e)
    this.Topmost = true;

How to provide a mysql database connection in single file in nodejs

I think that you should use a connection pool instead of share a single connection. A connection pool would provide a much better performance, as you can check here.

As stated in the library documentation, it occurs because the MySQL protocol is sequential (this means that you need multiple connections to execute queries in parallel).

Connection Pool Docs

Laravel view not found exception

In my case I had to run php artisan optimize:clear in order to make everything to work again.

Error: Specified cast is not valid. (SqlManagerUI)

I had a similar error "Specified cast is not valid" restoring from SQL Server 2012 to SQL Server 2008 R2

First I got the MDF and LDF Names:

FROM  DISK = N'C:\Users\dell laptop\DotNetSandBox\DBBackups\Davincis3.bak' 

Second I restored with a MOVE using those names returned:

FROM DISK = 'C:\Users\dell laptop\DotNetSandBox\DBBackups\Davincis3.bak'
   MOVE 'JQueryExampleDb' TO 'C:\Program Files\Microsoft SQL Server\MSSQL10_50.MSSQLSERVER\MSSQL\DATA\Davincis3.mdf', 
   MOVE 'JQueryExampleDB_log' TO 'C:\Program Files\Microsoft SQL Server\MSSQL10_50.MSSQLSERVER\MSSQL\DATA\Davincis3.ldf', 

I have no clue as to the name "JQueryExampleDb", but this worked for me.

Nevertheless, backups (and databases) are not backwards compatible with older versions.

SQL SERVER: Check if variable is null and then assign statement for Where Clause

is null can be used to check whether null data is coming from a query as in following example:

 declare @Mem varchar(20),@flag int
select @mem=MemberClub from [dbo].[UserMaster] where UserID=@uid
if(@Mem is null)
    set @flag= 0;
    set @flag=1;
return @flag;

Retrieving Android API version programmatically

android.os.Build.VERSION.SDK should give you the value of the API Level. You can easily find the mapping from api level to android version in the android documentation. I believe, 8 is for 2.2, 7 for 2.1, and so on.

Android: How to add R.raw to project?

Create a raw android resource directory. enter image description here

Once the raw directory is created, Make sure to add a valid media file

  1. Make sure to follow proper naming conventions (lower case letters with underscore '_' as separators)
  2. Media file should have a proper encoding and formatted media file in one of the supported formats.

After following the above procedure, you should be able to access your media files by using R.raw.media_file

How do you import an Eclipse project into Android Studio now?

Stop installing android studio 3.0.1 and go back 2.3.3 ( Stable version) . Check for the stable version and you can find them a lot

All you have to do uninstall and go back to the other version. Yes it asks to create gradle file seperately which is completely new to me!

Failure is the stepping stone for success..

How to use <DllImport> in VB.NET?

I saw in getwindowtext (user32) on that you can place a MarshalAs statement to state that the StringBuffer is equivalent to LPSTR.

<DllImport("user32.dll", SetLastError:=True, CharSet:=CharSet.Ansi)> _
Public Function GetWindowText(hwnd As IntPtr, <MarshalAs(UnManagedType.LPStr)>lpString As System.Text.StringBuilder, cch As Integer) As Integer
End Function

How do I call an Angular.js filter with multiple arguments?

If you want to call your filter inside ng-options the code will be as follows:

ng-options="productSize as ( productSize | sizeWithPrice: product )  for productSize in productSizes track by"

where the filter is sizeWithPriceFilter and it has two parameters product and productSize

MongoDB - Update objects in a document's array (nested updating)

There is no way to do this in single query. You have to search the document in first query:

If document exists: {user_id : 123456 , "items.item_name" : "my_item_two" } , 
                {$inc : {"items.$.price" : 1} } , 
                false , 

Else {user_id : 123456 } , 
                {$addToSet : {"items" : {'item_name' : "my_item_two" , 'price' : 1 }} } ,
                false , 

No need to add condition {$ne : "my_item_two" }.

Also in multithreaded enviourment you have to be careful that only one thread can execute the second (insert case, if document did not found) at a time, otherwise duplicate embed documents will be inserted.

Convert to date format dd/mm/yyyy

$source    =    'your varible name';
$date    =     new DateTime($source);
$_REQUEST["date"]    =     $date->format('d-m-Y');

echo $_REQUEST["date"];

Error handling in C code

In addition to what has been said, prior to returning your error code, fire off an assert or similar diagnostic when an error is returned, as it will make tracing a lot easier. The way I do this is to have a customised assert that still gets compiled in at release but only gets fired when the software is in diagnostics mode, with an option to silently report to a log file or pause on screen.

I personally return error codes as negative integers with no_error as zero , but it does leave you with the possible following bug

if (MyFunc())

An alternative is have a failure always returned as zero, and use a LastError() function to provide details of the actual error.

How can I capture the result of var_dump to a string?

From the PHP manual:

This function displays structured information about one or more expressions that includes its type and value.

So, here is the real return version of PHP's var_dump(), which actually accepts a variable-length argument list:

function var_dump_str()
    $argc = func_num_args();
    $argv = func_get_args();

    if ($argc > 0) {
        call_user_func_array('var_dump', $argv);
        $result = ob_get_contents();
        return $result;

    return '';

Google Maps API 3 - Custom marker color for default (dot) marker

Hi you can use icon as SVG and set colors. See this code

 * declare map and places as a global variable_x000D_
var map;_x000D_
var places = [_x000D_
    ['Place 1', "<h1>Title 1</h1>", -0.690542, -76.174856,"red"],_x000D_
    ['Place 2', "<h1>Title 2</h1>", -5.028249, -57.659052,"blue"],_x000D_
    ['Place 3', "<h1>Title 3</h1>", -0.028249, -77.757507,"green"],_x000D_
    ['Place 4', "<h1>Title 4</h1>", -0.800101286, -76.78747820,"orange"],_x000D_
    ['Place 5', "<h1>Title 5</h1>", -0.950198, -78.959302,"#FF33AA"]_x000D_
 * use google maps api built-in mechanism to attach dom events_x000D_
google.maps.event.addDomListener(window, "load", function () {_x000D_
     * create map_x000D_
    var map = new google.maps.Map(document.getElementById("map_div"), {_x000D_
        mapTypeId: google.maps.MapTypeId.ROADMAP,_x000D_
     * create infowindow (which will be used by markers)_x000D_
    var infoWindow = new google.maps.InfoWindow();_x000D_
     * create bounds (which will be used auto zoom map)_x000D_
    var bounds = new google.maps.LatLngBounds();_x000D_
     * marker creater function (acts as a closure for html parameter)_x000D_
    function createMarker(options, html) {_x000D_
        var marker = new google.maps.Marker(options);_x000D_
        if (html) {_x000D_
            google.maps.event.addListener(marker, "click", function () {_x000D_
      , this);_x000D_
                map.setZoom(map.getZoom() + 1)_x000D_
        return marker;_x000D_
     * add markers to map_x000D_
    for (var i = 0; i < places.length; i++) {_x000D_
        var point = places[i];_x000D_
            position: new google.maps.LatLng(point[2], point[3]),_x000D_
            map: map,_x000D_
            icon: {_x000D_
                path: "M27.648 -41.399q0 -3.816 -2.7 -6.516t-6.516 -2.7 -6.516 2.7 -2.7 6.516 2.7 6.516 6.516 2.7 6.516 -2.7 2.7 -6.516zm9.216 0q0 3.924 -1.188 6.444l-13.104 27.864q-0.576 1.188 -1.71 1.872t-2.43 0.684 -2.43 -0.684 -1.674 -1.872l-13.14 -27.864q-1.188 -2.52 -1.188 -6.444 0 -7.632 5.4 -13.032t13.032 -5.4 13.032 5.4 5.4 13.032z",_x000D_
                scale: 0.6,_x000D_
                strokeWeight: 0.2,_x000D_
                strokeColor: 'black',_x000D_
                strokeOpacity: 1,_x000D_
                fillColor: point[4],_x000D_
                fillOpacity: 0.85,_x000D_
        }, point[1]);_x000D_
<script type="text/javascript" src=""></script>_x000D_
<div id="map_div" style="height: 400px;"></div>

Wait for all promises to resolve

You can use "await" in an "async function".

app.controller('MainCtrl', async function($scope, $q, $timeout) {
  var all = await $q.all([one.promise, two.promise, three.promise]); 

NOTE: I'm not 100% sure you can call an async function from a non-async function and have the right results.

That said this wouldn't ever be used on a website. But for load-testing/integration test...maybe.

Example code:

async function waitForIt(printMe) {_x000D_
  console.log("..."+await req());_x000D_
function req() {_x000D_
  var promise = new Promise(resolve => {_x000D_
    setTimeout(() => {_x000D_
    }, 2000);_x000D_
    return promise;_x000D_
waitForIt("Legen-Wait For It");

How to print matched regex pattern using awk?

If you are only interested in the last line of input and you expect to find only one match (for example a part of the summary line of a shell command), you can also try this very compact code, adopted from How to print regexp matches using `awk`?:

$ echo "xxx yyy zzz" | awk '{match($0,"yyy",a)}END{print a[0]}'

Or the more complex version with a partial result:

$ echo "xxx=a yyy=b zzz=c" | awk '{match($0,"yyy=([^ ]+)",a)}END{print a[1]}'

Warning: the awk match() function with three arguments only exists in gawk, not in mawk

Here is another nice solution using a lookbehind regex in grep instead of awk. This solution has lower requirements to your installation:

$ echo "xxx=a yyy=b zzz=c" | grep -Po '(?<=yyy=)[^ ]+'

MySQL - Rows to Columns

    sum( if( itemname = 'A', itemvalue, 0 ) ) AS A,  
    sum( if( itemname = 'B', itemvalue, 0 ) ) AS B, 
    sum( if( itemname = 'C', itemvalue, 0 ) ) AS C 

HTML input arrays

Follow it...

<form action="index.php" method="POST">
<input type="number" name="array[]" value="1">
<input type="number" name="array[]" value="2">
<input type="number" name="array[]" value="3"> <!--taking array input by input name array[]-->
<input type="number" name="array[]" value="4">
<input type="submit" name="submit">
echo "Input :" .$a[3];  // Displaying Selected array Value
foreach ($a as $v) {
    print_r($v); //print all array element.

Iterating through a list to render multiple widgets in Flutter?

The Dart language has aspects of functional programming, so what you want can be written concisely as:

List<String> list = ['one', 'two', 'three', 'four'];
List<Widget> widgets = => new Text(name)).toList();

Read this as "take each name in list and map it to a Text and form them back into a List".

The module was expected to contain an assembly manifest

I got the error in the following case:

  1. A .NET EXE file (#1) was referencing another .NET EXE file (#2)
  2. I was trying to obfuscate EXE #2 with Themida
  3. when running the EXE #1 it was crashing with the error "The module was expected to contain an assembly manifest"

I simply avoided the obfuscation and the error is gone. not a real solution, but at least I know what caused it...

Nested Recycler view height doesn't wrap its content

An alternative to extend LayoutManager can be just set the size of the view manually.

Number of items per row height (if all the items have the same height and the separator is included on the row)

LinearLayout.LayoutParams params = (LinearLayout.LayoutParams) mListView.getLayoutParams();
params.height = mAdapter.getItemCount() * getResources().getDimensionPixelSize(R.dimen.row_height);

Is still a workaround, but for basic cases it works.

Styling JQuery UI Autocomplete

You can overwrite the classes in your own css using !important, e.g. if you want to get rid of the rounded corners.

border-radius: 0px !important;

UITableView set to static cells. Is it possible to hide some of the cells programmatically?

In > Swift 2.2, I've combined few answers here.

Make an outlet from storyboard to link to your staticCell.

@IBOutlet weak var updateStaticCell: UITableViewCell!

override func viewDidLoad() {
    updateStaticCell.hidden = true

override func tableView(tableView: UITableView, heightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat {
    if indexPath.row == 0 {
        return 0
    } else {
        return super.tableView(tableView, heightForRowAtIndexPath: indexPath)

I want to hide my first cell so I set the height to 0 as described above.

How would you count occurrences of a string (actually a char) within a string?

I felt that we were lacking certain kinds of sub string counting, like unsafe byte-by-byte comparisons. I put together the original poster's method and any methods I could think of.

These are the string extensions I made.

namespace Example
    using System;
    using System.Text;

    public static class StringExtensions
        public static int CountSubstr(this string str, string substr)
            return (str.Length - str.Replace(substr, "").Length) / substr.Length;

        public static int CountSubstr(this string str, char substr)
            return (str.Length - str.Replace(substr.ToString(), "").Length);

        public static int CountSubstr2(this string str, string substr)
            int substrlen = substr.Length;
            int lastIndex = str.IndexOf(substr, 0, StringComparison.Ordinal);
            int count = 0;
            while (lastIndex != -1)
                lastIndex = str.IndexOf(substr, lastIndex + substrlen, StringComparison.Ordinal);

            return count;

        public static int CountSubstr2(this string str, char substr)
            int lastIndex = str.IndexOf(substr, 0);
            int count = 0;
            while (lastIndex != -1)
                lastIndex = str.IndexOf(substr, lastIndex + 1);

            return count;

        public static int CountChar(this string str, char substr)
            int length = str.Length;
            int count = 0;
            for (int i = 0; i < length; ++i)
                if (str[i] == substr)

            return count;

        public static int CountChar2(this string str, char substr)
            int count = 0;
            foreach (var c in str)
                if (c == substr)

            return count;

        public static unsafe int CountChar3(this string str, char substr)
            int length = str.Length;
            int count = 0;
            fixed (char* chars = str)
                for (int i = 0; i < length; ++i)
                    if (*(chars + i) == substr)

            return count;

        public static unsafe int CountChar4(this string str, char substr)
            int length = str.Length;
            int count = 0;
            fixed (char* chars = str)
                for (int i = length - 1; i >= 0; --i)
                    if (*(chars + i) == substr)

            return count;

        public static unsafe int CountSubstr3(this string str, string substr)
            int length = str.Length;
            int substrlen = substr.Length;
            int count = 0;
            fixed (char* strc = str)
                fixed (char* substrc = substr)
                    int n = 0;

                    for (int i = 0; i < length; ++i)
                        if (*(strc + i) == *(substrc + n))
                            if (n == substrlen)
                                n = 0;
                            n = 0;

            return count;

        public static int CountSubstr3(this string str, char substr)
            return CountSubstr3(str, substr.ToString());

        public static unsafe int CountSubstr4(this string str, string substr)
            int length = str.Length;
            int substrLastIndex = substr.Length - 1;
            int count = 0;
            fixed (char* strc = str)
                fixed (char* substrc = substr)
                    int n = substrLastIndex;

                    for (int i = length - 1; i >= 0; --i)
                        if (*(strc + i) == *(substrc + n))
                            if (--n == -1)
                                n = substrLastIndex;
                            n = substrLastIndex;

            return count;

        public static int CountSubstr4(this string str, char substr)
            return CountSubstr4(str, substr.ToString());

Followed by the test code...

static void Main()
    const char matchA = '_';
    const string matchB = "and";
    const string matchC = "muchlongerword";
    const string testStrA = "_and_d_e_banna_i_o___pfasd__and_d_e_banna_i_o___pfasd_";
    const string testStrB = "and sdf and ans andeians andano ip and and sdf and ans andeians andano ip and";
    const string testStrC =
        "muchlongerword amuchlongerworsdfmuchlongerwordsdf jmuchlongerworijv muchlongerword sdmuchlongerword dsmuchlongerword";
    const int testSize = 1000000;
    var timer = new Stopwatch();
    for (int i = 0; i < testSize; ++i)
    Console.WriteLine("CS1 chr: " + timer.Elapsed.TotalMilliseconds + "ms");

    for (int i = 0; i < testSize; ++i)
    Console.WriteLine("CS1 and: " + timer.Elapsed.TotalMilliseconds + "ms");

    for (int i = 0; i < testSize; ++i)
    Console.WriteLine("CS1 mlw: " + timer.Elapsed.TotalMilliseconds + "ms");

    for (int i = 0; i < testSize; ++i)
    Console.WriteLine("CS2 chr: " + timer.Elapsed.TotalMilliseconds + "ms");

    for (int i = 0; i < testSize; ++i)
    Console.WriteLine("CS2 and: " + timer.Elapsed.TotalMilliseconds + "ms");

    for (int i = 0; i < testSize; ++i)
    Console.WriteLine("CS2 mlw: " + timer.Elapsed.TotalMilliseconds + "ms");

    for (int i = 0; i < testSize; ++i)
    Console.WriteLine("CS3 chr: " + timer.Elapsed.TotalMilliseconds + "ms");

    for (int i = 0; i < testSize; ++i)
    Console.WriteLine("CS3 and: " + timer.Elapsed.TotalMilliseconds + "ms");

    for (int i = 0; i < testSize; ++i)
    Console.WriteLine("CS3 mlw: " + timer.Elapsed.TotalMilliseconds + "ms");

    for (int i = 0; i < testSize; ++i)
    Console.WriteLine("CS4 chr: " + timer.Elapsed.TotalMilliseconds + "ms");

    for (int i = 0; i < testSize; ++i)
    Console.WriteLine("CS4 and: " + timer.Elapsed.TotalMilliseconds + "ms");

    for (int i = 0; i < testSize; ++i)
    Console.WriteLine("CS4 mlw: " + timer.Elapsed.TotalMilliseconds + "ms");

    for (int i = 0; i < testSize; ++i)
    Console.WriteLine("CC1 chr: " + timer.Elapsed.TotalMilliseconds + "ms");

    for (int i = 0; i < testSize; ++i)
    Console.WriteLine("CC2 chr: " + timer.Elapsed.TotalMilliseconds + "ms");

    for (int i = 0; i < testSize; ++i)
    Console.WriteLine("CC3 chr: " + timer.Elapsed.TotalMilliseconds + "ms");

    for (int i = 0; i < testSize; ++i)
    Console.WriteLine("CC4 chr: " + timer.Elapsed.TotalMilliseconds + "ms");

Results: CSX corresponds with CountSubstrX and CCX corresponds with CountCharX. "chr" searches a string for '_', "and" searches a string for "and", and "mlw" searches a string for "muchlongerword"

CS1 chr: 824.123ms
CS1 and: 586.1893ms
CS1 mlw: 486.5414ms
CS2 chr: 127.8941ms
CS2 and: 806.3918ms
CS2 mlw: 497.318ms
CS3 chr: 201.8896ms
CS3 and: 124.0675ms
CS3 mlw: 212.8341ms
CS4 chr: 81.5183ms
CS4 and: 92.0615ms
CS4 mlw: 116.2197ms
CC1 chr: 66.4078ms
CC2 chr: 64.0161ms
CC3 chr: 65.9013ms
CC4 chr: 65.8206ms

And finally, I had a file with 3.6 million characters. It was "derp adfderdserp dfaerpderp deasderp" repeated 100,000 times. I searched for "derp" inside the file with the above methods 100 times these results.

CS1Derp: 1501.3444ms
CS2Derp: 1585.797ms
CS3Derp: 376.0937ms
CS4Derp: 271.1663ms

So my 4th method is definitely the winner, but, realistically, if a 3.6 million character file 100 times only took 1586ms as the worse case, then all of this is quite negligible.

By the way, I also scanned for the 'd' char in the 3.6 million character file with 100 times CountSubstr and CountChar methods. Results...

CS1  d : 2606.9513ms
CS2  d : 339.7942ms
CS3  d : 960.281ms
CS4  d : 233.3442ms
CC1  d : 302.4122ms
CC2  d : 280.7719ms
CC3  d : 299.1125ms
CC4  d : 292.9365ms

The original posters method is very bad for single character needles in a large haystack according to this.

Note: All values were updated to Release version output. I accidentally forgot to build on Release mode upon the first time I posted this. Some of my statements have been amended.

The FastCGI process exited unexpectedly

After much pain and suffering, turns out I needed to install the "Visual C++ Redistributable for Visual Studio 2012 Update 4 32-bit version", even on my 64-bit server.

Entity Framework The underlying provider failed on Open

I saw this error when a colleague was trying to connect to a database that was protected behind a VPN. The user had unknownling switched to a wireless network that did not have VPN access. One way to test this scenario is to see if you can establish a connection in another means, such as SSMS, and see if that fails as well.

Docker error : no space left on device

As already mentioned,

docker system prune

helps, but with Docker 17.06.1 and later without pruning unused volumes. Since Docker 17.06.1, the following command prunes volumes, too:

docker system prune --volumes

From the Docker documentation:

The docker system prune command is a shortcut that prunes images, containers, and networks. In Docker 17.06.0 and earlier, volumes are also pruned. In Docker 17.06.1 and higher, you must specify the --volumes flag for docker system prune to prune volumes.

If you want to prune volumes and keep images and containers:

docker volume prune

removing table border

Use table style Border-collapse at the table level

How to display raw html code in PRE or something like it but without escaping it

@GitaarLAB and @Jukka elaborate that <xmp> tag is obsolete, but still the best. When I use it like this

<div>Lorem ipsum</div>

then the first EOL is inserted in the code, and it looks awful.

It can be solved by removing that EOL

<xmp><div>Lorem ipsum</div>

but then it looks bad in the source. I used to solve it with wrapping <div>, but recently I figured out a nice CSS3 rule, I hope it also helps somebody:

xmp { margin: 5px 0; padding: 0 5px 5px 5px; background: #CCC; }
xmp:before { content: ""; display: block; height: 1em; margin: 0 -5px -2em -5px; }

This looks better.

if A vs if A is not None:

None is a special value in Python which usually designates an uninitialized variable. To test whether A does not have this particular value you use:

if A is not None

Falsey values are a special class of objects in Python (e.g. false, []). To test whether A is falsey use:

if not A

Thus, the two expressions are not the same And you'd better not treat them as synonyms.

P.S. None is also falsey, so the first expression implies the second. But the second covers other falsey values besides None. Now... if you can be sure that you can't have other falsey values besides None in A, then you can replace the first expression with the second.

Find what 2 numbers add to something and multiply to something

With the multiplication, I recommend using the modulo operator (%) to determine which numbers divide evenly into the target number like:

$factors = array();
for($i = 0; $i < $target; $i++){
    if($target % $i == 0){
        $temp = array()
        $a = $i;
        $b = $target / $i;
        $temp["a"] = $a;
        $temp["b"] = $b;
        $temp["index"] = $i;
        array_push($factors, $temp);

This would leave you with an array of factors of the target number.

Android ImageView Fixing Image Size

Try this

ImageView img
    Bitmap bmp;
    int width=100;
    int height=100;
    bmp=BitmapFactory.decodeResource(getResources(),R.drawable.image);//image is your image                                                            
    bmp=Bitmap.createScaledBitmap(bmp, width,height, true);

Or If you want to load complete image size in memory then you can use


Cross-browser bookmark/add to favorites JavaScript

jQuery Version

JavaScript (modified from a script I found on someone's site - I just can't find the site again, so I can't give the person credit):

$(document).ready(function() {
  $("#bookmarkme").click(function() {
    if (window.sidebar) { // Mozilla Firefox Bookmark
    } else if(window.external) { // IE Favorite
      window.external.AddFavorite(location.href,document.title); }
    else if(window.opera && window.print) { // Opera Hotlist
      return true;


<a id="bookmarkme" href="#" rel="sidebar" title="bookmark this page">Bookmark This Page</a>

IE will show an error if you don't run it off a server (it doesn't allow JavaScript bookmarks via JavaScript when viewing it as a file://...).

Preserve Line Breaks From TextArea When Writing To MySQL

Two solutions for this:

  1. PHP function nl2br():


    echo nl2br("This\r\nis\n\ra\nstring\r");
    // will output
    This<br />
    is<br />
    a<br />
    string<br />
  2. Wrap the input in <pre></pre> tags.

    See: W3C Wiki - HTML/Elements/pre

How do I merge my local uncommitted changes into another Git branch?

Since your files are not yet committed in branch1:

git stash
git checkout branch2
git stash pop


git stash
git checkout branch2
git stash list       # to check the various stash made in different branch
git stash apply x    # to select the right one

As commented by benjohn (see git stash man page):

To also stash currently untracked (newly added) files, add the argument -u, so:

git stash -u

Comparing two files in linux terminal

You can also use: colordiff: Displays the output of diff with colors.

About vimdiff: It allows you to compare files via SSH, for example :

vimdiff /var/log/secure scp://

Extracted from:

Can an Option in a Select tag carry multiple values?


<SELECT NAME="Testing" id="Testing">  
  <OPTION VALUE="1,2010"> One  
  <OPTION VALUE="2,2122"> Two  
  <OPTION VALUE="3,0"> Three

For JS

  var valueOne= $('#Testing').val().split(',')[0];
  var valueTwo =$('#Testing').val().split(',')[1];
  console.log(valueOne); //output 1
  console.log(valueTwo); //output 2010


  $selectedValue= explode(',', $value);
  $valueOne= $exploded_value[0]; //output 1
  $valueTwo= $exploded_value[1]; //output 2010

Git status shows files as changed even though contents are the same

Have you changed the mode of the files? I did it on my machine and the local dev machine had 777 given to all the files whereas the repo had 755 which showed every file as modified. I did git diff and it showed the old mode and new mode are different. If that is the problem then you can easily ignore them by git config core.filemode false

Xcode 4: create IPA file instead of .xcarchive

Just setting Skip Install to YES did not work for me. Hopefully this will help somebody.

I went to dependence of my project targets: Coreplot-CocoaTouch. Then went to Coreplot-CocoaTouch Targets. In its Targets opened Build Phases. Then opened Copy Headers. There I had some of headers in Public, some in Private and some in Project. Moved ALL of them to Project.

Of course, in Build Settings of Coreplot-CocoaTouch Targets checked that Skip Install was set to YES in Deployment options.

And this time Archive made an archive that could be signed and .ipa produced.

How to create a numpy array of all True or all False?

>>> a = numpy.full((2,4), True, dtype=bool)
>>> a[1][3]
>>> a
array([[ True,  True,  True,  True],
       [ True,  True,  True,  True]], dtype=bool)

numpy.full(Size, Scalar Value, Type). There is other arguments as well that can be passed, for documentation on that, check

Bootstrap how to get text to vertical align in a div container

  transform: translateY(-50%);
  -webkit-transform: translateY(-50%);
  -ms-transform: translateY(-50%);


The top:50% style essentially pushes the header element down 50% from the top of the parent element. The translateY stylings also act in a similar manner by moving then element down 50% from the top.

Please note that this works well for headers with 1 (maybe 2) lines of text as this simply moves the top of the header element down 50% and then the rest of the content fills in below that, which means that with multiple lines of text it would appear to be slightly below vertically aligned.

A possible fix for multiple lines would be to use a percentage slightly less than 50%.

cast_sender.js error: Failed to load resource: net::ERR_FAILED in Chrome

I'm going to add to the answer given before.

It's not a bug in your code or the browser's code. It's the JavaScript code inside the YouTube iframe polls for the extensions it could interoperate with in case they were installed (likely to determine if the extension is installed).

Look at the source of www-embed-player.js (loaded from, it's YouTube static files CDN). You'll find the following:

function Wj(a){return"chrome-extension://"+a+"/cast_sender.js"}

javascript functions to show and hide divs

I usually do this with classes, that seems to force the browsers to reassess all the styling.

.hiddendiv {display:none;}
.visiblediv {display:block;}

then use;

function show() {  
function close() {  

Note the casing of "className" that trips me up a lot

Copying data from one SQLite database to another

You'll have to attach Database X with Database Y using the ATTACH command, then run the appropriate Insert Into commands for the tables you want to transfer.


Or, if the columns are not matched up in order:

INSERT INTO X.TABLE(fieldname1, fieldname2) SELECT fieldname1, fieldname2 FROM Y.TABLE;

Escaping ampersand character in SQL string

Escape is set to \ by default, so you don't need to set it; but if you do, don't wrap it in quotes.

Ampersand is the SQL*Plus substitution variable marker; but you can change it, or more usefully in your case turn it off completely, with:

set define off

Then you don't need to bother escaping the value at all.

Dump a list in a pickle file and retrieve it back later

Pickling will serialize your list (convert it, and it's entries to a unique byte string), so you can save it to disk. You can also use pickle to retrieve your original list, loading from the saved file.

So, first build a list, then use pickle.dump to send it to a file...

Python 3.4.1 (default, May 21 2014, 12:39:51) 
[GCC 4.2.1 Compatible Apple LLVM 5.0 (clang-500.2.79)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> mylist = ['I wish to complain about this parrot what I purchased not half an hour ago from this very boutique.', "Oh yes, the, uh, the Norwegian Blue...What's,uh...What's wrong with it?", "I'll tell you what's wrong with it, my lad. 'E's dead, that's what's wrong with it!", "No, no, 'e's uh,...he's resting."]
>>> import pickle
>>> with open('parrot.pkl', 'wb') as f:
...   pickle.dump(mylist, f)

Then quit and come back later… and open with pickle.load...

Python 3.4.1 (default, May 21 2014, 12:39:51) 
[GCC 4.2.1 Compatible Apple LLVM 5.0 (clang-500.2.79)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import pickle
>>> with open('parrot.pkl', 'rb') as f:
...   mynewlist = pickle.load(f)
>>> mynewlist
['I wish to complain about this parrot what I purchased not half an hour ago from this very boutique.', "Oh yes, the, uh, the Norwegian Blue...What's,uh...What's wrong with it?", "I'll tell you what's wrong with it, my lad. 'E's dead, that's what's wrong with it!", "No, no, 'e's uh,...he's resting."]

Print text instead of value from C enum

I know I am late to the party, but how about this?

const char* dayNames[] = { [Sunday] = "Sunday", [Monday] = "Monday", /*and so on*/ };
printf("%s", dayNames[Sunday]); // prints "Sunday"

This way, you do not have to manually keep the enum and the char* array in sync. If you are like me, chances are that you will later change the enum, and the char* array will print invalid strings. This may not be a feature universally supported. But afaik, most of the mordern day C compilers support this designated initialier style.

You can read more about designated initializers here.

Compiling problems: cannot find crt1.o

Debian / Ubuntu

The problem is you likely only have the gcc for your current architecture and that's 64bit. You need the 32bit support files. For that, you need to install them

sudo apt install gcc-multilib

How to map with index in Ruby?

In ruby 1.9.3 there is a chainable method called with_index which can be chained to map.

For example: { |item, index| ... }

Get the first key name of a JavaScript object

In Javascript you can do the following:


How to pass a Javascript Array via JQuery Post so that all its contents are accessible via the PHP $_POST array?

I think we should sent in this format

var array = [1, 2, 3, 4, 5];
$.post('/controller/MyAction', $.param({ data: array }, true), function(data) {});

Its already mentioned in Pass array to mvc Action via AJAX

It worked for me

Twitter Bootstrap alert message close and open again

This worked for me best:

$('.alert').on('', function (e) {

Angular 2 two way binding using ngModel is not working

In my case, I was missing a "name" attribute on my input element.

How to install Maven 3 on Ubuntu 18.04/17.04/16.10/16.04 LTS/15.10/15.04/14.10/14.04 LTS/13.10/13.04 by using apt-get?

It's best to use miske's answer.

Properly installing natecarlson's repository

If you really want to use natecarlson's repository, the instructions just below can do any of the following:

  1. set it up from scratch
  2. repair it if apt-get update gives a 404 error after add-apt-repository
  3. repair it if apt-get update gives a NO_PUBKEY error after manually adding it to /etc/apt/sources.list

Open a terminal and run the following:

sudo -i

Enter your password if necessary, then paste the following into the terminal:

export GOOD_RELEASE='precise'
export BAD_RELEASE="`lsb_release -cs`"
cd /etc/apt
sed -i '/natecarlson\/maven3/d' sources.list
cd sources.list.d
rm -f natecarlson-maven3-*.list*
apt-add-repository -y ppa:natecarlson/maven3
mv natecarlson-maven3-${BAD_RELEASE}.list natecarlson-maven3-${GOOD_RELEASE}.list
sed -i "s/${BAD_RELEASE}/${GOOD_RELEASE}/" natecarlson-maven3-${GOOD_RELEASE}.list
apt-get update
echo Done!

Removing natecarlson's repository

If you installed natecarlson's repository (either using add-apt-repository or manually added to /etc/apt/sources.list) and you don't want it anymore, open a terminal and run the following:

sudo -i

Enter your password if necessary, then paste the following into the terminal:

cd /etc/apt
sed -i '/natecarlson\/maven3/d' sources.list
cd sources.list.d
rm -f natecarlson-maven3-*.list*
apt-get update
echo Done!

Creating a config file in PHP

Use an INI file is a flexible and powerful solution! PHP has a native function to handle it properly. For example, it is possible to create an INI file like this:


db_name     = mydatabase
db_user     = myuser
db_password = mypassword

app_email = [email protected]
app_url   =

So the only thing you need to do is call:

$ini = parse_ini_file('app.ini');

Then you can access the definitions easily using the $ini array.

echo $ini['db_name'];     // mydatabase
echo $ini['db_user'];     // myuser
echo $ini['db_password']; // mypassword
echo $ini['app_email'];   // [email protected]

IMPORTANT: For security reasons the INI file must be in a non public folder

Can we import XML file into another XML file?

Mads Hansen's solution is good but to succeed in reading the external file in .NET 4 took some time to figure out using hints in the comments about resolvers, ProhibitDTD and so on.

This is how it's done:

        XmlReaderSettings settings = new XmlReaderSettings();
        settings.DtdProcessing = DtdProcessing.Parse;
        XmlUrlResolver resolver = new XmlUrlResolver();
        resolver.Credentials = System.Net.CredentialCache.DefaultCredentials;
        settings.XmlResolver = resolver;
        var reader = XmlReader.Create("logfile.xml", settings);
        XmlDocument doc = new XmlDocument();
        foreach (XmlElement element in doc.SelectNodes("//event"))
            var ch = element.ChildNodes;
            var count = ch.Count;


<?xml version="1.0"?>
<!DOCTYPE logfile [
<!ENTITY events    
 SYSTEM "events.txt">



Android Studio Run/Debug configuration error: Module not specified

You have 3 ways:

  1. Clean Project in Android Studio menu

    Build -> Clean Project and use Build -> Rebuild

  1. Remove all the modules in settings.gradle

    • Open settings.gradle project
    • Remove include ':app' and and other modules
    • Sync gradle
    • Add include ':app' and and other modules
    • Sync gradle again

  1. Remove all code in

    • Open project
    • Remove all code





    • Sync gradle

    • Add code again
    • Sync gradle again

Undefined reference to `pow' and `floor'

You need to compile with the link flag -lm, like this:

gcc fib.c -lm -o fibo

This will tell gcc to link your code against the math lib. Just be sure to put the flag after the objects you want to link.

Superscript in CSS only?

Here's the exact way sup uses:


Found this via google chrome inspect element.

How to change progress bar's progress color in Android

It is so simple using attr , if you are dealing with multistyle apps:

try this way:

Declare below attribute attrs.xml

 <attr name="circularProgressTheme" format="reference"></attr>

Paste below code in styles.xml

 <style name="ProgressThemeWhite" parent="ThemeOverlay.AppCompat.Light">
        <item name="colorAccent">#FF0000</item>

    <style name="circularProgressThemeWhite">
        <item name="android:theme">@style/ProgressThemeWhite</item>

  <style name="AppTheme" parent="Theme.AppCompat.NoActionBar">

   <item name="circularProgressTheme">@style/circularProgressThemeWhite</item>


use progress bar like below


execute function after complete page load

call a function after complete page load set time out

setTimeout(function() {_x000D_
   var val = $('.GridStyle tr:nth-child(2) td:nth-child(4)').text();_x000D_
 for(var i, j = 0; i = ddl2.options[j]; j++) {_x000D_
  if(i.text == val) {      _x000D_
   ddl2.selectedIndex = i.index;_x000D_
 } _x000D_
}, 1000);

Convert Char to String in C

FYI you dont have string datatype in C. Use array of characters to store the value and manipulate it. Change your variable c into an array of characters and use it inside a loop to get values.

char c[10];
int i=0;

The other way to do is to use pointers and allocate memory dynamically and assign values.

Eclipse: How to install a plugin manually?

You can try this

click Help>Install New Software on the menu bar

enter image description here

enter image description here

enter image description here

enter image description here

Steps to upload an iPhone application to the AppStore

Check that your singing identity IN YOUR TARGET properties is correct. This one over-rides what you have in your project properties.

Also: I dunno if this is true - but I wasn't getting emails detailing my binary rejections when I did the "ready for binary upload" from a PC - but I DID get an email when I did this on the MAC

ESLint - "window" is not defined. How to allow global variables in package.json

There is a builtin environment: browser that includes window.

Example .eslintrc.json:

"env": {
    "browser": true,
    "node": true,
    "jasmine": true

More information:

Also see the package.json answer by chevin99 below.

Swift: Testing optionals for nil

To add to the other answers, instead of assigning to a differently named variable inside of an if condition:

var a: Int? = 5

if let b = a {
   // do something

you can reuse the same variable name like this:

var a: Int? = 5

if let a = a {
    // do something

This might help you avoid running out of creative variable names...

This takes advantage of variable shadowing that is supported in Swift.

"Invalid form control" only in Google Chrome

No validate will do the job.

<form action="whatever" method="post" novalidate>

Evaluate if list is empty JSTL

empty is an operator:

The empty operator is a prefix operation that can be used to determine whether a value is null or empty.

<c:if test="${empty myObject.featuresList}">

Soft Edges using CSS?

Another option is to use one of my personal favorite CSS tools: box-shadow.

A box shadow is really a drop-shadow on the node. It looks like this:

-moz-box-shadow: 1px 2px 3px rgba(0,0,0,.5);
-webkit-box-shadow: 1px 2px 3px rgba(0,0,0,.5);
box-shadow: 1px 2px 3px rgba(0,0,0,.5);

The arguments are:

1px: Horizontal offset of the effect. Positive numbers shift it right, negative left.
2px: Vertical offset of the effect. Positive numbers shift it down, negative up.
3px: The blur effect.  0 means no blur.
color: The color of the shadow.

So, you could leave your current design, and add a box-shadow like:

box-shadow: 0px -2px 2px rgba(34,34,34,0.6);

This should give you a 'blurry' top-edge.

This website will help with more information:

Java Immutable Collections

Collection<String> c1 = new ArrayList<String>();
Collection<String> c2 = Collections.unmodifiableList(c1);

c1 is mutable (i.e. neither unmodifiable nor immutable).
c2 is unmodifiable: it can't be changed itself, but if later on I change c1 then that change will be visible in c2.

This is because c2 is simply a wrapper around c1 and not really an independent copy. Guava provides the ImmutableList interface and some implementations. Those work by actually creating a copy of the input (unless the input is an immutable collection on its own).

Regarding your second question:

The mutability/immutability of a collection does not depend on the mutability/immutability of the objects contained therein. Modifying an object contained in a collection does not count as a "modification of the collection" for this description. Of course if you need a immutable collection, you usually also want it to contain immutable objects.

Tomcat: How to find out running tomcat version

run the following

/usr/local/tomcat/bin/ version

its response will be something like:

Using CATALINA_BASE:   /usr/local/tomcat
Using CATALINA_HOME:   /usr/local/tomcat
Using CATALINA_TMPDIR: /var/tmp/
Using JRE_HOME:        /usr
Using CLASSPATH:       /usr/local/tomcat/bin/bootstrap.jar:/usr/local/tomcat/bin/tomcat-juli.jar
Using CATALINA_PID:    /var/
Server version: Apache Tomcat/7.0.30
Server built:   Sep 27 2012 05:13:37
Server number:
OS Name:        Linux
OS Version:     2.6.32-504.3.3.el6.x86_64
Architecture:   amd64
JVM Version:    1.7.0_60-b19
JVM Vendor:     Oracle Corporation

How to decorate a class?

No one has explained that you can dynamically define classes. So you can have a decorator that defines (and returns) a subclass:

def addId(cls):

    class AddId(cls):

        def __init__(self, id, *args, **kargs):
            super(AddId, self).__init__(*args, **kargs)
            self.__id = id

        def getId(self):
            return self.__id

    return AddId

Which can be used in Python 2 (the comment from Blckknght which explains why you should continue to do this in 2.6+) like this:

class Foo:

FooId = addId(Foo)

And in Python 3 like this (but be careful to use super() in your classes):

class Foo:

So you can have your cake and eat it - inheritance and decorators!

remove / reset inherited css from an element

As long as they are attributes like classes and ids you can remove them by javascript/jQuery class modifiers.

document.getElementById("MyElement").className = "";

There is no way to remove specific tag CSS other than overriding them (or using another element).

Hexadecimal string to byte array in C

As far as I know, there's no standard function to do so, but it's simple to achieve in the following manner:

#include <stdio.h>

int main(int argc, char **argv) {
    const char hexstring[] = "DEadbeef10203040b00b1e50", *pos = hexstring;
    unsigned char val[12];

     /* WARNING: no sanitization or error-checking whatsoever */
    for (size_t count = 0; count < sizeof val/sizeof *val; count++) {
        sscanf(pos, "%2hhx", &val[count]);
        pos += 2;

    for(size_t count = 0; count < sizeof val/sizeof *val; count++)
        printf("%02x", val[count]);

    return 0;


As Al pointed out, in case of an odd number of hex digits in the string, you have to make sure you prefix it with a starting 0. For example, the string "f00f5" will be evaluated as {0xf0, 0x0f, 0x05} erroneously by the above example, instead of the proper {0x0f, 0x00, 0xf5}.

Amended the example a little bit to address the comment from @MassimoCallegari

CORS error :Request header field Authorization is not allowed by Access-Control-Allow-Headers in preflight response

This is an API issue, you won't get this error if using Postman/Fielder to send HTTP requests to API. In case of browsers, for security purpose, they always send OPTIONS request/preflight to API before sending the actual requests (GET/POST/PUT/DELETE). Therefore, in case, the request method is OPTION, not only you need to add "Authorization" into "Access-Control-Allow-Headers", but you need to add "OPTIONS" into "Access-Control-allow-methods" as well. This was how I fixed:

if (context.Request.Method == "OPTIONS")
            context.Response.Headers.Add("Access-Control-Allow-Origin", new[] { (string)context.Request.Headers["Origin"] });
            context.Response.Headers.Add("Access-Control-Allow-Headers", new[] { "Origin, X-Requested-With, Content-Type, Accept, Authorization" });
            context.Response.Headers.Add("Access-Control-Allow-Methods", new[] { "GET, POST, PUT, DELETE, OPTIONS" });
            context.Response.Headers.Add("Access-Control-Allow-Credentials", new[] { "true" });


How to include a class in PHP

  1. require('/yourpath/yourphp.php');

  2. require_once('/yourpath/yourphp.php');

  3. include '/yourpath/yourphp.php';

  4. use \Yourapp\Yourname


Avoid using require_once because it is slow: Why is require_once so bad to use?

ExecutorService that interrupts tasks after a timeout

Wrap the task in FutureTask and you can specify timeout for the FutureTask. Look at the example in my answer to this question,

java native Process timeout

using batch echo with special characters

One easy solution is to use delayed expansion, as this doesn't change any special characters.

set "line=<?xml version="1.0" encoding="utf-8" ?>"
setlocal EnableDelayedExpansion
  echo !line!
) > myfile.xml

EDIT : Another solution is to use a disappearing quote.

This technic uses a quotation mark to quote the special characters

@echo off
setlocal EnableDelayedExpansion
set ""="
echo !"!<?xml version="1.0" encoding="utf-8" ?>

The trick works, as in the special characters phase the leading quotation mark in !"! will preserve the rest of the line (if there aren't other quotes).
And in the delayed expansion phase the !"! will replaced with the content of the variable " (a single quote is a legal name!).

If you are working with disabled delayed expansion, you could use a FOR /F loop instead.

for /f %%^" in ("""") do echo(%%~" <?xml version="1.0" encoding="utf-8" ?>

But as the seems to be a bit annoying you could also build a macro.

set "print=for /f %%^" in ("""") do echo(%%~""

%print%<?xml version="1.0" encoding="utf-8" ?>
%print% Special characters like &|<>^ works now without escaping

How to call Base Class's __init__ method from the child class?

You could use super(ChildClass, self).__init__()

class BaseClass(object):
    def __init__(self, *args, **kwargs):

class ChildClass(BaseClass):
    def __init__(self, *args, **kwargs):
        super(ChildClass, self).__init__(*args, **kwargs)

Your indentation is incorrect, here's the modified code:

class Car(object):
    condition = "new"

    def __init__(self, model, color, mpg):
        self.model = model
        self.color = color
        self.mpg   = mpg

class ElectricCar(Car):
    def __init__(self, battery_type, model, color, mpg):
        super(ElectricCar, self).__init__(model, color, mpg)

car = ElectricCar('battery', 'ford', 'golden', 10)
print car.__dict__

Here's the output:

{'color': 'golden', 'mpg': 10, 'model': 'ford', 'battery_type': 'battery'}

Array initialization syntax when not in a declaration

For those of you, who doesn't like this monstrous new AClass[] { ... } syntax, here's some sugar:

public AClass[] c(AClass... arr) { return arr; }

Use this little function as you like:

AClass[] array;
array = c(object1, object2);

UIWebView open links in Safari

UIWebView and UIWebViewDelegate are deprecated. You won't be allowed to push an update to the Appstore with it. Reference

Use WKWebView and WKNavigationDelegate

Sample code:

class YourClass: WKNavigationDelegate {

    override public func viewDidLoad() {
        let webView = WKWebView()
        webView.navigationDelegate = self
    public func webView(_ webView: WKWebView,
                    didReceive challenge: URLAuthenticationChallenge,
                    completionHandler: @escaping (URLSession.AuthChallengeDisposition, URLCredential?) -> Void) {
        let cred = URLCredential(trust: challenge.protectionSpace.serverTrust!)
        completionHandler(.useCredential, cred)

    public func webView(_ webView: WKWebView,
                    decidePolicyFor navigationAction: WKNavigationAction,
                    decisionHandler: @escaping (WKNavigationActionPolicy) -> Swift.Void) {

Bind TextBox on Enter-key press

In case you are using MultiBinding with your TextBox you need to use BindingOperations.GetMultiBindingExpression method instead of BindingOperations.GetBindingExpression.

// Get the correct binding expression based on type of binding
//(simple binding or multi binding.
BindingExpressionBase binding = 
  BindingOperations.GetBindingExpression(element, prop);
if (binding == null)
    binding = BindingOperations.GetMultiBindingExpression(element, prop);

if (binding != null)
     object value = element.GetValue(prop);
     if (string.IsNullOrEmpty(value.ToString()) == true)

How to get current instance name from T-SQL

I found this:

EXECUTE xp_regread
        @rootkey = 'HKEY_LOCAL_MACHINE',
        @key = 'SOFTWARE\Microsoft\Microsoft SQL Server',
        @value_name = 'InstalledInstances'

That will give you list of all instances installed in your server.

The ServerName property of the SERVERPROPERTY function and @@SERVERNAME return similar information. The ServerName property provides the Windows server and instance name that together make up the unique server instance. @@SERVERNAME provides the currently configured local server name.

And Microsoft example for current server is:

SELECT CONVERT(sysname, SERVERPROPERTY('servername'));

This scenario is useful when there are multiple instances of SQL Server installed on a Windows server, and the client must open another connection to the same instance used by the current connection.

How to send an HTTPS GET Request in C#

Add ?var1=data1&var2=data2 to the end of url to submit values to the page via GET:

using System.Net;
using System.IO;

string url = "";

HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
Stream resStream = response.GetResponseStream();

8080 port already taken issue when trying to redeploy project from Spring Tool Suite IDE

One simple solution for me that worked was to : - Restart the IDE, since the stop Button was no longer visible.

How do I keep two side-by-side divs the same height?

I know its been a long time but I share my solution anyway. This is a jQuery trick.

--- HTML

<div class="custom-column">
    <div class="column-left">
    <div class="column-right">

<div class="custom-column">
    <div class="column-left">
    <div class="column-right">

---- CSS

.custom-column { margin-bottom:10px; }
.custom-column:after { clear:both; content:""; display:block; width:100%; }
    .column-left { float:left; width:25%; background:#CCC; }
    .column-right { float:right; width:75%; background:#EEE; }


<script src="js/jquery.min.js"></script>
    $balancer = function() {
            } else {




When are static variables initialized?

The static variable can be intialize in the following three ways as follow choose any one you like

  1. you can intialize it at the time of declaration
  2. or you can do by making static block eg:

    static {
            // whatever code is needed for initialization goes here
  3. There is an alternative to static blocks — you can write a private static method

    class name {
        public static varType myVar = initializeVar();
        private static varType initializeVar() {
            // initialization code goes here

Matplotlib subplots_adjust hspace so titles and xlabels don't overlap?

I find this quite tricky, but there is some information on it here at the MatPlotLib FAQ. It is rather cumbersome, and requires finding out about what space individual elements (ticklabels) take up...

Update: The page states that the tight_layout() function is the easiest way to go, which attempts to automatically correct spacing.

Otherwise, it shows ways to acquire the sizes of various elements (eg. labels) so you can then correct the spacings/positions of your axes elements. Here is an example from the above FAQ page, which determines the width of a very wide y-axis label, and adjusts the axis width accordingly:

import matplotlib.pyplot as plt
import matplotlib.transforms as mtransforms
fig = plt.figure()
ax = fig.add_subplot(111)
labels = ax.set_yticklabels(('really, really, really', 'long', 'labels'))

def on_draw(event):
   bboxes = []
   for label in labels:
       bbox = label.get_window_extent()
       # the figure transform goes from relative coords->pixels and we
       # want the inverse of that
       bboxi = bbox.inverse_transformed(fig.transFigure)

   # this is the bbox that bounds all the bboxes, again in relative
   # figure coords
   bbox = mtransforms.Bbox.union(bboxes)
   if fig.subplotpars.left < bbox.width:
       # we need to move it over
       fig.subplots_adjust(left=1.1*bbox.width) # pad a little
   return False

fig.canvas.mpl_connect('draw_event', on_draw)

How can I get file extensions with JavaScript?

If you are dealing with web urls, you can use:

function getExt(filepath){
     return filepath.split("?")[0].split("#")[0].split('.').pop();

getExt("../js/logic.v2.min.js") // js
getExt("") // php
getExt("") // html
getExt("c:\\logs\\yesterday.log"); // log


Convert string to int if string is a number

Cast to long or cast to int, be aware of the following.

These functions are one of the view functions in Excel VBA that are depending on the system regional settings. So if you use a comma in your double like in some countries in Europe, you will experience an error in the US.

E.g., in european excel-version 0,5 will perform well with CDbl(), but in US-version it will result in 5. So I recommend to use the following alternative:

Public Function CastLong(var As Variant)

    ' replace , by .
    var = Replace(var, ",", ".")        

    Dim l As Long
    On Error Resume Next
    l = Round(Val(var))

    ' if error occurs, l will be 0
    CastLong = l

End Function

' similar function for cast-int, you can add minimum and maximum value if you like
' to prevent that value is too high or too low.
Public Function CastInt(var As Variant)

    ' replace , by .
    var = Replace(var, ",", ".")

    Dim i As Integer
    On Error Resume Next
    i = Round(Val(var))

    ' if error occurs, i will be 0
    CastInt = i

End Function

Of course you can also think of cases where people use commas and dots, e.g., three-thousand as 3,000.00. If you require functionality for these kind of cases, then you have to check for another solution.

WAMP Server ERROR "Forbidden You don't have permission to access /phpmyadmin/ on this server."

For WampServer 2.2 with Apache 2.4.2 I ended up with:

Options Indexes FollowSymLinks MultiViews
AllowOverride all
Require local

Meaning of 'const' last in a function declaration of a class?

Here const means that at that function any variable's value can not change

class Test{
    int a;
    void test()const{
        a = 10;

And like this example, if you try to change the value of a variable in the test function you will get an error.

addEventListener, "change" and option selection

The problem is that you used the select option, this is where you went wrong. Select signifies that a textbox or textArea has a focus. What you need to do is use change. "Fires when a new choice is made in a select element", also used like blur when moving away from a textbox or textArea.

function start(){
      document.getElementById("activitySelector").addEventListener("change", addActivityItem, false);

function addActivityItem(){
      //option is selected

window.addEventListener("load", start, false);

Vertical divider CSS

<div class="headerdivider"></div>


.headerdivider {
    border-left: 1px solid #38546d;
    background: #16222c;
    width: 1px;
    height: 80px;
    position: absolute;
    right: 250px;
    top: 10px;

How to create JSON string in C#

The DataContractJSONSerializer will do everything for you with the same easy as the XMLSerializer. Its trivial to use this in a web app. If you are using WCF, you can specify its use with an attribute. The DataContractSerializer family is also very fast.

ParseError: not well-formed (invalid token) using cElementTree

See this answer to another question and the according part of the XML spec.

The backspace U+0008 is an invalid character in XML documents. It must be represented as escaped entity &#8; and cannot occur plainly.

If you need to process this XML snippet, you must replace \x08 in s before feeding it into an XML parser.

Correct way to handle conditional styling in React

You can use somthing like this.

render () {
    var btnClass = 'btn';
    if (this.state.isPressed) btnClass += ' btn-pressed';
    else if (this.state.isHovered) btnClass += ' btn-over';
    return <button className={btnClass}>{this.props.label}</button>;

Or else, you can use classnames NPM package to make dynamic and conditional className props simpler to work with (especially more so than conditional string manipulation).

classNames('foo', 'bar'); // => 'foo bar'
classNames('foo', { bar: true }); // => 'foo bar'
classNames({ 'foo-bar': true }); // => 'foo-bar'
classNames({ 'foo-bar': false }); // => ''
classNames({ foo: true }, { bar: true }); // => 'foo bar'
classNames({ foo: true, bar: true }); // => 'foo bar'

SQL Server: UPDATE a table by using ORDER BY

I ran into the same problem and was able to resolve it in very powerful way that allows unlimited sorting possibilities.

I created a View using (saving) 2 sort orders (*explanation on how to do so below).

After that I simply applied the update queries to the View created and it worked great.

Here are the 2 queries I used on the view:

1st Query:

Update  MyView
Set SortID=0

2nd Query:

DECLARE @sortID int
SET     @sortID = 0
SET     @sortID = sortID = @sortID + 1

*To be able to save the sorting on the View I put TOP into the SELECT statement. This very useful workaround allows the View results to be returned sorted as set when the View was created when the View is opened. In my case it looked like:

(NOTE: Using this workaround will place an big load on the server if using a large table and it is therefore recommended to include as few fields as possible in the view if working with large tables)

SELECT     TOP (600000) 
dbo.Items.ID, dbo.Items.Code, dbo.Items.SortID, dbo.Supplier.Date, 
dbo.Supplier.Code AS Expr1
FROM         dbo.Items INNER JOIN
                      dbo.Supplier ON dbo.Items.SupplierCode = dbo.Supplier.Code
ORDER BY dbo.Supplier.Date, dbo.Items.ID DESC

Running: SQL Server 2005 on a Windows Server 2003

Additional Keywords: How to Update a SQL column with Ascending or Descending Numbers - Numeric Values / how to set order in SQL update statement / how to save order by in sql view / increment sql update / auto autoincrement sql update / create sql field with ascending numbers

How to execute a function when page has fully loaded?

Try this it Only Run After Entire Page Has Loaded

By Javascript

window.onload = function(){
    // code goes here

By Jquery

$(window).bind("load", function() {
    // code goes here

How SID is different from Service name in Oracle tnsnames.ora

what is a SID and Service name

please look into oracle's documentation at

In case if the above link is not accessable in future, At the time time of writing this answer, the above link will direct you to, "Database Service and Database Instance Identification" topic in Connectivity Concepts chapter of "Database Net Services Administrator's Guide". This guide is published by oracle as part of "Oracle Database Online Documentation, 10g Release 2 (10.2)"

When I have to use one or another? Why do I need two of them?

Consider below mapping in a RAC Environment,

bob1    bob
bob2    bob
bob3    bob
bob4    bob

if load balancing is configured, the listener will 'balance' the workload across all four SIDs. Even if load balancing is configured, you can connect to bob1 all the time if you want to by using the SID instead of SERVICE_NAME.

Please refer,

equals vs Arrays.equals in Java

array1.equals(array2) is the same as array1 == array2, i.e. is it the same array. As @alf points out it's not what most people expect.

Arrays.equals(array1, array2) compares the contents of the arrays.

Similarly array.toString() may not be very useful and you need to use Arrays.toString(array).

Getting the thread ID from a thread

In C# when debugging threads for example, you can see each thread's ID.

This will be the Ids of the managed threads. ManagedThreadId is a member of Thread so you can get the Id from any Thread object. This will get you the current ManagedThreadID:


To get an OS thread by its OS thread ID (not ManagedThreadID), you can try a bit of linq.

int unmanagedId = 2345;
ProcessThread myThread = (from ProcessThread entry in Process.GetCurrentProcess().Threads
   where entry.Id == unmanagedId 
   select entry).First();

It seems there is no way to enumerate the managed threads and no relation between ProcessThread and Thread, so getting a managed thread by its Id is a tough one.

For more details on Managed vs Unmanaged threading, see this MSDN article.

Width of input type=text element

input width is 10 + 2 times 1 px for border

Make a div into a link

<a href="…" style="cursor: pointer;"><div> … </div></a>

How to add double quotes to a string that is inside a variable?

Start each row with \"-\" to create bullet list.

Java JTable setting Column Width

Use this code. It worked for me. I considered for 3 columns. Change the loop value for your code.

TableColumn column = null;
for (int i = 0; i < 3; i++) {
    column = table.getColumnModel().getColumn(i);
    if (i == 0) 
    if (i == 2)

How to debug .htaccess RewriteRule not working

Generally any change in the .htaccess should have visible effects. If no effect, check your configuration apache files, something like:

<Directory ..>
    AllowOverride None

Should be changed to

AllowOverride All

And you'll be able to change directives in .htaccess files.

Array of Matrices in MATLAB

if you know what unknown is,

you can do something like

myArray = zeros(2,2);
for i: 1:unknown
  myArray(:,i) = zeros(x,y);

However it has been a while since I last used matlab. so this page might shed some light on the matter :

Where can I read the Console output in Visual Studio 2015

What may be happening is that your console is closing before you get a chance to see the output. I would add Console.ReadLine(); after your Console.WriteLine("Hello World"); so your code would look something like this:

static void Main(string[] args)
        Console.WriteLine("Hello World");


This way, the console will display "Hello World" and a blinking cursor underneath. The Console.ReadLine(); is the key here, the program waits for the users input before closing the console window.

How do I display a ratio in Excel in the format A:B?

Try this formula:



A   B   C
33  11  3:1
25  5   5:1
6   4   3:2


  • TEXT(A1/B1,"?/?") turns A/B into an improper fraction
  • SUBSTITUTE(...) replaces the "/" in the fraction with a colon

This doesn't require any special toolkits or macros. The only downside might be that the result is considered text--not a number--so you can easily use it for further calculations.

Note: as @Robin Day suggested, increase the number of question marks (?) as desired to reduce rounding (thanks Robin!).

Adding external library into Qt Creator project

I would like to add for the sake of completeness that you can also add just the LIBRARY PATH where it will look for a dependent library (which may not be directly referenced in your code but a library you use may need it).

For comparison, this would correspond to what LIBPATH environment does but its kind of obscure in Qt Creator and not well documented.

The way i came around this is following:

LIBS += -L"$$_PRO_FILE_PWD_/Path_to_Psapi_lib/"

Essentially if you don't provide the actual library name, it adds the path to where it will search dependent libraries. The difference in syntax is small but this is very useful to supply just the PATH where to look for dependent libraries. It sometime is just a pain to supply each path individual library where you know they are all in certain folder and Qt Creator will pick them up.

Internet Access in Ubuntu on VirtualBox

I had a similar issue in windows 7 + ubuntu 12.04 as guest. I resolved by

  • open 'network and sharing center' in windows
  • right click 'nw-bridge' -> 'properties'
  • Select "virtual box host only network" for the option "select adapters you want to use to connect computers on your local network"
  • go to virtual box.. select the network type as NAT.

How do I use boolean variables in Perl?

I recommend use boolean;. You have to install the boolean module from cpan though.

How to do IF NOT EXISTS in SQLite

You can also set a Constraint on a Table with the KEY fields and set On Conflict "Ignore"

When an applicable constraint violation occurs, the IGNORE resolution algorithm skips the one row that contains the constraint violation and continues processing subsequent rows of the SQL statement as if nothing went wrong. Other rows before and after the row that contained the constraint violation are inserted or updated normally. No error is returned when the IGNORE conflict resolution algorithm is used.

SQLite Documentation

'ls' in CMD on Windows is not recognized

Use the command dir to list all the directories and files in a directory; ls is a unix command.

How to return a resultset / cursor from a Oracle PL/SQL anonymous block that executes Dynamic SQL?

in SQL*Plus you could also use a REFCURSOR variable:

  2   V_Sqlstatement Varchar2(2000);
  3  BEGIN
  4   V_Sqlstatement := 'SELECT * FROM DUAL';
  5   OPEN :x for v_Sqlstatement;
  6  End;
  7  /

ProcÚdure PL/SQL terminÚe avec succÞs.

SQL> print x;


Omit rows containing specific column of NA

Try this:$y)

What is python's site-packages directory?

When you use --user option with pip, the package gets installed in user's folder instead of global folder and you won't need to run pip command with admin privileges.

The location of user's packages folder can be found using:

python -m site --user-site

This will print something like:


When you don't use --user option with pip, the package gets installed in global folder given by:

python -c "import site; print(site.getsitepackages())"

This will print something like:

['C:\\Program Files\\Anaconda3', 'C:\\Program Files\\Anaconda3\\lib\\site-packages'

Note: Above printed values are for On Windows 10 with Anaconda 4.x installed with defaults.

Get name of currently executing test in JUnit 4

Based on the previous comment and further considering I created an extension of TestWather which you can use in your JUnit test methods with this:

public class ImportUtilsTest {
    private static final Logger LOGGER = Logger.getLogger(ImportUtilsTest.class);

    public TestWatcher testWatcher = new JUnitHelper(LOGGER);

    public test1(){

The test helper class is the next:

public class JUnitHelper extends TestWatcher {
private Logger LOGGER;

public JUnitHelper(Logger LOGGER) {
    this.LOGGER = LOGGER;

protected void starting(final Description description) {"STARTED " + description.getMethodName());

protected void succeeded(Description description) {"SUCCESSFUL " + description.getMethodName());

protected void failed(Throwable e, Description description) {
    LOGGER.error("FAILURE " + description.getMethodName());


How to get build time stamp from Jenkins build variables?

Try use Build Timestamp Plugin and use BUILD_TIMESTAMP variable.

Evaluate empty or null JSTL c tags

to also check blank string, I suggest following

<%@ taglib prefix="fn" uri=""%>
<%@ taglib prefix="c" uri=""%>

<c:if test="${empty fn:trim(var1)}">


It also handles nulls

MySQL my.cnf performance tuning recommendations

Try starting with the Percona wizard and comparing their recommendations against your current settings one by one. Don't worry there aren't as many applicable settings as you might think.

Update circa 2020: Sorry, this tool reached it's end of life:

Everyone points to key_buffer_size first which you have addressed. With 96GB memory I'd be wary of any tiny default value (likely to be only 96M!).

Rotating and spacing axis labels in ggplot2

Change the last line to

q + theme(axis.text.x = element_text(angle = 90, vjust = 0.5, hjust=1))

By default, the axes are aligned at the center of the text, even when rotated. When you rotate +/- 90 degrees, you usually want it to be aligned at the edge instead:

alt text

The image above is from this blog post.

Cannot implicitly convert type 'string' to 'System.Threading.Tasks.Task<string>'

The listed return type of the method is Task<string>. You're trying to return a string. They are not the same, nor is there an implicit conversion from string to Task<string>, hence the error.

You're likely confusing this with an async method in which the return value is automatically wrapped in a Task by the compiler. Currently that method is not an async method. You almost certainly meant to do this:

private async Task<string> methodAsync() 
    await Task.Delay(10000);
    return "Hello";

There are two key changes. First, the method is marked as async, which means the return type is wrapped in a Task, making the method compile. Next, we don't want to do a blocking wait. As a general rule, when using the await model always avoid blocking waits when you can. Task.Delay is a task that will be completed after the specified number of milliseconds. By await-ing that task we are effectively performing a non-blocking wait for that time (in actuality the remainder of the method is a continuation of that task).

If you prefer a 4.0 way of doing it, without using await , you can do this:

private Task<string> methodAsync() 
    return Task.Delay(10000)
        .ContinueWith(t => "Hello");

The first version will compile down to something that is more or less like this, but it will have some extra boilerplate code in their for supporting error handling and other functionality of await we aren't leveraging here.

If your Thread.Sleep(10000) is really meant to just be a placeholder for some long running method, as opposed to just a way of waiting for a while, then you'll need to ensure that the work is done in another thread, instead of the current context. The easiest way of doing that is through Task.Run:

private Task<string> methodAsync() 
    return Task.Run(()=>
            return "Hello";

Or more likely:

private Task<string> methodAsync() 
    return Task.Run(()=>
            return SomeLongRunningMethodThatReturnsAString();

Why should a Java class implement comparable?

Comparable is used to compare instances of your class. We can compare instances from many ways that is why we need to implement a method compareTo in order to know how (attributes) we want to compare instances.

Dog class:

package test;
import java.util.Arrays;

public class Main {

    public static void main(String[] args) {
        Dog d1 = new Dog("brutus");
        Dog d2 = new Dog("medor");
        Dog d3 = new Dog("ara");
        Dog[] dogs = new Dog[3];
        dogs[0] = d1;
        dogs[1] = d2;
        dogs[2] = d3;

        for (int i = 0; i < 3; i++) {
         * Output:
         * brutus
         * medor
         * ara

        Arrays.sort(dogs, Dog.NameComparator);
        for (int i = 0; i < 3; i++) {
         * Output:
         * ara
         * medor
         * brutus


Main class:

package test;

import java.util.Arrays;

public class Main {

    public static void main(String[] args) {
        Dog d1 = new Dog("brutus");
        Dog d2 = new Dog("medor");
        Dog d3 = new Dog("ara");
        Dog[] dogs = new Dog[3];
        dogs[0] = d1;
        dogs[1] = d2;
        dogs[2] = d3;

        for (int i = 0; i < 3; i++) {
         * Output:
         * brutus
         * medor
         * ara

        Arrays.sort(dogs, Dog.NameComparator);
        for (int i = 0; i < 3; i++) {
         * Output:
         * ara
         * medor
         * brutus


Here is a good example how to use comparable in Java:

React Hooks useState() with Object

Generally you should watch out for deeply nested objects in React state. To avoid unexpected behavior, the state should be updated immutably. When you have deep objects, you end up deep cloning them for immutability, which can be quite expensive in React. Why?

Once you deep clone the state, React will recalculate and re-render everything that depends on the variables, even though they haven't changed!

So, before trying to solve your issue, think how you can flatten the state first. As soon as you do that, you will find beautiful tools that will help dealing with large states, such as useReducer().

In case you thought about it, but are still convinced you need to use a deeply nested state tree, you can still use useState() with libraries like immutable.js and Immutability-helper. They make it simple to update or clone deep objects without having to worry about mutability.

Minimum Hardware requirements for Android development

I did the following experiment at home:

let's compare how 2 computers compile the same android application in eclipse. Here are the competitors:

"the monster" - pentinum i7 - 16 gig RAM - solid state hard drive

"peabody" - pentinum i3 - 4 gig RAM

The results: when I compiled the same application in eclipse, the monster and peabody took exactly the same amount of time to bring up the emulator to the point where you have to slide the button to run the app: 1 minute 12 seconds.

After that point, the monster executed the app 30-40 seconds faster than peabody.

The monster costs about $500 more than the peabody. So the question is, is it really worth it? In my opinion, No. I can wait the extra 30-40 seconds

How to insert pandas dataframe via mysqldb into database?

This should do the trick:

import pandas as pd
import pymysql
from sqlalchemy import create_engine

# Create engine
engine = create_engine('mysql://USER_NAME_HERE:PASS_HERE@HOST_ADRESS_HERE/DB_NAME_HERE')

# Create the connection and close it(whether successed of failed)
with engine.begin() as connection:
  df.to_sql(name='INSERT_TABLE_NAME_HERE/INSERT_NEW_TABLE_NAME', con=connection, if_exists='append', index=False)

How to round an image with Glide library?

Here is a more modular and cleaner way to circle crop your bitmap in Glide:

  1. Create a custom transformation by extending BitmapTransformation then override transform method like this :

For Glide 4.x.x

public class CircularTransformation extends BitmapTransformation {

protected Bitmap transform(BitmapPool pool, Bitmap toTransform, int outWidth, int outHeight) {
    RoundedBitmapDrawable circularBitmapDrawable =
            RoundedBitmapDrawableFactory.create(null, toTransform);
    Bitmap bitmap = pool.get(outWidth, outHeight, Bitmap.Config.ARGB_8888);
    Canvas canvas = new Canvas(bitmap);
    circularBitmapDrawable.setBounds(0, 0, outWidth, outHeight);
    return bitmap;

public void updateDiskCacheKey(MessageDigest messageDigest) {}


For Glide 3.x.x

public class CircularTransformation extends BitmapTransformation {

protected Bitmap transform(BitmapPool pool, Bitmap toTransform, int outWidth, int outHeight) {
    RoundedBitmapDrawable circularBitmapDrawable =
            RoundedBitmapDrawableFactory.create(null, toTransform);
    Bitmap bitmap = pool.get(outWidth, outHeight, Bitmap.Config.ARGB_8888);
    Canvas canvas = new Canvas(bitmap);
    circularBitmapDrawable.setBounds(0, 0, outWidth, outHeight);
    return bitmap;

public String getId() {
    // Return some id that uniquely identifies your transformation.
    return "CircularTransformation";

  1. Then set it in Glide builder where you need it:
   .transform(new CircularTransformation())

Hope this helps :)

How to call a function after a div is ready?

To do something after certain div load from function .load(). I think this exactly what you need:

  $('#divIDer').load(document.URL +  ' #divIDer',function() {

       // call here what you want .....


Jquery Setting Value of Input Field

change your jquery loading setting to onload in jsfiddle . . .it works . . .

Starting a node.js server

Run cmd and then run node server.js. In your example, you are trying to use the REPL to run your command, which is not going to work. The ellipsis is node.js expecting more tokens before closing the current scope (you can type code in and run it on the fly here)

How does one represent the empty char?

You can use c[i]= '\0' or simply c[i] = (char) 0.

The null/empty char is simply a value of zero, but can also be represented as a character with an escaped zero.

Installing Android Studio, does not point to a valid JVM installation error

Follow @abs solution

If you still continue to get the error even after setting the JAVA_HOME variable Copy the studio folder to your C drive and then run the studio.exe or studio64.exe depending upon your java versio

Git Pull vs Git Rebase

git-pull - Fetch from and integrate with another repository or a local branch GIT PULL

Basically you are pulling remote branch to your local, example:

git pull origin master

Will pull master branch into your local repository

git-rebase - Forward-port local commits to the updated upstream head GIT REBASE

This one is putting your local changes on top of changes done remotely by other users. For example:

  • You have committed some changes on your local branch for example called SOME-FEATURE
  • Your friend in the meantime was working on other features and he merged his branch into master

Now you want to see his and your changes on your local branch. So then you checkout master branch:

git checkout master

then you can pull:

git pull origin master

and then you go to your branch:

git checkout SOME-FEATURE

and you can do rebase master to get lastest changes from it and put your branch commits on top:

git rebase master

I hope now it's a bit more clear for you.

How to hash a string into 8 digits?

I am sharing our nodejs implementation of the solution as implemented by @Raymond Hettinger.

var crypto = require('crypto');
var s = 'she sells sea shells by the sea shore';
console.log(BigInt('0x' + crypto.createHash('sha1').update(s).digest('hex'))%(10n ** 8n));

How to read a single character at a time from a file in Python?


myfile = open(filename)
onecaracter =

How to search for a string in an arraylist

 List <String> list = new ArrayList();  

           List <String> listClone = new ArrayList<String>(); 
           for (String string : list) {

Start ssh-agent on login

Add this to your ~/.bashrc, then logout and back in to take effect.

if [ ! -S ~/.ssh/ssh_auth_sock ]; then
  eval `ssh-agent`
  ln -sf "$SSH_AUTH_SOCK" ~/.ssh/ssh_auth_sock
export SSH_AUTH_SOCK=~/.ssh/ssh_auth_sock
ssh-add -l > /dev/null || ssh-add

This should only prompt for a password the first time you login after each reboot. It will keep reusing the same ssh-agent as long as it stays running.

Converting DateTime format using razor

In general, the written month is escaped as MMM, the 4-digit year as yyyy, so your format string should look like "dd MMM yyyy"

DateTime.ToString("dd MMM yyyy")

JavaScript calculate the day of the year (1 - 366)

This is a solution that avoids the troublesome Date object and timezone issues, it requires that your input date be in the format "yyyy-dd-mm". If you want to change the format, then modify date_str_to_parts function:

    function get_day_of_year(str_date){
    var date_parts = date_str_to_parts(str_date);
    var is_leap = (date_parts.year%4)==0;
    var acct_for_leap = (is_leap && date_parts.month>2);
    var day_of_year = 0;

    var ary_months = [
        31, //jan
        28, //feb(non leap)
        31, //march
        30, //april
        31, //may
        30, //june
        31, //july
        31, //aug
        30, //sep
        31, //oct
        30, //nov   
        31  //dec

    for(var i=1; i < date_parts.month; i++){
        day_of_year += ary_months[i];

    day_of_year +=;

    if( acct_for_leap ) day_of_year+=1;

    return day_of_year;


function date_str_to_parts(str_date){
    return {

Warning: session_start(): Cannot send session cookie - headers already sent by (output started at

  1. session_start() must be at the top of your source, no html or other output befor!
  2. your can only send session_start() one time
  3. by this way if(session_status()!=PHP_SESSION_ACTIVE) session_start()

Formatting Decimal places in R

You can try my package formattable.

> # devtools::install_github("renkun-ken/formattable")
> library(formattable)
> x <- formattable(1.128347132904321674821, digits = 2, format = "f")
> x
[1] 1.13

The good thing is, x is still a numeric vector and you can do more calculations with the same formatting.

> x + 1
[1] 2.13

Even better, the digits are not lost, you can reformat with more digits any time :)

> formattable(x, digits = 6, format = "f")
[1] 1.128347

Laravel Check If Related Model Exists

After Php 7.1, The accepted answer won't work for all types of relationships.

Because depending of type the relationship, Eloquent will return a Collection, a Model or Null. And in Php 7.1 count(null) will throw an error.

So, to check if the relation exist you can use:

For relationships single: For example hasOne and belongsTo

if(!is_null($model->relation)) {

For relationships multiple: For Example: hasMany and belongsToMany

if ($model->relation->isNotEmpty()) {

How to remove duplicates from Python list and keep order?

A list can be sorted and deduplicated using built-in functions:

myList = sorted(set(myList))
  • set is a built-in function for Python >= 2.3
  • sorted is a built-in function for Python >= 2.4

Adding gif image in an ImageView in android

As @Ahmad said in a comment, you can just use the following code to display a gif!

Just simply pop this code in the onCreate method and you're good to go! Also, place your gif inside the assets folder (if you don't have the assets folder, create one under src/main)

WebView wView = new WebView(this);

Keylistener in Javascript

Here's an update for modern browsers in 2019

let playerSpriteX = 0;_x000D_
document.addEventListener('keyup', (e) => {_x000D_
  if (e.code === "ArrowUp")        playerSpriteX += 10_x000D_
  else if (e.code === "ArrowDown") playerSpriteX -= 10_x000D_
  document.getElementById('test').innerHTML = 'playerSpriteX = ' + playerSpriteX;_x000D_
Click on this window to focus it, and hit keys up and down_x000D_
<div id="test">playerSpriteX = 0</div>

Original answer from 2013

window.onkeyup = function(e) {
   var key = e.keyCode ? e.keyCode : e.which;

   if (key == 38) {
       playerSpriteX += 10;
   }else if (key == 40) {
       playerSpriteX -= 10;


How to use JQuery with ReactJS

You should try and avoid jQuery in ReactJS. But if you really want to use it, you'd put it in componentDidMount() lifecycle function of the component.


class App extends React.Component {
  componentDidMount() {
    // Jquery here $(...)...

  // ...

Ideally, you'd want to create a reusable Accordion component. For this you could use Jquery, or just use plain javascript + CSS.

class Accordion extends React.Component {
  constructor() {
    this._handleClick = this._handleClick.bind(this);

  componentDidMount() {

  _handleClick() {
    const acc = this._acc.children;
    for (let i = 0; i < acc.length; i++) {
      let a = acc[i];
      a.onclick = () => a.classList.toggle("active");

  render() {
    return (
        ref={a => this._acc = a} 

Then you can use it in any component like so:

class App extends React.Component {
  render() {
    return (
          <div className="accor">
            <div className="head">Head 1</div>
            <div className="body"></div>

Codepen link here: (I changed this link to https ^)

How to Deserialize XML document

If you're getting errors using xsd.exe to create your xsd file, then use the XmlSchemaInference class as mentioned on msdn. Here's a unit test to demonstrate:

using System.Xml;
using System.Xml.Schema;

public void GenerateXsdFromXmlTest()
    string folder = @"C:\mydir\mydata\xmlToCSharp";
    XmlReader reader = XmlReader.Create(folder + "\some_xml.xml");
    XmlSchemaSet schemaSet = new XmlSchemaSet();
    XmlSchemaInference schema = new XmlSchemaInference();

    schemaSet = schema.InferSchema(reader);

    foreach (XmlSchema s in schemaSet.Schemas())
        XmlWriter xsdFile = new XmlTextWriter(folder + "\some_xsd.xsd", System.Text.Encoding.UTF8);

// now from the visual studio command line type: xsd some_xsd.xsd /classes

Which Eclipse version should I use for an Android app?

Eclipse 3.5 for Java Developer is the best option for you and 3.6 version is good but not at all because of compatibility issues.


Well I fond this post because I got a similar error. So I added the top line like in your controller respond_to :html, :json

then I got a different error(see below)

The controller-level respond_to' feature has been extracted to theresponders` gem. Add it to your Gemfile to continue using this feature: gem 'responders', '~> 2.0' Consult the Rails upgrade guide for details. But that had nothing to do with it.

Pandas - Compute z-score for all columns

Here's other way of getting Zscore using custom function:

In [6]: import pandas as pd; import numpy as np

In [7]: np.random.seed(0) # Fixes the random seed

In [8]: df = pd.DataFrame(np.random.randn(5,3), columns=["randomA", "randomB","randomC"])

In [9]: df # watch output of dataframe
    randomA   randomB   randomC
0  1.764052  0.400157  0.978738
1  2.240893  1.867558 -0.977278
2  0.950088 -0.151357 -0.103219
3  0.410599  0.144044  1.454274
4  0.761038  0.121675  0.443863

## Create custom function to compute Zscore 
In [10]: def z_score(df):
   ....:         df.columns = [x + "_zscore" for x in df.columns.tolist()]
   ....:         return ((df - df.mean())/df.std(ddof=0))

## make sure you filter or select columns of interest before passing dataframe to function
In [11]: z_score(df) # compute Zscore
   randomA_zscore  randomB_zscore  randomC_zscore
0        0.798350       -0.106335        0.731041
1        1.505002        1.939828       -1.577295
2       -0.407899       -0.875374       -0.545799
3       -1.207392       -0.463464        1.292230
4       -0.688061       -0.494655        0.099824

Result reproduced using scipy.stats zscore

In [12]: from scipy.stats import zscore

In [13]: df.apply(zscore) # (Credit: Manuel)
    randomA   randomB   randomC
0  0.798350 -0.106335  0.731041
1  1.505002  1.939828 -1.577295
2 -0.407899 -0.875374 -0.545799
3 -1.207392 -0.463464  1.292230
4 -0.688061 -0.494655  0.099824

How to find the number of days between two dates

DATEDIFF(d, 'Start Date', 'End Date')

do it

What does `m_` variable prefix mean?

As stated in many other responses, m_ is a prefix that denotes member variables. It is/was commonly used in the C++ world and propagated to other languages too, including Java.

In a modern IDE it is completely redundant as the syntax highlighting makes it evident which variables are local and which ones are members. However, by the time syntax highlighting appeared in the late 90s, the convention had been around for many years and was firmly set (at least in the C++ world).

I do not know which tutorials you are referring to, but I will guess that they are using the convention due to one of two factors:

  • They are C++ tutorials, written by people used to the m_ convention, and/or...
  • They write code in plain (monospaced) text, without syntax highlighting, so the m_ convention is useful to make the examples clearer.

How do I get the SharedPreferences from a PreferenceActivity in Android?

having to pass context around everywhere is really annoying me. the code becomes too verbose and unmanageable. I do this in every project instead...

public class global {
    public static Activity globalContext = null;

and set it in the main activity create

public void onCreate(Bundle savedInstanceState) {
    Thread.setDefaultUncaughtExceptionHandler(new CustomExceptionHandler(


    global.globalContext = this;

also all preference keys should be language independent, I'm shocked nobody has mentioned that.


now call it very simply like this in one line of code

global.globalContext.getSharedPreferences(global.APPNAME_PREF, global.MODE_PRIVATE).getBoolean("isMetric", true);

How to enable cURL in PHP / XAMPP

check if curl module is available

$ ls -la /etc/php5/mods-available/

enable the curl module

$ sudo php5enmod curl


How to access a dictionary key value present inside a list?

First of all don't use 'list' as variable name.

If you have simple dictionaries with unique keys then you can do the following(note that new dictionary object with all items from sub-dictionaries will be created):

res  = {}
for line in listOfDicts:
>>> 4


getValues = lambda key,inputData: [subVal[key] for subVal in inputData if key in subVal]
getValues('d', listOfDicts)
>>> [4]

Or very base:

def get_value(listOfDicts, key):
    for subVal in listOfDicts:
        if key in subVal:
            return subVal[key]

Find out how much memory is being used by an object in Python

I haven't any personal experience with either of the following, but a simple search for a "Python [memory] profiler" yield:

  • PySizer, "a memory profiler for Python," found at However the page seems to indicate that the project hasn't been updated for a while, and refers to...

  • Heapy, "support[ing] debugging and optimization regarding memory related issues in Python programs," found at

Hope that helps.

How to set size for local image using knitr for markdown?

The knitr::include_graphics solution worked well for resizing the figures, but I was unable to figure out how to use it to produce side-by-side resized figures. I found this post useful for doing so.

Toolbar Navigation Hamburger Icon missing

ok to hide back arrow use


then find hamburger icon in web ->hamburger

and finally, set this drawable in your project with action bar method:


Find a file by name in Visual Studio Code

It is CMD + P (or CTRL + P) by default. However the keyboard bindings may differ according to your preferences.

To know your bindings go to the "Keyboard Shortcuts" settings and search for "Go to File"

Responsive font size in CSS

You can make the font size responsive if defining it in vw (viewport width). However, not all browsers support it. The solution is to use JavaScript to change the base font size depending on the browser width and set all font sizes in %.

Here is an article describing how to make responsive fontsizes:

MongoDB inserts float when trying to insert integer

If the value type is already double, then update the value with $set command can not change the value type double to int when using NumberInt() or NumberLong() function. So, to Change the value type, it must update the whole record.

var re ={"name": "zero"})
re['value']=NumberInt(0){"name": "zero"}, re)

Function for C++ struct

Yes, a struct is identical to a class except for the default access level (member-wise and inheritance-wise). (and the extra meaning class carries when used with a template)

Every functionality supported by a class is consequently supported by a struct. You'd use methods the same as you'd use them for a class.

struct foo {
  int bar;
  foo() : bar(3) {}   //look, a constructor
  int getBar() 
    return bar; 

foo f;
int y = f.getBar(); // y is 3

Async image loading from url inside a UITableView cell - image changes to wrong image while scrolling

 - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath 
        MyCell *cell = [tableView dequeueReusableCellWithIdentifier:@"cell" forIndexPath:indexPath];

        cell.poster.image = nil; // or cell.poster.image = [UIImage imageNamed:@"placeholder.png"];

        NSURL *url = [NSURL URLWithString:[NSString stringWithFormat:@"", self.myJson[indexPath.row][@"movieId"]]];

        NSURLSessionTask *task = [[NSURLSession sharedSession] dataTaskWithURL:url completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
            if (data) {
                UIImage *image = [UIImage imageWithData:data];
                if (image) {
                    dispatch_async(dispatch_get_main_queue(), ^{
                        MyCell *updateCell = (id)[tableView cellForRowAtIndexPath:indexPath];
                        if (updateCell)
                            updateCell.poster.image = image;
        [task resume];

        return cell;

How to convert integer to string in C?

Use sprintf():

int someInt = 368;
char str[12];
sprintf(str, "%d", someInt);

All numbers that are representable by int will fit in a 12-char-array without overflow, unless your compiler is somehow using more than 32-bits for int. When using numbers with greater bitsize, e.g. long with most 64-bit compilers, you need to increase the array size—at least 21 characters for 64-bit types.

What is a JavaBean exactly?

JavaBeans is a standard, and its basic syntax requirements have been clearly explained by the other answers.

However, IMO, it is more than a simple syntax standard. The real meaning or intended usage of JavaBeans is, together with various tool supports around the standard, to facilitate code reuse and component-based software engineering, i.e. enable developers to build applications by assembling existing components (classes) and without having to write any code (or only have to write a little glue code). Unfortunately this technology is way under-estimated and under-utilized by the industry, which can be told from the answers in this thread.

If you read Oracle's tutorial on JavaBeans, you can get a better understanding in that.

Conditional Formatting (IF not empty)

An equivalent result, "other things being equal", would be to format all cells grey and then use Go To Special to select the blank cells prior to removing their grey highlighting.

I get a "An attempt was made to load a program with an incorrect format" error on a SQL Server replication project

For those who get this error in an ASP.NET MVC 3 project, within Visual Studio itself:

In an ASP.NET MVC 3 app I'm working on, I tried adding a reference to Microsoft.SqlServer.BatchParser to a project to resolve a problem where it was missing on a deployment server. (Our app uses SMO; the correct fix was to install SQL Server Native Client and a couple other things on the deployment server.)

Even after I removed the reference to BatchParser, I kept getting the "An attempt was made..." error, referencing the BatchParser DLL, on every ASP.NET MVC 3 page I opened, and that error was followed by dozens of page parsing errors.

If this happens to you, do a file search and see if the DLL is still in one of your project's \bin folders. Even if you do a rebuild, Visual Studio doesn't necessarily clear out everything in all your \bin folders. When I deleted the DLL from the bin and built again, the error went away.

Swap x and y axis without manually swapping values

Using Excel 2010 x64. XY plot: I could not see no tabs (it is late and I am probably tired blind, 250 limit?). Here is what worked for me:

Swap the data columns, to end with X_data in column A and Y_data in column B.

My original data had Y_data in column A and X_data in column B, and the graph was rotated 90deg clockwise. I was suffering. Then it hit me: an Excel XY plot literally wants {x,y} pairs, i.e. X_data in first column and Y_data in second column. But it does not tell you this right away. For me an XY plot means Y=f(X) plotted.

How do check if a PHP session is empty?

I know this is old, but I ran into an issue where I was running a function after checking if there was a session. It would throw an error everytime I tried loading the page after logging out, still worked just logged an error page. Make sure you use exit(); if you are running into the same problem.

     function sessionexists(){
     return true;
     return false;

        if (!sessionexists()){

How to read file binary in C#?

Generally, I don't really see a possible way to do this. I've exhausted all of the options that the earlier comments gave you, and they don't seem to work. You could try this:

        `private void button1_Click(object sender, EventArgs e)
        Stream myStream = null;
        OpenFileDialog openFileDialog1 = new OpenFileDialog();
        openFileDialog1.InitialDirectory = "This PC\\Documents";
        openFileDialog1.Filter = "All Files (*.*)|*.*";
        openFileDialog1.FilterIndex = 1;
        openFileDialog1.RestoreDirectory = true;
        openFileDialog1.Title = "Open a file with code";

        if (openFileDialog1.ShowDialog() == DialogResult.OK)
            string exeCode = string.Empty;
            using (BinaryReader br = new BinaryReader(File.OpenRead(openFileDialog1.FileName))) //Sets a new integer to the BinaryReader
                br.BaseStream.Seek(0x4D, SeekOrigin.Begin); //The seek is starting from 0x4D
                exeCode = Encoding.UTF8.GetString(br.ReadBytes(1000000000)); //Reads as many bytes as it can from the beginning of the .exe file
            using (BinaryReader br = new BinaryReader(File.OpenRead(openFileDialog1.FileName)))
                br.Close(); //Closes the BinaryReader. Without it, opening the file with any other command will result the error "This file is being used by another process".

            richTextBox1.Text = exeCode;
  • That's the code for the "Open..." button, but here's the code for the "Save..." button:

    ` private void button2_Click(object sender, EventArgs e) { SaveFileDialog save = new SaveFileDialog();

        save.Filter = "All Files (*.*)|*.*";
        save.Title = "Save Your Changes";
        save.InitialDirectory = "This PC\\Documents";
        save.FilterIndex = 1;
        if (save.ShowDialog() == DialogResult.OK)
            using (BinaryWriter bw = new BinaryWriter(File.OpenWrite(save.FileName))) //Sets a new integer to the BinaryReader
                bw.BaseStream.Seek(0x4D, SeekOrigin.Begin); //The seek is starting from 0x4D
    • That's the save button. This works fine, but only shows the '!This cannot be run in DOS-Mode!' - Otherwise, if you can fix this, I don't know what to do.

    • My Site

How to have Android Service communicate with Activity

To follow up on @MrSnowflake answer with a code example. This is the XABBER now open source Application class. The Application class is centralising and coordinating Listeners and ManagerInterfaces and more. Managers of all sorts are dynamically loaded. Activity´s started in the Xabber will report in what type of Listener they are. And when a Service start it report in to the Application class as started. Now to send a message to an Activity all you have to do is make your Activity become a listener of what type you need. In the OnStart() OnPause() register/unreg. The Service can ask the Application class for just that listener it need to speak to and if it's there then the Activity is ready to receive.

Going through the Application class you'll see there's a loot more going on then this.

Cordova - Error code 1 for command | Command failed for

I removed android platforms and installed again then worked. I wrote these lines in command window:

cordova platform remove android
cordova platform add android

get list of packages installed in Anaconda

For more conda list usage details:

usage: list [-h][-n ENVIRONMENT | -p PATH][--json] [-v] [-q]
[--show-channel-urls] [-c] [-f] [--explicit][--md5] [-e] [-r] [--no-pip][regex]

How does ApplicationContextAware work in Spring?

Interface to be implemented by any object that wishes to be notified of the ApplicationContext that it runs in.

above is excerpted from the Spring doc website

So, it seemed to be invoked when Spring container has started, if you want to do something at that time.

It just has one method to set the context, so you will get the context and do something to sth now already in context I think.

Reason to Pass a Pointer by Reference in C++?

One example is when you write a parser function and pass it a source pointer to read from, if the function is supposed to push that pointer forward behind the last character which has been correctly recognized by the parser. Using a reference to a pointer makes it clear then that the function will move the original pointer to update its position.

In general, you use references to pointers if you want to pass a pointer to a function and let it move that original pointer to some other position instead of just moving a copy of it without affecting the original.

Why is JsonRequestBehavior needed?

Improving upon the answer of @Arjen de Mooij a bit by making the AllowJsonGetAttribute applicable to mvc-controllers (not just individual action-methods):

using System.Web.Mvc;
public sealed class AllowJsonGetAttribute : ActionFilterAttribute, IActionFilter
    void IActionFilter.OnActionExecuted(ActionExecutedContext context)
        var jsonResult = context.Result as JsonResult;
        if (jsonResult == null) return;

        jsonResult.JsonRequestBehavior = JsonRequestBehavior.AllowGet;

    public override void OnResultExecuting(ResultExecutingContext filterContext)
        var jsonResult = filterContext.Result as JsonResult;
        if (jsonResult == null) return;

        jsonResult.JsonRequestBehavior = JsonRequestBehavior.AllowGet;

Does Notepad++ show all hidden characters?

For non-printing characters, you can do the following:

  • if you could identify the character, where cursor takes 2 arrow keys to move, just select that character.
  • do Ctrl-F
  • now you can count or replace or even mark all such characters

How do I run two commands in one line in Windows CMD?

If you want to create a cmd shortcut (for example on your desktop) add /k parameter (/k means keep, /c will close window):

cmd /k echo hello && cd c:\ && cd Windows

Proper way to set response status and JSON content in a REST API made with nodejs and express

res.sendStatus(status) has been added as of version 4.9.0

you can use one of these res.sendStatus() || res.status() methods

below is difference in between res.sendStatus() || res.status()

res.sendStatus(200) // equivalent to res.status(200).send('OK')
res.sendStatus(403) // equivalent to res.status(403).send('Forbidden')
res.sendStatus(404) // equivalent to res.status(404).send('Not Found')
res.sendStatus(500) // equivalent to res.status(500).send('Internal Server Error')

I hope someone finds this helpful thanks

Importing Excel into a DataTable Quickly

MS Office Interop is slow and even Microsoft does not recommend Interop usage on server side and cannot be use to import large Excel files. For more details see why not to use OLE Automation from Microsoft point of view.

Instead, you can use any Excel library, like EasyXLS for example. This is a code sample that shows how to read the Excel file:

ExcelDocument workbook = new ExcelDocument();
DataSet ds = workbook.easy_ReadXLSActiveSheet_AsDataSet("excel.xls");
DataTable dataTable = ds.Tables[0];

If your Excel file has multiple sheets or for importing only ranges of cells (for better performances) take a look to more code samples on how to import Excel to DataTable in C# using EasyXLS.