Programs & Examples On #Graphic effects

How to convert a structure to a byte array in C#?

        Header header = new Header();
        Byte[] headerBytes = new Byte[Marshal.SizeOf(header)];
        Marshal.Copy((IntPtr)(&header), headerBytes, 0, headerBytes.Length);

This should do the trick quickly, right?

Selenium -- How to wait until page is completely loaded

You can do this in many ways before clicking on add items:

WebDriverWait wait = new WebDriverWait(driver, 40);
wait.until(ExpectedConditions.elementToBeClickable("urelementid")));// instead of id u can use cssSelector or xpath of ur element.



You can also wait like this. If you want to wait until invisible of previous page element:


Here is the link where you can find all the Selenium WebDriver APIs that can be used for wait and its documentation.

What is the difference between find(), findOrFail(), first(), firstOrFail(), get(), list(), toArray()

  1. find($id) takes an id and returns a single model. If no matching model exist, it returns null.

  2. findOrFail($id) takes an id and returns a single model. If no matching model exist, it throws an error1.

  3. first() returns the first record found in the database. If no matching model exist, it returns null.

  4. firstOrFail() returns the first record found in the database. If no matching model exist, it throws an error1.

  5. get() returns a collection of models matching the query.

  6. pluck($column) returns a collection of just the values in the given column. In previous versions of Laravel this method was called lists.

  7. toArray() converts the model/collection into a simple PHP array.

Note: a collection is a beefed up array. It functions similarly to an array, but has a lot of added functionality, as you can see in the docs.

Unfortunately, PHP doesn't let you use a collection object everywhere you can use an array. For example, using a collection in a foreach loop is ok, put passing it to array_map is not. Similarly, if you type-hint an argument as array, PHP won't let you pass it a collection. Starting in PHP 7.1, there is the iterable typehint, which can be used to accept both arrays and collections.

If you ever want to get a plain array from a collection, call its all() method.

1 The error thrown by the findOrFail and firstOrFail methods is a ModelNotFoundException. If you don't catch this exception yourself, Laravel will respond with a 404, which is what you want most of the time.

Extracting specific columns from a data frame

You can use with :

with(df, data.frame(A, B, E))

How to get a tab character?

I use <span style="display: inline-block; width: 2ch;">&#9;</span> for a two characters wide tab.

MySQL: Set user variable from result of query

Use this way so that result will not be displayed while running stored procedure.

The query:

SELECT a.strUserID FROM tblUsers a WHERE a.lngUserID = lngUserID LIMIT 1 INTO @strUserID;

How to deserialize a JObject to .NET object

Too late, just in case some one is looking for another way:

void Main()
    string jsonString = @"{
  'Stores': [
    'Lambton Quay',
    'Willis Street'
  'Manufacturers': [
      'Name': 'Acme Co',
      'Products': [
          'Name': 'Anvil',
          'Price': 50
      'Name': 'Contoso',
      'Products': [
          'Name': 'Elbow Grease',
          'Price': 99.95
          'Name': 'Headlight Fluid',
          'Price': 4

    Product product = new Product();
    //Serializing to Object
    Product obj = JObject.Parse(jsonString).SelectToken("$.Manufacturers[?(@.Name == 'Acme Co' && @.Name != 'Contoso')]").ToObject<Product>();


public class Product
    public string Name { get; set; }
    public decimal Price { get; set; }

Writing List of Strings to Excel CSV File in Python

I know I'm a little late, but something I found that works (and doesn't require using csv) is to write a for loop that writes to your file for every element in your list.

# Define Data
RESULTS = ['apple','cherry','orange','pineapple','strawberry']

# Open File
resultFyle = open("output.csv",'w')

# Write data to file
for r in RESULTS:
    resultFyle.write(r + "\n")

I don't know if this solution is any better than the ones already offered, but it more closely reflects your original logic so I thought I'd share.

How to show a confirm message before delete?

You can better use as follows

 <a href="url_to_delete" onclick="return confirm('Are you sure you want to delete this item?');">Delete</a>

Does reading an entire file leave the file handle open?

You can use pathlib.

For Python 3.5 and above:

from pathlib import Path
contents = Path(file_path).read_text()

For older versions of Python use pathlib2:

$ pip install pathlib2


from pathlib2 import Path
contents = Path(file_path).read_text()

This is the actual read_text implementation:

def read_text(self, encoding=None, errors=None):
    Open the file in text mode, read it, and close the file.
    with'r', encoding=encoding, errors=errors) as f:

Does a VPN Hide my Location on Android?

Your question can be conveniently divided into several parts:

Does a VPN hide location? Yes, he is capable of this. This is not about GPS determining your location. If you try to change the region via VPN in an application that requires GPS access, nothing will work. However, sites define your region differently. They get an IP address and see what country or region it belongs to. If you can change your IP address, you can change your region. This is exactly what VPNs can do.

How to hide location on Android? There is nothing difficult in figuring out how to set up a VPN on Android, but a couple of nuances still need to be highlighted. Let's start with the fact that not all Android VPNs are created equal. For example, VeePN outperforms many other services in terms of efficiency in circumventing restrictions. It has 2500+ VPN servers and a powerful IP and DNS leak protection system.

You can easily change the location of your Android device by using a VPN. Follow these steps for any device model (Samsung, Sony, Huawei, etc.):

  1. Download and install a trusted VPN.

  2. Install the VPN on your Android device.

  3. Open the application and connect to a server in a different country.

  4. Your Android location will now be successfully changed!

Is it legal? Yes, changing your location on Android is legal. Likewise, you can change VPN settings in Microsoft Edge on your PC, and all this is within the law. VPN allows you to change your IP address, safeguarding your privacy and protecting your actual location from being exposed. However, VPN laws may vary from country to country. There are restrictions in some regions.

Brief summary: Yes, you can change your region on Android and a VPN is a necessary assistant for this. It's simple, safe and legal. Today, VPN is the best way to change the region and unblock sites with regional restrictions.

Authentication issues with WWW-Authenticate: Negotiate

The web server is prompting you for a SPNEGO (Simple and Protected GSSAPI Negotiation Mechanism) token.

This is a Microsoft invention for negotiating a type of authentication to use for Web SSO (single-sign-on):

  • either NTLM
  • or Kerberos.


How can I pretty-print JSON in a shell script?

On *nix, reading from stdin and writing to stdout works better:

#!/usr/bin/env python
Convert JSON data to human-readable form.

(Reads from stdin and writes to stdout)

import sys
    import simplejson as json
    import json

print json.dumps(json.loads(, indent=4)

Put this in a file (I named mine "prettyJSON" after AnC's answer) in your PATH and chmod +x it, and you're good to go.

Looking for simple Java in-memory cache

Ehcache is a pretty good solution for this and has a way to peek (getQuiet() is the method) such that it doesn't update the idle timestamp. Internally, Ehcache is implemented with a set of maps, kind of like ConcurrentHashMap, so it has similar kinds of concurrency benefits.

How do I check if an array includes a value in JavaScript?

I looked through submitted answers and got that they only apply if you search for the object via reference. A simple linear search with reference object comparison.

But lets say you don't have the reference to an object, how will you find the correct object in the array? You will have to go linearly and deep compare with each object. Imagine if the list is too large, and the objects in it are very big containing big pieces of text. The performance drops drastically with the number and size of the elements in the array.

You can stringify objects and put them in the native hash table, but then you will have data redundancy remembering these keys cause JavaScript keeps them for 'for i in obj', and you only want to check if the object exists or not, that is, you have the key.

I thought about this for some time constructing a JSON Schema validator, and I devised a simple wrapper for the native hash table, similar to the sole hash table implementation, with some optimization exceptions which I left to the native hash table to deal with. It only needs performance benchmarking... All the details and code can be found on my blog: I will soon post benchmark results.

The complete solution works like this:

var a = {'a':1,
 'd':{'q':1, 'b':{'q':1, 'b':8},'c':4},

 var b = {'a':1, 

 var c = "Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.";

 var hc = new HashCache([{a:3, b:2, c:5}, {a:15, b:2, c:'foo'}]); //init

 hc.put({a:1, b:1});
 hc.put({b:1, a:1});
 console.log(hc.exists({b:1, a:1}));

Wait until all promises complete even if some rejected

I've been using following codes since ES5.

Promise.wait = function(promiseQueue){
    if( !Array.isArray(promiseQueue) ){
        return Promise.reject('Given parameter is not an array!');

    if( promiseQueue.length === 0 ){
        return Promise.resolve([]);

    return new Promise((resolve, reject) =>{
        let _pQueue=[], _rQueue=[], _readyCount=false;
        promiseQueue.forEach((_promise, idx) =>{
            // Create a status info object
            _rQueue.push({rejected:false, seq:idx, result:null});

        _pQueue.forEach((_promise, idx)=>{
            let item = _rQueue[idx];
                    item.resolved = true;
                    item.result = result;
                    item.resolved = false;
                    item.result = error;

                if ( _rQueue.length === _readyCount ) {
                    let result = true;

The usage signature is just like Promise.all. The major difference is that Promise.wait will wait for all the promises to finish their jobs.

Recording video feed from an IP camera over a network

Motion is an alternative to Zoneminder. It has a steeper setup curve as everything is configured via config files.However, the config files are nicely commented and it's easier than it sounds. It's very reliable once running as well.

To add a Foscam camera (mentioned above) use the following syntax to stream the video from the camera.

netcam_url http://<IPADDRESS>/videostream.cgi?user=admin?pwd=

Where the user is admin with a blank password (the default for Foscam cameras).

For really high uptime/reliablity consider using a monitoring tool such as Monit. This works well with Motion.

With android studio no jvm found, JAVA_HOME has been set

Though, the question is asked long back, I see this same issue recently after installing Android Studio 2.1.0v, and JDK 7.80 on my PC Windows 10, 32 bit OS. I got this error.

No JVM installation found. Please install a 32 bit JDK. If you already have a JDK installed define a JAVA_HOME variable in Computer > System Properties > System Settings > Environment Variables.

I tried different ways to fix this nothing worked. But As per System Requirements in this Android developer website link.

Its solved after installing JDK 8(jdk-8u101-windows-i586.exe) JDK download site link.

Hope it helps somebody.

How to create a sticky left sidebar menu using bootstrap 3?

You can also try to use a Polyfill like Fixed-Sticky. Especially when you are using Bootstrap4 the affix component is no longer included:

Dropped the Affix jQuery plugin. We recommend using a position: sticky polyfill instead.

In Maven how to exclude resources from the generated jar?

Put those properties files in src/test/resources. Files in src/test/resources are available within Eclipse automatically via eclipse:eclipse but will not be included in the packaged JAR by Maven.

Vim: How to insert in visual block mode?

  1. press ctrl and v // start select
  2. press shift and i // then type in any text
  3. press esc esc // press esc twice

Repeat a string in JavaScript a number of times

I'm going to expand on @bonbon's answer. His method is an easy way to "append N chars to an existing string", just in case anyone needs to do that. For example since "a google" is a 1 followed by 100 zeros.

for(var google = '1'; google.length < 1 + 100; google += '0'){}_x000D_
document.getElementById('el').innerText = google;
<div>This is "a google":</div>_x000D_
<div id="el"></div>

NOTE: You do have to add the length of the original string to the conditional.

How to create a laravel hashed password

Compare password in laravel and lumen:

This may be possible that bcrypt function does not work with php7 then you can use below code in laravel and lumen as per your requirements:

use Illuminate\Support\Facades\Hash;

$test = app('hash')->make("test");
if (Hash::check('test', $test)) {
   echo "matched";
} else {
   echo "no matched";

I hope, this help will make you happy :)

How to check string length and then select substring in Sql Server

To conditionally check the length of the string, use CASE.

SELECT  CASE WHEN LEN(comments) <= 60 
             THEN comments
             ELSE LEFT(comments, 60) + '...'
        END  As Comments
FROM    myView

Regex to remove all special characters from string?

Depending on your definition of "special character", I think "[^a-zA-Z0-9]" would probably do the trick. That would find anything that is not a small letter, a capital letter, or a digit.

How to use `subprocess` command with pipes

command = "ps -A | grep 'process_name'"
output = subprocess.check_output(["bash", "-c", command])

Write to UTF-8 file in Python

Read the following:

Do this

with"test_output", "w", "utf-8-sig") as temp:
    temp.write("hi mom\n")
    temp.write(u"This has ?")

The resulting file is UTF-8 with the expected BOM.


Taking a point from both Boycs Answer and mtmurdock's subsequent answer I have the following stored proc on all of my development or staging databases. I've added some switches to fit my own requirement if I need to add in statements to reseed the data for certain columns.

(Note: I would have added this as a comment to Boycs brilliant answer but I haven't got enough reputation to do that yet. So please accept my apologies for adding this as an entirely new answer.)

ALTER PROCEDURE up_ResetEntireDatabase
@IncludeIdentReseed BIT,
@IncludeDataReseed BIT

EXEC sp_MSForEachTable 'DELETE FROM ?'

IF @IncludeIdentReseed = 1
    EXEC sp_MSForEachTable 'DBCC CHECKIDENT (''?'' , RESEED, 1)'


IF @IncludeDataReseed = 1
    -- Populate Core Data Table Here

And then once ready the execution is really simple:

EXEC up_ResetEntireDatabase 1, 1

One line if statement not working

if else condition can be covered with ternary operator

@item.rigged? ? 'Yes' : 'No'

How do you know a variable type in java?

I agree with what Joachim Sauer said, not possible to know (the variable type! not value type!) unless your variable is a class attribute (and you would have to retrieve class fields, get the right field by name...)

Actually for me it's totally impossible that any method give you the right answer since the answer would be different on the exact same object, according to the context in which you call this method...

As teehoo said, if you know at compile a defined list of types to test you can use instanceof but you will also get subclasses returning true...

One possible solution would also be to inspire yourself from the implementation of java.lang.reflect.Field and create your own Field class, and then declare all your local variables as this custom Field implementation... but you'd better find another solution, i really wonder why you need the variable type, and not just the value type?

How to replace local branch with remote branch entirely in Git?

The ugly but simpler way: delete your local folder, and clone the remote repository again.

Kendo grid date column not formatting

I found this piece of information and got it to work correctly. The data given to me was in string format so I needed to parse the string using kendo.parseDate before formatting it with kendo.toString.

columns: [
        field: "FirstName",
        title: "FIRST NAME"
        field: "LastName",
        title: "LAST NAME"
        field: "DateOfBirth",
        title: "DATE OF BIRTH",
        template: "#= kendo.toString(kendo.parseDate(DateOfBirth, 'yyyy-MM-dd'), 'MM/dd/yyyy') #"


  1. format-date-in-grid
  2. jsfiddle
  3. kendo ui date formatting

Disable vertical sync for glxgears

For intel drivers, there is also this method

Disable Vertical Synchronization (VSYNC)

The intel-driver uses Triple Buffering for vertical synchronization, this allows for full performance and avoids tearing. To turn vertical synchronization off (e.g. for benchmarking) use this .drirc in your home directory:

<device screen="0" driver="dri2">
    <application name="Default">
        <option name="vblank_mode" value="0"/>

MySQLDump one INSERT statement for each data row


mysqldump --extended-insert=FALSE 

Be aware that multiple inserts will be slower than one big insert.

Parsing JSON object in PHP using json_decode

If you use the following instead:

$json = file_get_contents($url);
$data = json_decode($json, TRUE);

The TRUE returns an array instead of an object.

how to implement regions/code collapse in javascript

Microsoft now has an extension for VS 2010 that provides this functionality:

JScript Editor Extensions

php - How do I fix this illegal offset type error

Illegal offset type errors occur when you attempt to access an array index using an object or an array as the index key.


$x = new stdClass();
$arr = array();
echo $arr[$x];
//illegal offset type

Your $xml array contains an object or array at $xml->entry[$i]->source for some value of $i, and when you try to use that as an index key for $s, you get that warning. You'll have to make sure $xml contains what you want it to and that you're accessing it correctly.

Understanding typedefs for function pointers in C

Use typedefs to define more complicated types i.e function pointers

I will take the example of defining a state-machine in C

    typedef  int (*action_handler_t)(void *ctx, void *data);

now we have defined a type called action_handler that takes two pointers and returns a int

define your state-machine

    typedef struct
      state_t curr_state;   /* Enum for the Current state */
      event_t event;  /* Enum for the event */
      state_t next_state;   /* Enum for the next state */
      action_handler_t event_handler; /* Function-pointer to the action */


The function pointer to the action looks like a simple type and typedef primarily serves this purpose.

All my event handlers now should adhere to the type defined by action_handler

    int handle_event_a(void *fsm_ctx, void *in_msg );

    int handle_event_b(void *fsm_ctx, void *in_msg );


Expert C programming by Linden

How to call a stored procedure from Java and JPA

Try this code:

return em.createNativeQuery("{call getEmployeeDetails(?,?)}",
                               .setParameter(1, employeeId)
                               .setParameter(2, companyId).getResultList();

How to remove default mouse-over effect on WPF buttons?

This Link helped me alot

Define a style in UserControl.Resources or Window.Resources

        <Style x:Key="MyButton" TargetType="Button">
            <Setter Property="OverridesDefaultStyle" Value="True" />
            <Setter Property="Cursor" Value="Hand" />
            <Setter Property="Template">
                    <ControlTemplate TargetType="Button">
                        <Border Name="border" BorderThickness="0" BorderBrush="Black" Background="{TemplateBinding Background}">
                            <ContentPresenter HorizontalAlignment="Center" VerticalAlignment="Center" />
                            <Trigger Property="IsMouseOver" Value="True">
                                <Setter Property="Opacity" Value="0.8" />

Then add the style to your button this way Style="{StaticResource MyButton}"

<Button Name="btnSecond" Width="350" Height="120" Margin="15" Style="{StaticResource MyButton}">
        <ImageBrush ImageSource="/Remove_Default_Button_Effect;component/Images/WithStyle.jpg"></ImageBrush>

How to align entire html body to the center?

body {
    margin:50px 0; 

#Content {
    margin:0 auto;
    border:1px dashed #333;

How to send post request to the below post method using postman rest client

  1. Open Postman.
  2. Enter URL in the URL bar http://{server:port}/json/metallica/post.
  3. Click Headers button and enter Content-Type as header and application/json in value.
  4. Select POST from the dropdown next to the URL text box.
  5. Select raw from the buttons available below URL text box.
  6. Select JSON from the following dropdown.
  7. In the textarea available below, post your request object:

     "title" : "test title",
     "singer" : "some singer"
  8. Hit Send.

  9. Refer to screenshot below: enter image description here

Stored Procedure parameter default value - is this a constant or a variable

It has to be a constant - the value has to be computable at the time that the procedure is created, and that one computation has to provide the value that will always be used.

Look at the definition of sys.all_parameters:

default_value sql_variant If has_default_value is 1, the value of this column is the value of the default for the parameter; otherwise, NULL.

That is, whatever the default for a parameter is, it has to fit in that column.

As Alex K pointed out in the comments, you can just do:

CREATE PROCEDURE [dbo].[problemParam] 
    @StartDate INT = NULL,
    @EndDate INT = NULL
   SET @StartDate = COALESCE(@StartDate,CONVERT(INT,(CONVERT(CHAR(8),GETDATE()-130,112))))

provided that NULL isn't intended to be a valid value for @StartDate.

As to the blog post you linked to in the comments - that's talking about a very specific context - that, the result of evaluating GETDATE() within the context of a single query is often considered to be constant. I don't know of many people (unlike the blog author) who would consider a separate expression inside a UDF to be part of the same query as the query that calls the UDF.

Copy files to network computers on windows command line

Below command will work in command prompt:

copy c:\folder\file.ext \\dest-machine\destfolder /Z /Y

To Copy all files:

copy c:\folder\*.* \\dest-machine\destfolder /Z /Y

What is the JSF resource library for and how should it be used?

Actually, all of those examples on the web wherein the common content/file type like "js", "css", "img", etc is been used as library name are misleading.

Real world examples

To start, let's look at how existing JSF implementations like Mojarra and MyFaces and JSF component libraries like PrimeFaces and OmniFaces use it. No one of them use resource libraries this way. They use it (under the covers, by @ResourceDependency or UIViewRoot#addComponentResource()) the following way:

<h:outputScript library="javax.faces" name="jsf.js" />
<h:outputScript library="primefaces" name="jquery/jquery.js" />
<h:outputScript library="omnifaces" name="omnifaces.js" />
<h:outputScript library="omnifaces" name="fixviewstate.js" />
<h:outputScript library="omnifaces.combined" name="[dynamicname].js" />
<h:outputStylesheet library="primefaces" name="primefaces.css" />
<h:outputStylesheet library="primefaces-aristo" name="theme.css" />
<h:outputStylesheet library="primefaces-vader" name="theme.css" />

It should become clear that it basically represents the common library/module/theme name where all of those resources commonly belong to.

Easier identifying

This way it's so much easier to specify and distinguish where those resources belong to and/or are coming from. Imagine that you happen to have a primefaces.css resource in your own webapp wherein you're overriding/finetuning some default CSS of PrimeFaces; if PrimeFaces didn't use a library name for its own primefaces.css, then the PrimeFaces own one wouldn't be loaded, but instead the webapp-supplied one, which would break the look'n'feel.

Also, when you're using a custom ResourceHandler, you can also apply more finer grained control over resources coming from a specific library when library is used the right way. If all component libraries would have used "js" for all their JS files, how would the ResourceHandler ever distinguish if it's coming from a specific component library? Examples are OmniFaces CombinedResourceHandler and GraphicResourceHandler; check the createResource() method wherein the library is checked before delegating to next resource handler in chain. This way they know when to create CombinedResource or GraphicResource for the purpose.

Noted should be that RichFaces did it wrong. It didn't use any library at all and homebrewed another resource handling layer over it and it's therefore impossible to programmatically identify RichFaces resources. That's exactly the reason why OmniFaces CombinedResourceHander had to introduce a reflection-based hack in order to get it to work anyway with RichFaces resources.

Your own webapp

Your own webapp does not necessarily need a resource library. You'd best just omit it.

<h:outputStylesheet name="css/style.css" />
<h:outputScript name="js/script.js" />
<h:graphicImage name="img/logo.png" />

Or, if you really need to have one, you can just give it a more sensible common name, like "default" or some company name.

<h:outputStylesheet library="default" name="css/style.css" />
<h:outputScript library="default" name="js/script.js" />
<h:graphicImage library="default" name="img/logo.png" />

Or, when the resources are specific to some master Facelets template, you could also give it the name of the template, so that it's easier to relate each other. In other words, it's more for self-documentary purposes. E.g. in a /WEB-INF/templates/layout.xhtml template file:

<h:outputStylesheet library="layout" name="css/style.css" />
<h:outputScript library="layout" name="js/script.js" />

And a /WEB-INF/templates/admin.xhtml template file:

<h:outputStylesheet library="admin" name="css/style.css" />
<h:outputScript library="admin" name="js/script.js" />

For a real world example, check the OmniFaces showcase source code.

Or, when you'd like to share the same resources over multiple webapps and have created a "common" project for that based on the same example as in this answer which is in turn embedded as JAR in webapp's /WEB-INF/lib, then also reference it as library (name is free to your choice; component libraries like OmniFaces and PrimeFaces also work that way):

<h:outputStylesheet library="common" name="css/style.css" />
<h:outputScript library="common" name="js/script.js" />
<h:graphicImage library="common" name="img/logo.png" />

Library versioning

Another main advantage is that you can apply resource library versioning the right way on resources provided by your own webapp (this doesn't work for resources embedded in a JAR). You can create a direct child subfolder in the library folder with a name in the \d+(_\d+)* pattern to denote the resource library version.

 |-- resources
 |    `-- default
 |         `-- 1_0
 |              |-- css
 |              |    `-- style.css
 |              |-- img
 |              |    `-- logo.png
 |              `-- js
 |                   `-- script.js

When using this markup:

<h:outputStylesheet library="default" name="css/style.css" />
<h:outputScript library="default" name="js/script.js" />
<h:graphicImage library="default" name="img/logo.png" />

This will generate the following HTML with the library version as v parameter:

<link rel="stylesheet" type="text/css" href="/contextname/javax.faces.resource/css/style.css.xhtml?ln=default&amp;v=1_0" />
<script type="text/javascript" src="/contextname/javax.faces.resource/js/script.js.xhtml?ln=default&amp;v=1_0"></script>
<img src="/contextname/javax.faces.resource/img/logo.png.xhtml?ln=default&amp;v=1_0" alt="" />

So, if you have edited/updated some resource, then all you need to do is to copy or rename the version folder into a new value. If you have multiple version folders, then the JSF ResourceHandler will automatically serve the resource from the highest version number, according to numerical ordering rules.

So, when copying/renaming resources/default/1_0/* folder into resources/default/1_1/* like follows:

 |-- resources
 |    `-- default
 |         |-- 1_0
 |         |    :
 |         |
 |         `-- 1_1
 |              |-- css
 |              |    `-- style.css
 |              |-- img
 |              |    `-- logo.png
 |              `-- js
 |                   `-- script.js

Then the last markup example would generate the following HTML:

<link rel="stylesheet" type="text/css" href="/contextname/javax.faces.resource/css/style.css.xhtml?ln=default&amp;v=1_1" />
<script type="text/javascript" src="/contextname/javax.faces.resource/js/script.js.xhtml?ln=default&amp;v=1_1"></script>
<img src="/contextname/javax.faces.resource/img/logo.png.xhtml?ln=default&amp;v=1_1" alt="" />

This will force the webbrowser to request the resource straight from the server instead of showing the one with the same name from the cache, when the URL with the changed parameter is been requested for the first time. This way the endusers aren't required to do a hard refresh (Ctrl+F5 and so on) when they need to retrieve the updated CSS/JS resource.

Please note that library versioning is not possible for resources enclosed in a JAR file. You'd need a custom ResourceHandler. See also How to use JSF versioning for resources in jar.

See also:

What are the time complexities of various data structures?


  • Set, Check element at a particular index: O(1)
  • Searching: O(n) if array is unsorted and O(log n) if array is sorted and something like a binary search is used,
  • As pointed out by Aivean, there is no Delete operation available on Arrays. We can symbolically delete an element by setting it to some specific value, e.g. -1, 0, etc. depending on our requirements
  • Similarly, Insert for arrays is basically Set as mentioned in the beginning


  • Add: Amortized O(1)
  • Remove: O(n)
  • Contains: O(n)
  • Size: O(1)

Linked List:

  • Inserting: O(1), if done at the head, O(n) if anywhere else since we have to reach that position by traveseing the linkedlist linearly.
  • Deleting: O(1), if done at the head, O(n) if anywhere else since we have to reach that position by traveseing the linkedlist linearly.
  • Searching: O(n)

Doubly-Linked List:

  • Inserting: O(1), if done at the head or tail, O(n) if anywhere else since we have to reach that position by traveseing the linkedlist linearly.
  • Deleting: O(1), if done at the head or tail, O(n) if anywhere else since we have to reach that position by traveseing the linkedlist linearly.
  • Searching: O(n)


  • Push: O(1)
  • Pop: O(1)
  • Top: O(1)
  • Search (Something like lookup, as a special operation): O(n) (I guess so)

Queue/Deque/Circular Queue:

  • Insert: O(1)
  • Remove: O(1)
  • Size: O(1)

Binary Search Tree:

  • Insert, delete and search: Average case: O(log n), Worst Case: O(n)

Red-Black Tree:

  • Insert, delete and search: Average case: O(log n), Worst Case: O(log n)

Heap/PriorityQueue (min/max):

  • Find Min/Find Max: O(1)
  • Insert: O(log n)
  • Delete Min/Delete Max: O(log n)
  • Extract Min/Extract Max: O(log n)
  • Lookup, Delete (if at all provided): O(n), we will have to scan all the elements as they are not ordered like BST


  • Insert/Delete: O(1) amortized
  • Re-size/hash: O(n)
  • Contains: O(1)

How do I get the value of text input field using JavaScript?

simple js

function copytext(text) {
    var textField = document.createElement('textarea');
    textField.innerText = text;

CSS: transition opacity on mouse-out?

I managed to find a solution using css/jQuery that I'm comfortable with. The original issue: I had to force the visibility to be shown while animating as I have elements hanging outside the area. Doing so, made large blocks of text now hang outside the content area during animation as well.

The solution was to start the main text elements with an opacity of 0 and use addClass to inject and transition to an opacity of 1. Then removeClass when clicked on again.

I'm sure there's an all jQquery way to do this. I'm just not the guy to do it. :)

So in it's most basic form...


Thanks for the help everyone.

How to enumerate an enum

Just by combining the top answers, I threw together a very simple extension:

public static class EnumExtensions
    /// <summary>
    /// Gets all items for an enum value.
    /// </summary>
    /// <typeparam name="T"></typeparam>
    /// <param name="value">The value.</param>
    /// <returns></returns>
    public static IEnumerable<T> GetAllItems<T>(this T value) where T : Enum
        return (T[])Enum.GetValues(typeof (T));

It is clean, simple, and, by @Jeppe-Stig-Nielsen's comment, fast.

Cannot get a text value from a numeric cell “Poi”

use the code
before reading the string value, Which can help you.
I am using POI version 3.17 Beta1 version, sure the version compatibility also..

JQuery - how to select dropdown item based on value

You should use


Here's an example:

<script src=""></script>
<select id='dropdownid'>
    <option value=''>- Please choose -</option>
    <option value='1'>1</option>
    <option value='2'>2</option>
    <option value='selectedvalue'>There we go!</option>
    <option value='3'>3</option>
    <option value='4'>4</option>
    <option value='5'>5</option>

How can I execute PHP code from the command line?

You can use:

 echo '<?php if(function_exists("my_func")) echo "function exists"; ' | php

The short tag "< ?=" can be helpful too:

 echo '<?= function_exists("foo") ? "yes" : "no";' | php
 echo '<?= 8+7+9 ;' | php

The closing tag "?>" is optional, but don't forget the final ";"!

Showing data values on stacked bar chart in ggplot2

From ggplot 2.2.0 labels can easily be stacked by using position = position_stack(vjust = 0.5) in geom_text.

ggplot(Data, aes(x = Year, y = Frequency, fill = Category, label = Frequency)) +
  geom_bar(stat = "identity") +
  geom_text(size = 3, position = position_stack(vjust = 0.5))

enter image description here

Also note that "position_stack() and position_fill() now stack values in the reverse order of the grouping, which makes the default stack order match the legend."

Answer valid for older versions of ggplot:

Here is one approach, which calculates the midpoints of the bars.


# calculate midpoints of bars (simplified using comment by @DWin)
Data <- ddply(Data, .(Year), 
   transform, pos = cumsum(Frequency) - (0.5 * Frequency)

# library(dplyr) ## If using dplyr... 
# Data <- group_by(Data,Year) %>%
#    mutate(pos = cumsum(Frequency) - (0.5 * Frequency))

# plot bars and add text
p <- ggplot(Data, aes(x = Year, y = Frequency)) +
     geom_bar(aes(fill = Category), stat="identity") +
     geom_text(aes(label = Frequency, y = pos), size = 3)

Resultant chart

Radio button validation in javascript

In addition to the Javascript solutions above, you can also use an HTML 5 solution by marking the radio buttons as required in the markup. This will eliminate the need for any Javascript and let the browser do the work for you.

See HTML5: How to use the "required" attribute with a "radio" input field for more information on how to do this well.

How can I install the VS2017 version of msbuild on a build server without installing the IDE?

The Visual Studio Build tools are a different download than the IDE. They appear to be a pretty small subset, and they're called Build Tools for Visual Studio 2019 (download).

You can use the GUI to do the installation, or you can script the installation of msbuild:

vs_buildtools.exe --add Microsoft.VisualStudio.Workload.MSBuildTools --quiet

Microsoft.VisualStudio.Workload.MSBuildTools is a "wrapper" ID for the three subcomponents you need:

  • Microsoft.Component.MSBuild
  • Microsoft.VisualStudio.Component.CoreBuildTools
  • Microsoft.VisualStudio.Component.Roslyn.Compiler

You can find documentation about the other available CLI switches here.

The build tools installation is much quicker than the full IDE. In my test, it took 5-10 seconds. With --quiet there is no progress indicator other than a brief cursor change. If the installation was successful, you should be able to see the build tools in %programfiles(x86)%\Microsoft Visual Studio\2019\BuildTools\MSBuild\Current\Bin.

If you don't see them there, try running without --quiet to see any error messages that may occur during installation.

php, mysql - Too many connections to database error

This can happen due to too many connection same time or many chat at same time. Also it can happen due too many session.

The best way to sort out this issue is restart MySQL.

service mysqld restart


service mysql restart


 /etc/init.d/mysqld restart

Find files in a folder using Java

Consider Apache Commons IO, it has a class called FileUtils that has a listFiles method that might be very useful in your case.

yii2 redirect in controller action does not work?

You can redirect by this method also:

return Yii::$app->response->redirect(['user/index', 'id' => 10]);

If you want to send the Header information immediately use with send().This method adds a Location header to the current response.

return Yii::$app->response->redirect(['user/index', 'id' => 10])->send();

If you want the complete URL then use like Url::to(['user/index', 'id' => 302]) with the header of use yii\helpers\Url;.

For more information check Here. Hope this will help someone.

How to Generate unique file names in C#

If you would like to have the datetime,hours,minutes can use a static variable. Append the value of this variable to the filename. You can start the counter with 0 and increment when you have created a file. This way the filename will surely be unique since you have seconds also in the file.

How to plot a 2D FFT in Matlab?

Assuming that I is your input image and F is its Fourier Transform (i.e. F = fft2(I))

You can use this code:

F = fftshift(F); % Center FFT

F = abs(F); % Get the magnitude
F = log(F+1); % Use log, for perceptual scaling, and +1 since log(0) is undefined
F = mat2gray(F); % Use mat2gray to scale the image between 0 and 1

imshow(F,[]); % Display the result

NSArray + remove item from array

Made a category like mxcl, but this is slightly faster.

My testing shows ~15% improvement (I could be wrong, feel free to compare the two yourself).

Basically I take the portion of the array thats in front of the object and the portion behind and combine them. Thus excluding the element.

- (NSArray *)prefix_arrayByRemovingObject:(id)object 
    if (!object) {
        return self;

    NSUInteger indexOfObject = [self indexOfObject:object];
    NSArray *firstSubArray = [self subarrayWithRange:NSMakeRange(0, indexOfObject)];
    NSArray *secondSubArray = [self subarrayWithRange:NSMakeRange(indexOfObject + 1, self.count - indexOfObject - 1)];
    NSArray *newArray = [firstSubArray arrayByAddingObjectsFromArray:secondSubArray];

    return newArray;

Find and replace specific text characters across a document with JS

The best would be to do this server-side or wrap the currency symbols in an element you can select before returning it to the browser, however if neither is an option, you can select all text nodes within the body and do the replace on them. Below i'm doing this using a plugin i wrote 2 years ago that was meant for highlighting text. What i'm doing is finding all occurrences of € and wrapping it in a span with the class currency-symbol, then i'm replacing the text of those spans.



    $.fn.highlightText = function () {
        // handler first parameter
        // is the first parameter a regexp?
        var re,
            argType = $.type(arguments[0]),
            defaultTagName = $.fn.highlightText.defaultTagName;

        if ( argType === "regexp" ) {
            // first argument is a regular expression
            re = arguments[0];
        // is the first parameter an array?
        else if ( argType === "array" ) {
            // first argument is an array, generate
            // regular expression string for later use
            reStr = arguments[0].join("|");
        // is the first parameter a string?
        else if ( argType === "string" ) {
            // store string in regular expression string
            // for later use
            reStr = arguments[0];
        // else, return out and do nothing because this
        // argument is required.
        else {

        // the second parameter is optional, however,
        // it must be a string or boolean value. If it is 
        // a string, it will be used as the highlight class.
        // If it is a boolean value and equal to true, it 
        // will be used as the third parameter and the highlight
        // class will default to "highlight". If it is undefined,
        // the highlight class will default to "highlight" and 
        // the third parameter will default to false, allowing
        // the plugin to match partial matches.
        // ** The exception is if the first parameter is a regular
        // expression, the third parameter will be ignored.
        argType = $.type(arguments[1]);
        if ( argType === "string" ) {
            hClass = arguments[1];
        else if ( argType === "boolean" ) {
            hClass = "highlight";
            if ( reStr ) {
                reStr = "\\b" + reStr + "\\b";
        else {
            hClass = "highlight";

        if ( arguments[2] && reStr ) {
            reStr = reStr = "\\b" + reStr + "\\b";

        // if re is not defined ( which means either an array or
        // string was passed as the first parameter ) create the
        // regular expression.
        if (!re) {
            re = new RegExp( "(" + reStr + ")", "ig" );

        // iterate through each matched element
        return this.each( function() {
            // select all contents of this element
            $( this ).find( "*" ).andSelf().contents()

            // filter to only text nodes that aren't already highlighted
            .filter( function () {
                return this.nodeType === 3 && $( this ).closest( "." + hClass ).length === 0;

            // loop through each text node
            .each( function () {
                var output;
                output = this.nodeValue
                    .replace( re, "<" + defaultTagName + " class='" + hClass + "'>$1</" + defaultTagName +">" );
                if ( output !== this.nodeValue ) {
                    $( this ).wrap( "<p></p>" ).parent()
                        .html( output ).contents().unwrap();

    $.fn.highlightText.defaultTagName = "span";

})( jQuery );


How can I select from list of values in Oracle

Starting from Oracle 12.2, you don't need the TABLE function, you can directly select from the built-in collection.

SQL> select * FROM sys.odcinumberlist(5,2,6,3,78);


SQL> select * FROM sys.odcivarchar2list('A','B','C','D');


How to concatenate text from multiple rows into a single text string in SQL server?

   declare @phone varchar(max)='' 
   select @phone=@phone + mobileno +',' from  members
   select @phone

nginx error "conflicting server name" ignored

There should be only one localhost defined, check sites-enabled or nginx.conf.

How do I capture SIGINT in Python?

In contrast to Matt J his answer, I use a simple object. This gives me the possibily to parse this handler to all the threads that needs to be stopped securlery.

class SIGINT_handler():
    def __init__(self):
        self.SIGINT = False

    def signal_handler(self, signal, frame):
        print('You pressed Ctrl+C!')
        self.SIGINT = True

handler = SIGINT_handler()
signal.signal(signal.SIGINT, handler.signal_handler)


while True:
    # task
    if handler.SIGINT:

How to define a two-dimensional array?


matrix = [[0]*5 for i in range(5)]

The *5 for the first dimension works because at this level the data is immutable.

Seeing if data is normally distributed in R

Normality tests don't do what most think they do. Shapiro's test, Anderson Darling, and others are null hypothesis tests AGAINST the the assumption of normality. These should not be used to determine whether to use normal theory statistical procedures. In fact they are of virtually no value to the data analyst. Under what conditions are we interested in rejecting the null hypothesis that the data are normally distributed? I have never come across a situation where a normal test is the right thing to do. When the sample size is small, even big departures from normality are not detected, and when your sample size is large, even the smallest deviation from normality will lead to a rejected null.

For example:

> set.seed(100)
> x <- rbinom(15,5,.6)
> shapiro.test(x)

    Shapiro-Wilk normality test

data:  x 
W = 0.8816, p-value = 0.0502

> x <- rlnorm(20,0,.4)
> shapiro.test(x)

    Shapiro-Wilk normality test

data:  x 
W = 0.9405, p-value = 0.2453

So, in both these cases (binomial and lognormal variates) the p-value is > 0.05 causing a failure to reject the null (that the data are normal). Does this mean we are to conclude that the data are normal? (hint: the answer is no). Failure to reject is not the same thing as accepting. This is hypothesis testing 101.

But what about larger sample sizes? Let's take the case where there the distribution is very nearly normal.

> library(nortest)
> x <- rt(500000,200)
> ad.test(x)

    Anderson-Darling normality test

data:  x 
A = 1.1003, p-value = 0.006975

> qqnorm(x)

enter image description here enter image description here

Here we are using a t-distribution with 200 degrees of freedom. The qq-plot shows the distribution is closer to normal than any distribution you are likely to see in the real world, but the test rejects normality with a very high degree of confidence.

Does the significant test against normality mean that we should not use normal theory statistics in this case? (another hint: the answer is no :) )

how to display variable value in alert box?

spans not have the value in html

one is the id for span tag

in javascript use


in jQuery use


function check() {
    var content = document.getElementById("one").innerText;


function check() {
        var content = $('#one').text();

List an Array of Strings in alphabetical order

java.util.Collections.sort(listOfCountryNames, Collator.getInstance());

Best way to find the intersection of multiple sets?

If you don't have Python 2.6 or higher, the alternative is to write an explicit for loop:

def set_list_intersection(set_list):
  if not set_list:
    return set()
  result = set_list[0]
  for s in set_list[1:]:
    result &= s
  return result

set_list = [set([1, 2]), set([1, 3]), set([1, 4])]
print set_list_intersection(set_list)
# Output: set([1])

You can also use reduce:

set_list = [set([1, 2]), set([1, 3]), set([1, 4])]
print reduce(lambda s1, s2: s1 & s2, set_list)
# Output: set([1])

However, many Python programmers dislike it, including Guido himself:

About 12 years ago, Python aquired lambda, reduce(), filter() and map(), courtesy of (I believe) a Lisp hacker who missed them and submitted working patches. But, despite of the PR value, I think these features should be cut from Python 3000.

So now reduce(). This is actually the one I've always hated most, because, apart from a few examples involving + or *, almost every time I see a reduce() call with a non-trivial function argument, I need to grab pen and paper to diagram what's actually being fed into that function before I understand what the reduce() is supposed to do. So in my mind, the applicability of reduce() is pretty much limited to associative operators, and in all other cases it's better to write out the accumulation loop explicitly.

Environment variables in Jenkins

What ultimately worked for me was the following steps:

  1. Configure the Environment Injector Plugin:
  2. Goto to the /job//configure screen
  3. In Build Environment section check "Inject environment variables to the build process"
  4. In "Properties Content" specified: TZ=America/New_York

Call asynchronous method in constructor?

A little late to the party, but I think many are struggling with this...

I've been searching for this as well. And to get your method/action running async without waiting or blocking the thread, you'll need to queue it via the SynchronizationContext, so I came up with this solution:

I've made a helper-class for it.

public static class ASyncHelper

    public static void RunAsync(Func<Task> func)
        var context = SynchronizationContext.Current;

        // you don't want to run it on a threadpool. So if it is null, 
        // you're not on a UI thread.
        if (context == null)
            throw new NotSupportedException(
                "The current thread doesn't have a SynchronizationContext");

        // post an Action as async and await the function in it.
        context.Post(new SendOrPostCallback(async state => await func()), null);

    public static void RunAsync<T>(Func<T, Task> func, T argument)
        var context = SynchronizationContext.Current;

        // you don't want to run it on a threadpool. So if it is null, 
        // you're not on a UI thread.
        if (context == null)
            throw new NotSupportedException(
                "The current thread doesn't have a SynchronizationContext");

        // post an Action as async and await the function in it.
        context.Post(new SendOrPostCallback(async state => await func((T)state)), argument);


public partial class Form1 : Form

    private async Task Initialize()
        // replace code here...
        await Task.Delay(1000);

    private async Task Run(string myString)

        // replace code here...
        await Task.Delay(1000);

    public Form1()

        // you don't have to await nothing.. (the thread must be running)
        ASyncHelper.RunAsync(Run, "test");

        // In your case

This works for Windows.Forms and WPF

How do I make Java register a string input with spaces? will return space-delimited strings. Use in.nextLine() if you want to read the whole line. After reading the string, use question = question.replaceAll("\\s","") to remove spaces.

Fastest JSON reader/writer for C++

rapidjson is a C++ JSON parser/generator designed to be fast and small memory footprint.

There is a performance comparison with YAJL and JsonCPP.


I created an open source project Native JSON benchmark, which evaluates 29 (and increasing) C/C++ JSON libraries, in terms of conformance and performance. This should be an useful reference.

How to get the selected date value while using Bootstrap Datepicker?

Bootstrap datepicker (the first result from bootstrap datepickcer search) has a method to get the selected date.

getDate: Returns a localized date object representing the internal date object of the first datepicker in the selection. For multidate pickers, returns the latest date selected.




Angular 4: How to include Bootstrap?

you work with cdn for bootstrap and jquery or install bootstarp directly in app with:

npm install ngx-bootstrap --save

also use, but this is not approperiate

Where is adb.exe in windows 10 located?

I know the question was in the context of "android studio 1.5", but I found this answer and have Xamarin installed.

In this case, the location is C:\Program Files (x86)\Android\android-sdk\platform-tools

jQuery 'input' event

jQuery has the following signature for the .on() method: .on( events [, selector ] [, data ], handler )

Events could be anyone of the ones listed on this reference:

Though, they are not all supported by every browser.

Mozilla states the following about the input event:

The DOM input event is fired synchronously when the value of an or element is changed. Additionally, it fires on contenteditable editors when its contents are changed.

Activate a virtualenv with a Python script

You should create all your virtualenvs in one folder, such as virt.

Assuming your virtualenv folder name is virt, if not change it

mkdir custom

Copy the below lines...

#!/usr/bin/env bash
bash --rcfile $ENV_PATH -i

Create a shell script file and paste the above lines...

touch custom/vhelper
nano custom/vhelper

Grant executable permission to your file:

sudo chmod +x custom/vhelper

Now export that custom folder path so that you can find it on the command-line by clicking tab...

export PATH=$PATH:"$HOME/custom"

Now you can use it from anywhere by just typing the below command...


Suppose it is abc then...

vhelper abc

Looking to understand the iOS UIViewController lifecycle

Haider's answer is correct for pre-iOS 6. However, as of iOS 6 viewDidUnload and viewWillUnload are never called. The docs state: "Views are no longer purged under low-memory conditions and so this method is never called."

FIFO class in Java

Not sure what you call FIFO these days since Queue is FILO, but when I was a student we used the Stack<E> with the simple push, pop, and a peek... It is really that simple, no need for complicating further with Queue and whatever the accepted answer suggests.

Access elements of parent window from iframe

You can access elements of parent window from within an iframe by using window.parent like this:

// using jquery    

Which is the same as:

// pure javascript

And if you have more than one nested iframes and you want to access the topmost iframe, then you can use like this:

// using jquery$("#element_id");

Which is the same as:

// pure javascript"element_id");

The action or event has been blocked by Disabled Mode

No. Go to database tools (for 2007) and click checkmark on the Message Bar. Then, after the message bar apears, click on Options, and then Enable. Hope this helps.


How to specify the JDK version in android studio?

For new Android Studio versions, go to C:\Program Files\Android\Android Studio\jre\bin(or to location of Android Studio installed files) and open command window at this location and type in following command in command prompt:-

java -version

Set background color of WPF Textbox in C# code

I take it you are creating the TextBox in XAML?

In that case, you need to give the text box a name. Then in the code-behind you can then set the Background property using a variety of brushes. The simplest of which is the SolidColorBrush:

myTextBox.Background = new SolidColorBrush(Colors.White);

Difference between thread's context class loader and normal classloader

There is an article on that explains the difference => Which ClassLoader should you use


Thread context classloaders provide a back door around the classloading delegation scheme.

Take JNDI for instance: its guts are implemented by bootstrap classes in rt.jar (starting with J2SE 1.3), but these core JNDI classes may load JNDI providers implemented by independent vendors and potentially deployed in the application's -classpath. This scenario calls for a parent classloader (the primordial one in this case) to load a class visible to one of its child classloaders (the system one, for example). Normal J2SE delegation does not work, and the workaround is to make the core JNDI classes use thread context loaders, thus effectively "tunneling" through the classloader hierarchy in the direction opposite to the proper delegation.

(2) from the same source:

This confusion will probably stay with Java for some time. Take any J2SE API with dynamic resource loading of any kind and try to guess which loading strategy it uses. Here is a sampling:

  • JNDI uses context classloaders
  • Class.getResource() and Class.forName() use the current classloader
  • JAXP uses context classloaders (as of J2SE 1.4)
  • java.util.ResourceBundle uses the caller's current classloader
  • URL protocol handlers specified via java.protocol.handler.pkgs system property are looked up in the bootstrap and system classloaders only
  • Java Serialization API uses the caller's current classloader by default

How to use enums in C++

You can use a trick to use scopes as you wish, just declare enum in such way:

struct Days 
   enum type

Days::type day = Days::Saturday;
if (day == Days::Saturday)

How to simulate a button click using code?

If you do not use the sender argument, why not refactor the button handler implementation to separate function, and call it from wherever you want (from the button handler and from the other place).

Anyway, it is a better and cleaner design - a code that needs to be called on button handler AND from some other places deserves to be refactored to own function. Plus it will help you separate UI handling from application logic code. You will also have a nice name to the function, not just onDateSelectedButtonClick().

Find OpenCV Version Installed on Ubuntu

To install this product you can see this tutorial: OpenCV on Ubuntu

There are listed the packages you need. So, with:

# dpkg -l | grep libcv2
# dpkg -l | grep libhighgui2

and more listed in the url you can find which packages are installed.


# dpkg -L libcv2

you can check where are installed

This operative is used for all debian packages.

Get all LI elements in array

After some years have passed, you can do that now with ES6 Array.from (or spread syntax):

const navbar = Array.from(document.querySelectorAll('#navbar>ul>li'));_x000D_
console.log('Get first: ', navbar[0].textContent);_x000D_
// If you need to iterate once over all these nodes, you can use the callback function:_x000D_
console.log('Iterate with Array.from callback argument:');_x000D_
Array.from(document.querySelectorAll('#navbar>ul>li'),li => console.log(li.textContent))_x000D_
// ... or a for...of loop:_x000D_
console.log('Iterate with for...of:');_x000D_
for (const li of document.querySelectorAll('#navbar>ul>li')) {_x000D_
.as-console-wrapper { max-height: 100% !important; top: 0; }
<div id="navbar">_x000D_
    <li id="navbar-One">One</li>_x000D_
    <li id="navbar-Two">Two</li>_x000D_
    <li id="navbar-Three">Three</li>_x000D_

Getting the text from a drop-down box

This works i tried it my self i thought i post it here in case someone need it...


How to set a fixed width column with CSS flexbox

In case anyone wants to have a responsive flexbox with percentages (%) it is much easier for media queries.

flex-basis: 25%;

This will be a lot smoother when testing.

$screen-xs:                                         480px;
$screen-sm:                                         768px;
$screen-md:                                         992px;
$screen-lg:                                         1200px;
$screen-xl:                                         1400px;
$screen-xxl:                                        1600px;

@media screen (max-width: $screen-lg) {
    flex-basis: 25%;

@media screen (max-width: $screen-md) {
    flex-basis: 33.33%;

Mercurial — revert back to old version and continue from there

The answers above were most useful and I learned a lot. However, for my needs the succinct answer is:

hg revert --all --rev ${1}

hg commit -m "Restoring branch ${1} as default"

where ${1} is the number of the revision or the name of the branch. These two lines are actually part of a bash script, but they work fine on their own if you want to do it manually.

This is useful if you need to add a hot fix to a release branch, but need to build from default (until we get our CI tools right and able to build from branches and later do away with release branches as well).

How to convert integer to char in C?

You can try atoi() library function. Also sscanf() and sprintf() would help.

Here is a small example to show converting integer to character string:

  int i = 247593;
  char str[10];

  sprintf(str, "%d", i);
  // Now str contains the integer as characters

Here for another Example

#include <stdio.h>

int main(void)
   char text[] = "StringX";
   int digit;
   for (digit = 0; digit < 10; ++digit)
      text[6] = digit + '0';
   return 0;

/* my output

Horizontal swipe slider with jQuery and touch devices support?

Take a look at iScroll v4 here:

It may not be jQuery, but it works on Desktop Mobile, and iPad quite well; I've used it on many projects and combined it with jQuery.

Good Luck!

lexical or preprocessor issue file not found occurs while archiving?

For what it's worth, my problem was completely unrelated to the error Xcode was giving. I stumbled onto a solution by deleting the .h reference, compiling, adding the reference back and compiling again. The actual error then became evident.

How to normalize a 2-dimensional numpy array in python less verbose?

it appears that this also works

def normalizeRows(M):
    row_sums = M.sum(axis=1)
    return M / row_sums

See whether an item appears more than once in a database column

To expand on Solomon Rutzky's answer, if you are looking for a piece of data that shows up in a range (i.e. more than once but less than 5x), you can use

having count(*) > 1 and count(*) < 5

And you can use whatever qualifiers you desire in there - they don't have to match, it's all just included in the 'having' statement.

Full-screen responsive background image

One hint about the "background-size: cover" solution, you have to put it after "background" definition, otherwise it won't work, for example this won't work:

html, body {
    height: 100%;
    background-size: cover;
    background:url("") no-repeat center center fixed;

How to install crontab on Centos

As seen in Install crontab on CentOS, the crontab package in CentOS is vixie-cron. Hence, do install it with:

yum install vixie-cron

And then start it with:

service crond start

To make it persistent, so that it starts on boot, use:

chkconfig crond on

On CentOS 7 you need to use cronie:

yum install cronie

On CentOS 6 you can install vixie-cron, but the real package is cronie:

yum install vixie-cron


yum install cronie

In both cases you get the same output:

 Package         Arch       Version         Repository      Size
 cronie          x86_64     1.4.4-12.el6    base             73 k
Installing for dependencies:
 cronie-anacron  x86_64     1.4.4-12.el6    base             30 k
 crontabs        noarch     1.10-33.el6     base             10 k
 exim            x86_64     4.72-6.el6      epel            1.2 M

Transaction Summary
Install       4 Package(s)

Subset a dataframe by multiple factor levels

Here's another:

data[data$Code == "A" | data$Code == "B", ]

It's also worth mentioning that the subsetting factor doesn't have to be part of the data frame if it matches the data frame rows in length and order. In this case we made our data frame from this factor anyway. So,

data[Code == "A" | Code == "B", ]

also works, which is one of the really useful things about R.

how to activate a textbox if I select an other option in drop down box


<select id = 'color2'
        name = 'color'
        onchange = "if ($('#color2').val() == 'others') {
                    } else {
  <option value="red">RED</option>
  <option value="blue">BLUE</option>
  <option value="others">others</option>

<input type = 'text'
       name = 'color'
       id = 'color' />

edit: requires JQuery plugin

Apache Maven install "'mvn' not recognized as an internal or external command" after setting OS environmental variables?

Delete M2 and M2_HOME from user variables and move to system variables. That will solve the problem

What's the difference between OpenID and OAuth?

There are three ways to compare OAuth and OpenID:

1. Purposes

OpenID was created for federated authentication, that is, letting a third-party authenticate your users for you, by using accounts they already have. The term federated is critical here because the whole point of OpenID is that any provider can be used (with the exception of white-lists). You don't need to pre-choose or negotiate a deal with the providers to allow users to use any other account they have.

OAuth was created to remove the need for users to share their passwords with third-party applications. It actually started as a way to solve an OpenID problem: if you support OpenID on your site, you can't use HTTP Basic credentials (username and password) to provide an API because the users don't have a password on your site.

The problem is with this separation of OpenID for authentication and OAuth for authorization is that both protocols can accomplish many of the same things. They each provide a different set of features which are desired by different implementations but essentially, they are pretty interchangeable. At their core, both protocols are an assertion verification method (OpenID is limited to the 'this is who I am' assertion, while OAuth provides an 'access token' that can be exchanged for any supported assertion via an API).

2. Features

Both protocols provide a way for a site to redirect a user somewhere else and come back with a verifiable assertion. OpenID provides an identity assertion while OAuth is more generic in the form of an access token which can then be used to "ask the OAuth provider questions". However, they each support different features:

OpenID - the most important feature of OpenID is its discovery process. OpenID does not require hard coding each the providers you want to use ahead of time. Using discovery, the user can choose any third-party provider they want to authenticate. This discovery feature has also caused most of OpenID's problems because the way it is implemented is by using HTTP URIs as identifiers which most web users just don't get. Other features OpenID has is its support for ad-hoc client registration using a DH exchange, immediate mode for optimized end-user experience, and a way to verify assertions without making another round-trip to the provider.

OAuth - the most important feature of OAuth is the access token which provides a long lasting method of making additional requests. Unlike OpenID, OAuth does not end with authentication but provides an access token to gain access to additional resources provided by the same third-party service. However, since OAuth does not support discovery, it requires pre-selecting and hard-coding the providers you decide to use. A user visiting your site cannot use any identifier, only those pre-selected by you. Also, OAuth does not have a concept of identity so using it for login means either adding a custom parameter (as done by Twitter) or making another API call to get the currently "logged in" user.

3. Technical Implementations

The two protocols share a common architecture in using redirection to obtain user authorization. In OAuth the user authorizes access to their protected resources and in OpenID, to their identity. But that's all they share.

Each protocol has a different way of calculating a signature used to verify the authenticity of the request or response, and each has different registration requirements.

How can I make a button have a rounded border in Swift?

To do this job in storyboard (Interface Builder Inspector)

With help of IBDesignable, we can add more options to Interface Builder Inspector for UIButton and tweak them on storyboard. First, add the following code to your project.

@IBDesignable extension UIButton {

    @IBInspectable var borderWidth: CGFloat {
        set {
            layer.borderWidth = newValue
        get {
            return layer.borderWidth

    @IBInspectable var cornerRadius: CGFloat {
        set {
            layer.cornerRadius = newValue
        get {
            return layer.cornerRadius

    @IBInspectable var borderColor: UIColor? {
        set {
            guard let uiColor = newValue else { return }
            layer.borderColor = uiColor.cgColor
        get {
            guard let color = layer.borderColor else { return nil }
            return UIColor(cgColor: color)

Then simply set the attributes for buttons on storyboard.

enter image description here

Scroll back to the top of scrollable div

var myDiv = document.getElementById('containerDiv');
myDiv.innerHTML = variableLongText;
myDiv.scrollTop = 0;

See the scrollTop attribute.

Inline JavaScript onclick function

This isn't really recommended, but you can do it all inline like so:

<a href="#" onClick="function test(){ /* Do something */  } test(); return false;"></a>

But I can't think of any situations off hand where this would be better than writing the function somewhere else and invoking it onClick.

Eclipse won't compile/run java file

right click somewhere on the file or in project explorer and choose 'run as'->'java application'

Adding an .env file to React Project

Today there is a simpler way to do that.

Just create the .env.local file in your root directory and set the variables there. In your case:

REACT_APP_API_KEY = 'my-secret-api-key'

Then you call it en your js file in that way:


React supports environment variables since [email protected] .You don't need external package to do that.

*note: I propose .env.local instead of .env because create-react-app add this file to gitignore when create the project.

Files priority:

npm start: .env.development.local, .env.development, .env.local, .env

npm run build: .env.production.local, .env.production, .env.local, .env

npm test: .env.test.local, .env.test, .env (note .env.local is missing)

More info:

Best way to store a key=>value array in JavaScript?

Simply do this

var key = "keyOne";
var obj = {};
obj[key] = someValue;

Align Bootstrap Navigation to Center

Try this css

.clearfix:before, .clearfix:after, .container:before, .container:after, .container-fluid:before, .container-fluid:after, .row:before, .row:after, .form-horizontal .form-group:before, .form-horizontal .form-group:after, .btn-toolbar:before, .btn-toolbar:after, .btn-group-vertical > .btn-group:before, .btn-group-vertical > .btn-group:after, .nav:before, .nav:after, .navbar:before, .navbar:after, .navbar-header:before, .navbar-header:after, .navbar-collapse:before, .navbar-collapse:after, .pager:before, .pager:after, .panel-body:before, .panel-body:after, .modal-footer:before, .modal-footer:after {
    content: " ";
    display: table-cell;

ul.nav {
    float: none;
    margin-bottom: 0;
    margin-left: auto;
    margin-right: auto;
    margin-top: 0;
    width: 240px;

Jenkins Git Plugin: How to build specific tag?

I did something like this and it worked :

Source Code Management



Name: ref
Refspec : +refs/tags/*:refs/remotes/origin/tags/* 

 Branches to build  
 Branch Specifier (blank for 'any') : v0.9.5.2

enter image description here

Jenkins log confirmed that it was getting the source from the tag

Checking out Revision 0b4d6e810546663e931cccb45640583b596c24b9 (v0.9.5.2)

Min / Max Validator in Angular 2 Final

Angualr itself provide a min and max number validation functionality.

Example - we have a field like age range then see the use of validation.

  age_range : ['',  Validators.min(1), Validators.max(18)]]

the age always be between 1 to 18.

How to access a mobile's camera from a web app?

I don't know of any way to access a mobile phone's camera from the web browser without some additional mechanism (i.e. Flash or some type of container that allows access to the hardware API)

For the latter have a look at PhoneGap:

With this you should be able to access the camera at least on iOS and Android-based devices.

Two Divs on the same row and center align both of them

both floated divs need to have a width!

set 50% of width to both and it works.

BTW, the outer div, with its margin: 0 auto will only center itself not the ones inside.

Print new output on same line

print("single",end=" ")

this will give output

single line

for the question asked use

i = 0 
while i <10:
     i += 1 
     print (i,end="")

rails generate model

For me what happened was that I generated the app with rails new rails new chapter_2 but the RVM --default had rails 4.0.2 gem, but my chapter_2 project use a new gemset with rails 3.2.16.

So when I ran

rails generate scaffold User name:string email:string

the console showed

   rails new APP_PATH [options]

So I fixed the RVM and the gemset with the rails 3.2.16 gem , and then generated the app again then I executed

 rails generate scaffold User name:string email:string

and it worked

Jquery post, response in new window

Accepted answer doesn't work with "use strict" as the "with" statement throws an error. So instead:

$.post(url, function (data) {
    var w ='about:blank', 'windowname');

Also, make sure 'windowname' doesn't have any spaces in it because that will fail in IE :)

Simulator or Emulator? What is the difference?

Simulation = For analysis and study

Emulation = For usage as a substitute

A simulator is an environment which models but an emulator is one that replicates the usage as on the original device or system.

Simulator mimics the activity of something that it is simulating. It "appears"(a lot can go with this "appears", depending on the context) to be the same as the thing being simulated. For example the flight simulator "appears" to be a real flight to the user, although it does not transport you from one place to another.

Emulator, on the other hand, actually "does" what the thing being emulated does, and in doing so it too "appears to be doing the same thing". An emulator may use different set of protocols for mimicking the thing being emulated, but the result/outcome is always the same as the original object. For example, EMU8086 emulates the 8086 microprocessor on your computer, which obviously is not running on 8086 (= different protocols), but the output it gives is what a real 8086 would give.

What does -save-dev mean in npm install grunt --save-dev

For me the first answer appears a bit confusing, so to make it short and clean:

npm install <package_name> saves any specified packages into dependencies by default. Additionally, you can control where and how they get saved with some additional flags:

npm install <package_name> --no-save Prevents saving to dependencies.

npm install <package_name> ---save-dev updates the devDependencies in your package. These are only used for local testing and development.

You can read more at in the dcu

How to call a method in MainActivity from another class?

You can easily call a method from any Fragment inside your Activity by doing a cast like this:




(activity as MainActivity).startChronometer()

Just remember to make sure this Fragment's activity is in fact MainActivity before you do it.

Hope this helps!

HTTP Error 500.19 and error code : 0x80070021

On Windows 8.1 or 10 include the .Net framework 4.5 or above as shown below

enter image description here

How to show current user name in a cell?

if you don't want to create a UDF in VBA or you can't, this could be an alternative.

=Cell("Filename",A1) this will give you the full file name, and from this you could get the user name with something like this:


This Formula runs only from a workbook saved earlier.

You must start from 4th position because of the first slash from the drive.

"Cannot GET /" with Connect on Node.js

You may also want to try st, a node module for serving static files. Setup is trivial.

npm install connect

npm install st

And here's how my server-dev.js file looks like:

var connect = require('connect');
var http = require('http');
var st = require('st');

var app = connect()


or (with cache disabled):

var connect = require('connect');
var http = require('http');
var st = require('st');

var app = connect();

var mount = st({
  path: 'app/dev',
  cache: false

http.createServer(function (req, res) {
  if (mount(req, res)) return;


Fetch first element which matches criteria

When you write a lambda expression, the argument list to the left of -> can be either a parenthesized argument list (possibly empty), or a single identifier without any parentheses. But in the second form, the identifier cannot be declared with a type name. Thus: s-> s.getStation().getName().equals(name));

is incorrect syntax; but s)-> s.getStation().getName().equals(name));

is correct. Or: -> s.getStation().getName().equals(name));

is also correct if the compiler has enough information to figure out the types.

Use Toast inside Fragment

Making a Toast inside Fragment

 Toast.makeText(getActivity(), "Your Text Here!", Toast.LENGTH_SHORT).show();


    Activity activityObj = this.getActivity();

    Toast.makeText(activityObj, "Your Text Here!", Toast.LENGTH_SHORT).show();


Toast.makeText(this, "Your Text Here!", Toast.LENGTH_SHORT).show();

Overriding the java equals() method - not working?

in Android Studio is alt + insert ---> equals and hashCode


public boolean equals(Object o) {
    if (this == o) return true;
    if (o == null || getClass() != o.getClass()) return false;

    Proveedor proveedor = (Proveedor) o;

    return getId() == proveedor.getId();


public int hashCode() {
    return getId();

Are there constants in JavaScript?

No, not in general. Firefox implements const but I know IE doesn't.

@John points to a common naming practice for consts that has been used for years in other languages, I see no reason why you couldn't use that. Of course that doesn't mean someone will not write over the variable's value anyway. :)

Microsoft.WebApplication.targets was not found, on the build server. What's your solution?

I have found this on MS connect:

Yes, you need to install Visual Studio 2010 on your build machine to build database projects. Doing so does not require an additional license of Visual Studio.

So, this is the only option that I have for now.

Init function in javascript and how it works

Its is called immediatly invoking function expression (IIFE). Mainly associated with the JavaScript closure concept. Main use is to run the function before the global variable changed, so that the expected behaviour of code can be retained.

git push >> fatal: no configured push destination

You are referring to the section "2.3.5 Deploying the demo app" of this "Ruby on Rails Tutorial ":

In section 2.3.1 Planning the application, note that they did:

$ git remote add origin [email protected]:<username>/demo_app.git
$ git push origin master

That is why a simple git push worked (using here an ssh address).
Did you follow that step and made that first push?

wouldn't be a writable URI for pushing to a GitHub repo.

https://[email protected]/levelone/demo_app.git

should be more appropriate.
Check what git remote -v returns, and if you need to replace the remote address, as described in GitHub help page, use git remote --set-url.

git remote set-url origin https://[email protected]/levelone/demo_app.git
git remote set-url origin [email protected]:levelone/demo_app.git

How do you use youtube-dl to download live streams (that are live)?

Before, this could be downloaded with streamlink but YouTube changed HLS rewinding with DASH. Therefore the way to do it below (that Prashant Adlinge commented) no longer works for YouTube:

streamlink --hls-live-restart STREAMURL best

More info here

best way to create object

Decide if you need an immutable object or not.

If you put public properties in your class, the state of every instance can be changed at every time in your code. So your class could be like this:

public class Person
    public string Name { get; set; }
    public int Age { get; set; }
    public Person(){}
    public Person(string name, int age)
        Name = name;
        Age = age;
    //Other properties, methods, events...

In that case, having a Person(string name, int age) constructor is not so useful.

The second option is to implement an immutable type. For example:

public class Person
    public string Name { get; private set; }
    public int Age { get; private set; }

    public Person(string name, int age)
        Name = name;
        Age = age;
    //Other properties, methods, events...

Now you have a constructor that sets the state for the instance, once, at creation time. Note that now setters for properties are private, so you can't change the state after your object is instantiated.

A best practice is to define classes as immutable every time if possible. To understand advantages of immutable classes I suggest you read this article.

What is perm space?

It holds stuff like class definitions, string pool, etc. I guess you could call it meta-data.

Way to go from recursion to iteration

Just killing time... A recursive function

void foo(Node* node)
    if(node == NULL)
    // Do something with node...

can be converted to

void foo(Node* node)
    if(node == NULL)

    // Do something with node...


    while(!stack.empty()) {
         node1 = stack.pop();
         if(node1 == NULL)
         // Do something with node1...


What are the ascii values of up down left right?

If you're programming in OpenGL, use GLUT. The following page should help:

GLUT_KEY_LEFT   Left function key
GLUT_KEY_RIGHT  Right function key
GLUT_KEY_UP     Up function key
GLUT_KEY_DOWN   Down function key


void processSpecialKeys(int key, int x, int y) {

switch(key) {
    case GLUT_KEY_F1 : 
            red = 1.0; 
            green = 0.0; 
            blue = 0.0; break;
    case GLUT_KEY_F2 : 
            red = 0.0; 
            green = 1.0; 
            blue = 0.0; break;
    case GLUT_KEY_F3 : 
            red = 0.0; 
            green = 0.0; 
            blue = 1.0; break;

Getting value from table cell in JavaScript...not jQuery

confer below code


    function addRow(){
 var table = document.getElementById('myTable');
//var row = document.getElementById("myTable");
var x = table.insertRow(0);
var e =table.rows.length-1;
var l =table.rows[e].cells.length;
//x.innerHTML = "&nbsp;";
 for (var c =0,  m=l; c < m; c++) {
   table.rows[0].cells[c].innerHTML  = "&nbsp;&nbsp;";


function addColumn(){
       var table = document.getElementById('myTable');
        for (var r = 0, n = table.rows.length; r < n; r++) {
                table.rows[r].cells[0].innerHTML =  "&nbsp;&nbsp;" ;



function deleteRow() {


function deleteColumn() {
   // var row = document.getElementById("myRow");
 var table = document.getElementById('myTable');
 for (var r = 0, n = table.rows.length; r < n; r++) {
    table.rows[r].deleteCell(0);//var table handle 

<input type="button" value="row +" onClick="addRow()" border=0       style='cursor:hand'>
    <input type="button" value="row -" onClick='deleteRow()' border=0 style='cursor:hand'>
    <input type="button" value="column +" onClick="addColumn()" border=0 style='cursor:hand'>
    <input type="button" value="column -" onClick='deleteColumn()' border=0 style='cursor:hand'>

    <table  id='myTable' border=1 cellpadding=0 cellspacing=0>
 <tr id='myRow'>          



If '<selector>' is an Angular component, then verify that it is part of this module

In my case I was writing unit tests for a component that uses sub-components, and I was writing tests to make sure those subcomponents were in the template:

it('should include the interview selection subview', () => {

I didn't get an error, but a warning:

WARN: ''app-interview' is not a known element:

  1. If 'app-interview' is an Angular component, then verify that it is part of this module. WARN: ''app-interview' is not a known element:
  2. If 'app-interview' is an Angular component, then verify that it is part of this module.
  3. If 'app-interview' is a Web Component then add 'CUSTOM_ELEMENTS_SCHEMA' to the '@NgModule.schemas' of this component to suppress this message.'

Also, the subcomponent did not show inside the browser during testing.

I used ng g c newcomponent to generate all the components, so they were already declared in the appmodule, but not the test module that for the component I was spec'ing.

beforeEach(async(() => {
      declarations: [ EditorComponent,

cannot call member function without object

If you want to call them like that, you should declare them static.

MySQL skip first 10 results

There is an OFFSET as well that should do the trick:

SELECT column FROM table

Authenticate Jenkins CI for Github private repository

Another option is to use GitHub personal access tokens:

  • Go to
  • Add repo scope
  • In Jenkins, add a GitHub source
  • Use Repository HTTPS URL
  • Add the HTTPS URL of the git repo (not the SSH one, eg.
  • Add credential
    • Kind: Username with Password
    • Username: the GitHub username
    • Password: the personal access token you created on GitHub
    • ID: something like github-token-for-my-username

I tested this on Jenkins ver. 2.222.1 and Jenkins GitHub plugin 1.29.5 with a private GitHub repo.

CSS Border Not Working

The height is a 100% unsure, try putting display: block; or display: inline-block;

How can I stage and commit all files, including newly added files, using a single command?

If you just want a "quick and dirty" way to stash changes on the current branch, you can use the following alias:

git config --global alias.temp '!git add -A && git commit -m "Temp"'  

After running that command, you can just type git temp to have git automatically commit all your changes to the current branch as a commit named "Temp". Then, you can use git reset HEAD~ later to "uncommit" the changes so you can continue working on them, or git commit --amend to add more changes to the commit and/or give it a proper name.

PHP PDO with foreach and fetch

foreach over a statement is just a syntax sugar for the regular one-way fetch() loop. If you want to loop over your data more than once, select it as a regular array first

$sql = "SELECT * FROM users";
$stm = $dbh->query($sql);
// here you go:
$users = $stm->fetchAll();

foreach ($users as $row) {
    print $row["name"] . "-" . $row["sex"] ."<br/>";
echo "<br/>";
foreach ($users as $row) {
    print $row["name"] . "-" . $row["sex"] ."<br/>";

Also quit that try..catch thing. Don't use it, but set the proper error reporting for PHP and PDO

pip install failing with: OSError: [Errno 13] Permission denied on directory

Just clarifying what worked for me after much pain in linux (ubuntu based) on permission denied errors, and leveraging from Bert's answer above, I now use ...

$ pip install --user <package-name>

or if running pip on a requirements file ...

$ pip install --user -r requirements.txt

and these work reliably for every pip install including creating virtual environments.

However, the cleanest solution in my further experience has been to install python-virtualenv and virtualenvwrapper with sudo apt-get install at the system level.

Then, inside virtual environments, use pip install without the --user flag AND without sudo. Much cleaner, safer, and easier overall.

How can we convert an integer to string in AngularJs

.toString() is available, or just add "" to the end of the int

var x = 3,
    toString = x.toString(),
    toConcat = x + "";

Angular is simply JavaScript at the core.

How do I break out of a loop in Scala?

import scala.util.control._

object demo_brk_963 
   def main(args: Array[String]) 
      var a = 0;
      var b = 0;
      val numList1 = List(1,2,3,4,5,6,7,8,9,10);
      val numList2 = List(11,12,13);

      val outer = new Breaks; //object for break
      val inner = new Breaks; //object for break

      outer.breakable // Outer Block
         for( a <- numList1)
            println( "Value of a: " + a);

            inner.breakable // Inner Block
               for( b <- numList2)
                  println( "Value of b: " + b);

                  if( b == 12 )
                      println( "break-INNER;");
            } // inner breakable
            if( a == 6 )
                println( "break-OUTER;");
      } // outer breakable.

Basic method to break the loop, using Breaks class. By declaring the loop as breakable.

Carousel with Thumbnails in Bootstrap 3.0

  1. Use the carousel's indicators to display thumbnails.
  2. Position the thumbnails outside of the main carousel with CSS.
  3. Set the maximum height of the indicators to not be larger than the thumbnails.
  4. Whenever the carousel has slid, update the position of the indicators, positioning the active indicator in the middle of the indicators.

I'm using this on my site (for example here), but I'm using some extra stuff to do lazy loading, meaning extracting the code isn't as straightforward as I would like it to be for putting it in a fiddle.

Also, my templating engine is smarty, but I'm sure you get the idea.

The meat...

Updating the indicators:

<ol class="carousel-indicators">
    {assign var='walker' value=0}
    {foreach from=$item["imagearray"] key="key" item="value"}
        <li data-target="#myCarousel" data-slide-to="{$walker}"{if $walker == 0} class="active"{/if}>
            <img src='http://farm{$value["farm"]}{$value["server"]}/{$value["id"]}_{$value["secret"]}_s.jpg'>

        {assign var='walker' value=1 + $walker}

Changing the CSS related to the indicators:

.carousel-indicators {
    height: 36px;
    overflow-x: hidden;
    white-space: nowrap;

.carousel-indicators li {
    text-indent: 0;
    width: 34px !important;
    height: 34px !important;
    border-radius: 0;

.carousel-indicators li img {
    width: 32px;
    height: 32px;
    opacity: 0.5;

.carousel-indicators li:hover img, .carousel-indicators img {
    opacity: 1;

.carousel-indicators .active {
    border-color: #337ab7;

When the carousel has slid, update the list of thumbnails:

$('#myCarousel').on('', function() {
    var widthEstimate = -1 * $(".carousel-indicators li:first").position().left + $(".carousel-indicators li:last").position().left + $(".carousel-indicators li:last").width(); 
    var newIndicatorPosition = $(".carousel-indicators").position().left + $(".carousel-indicators").width() / 2;
    var toScroll = newIndicatorPosition + indicatorPosition;
    var adjustedScroll = toScroll - ($(".carousel-indicators").width() / 2);
    if (adjustedScroll < 0)
        adjustedScroll = 0;

    if (adjustedScroll > widthEstimate - $(".carousel-indicators").width())
        adjustedScroll = widthEstimate - $(".carousel-indicators").width();

    $('.carousel-indicators').animate({ scrollLeft: adjustedScroll }, 800);

    indicatorPosition = adjustedScroll;

And, when your page loads, set the initial scroll position of the thumbnails:

var indicatorPosition = 0;

Calling a function within a Class method?

  class sampleClass
        public function f1()
           return "f1 run";

        public function f2()
           echo ("f2 run" );
           $result =  $this->f1();
           echo ($result);



output :

f2 run f1 run

How to hide Bootstrap previous modal when you opening new one?

Toggle both modals


Control the size of points in an R scatterplot?

As rcs stated, cex will do the job in base graphics package. I reckon that you're not willing to do your graph in ggplot2 but if you do, there's a size aesthetic attribute, that you can easily control (ggplot2 has user-friendly function arguments: instead of typing cex (character expansion), in ggplot2 you can type e.g. size = 2 and you'll get 2mm point).

Here's the example:

### base graphics ###
plot(mpg ~ hp, data = mtcars, pch = 16, cex = .9)

### ggplot2 ###
# with qplot()
qplot(mpg, hp, data = mtcars, size = I(2))
# or with ggplot() + geom_point()
ggplot(mtcars, aes(mpg, hp), size = 2) + geom_point()
# or another solution:
ggplot(mtcars, aes(mpg, hp)) + geom_point(size = 2)

How to ignore ansible SSH authenticity checking?

The most problems appear when you want to add new host to dynamic inventory (via add_host module) in playbook. I don't want to disable fingerprint host checking permanently so solutions like disabling it in a global config file are not ok for me. Exporting var like ANSIBLE_HOST_KEY_CHECKING before running playbook is another thing to do before running that need to be remembered.

It's better to add local config file in the same dir where playbook is. Create file named ansible.cfg and paste following text:

host_key_checking = False

No need to remember to add something in env vars or add to ansible-playbook options. It's easy to put this file to ansible git repo.

Can I add and remove elements of enumeration at runtime in Java

No, enums are supposed to be a complete static enumeration.

At compile time, you might want to generate your enum .java file from another source file of some sort. You could even create a .class file like this.

In some cases you might want a set of standard values but allow extension. The usual way to do this is have an interface for the interface and an enum that implements that interface for the standard values. Of course, you lose the ability to switch when you only have a reference to the interface.

Detect if a page has a vertical scrollbar?

This one did works for me:

function hasVerticalScroll(node){
    if(node == undefined){
            return document.body.offsetHeight> window.innerHeight;
        else {
            return  document.documentElement.scrollHeight > 
                document.documentElement.offsetHeight ||
    else {
        return node.scrollHeight> node.offsetHeight;

For the body, just use hasVerticalScroll().

How to remove border of drop down list : CSS

This solution seems not working for me.

select {
    border: 0px;
    outline: 0px;

But you may set select border to the background color of the container and it will work.

Calling stored procedure from another stored procedure SQL Server

First of all, if table2's idProduct is an identity, you cannot insert it explicitly until you set IDENTITY_INSERT on that table


before the insert.

So one of two, you modify your second stored and call it with only the parameters productName and productDescription and then get the new ID

EXEC test2 'productName', 'productDescription'

or you already have the ID of the product and you don't need to call SCOPE_IDENTITY() and can make the insert on table1 with that ID

Delete a row in Excel VBA

Chris Nielsen's solution is simple and will work well. A slightly shorter option would be...


...note there is no need to specify a Shift when deleting a row as, by definition, it's not possible to shift left

Incidentally, my preferred method for deleting rows is to use...

ws.Rows(Rand) = "" the initial loop. I then use a Sort function to push these rows to the bottom of the data. The main reason for this is because deleting single rows can be a very slow procedure (if you are deleting >100). It also ensures nothing gets missed as per Robert Ilbrink's comment

You can learn the code for sorting by recording a macro and reducing the code as demonstrated in this expert Excel video. I have a suspicion that the neatest method (Range("A1:Z10").Sort Key1:=Range("A1"), Order1:=xlSortAscending/Descending, Header:=xlYes/No) can only be discovered on pre-2007 versions of Excel...but you can always reduce the 2007/2010 equivalent code

Couple more points...if your list is not already sorted by a column and you wish to retain the order, you can stick the row number 'Rand' in a spare column to the right of each row as you loop through. You would then sort by that comment and eliminate it

If your data rows contain formatting, you may wish to find the end of the new data range and delete the rows that you cleared earlier. That's to keep the file size down. Note that a single large delete at the end of the procedure will not impair your code's performance in the same way that deleting single rows does

Babel 6 regeneratorRuntime is not defined

babel-polyfill (deprecated as of Babel 7.4) is required. You must also install it in order to get async/await working.

npm i -D babel-core babel-polyfill babel-preset-es2015 babel-preset-stage-0 babel-loader


"devDependencies": {
  "babel-core": "^6.0.20",
  "babel-polyfill": "^6.0.16",
  "babel-preset-es2015": "^6.0.15",
  "babel-preset-stage-0": "^6.0.15"


  "presets": [ "es2015", "stage-0" ]

.js with async/await (sample code)

"use strict";

export default async function foo() {
  var s = await bar();

function bar() {
  return "bar";

In the startup file


If you are using webpack you need to put it as the first value of your entry array in your webpack configuration file (usually webpack.config.js), as per @Cemen comment:

module.exports = {
  entry: ['babel-polyfill', './test.js'],

  output: {
    filename: 'bundle.js'       

  module: {
    loaders: [
      { test: /\.jsx?$/, loader: 'babel', }

If you want to run tests with babel then use:

mocha --compilers js:babel-core/register --require babel-polyfill

Proper way to wait for one function to finish before continuing?

It appears you're missing an important point here: JavaScript is a single-threaded execution environment. Let's look again at your code, note I've added alert("Here"):

var isPaused = false;

function firstFunction(){
    isPaused = true;
        // do something
    isPaused = false;

function secondFunction(){


    function waitForIt(){
        if (isPaused) {
        } else {
            // go do that thing

You don't have to wait for isPaused. When you see the "Here" alert, isPaused will be false already, and firstFunction will have returned. That's because you cannot "yield" from inside the for loop (// do something), the loop may not be interrupted and will have to fully complete first (more details: Javascript thread-handling and race-conditions).

That said, you still can make the code flow inside firstFunction to be asynchronous and use either callback or promise to notify the caller. You'd have to give up upon for loop and simulate it with if instead (JSFiddle):

function firstFunction()
    var deferred = $.Deferred();

    var i = 0;
    var nextStep = function() {
        if (i<10) {
            // Do something
            printOutput("Step: " + i);
            setTimeout(nextStep, 500); 
        else {
    return deferred.promise();

function secondFunction()
    var promise = firstFunction();
    promise.then(function(result) { 
        printOutput("Result: " + result);

On a side note, JavaScript 1.7 has introduced yield keyword as a part of generators. That will allow to "punch" asynchronous holes in otherwise synchronous JavaScript code flow (more details and an example). However, the browser support for generators is currently limited to Firefox and Chrome, AFAIK.

React - changing an uncontrolled input

One potential downside with setting the field value to "" (empty string) in the constructor is if the field is an optional field and is left unedited. Unless you do some massaging before posting your form, the field will be persisted to your data storage as an empty string instead of NULL.

This alternative will avoid empty strings:

constructor(props) {
    this.state = {
        name: null


<input name="name" type="text" value={ || ''}/>

When do I need a fb:app_id or fb:admins?

To use the Like Button and have the Open Graph inspect your website, you need an application.

So you need to associate the Like Button with a fb:app_id

If you want other users to see the administration page for your website on Facebook you add fb:admins. So if you are the developer of the application and the website owner there is no need to add fb:admins

Google Chrome redirecting localhost to https

NEW DEVELOPMENTS! (if you have Chrome 63+)

If your localhost domain is .dev then I don't think the previously accepted and working answers no longer apply. This is because as of the Chrome 63 Chrome will force .dev domains to HTTPS via preloaded HSTS.

What this means is, .dev basically won't work at all anymore unless you have proper signed SSL certificate -- no more self signed certificates allowed! Learn more at this blog post.

So to fix this issue now and to avoid this happening again in the future .test is one recommended domain because it is reserved by IETF for testing / dev purposes. You should also be able to use .localhost for local dev.

Source file 'Properties\AssemblyInfo.cs' could not be found

This can also happen if you have a solution containing the project open in Visual Studio, then use your source control software to change to an older commit that does not contain that project. Normally, this would be obvious as all the project files would disappear as well. But, if it's a new project with very few or no files at all, it could be puzzling to see that just this one file, AssemblyInfo.cs, is missing. And, it's more likely you'd be messing about with an AssemblyInfo.cs when a project is new, so might miss that another file or two is also missing.

The cure is to do any of the following:

  • Fetch the missing AssemblyInfo.cs and any other missing files from another commit, taking care to manage and save your .csproj file so the referenced files don't vanish from the project—perhaps by adding and removing a random .cs file to cause changes to need to be saved (since visual studio thinks the .csproj file has been saved when it hasn't).
  • Close and reopen Visual Studio without saving (if the project file isn't really saved) or remove the project. Removing makes sense if you didn't actually want the project created yet, since it will be created in the later commit.
  • Recreate the AssemblyInfo.cs file manually. Just copy another project, and change the details, especially the GUID so it matches the one from the .sln file.

TensorFlow, "'module' object has no attribute 'placeholder'"

import tensorflow.compat.v1 as tf


works. I am using Python 3.7 and tensorflow 2.0.

Passing parameters to click() & bind() event in jquery?

From where would you get these values? If they're from the button itself, you could just do {

If they're a variable in the binding scope, you can access them from without

var id = 1; {

If they're a variable in the binding scope, that might change before the click is called, you'll need to create a new closure

for(var i = 0; i < 5; i++) {
   $('#button'+i).click((function(id) {
      return function() {

How to cin to a vector

As is, you're only reading in a single integer and pushing it into your vector. Since you probably want to store several integers, you need a loop. E.g., replace

cin >> input;


while (cin >> input)

What this does is continually pull in ints from cin for as long as there is input to grab; the loop continues until cin finds EOF or tries to input a non-integer value. The alternative is to use a sentinel value, though this prevents you from actually inputting that value. Ex:

while ((cin >> input) && input != 9999)

will read until you try to input 9999 (or any of the other states that render cin invalid), at which point the loop will terminate.

how to permit an array with strong parameters

when you want to permit multiple array fields you will have to list array fields at last while permitting ,as given -

params.require(:questions).permit(:question, :user_id, answers: [], selected_answer: [] )

(this works)

How to use double or single brackets, parentheses, curly braces

Parentheses in function definition

Parentheses () are being used in function definition:

function_name () { command1 ; command2 ; }

That is the reason you have to escape parentheses even in command parameters:

$ echo (
bash: syntax error near unexpected token `newline'

$ echo \(

$ echo () { command echo The command echo was redefined. ; }
$ echo anything
The command echo was redefined. Repeater get current index, pointer, or counter

To display the item number on the repeater you can use the Container.ItemIndex property.

<asp:repeater id="rptRepeater" runat="server">
        Item <%# Container.ItemIndex + 1 %>| <%# Eval("Column1") %>
        <br />

How should I call 3 functions in order to execute them one after the other?

I believe the async library will provide you a very elegant way to do this. While promises and callbacks can get a little hard to juggle with, async can give neat patterns to streamline your thought process. To run functions in serial, you would need to put them in an async waterfall. In async lingo, every function is called a task that takes some arguments and a callback; which is the next function in the sequence. The basic structure would look something like:

  // A list of functions
      // Function no. 1 in sequence
      callback(null, arg);
  function(arg, callback){
      // Function no. 2 in sequence
function(err, results){
   // Optional final callback will get results for all prior functions

I've just tried to briefly explain the structure here. Read through the waterfall guide for more information, it's pretty well written.

ImportError: No module named apiclient.discovery

I had the same problem because of a bug in the installation of the URITemplate module.

This solved the problem:

pip install --force-reinstall

IE 8: background-size fix

I use the filter solution above, for ie8. However.. In order to solve the freezing links problem , do also the following:

background: no-repeat center center fixed\0/; /* IE8 HACK */

This has solved the frozen links problem for me.

Bulk Insert Correctly Quoted CSV File in SQL Server

There is another solution for this.

Consider the quotes as part of the fields delimiter, by editing the fmt file.

You can check this out for more information:

An extract of the link above:

The only way to remove the quotation marks would be to modify the column delimiters specified during the import operation. The only drawback here is that if you inspect the data to be inserted, you will very quickly realize that the column delimiters are different for each column (Delimiters highlighted above).

So to specify different column delimiters for each column, you would need to use a format file if you plan to use Bulk Insert or BCP. If you generate a format file for the above table structure, it would be as follows:

1       SQLCHAR       0       5       "\t"     1     FName              SQL_Latin1_General_CP1_CI_AS
2       SQLCHAR       0       5       "\t"     2     LName              SQL_Latin1_General_CP1_CI_AS
3       SQLCHAR       0       50      "\r\n"   3     Company            SQL_Latin1_General_CP1_CI_AS

Modify the format file to represent the correct column delimiters for each column. The new format file to be used will look like this:

1       SQLCHAR       0       0     "\""      0     FIRST_QUOTE      SQL_Latin1_General_CP1_CI_AS
2       SQLCHAR       0       5     "\",\""   1     FNAME               SQL_Latin1_General_CP1_CI_AS
3       SQLCHAR       0       5     "\",\""   2     LNAME            SQL_Latin1_General_CP1_CI_AS
4       SQLCHAR       0       50    "\"\r\n"  3     COMPANY          SQL_Latin1_General_CP1_CI_AS

angularjs to output plain text instead of html

You want to use the built-in browser HTML strip for that instead of applying yourself a regexp. It is more secure since the ever green browser does the work for you.

angular.module('myApp.filters', []).
  filter('htmlToPlaintext', function() {
    return function(text) {
      return stripHtml(text);

var stripHtml = (function () {
  var tmpEl = $document[0].createElement("DIV");
  function strip(html) {
    if (!html) {
      return "";
    tmpEl.innerHTML = html;
    return tmpEl.textContent || tmpEl.innerText || "";
  return strip;

The reason for wrapping it in an self-executing function is for reusing the element creation.

Failed to locate the winutils binary in the hadoop binary path

Simple Solution: Download it from here and add to $HADOOP_HOME/bin



For hadoop-2.6.0 you can download binaries from Titus Barik blog >>.

I have not only needed to point HADOOP_HOME to extracted directory [path], but also provide system property -Djava.library.path=[path]\bin to load native libs (dll).

Passing by reference in C

In C, Pass-by-reference is simulated by passing the address of a variable (a pointer) and dereferencing that address within the function to read or write the actual variable. This will be referred to as "C style pass-by-reference."


How do I convert a numpy array to (and display) an image?

The following should work:

from matplotlib import pyplot as plt
plt.imshow(data, interpolation='nearest')

If you are using Jupyter notebook/lab, use this inline command before importing matplotlib:

%matplotlib inline 

What should main() return in C and C++?

I believe that main() should return either EXIT_SUCCESS or EXIT_FAILURE. They are defined in stdlib.h

How can I create an executable JAR with dependencies using Maven?

I won't answer directly the question as other have already done that before, but I really wonder if it's a good idea to embed all the dependencies in the project's jar itself.

I see the point (ease of deployment / usage) but it depends of the use case of your poject (and there may be alternatives (see below)).

If you use it fully standalone, why not.

But if you use your project in other contexts (like in a webapp, or dropped in a folder where other jars are sitting), you may have jar duplicates in your classpath (the ones in the folder, the one in the jars). Maybe not a bid deal but i usually avoid this.

A good alternative :

  • deploy your application as a .zip / .war : the archive contains your project's jar and all dependent jars ;
  • use a dynamic classloader mechanism (see Spring, or you can easily do this yourself) to have a single entry point of your project (a single class to start - see the Manifest mechanism on another answer), which will add (dynamically) to the current classpath all the other needed jars.

Like this, with in the end just a manifest and a "special dynamic classloader main", you can start your project with :

java -jar ProjectMainJar.jar com.stackoverflow.projectName.MainDynamicClassLoaderClass

How can I be notified when an element is added to the page?

You can use livequery plugin for jQuery. You can provide a selector expression such as:

$("input[type=button].removeItemButton").livequery(function () {
    $("#statusBar").text('You may now remove items.');

Every time a button of a removeItemButton class is added a message appears in a status bar.

In terms of efficiency you might want avoid this, but in any case you could leverage the plugin instead of creating your own event handlers.

Revisited answer

The answer above was only meant to detect that an item has been added to the DOM through the plugin.

However, most likely, a jQuery.on() approach would be more appropriate, for example:

$("#myParentContainer").on('click', '.removeItemButton', function(){
          alert($(this).text() + ' has been removed');

If you have dynamic content that should respond to clicks for example, it's best to bind events to a parent container using jQuery.on.

Inserting an image with PHP and FPDF

You can use $pdf->GetX() and $pdf->GetY() to get current cooridnates and use them to insert image.

$pdf->Image($image1, 5, $pdf->GetY(), 33.78);

or even

$pdf->Image($image1, 5, null, 33.78);

(ALthough in first case you can add a number to create a bit of a space)

$pdf->Image($image1, 5, $pdf->GetY() + 5, 33.78);

JPanel vs JFrame in Java

You should not extend the JFrame class unnecessarily (only if you are adding extra functionality to the JFrame class)


JFrame extends Component and Container.

It is a top level container used to represent the minimum requirements for a window. This includes Borders, resizability (is the JFrame resizeable?), title bar, controls (minimize/maximize allowed?), and event handlers for various Events like windowClose, windowOpened etc.


JPanel extends Component, Container and JComponent

It is a generic class used to group other Components together.

  • It is useful when working with LayoutManagers e.g. GridLayout f.i adding components to different JPanels which will then be added to the JFrame to create the gui. It will be more manageable in terms of Layout and re-usability.

  • It is also useful for when painting/drawing in Swing, you would override paintComponent(..) and of course have the full joys of double buffering.

A Swing GUI cannot exist without a top level container like (JWindow, Window, JFrame Frame or Applet), while it may exist without JPanels.

Get size of an Iterable in Java

You can cast your iterable to a list then use .size() on it.


For the sake of clarity, the above method will require the following import:


Making interface implementations async

An abstract class can be used instead of an interface (in C# 7.3).

// Like interface
abstract class IIO
    public virtual async Task<string> DoOperation(string Name)
        throw new NotImplementedException(); // throwing exception
        // return await Task.Run(() => { return ""; }); // or empty do

// Implementation
class IOImplementation : IIO
    public override async Task<string> DoOperation(string Name)
        return await await Task.Run(() =>
            if(Name == "Spiderman")
                return "ok";
            return "cancel";

Python: Find in list

Finding the first occurrence

There's a recipe for that in itertools:

def first_true(iterable, default=False, pred=None):
    """Returns the first true value in the iterable.

    If no true value is found, returns *default*

    If *pred* is not None, returns the first item
    for which pred(item) is true.

    # first_true([a,b,c], x) --> a or b or c or x
    # first_true([a,b], x, f) --> a if f(a) else b if f(b) else x
    return next(filter(pred, iterable), default)

For example, the following code finds the first odd number in a list:

>>> first_true([2,3,4,5], None, lambda x: x%2==1)

How to enable CORS in ASP.NET Core

If you are hosting on IIS, one possible reason is you are getting this is because IIS is blocking OPTIONS verb. I spent almost an hour because of this:

One telltale indication is you are getting 404 error during OPTIONS request.

To fix this, you need to explicitly tell IIS not to block OPTIONS request.

Go to Request Filtering:

IIS Request Filtering

Make sure OPTIONS is allowed:

Make sure OPTIONS is True

Or, just create a web.config with the following setting:

                <remove verb="OPTIONS" />
                <add verb="OPTIONS" allowed="true" />

Original purpose of <input type="hidden">?

The values of form elements including type='hidden' are submitted to the server when the form is posted. input type="hidden" values are not visible in the page. Maintaining User IDs in hidden fields, for example, is one of the many uses.

SO uses a hidden field for the upvote click.

<input value="16293741" name="postId" type="hidden">

Using this value, the server-side script can store the upvote.

converting numbers in to words C#

public static string NumberToWords(int number)
    if (number == 0)
        return "zero";

    if (number < 0)
        return "minus " + NumberToWords(Math.Abs(number));

    string words = "";

    if ((number / 1000000) > 0)
        words += NumberToWords(number / 1000000) + " million ";
        number %= 1000000;

    if ((number / 1000) > 0)
        words += NumberToWords(number / 1000) + " thousand ";
        number %= 1000;

    if ((number / 100) > 0)
        words += NumberToWords(number / 100) + " hundred ";
        number %= 100;

    if (number > 0)
        if (words != "")
            words += "and ";

        var unitsMap = new[] { "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten", "eleven", "twelve", "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "eighteen", "nineteen" };
        var tensMap = new[] { "zero", "ten", "twenty", "thirty", "forty", "fifty", "sixty", "seventy", "eighty", "ninety" };

        if (number < 20)
            words += unitsMap[number];
            words += tensMap[number / 10];
            if ((number % 10) > 0)
                words += "-" + unitsMap[number % 10];

    return words;

How to remove all debug logging calls before building the release version of an Android app?

This is how I solve it in my Kotlin Project before going to production:

buildTypes {
        release {
            minifyEnabled true
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), ''

-assumenosideeffects class android.util.Log {
    public static boolean isLoggable(java.lang.String, int);
    public static int d(...);
    public static int w(...);
    public static int v(...);
    public static int i(...);
    public static int e(...);

How to import a SQL Server .bak file into MySQL?

I did not manage to find a way to do it directly.

Instead I imported the bak file into SQL Server 2008 Express, and then used MySQL Migration Toolkit.

Worked like a charm!

C# Inserting Data from a form into an access Database

This answer will help in case, If you are working with Data Bases then mostly take the help of try-catch block statement, which will help and guide you with your code. Here i am showing you that how to insert some values in Data Base with a Button Click Event.

 private void button2_Click(object sender, EventArgs e)
        System.Data.OleDb.OleDbConnection conn = new System.Data.OleDb.OleDbConnection();
        conn.ConnectionString = @"Provider=Microsoft.ACE.OLEDB.12.0;" +
    @"Data source= C:\Users\pir fahim shah\Documents\TravelAgency.accdb";

           String ticketno=textBox1.Text.ToString();                 
           String Purchaseprice=textBox2.Text.ToString();
           String sellprice=textBox3.Text.ToString();
           String my_querry = "INSERT INTO Table1(TicketNo,Sellprice,Purchaseprice)VALUES('"+ticketno+"','"+sellprice+"','"+Purchaseprice+"')";

            OleDbCommand cmd = new OleDbCommand(my_querry, conn);

            MessageBox.Show("Data saved successfuly...!");
         catch (Exception ex)
             MessageBox.Show("Failed due to"+ex.Message);

Sending email with PHP from an SMTP server

In cases where you are hosting a Wordpress site on Linux and have server access you can save some headaches by installing msmtp which allows you to send via smtp from the standard php mail() function. msmtp is a simpler alternative to postfix which requires a bit more configuration.

Here are the steps:

Install msmtp

sudo apt-get install msmtp-mta ca-certificates

Create a new configuration file:

sudo nano /etc/msmtprc

...with the following configuration information:

# Set defaults.    

# Enable or disable TLS/SSL encryption.
tls on
tls_starttls on
tls_trust_file /etc/ssl/certs/ca-certificates.crt

# Set up a default account's settings.
account default
host <>
port 587
auth on
user <[email protected]>
password <password>
from <[email protected]>
syslog LOG_MAIL

You need to replace the configuration data represented by everything within "<" and ">" (inclusive, remove these). For host/username/password, use your normal credentials for sending mail through your mail provider.

Tell PHP to use it

sudo nano /etc/php5/apache2/php.ini

Add this single line:

sendmail_path = /usr/bin/msmtp -t

Complete documention can be found here:

Inner Joining three tables

try this:

JOIN TableB ON TableA.primary_key = TableB.foreign_key 
JOIN TableB ON TableB.foreign_key = TableC.foreign_key

Install apps silently, with granted INSTALL_PACKAGES permission

An 3rd party application cannot install an Android App sliently. However, a 3rd party application can ask the Android OS to install a application.

So you should define this:

Intent intent = new Intent(Intent.ACTION_VIEW);
intent.setDataAndType(Uri.parse("file:///sdcard/app.apk", "application/");

You can also try to install it as a system app to grant the permission and ignore this define. (Root Required)

You can run the following command on your 3rd party app to install an app on the rooted device.

The code is:

private void installApk(String filename) {
File file = new File(filename); 
    try {   
        final String command = "pm install -r " + file.getAbsolutePath();
        Process proc = Runtime.getRuntime().exec(new String[] { "su", "-c", command });
    } catch (Exception e) {

I hope that this answer is helpful for you.