Programs & Examples On #Jquery attributes

jQuery .attr("disabled", "disabled") not working in Chrome

My issue with this was that the element using the disabled attr needed to be defined as a form element, .ie input type for it to work. Both worked with attr() and prop() but chose the latter for future maintainability.

How can I select all children of an element except the last child?

Using nick craver's solution with selectivizr allows for a cross browser solution (IE6+)

How do I find an array item with TypeScript? (a modern, easier way)

Playing with the tsconfig.json You can also targeting es5 like this :

    "compilerOptions": {
        "experimentalDecorators": true,
        "module": "commonjs", 
        "target": "es5"

How can I catch a ctrl-c event?

Yeah, this is a platform dependent question.

If you are writing a console program on POSIX, use the signal API (#include <signal.h>).

In a WIN32 GUI application you should handle the WM_KEYDOWN message.

Which is the default location for keystore/truststore of Java applications?

In Java, according to the JSSE Reference Guide, there is no default for the keystore, the default for the truststore is "jssecacerts, if it exists. Otherwise, cacerts".

A few applications use ~/.keystore as a default keystore, but this is not without problems (mainly because you might not want all the application run by the user to use that trust store).

I'd suggest using application-specific values that you bundle with your application instead, it would tend to be more applicable in general.

postgresql return 0 if returned value is null

(this answer was added to provide shorter and more generic examples to the question - without including all the case-specific details in the original question).

There are two distinct "problems" here, the first is if a table or subquery has no rows, the second is if there are NULL values in the query.

For all versions I've tested, postgres and mysql will ignore all NULL values when averaging, and it will return NULL if there is nothing to average over. This generally makes sense, as NULL is to be considered "unknown". If you want to override this you can use coalesce (as suggested by Luc M).

$ create table foo (bar int);

$ select avg(bar) from foo;

(1 row)

$ select coalesce(avg(bar), 0) from foo;
(1 row)

$ insert into foo values (3);
$ insert into foo values (9);
$ insert into foo values (NULL);
$ select coalesce(avg(bar), 0) from foo;
(1 row)

of course, "from foo" can be replaced by "from (... any complicated logic here ...) as foo"

Now, should the NULL row in the table be counted as 0? Then coalesce has to be used inside the avg call.

$ select coalesce(avg(coalesce(bar, 0)), 0) from foo;
(1 row)

How to fix 'android.os.NetworkOnMainThreadException'?

You have to simple add following line in manifest.xml after manifest tag

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

and in activity file add following code after binding statement

if (android.os.Build.VERSION.SDK_INT > 9) {
   StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();

Convert JavaScript string in dot notation into an object reference

You can use the library available at npm, which simplifies this process.

 var dot = require('dot-object');

var obj = {
 some: {
   nested: {
     value: 'Hi there!'

var val = dot.pick('some.nested.value', obj);

// Result: Hi there!

String.equals() with multiple conditions (and one action on result)


  • Use String.equals():

    if (some_string.equals("john") ||
        some_string.equals("mary") ||
  • Use a regular expression:

    if (some_string.matches("john|mary|peter"))
  • Store a list of strings to be matched against in a Collection and search the collection:

    Set<String> names = new HashSet<String>();
    if (names.contains(some_string))

Loop through all the resources in a .resx file

Using LINQ to SQL:

        .Where(_ => _.Name == "data")
        .Select(_ => $"{ _.Attributes().First(a => a.Name == "name").Value} - {_.Value}");

Python 2.6: Class inside a Class?

I think you are confusing objects and classes. A class inside a class looks like this:

class Foo(object):
    class Bar(object):

>>> foo = Foo()
>>> bar = Foo.Bar()

But it doesn't look to me like that's what you want. Perhaps you are after a simple containment hierarchy:

class Player(object):
    def __init__(self, ... airplanes ...) # airplanes is a list of Airplane objects
        self.airplanes = airplanes

class Airplane(object):
    def __init__(self, ... flights ...) # flights is a list of Flight objects
        ... = flights

class Flight(object):
    def __init__(self, ... duration ...)
        self.duration = duration

Then you can build and use the objects thus:

player = Player(...[
    Airplane(... [
        ] ... ),

player.airplanes[5].flights[6].duration = 5

Adding a leading zero to some values in column in MySQL

A previous answer using LPAD() is optimal. However, in the event you want to do special or advanced processing, here is a method that allows more iterative control over the padding. Also serves as an example using other constructs to achieve the same thing.

    mycolumn = CONCAT(
            8 - LENGTH(mycolumn)
    LENGTH(mycolumn) < 8;

Setting up JUnit with IntelliJ IDEA

I needed to enable the JUnit plugin, after I linked my project with the jar files.

To enable the JUnit plugin, go to File->Settings, type "JUnit" in the search bar, and under "Plugins," check "JUnit.

vikingsteve's advice above will probably get the libraries linked right. Otherwise, open File->Project Structure, go to Libraries, hit the plus, and then browse to

C:\Program Files (x86)\JetBrains\IntelliJ IDEA Community Edition 14.1.1\lib\

and add these jar files:


How to change text color of cmd with windows batch script every 1 second

Try this command:

@echo off
color 0
color 1
color 2
color 3
color 4
color 5
color 6
color 8
color 9
color A
color B
color C
color D
color E
goto loop

This should create color changing text go in a loop.
Edit: You can change the words rainbow to whatever you want.

How can I print out all possible letter combinations a given phone number can represent?

Scala solution:

def mnemonics(phoneNum: String, dict: IndexedSeq[String]): Iterable[String] = {
  def mnemonics(d: Int, prefix: String): Seq[String] = {
    if (d >= phoneNum.length) {
    } else {
      for {
        ch <- dict(phoneNum.charAt(d).asDigit)
        num <- mnemonics(d + 1, s"$prefix$ch")
      } yield num

  mnemonics(0, "")

Assuming each digit maps to at most 4 characters, the number of recursive calls T satisfy the inequality T(n) <= 4T(n-1), which is of the order 4^n.

Remove leading zeros from a number in Javascript


"014".replace(/^0+/, '')

How can I stop "property does not exist on type JQuery" syntax errors when using Typescript?

I think this is the most readable solution:

($("div.printArea") as any).printArea();

How do I clone a generic List in Java?

This should also work:

ArrayList<String> orig = new ArrayList<String>();
ArrayList<String> copy = (ArrayList<String>) orig.clone()

How do I solve the "server DNS address could not be found" error on Windows 10?

Steps to manually configure DNS:

  1. You can access Network and Sharing center by right clicking on the Network icon on the taskbar.

  2. Now choose adapter settings from the side menu.

  3. This will give you a list of the available network adapters in the system . From them right click on the adapter you are using to connect to the internet now and choose properties option.

  4. In the networking tab choose ‘Internet Protocol Version 4 (TCP/IPv4)’.

  5. Now you can see the properties dialogue box showing the properties of IPV4. Here you need to change some properties.

    Select ‘use the following DNS address’ option. Now fill the following fields as given here.

    Preferred DNS server:

    Alternate DNS server :

    This is an available Open DNS address. You may also use google DNS server addresses.

    After filling these fields. Check the ‘validate settings upon exit’ option. Now click OK.

You have to add this DNS server address in the router configuration also (by referring the router manual for more information).

Refer : for above method & alternative

If none of this works, then open command prompt(Run as Administrator) and run these:

ipconfig /flushdns
ipconfig /registerdns
ipconfig /release
ipconfig /renew
NETSH winsock reset catalog
NETSH int ipv4 reset reset.log
NETSH int ipv6 reset reset.log

Hopefully that fixes it, if its still not fixed there is a chance that its a NIC related issue(driver update or h/w).

Also FYI, this has a thread on Microsoft community : Windows 10 - DNS Issue

Can you disable tabs in Bootstrap?

Here's my attempt. To disable a tab:

  1. Add "disabled" class to tab's LI;
  2. Remove 'data-toggle' attribute from LI > A;
  3. Suppress 'click' event on LI > A.


var toggleTabs = function(state) {
    disabledTabs = ['#tab2', '#tab3'];
    $.each(disabledTabs, $.proxy(function(idx, tabSelector) {
        tab = $(tabSelector);
        if (tab.length) {
            if (state) {
                // Enable tab click.
                $(tab).toggleClass('disabled', false);
                $('a', tab).attr('data-toggle', 'tab').off('click');
            } else {
                // Disable tab click.
                $(tab).toggleClass('disabled', true);
                $('a', tab).removeAttr('data-toggle').on('click', function(e){
    }, this));
};, true);

Cutting the videos based on start and end time using ffmpeg

    ffmpeg -i movie.mp4 -vf trim=3:8 cut.mp4

Drop everything except from second 3 to second 8.

Razor View Engine : An expression tree may not contain a dynamic operation

It seems to me that you have an untyped view. By default, Razor views in MVC3 RC are typed as dynamic. However, lambdas do not support dynamic members. You have to strongly type your model. At the top of your view file add

@model SampleModel

How to get the system uptime in Windows?

I use this little PowerShell snippet:

function Get-SystemUptime {
    $operatingSystem = Get-WmiObject Win32_OperatingSystem
    "$((Get-Date) - ([Management.ManagementDateTimeConverter]::ToDateTime($operatingSystem.LastBootUpTime)))"

which then yields something like the following:

PS> Get-SystemUptime

Laravel blank white screen

Got this from the Laravel forums, but if you recently upgraded Laravel versions AND PHP versions AND are running nginx, make sure you have changed your nginx configuration file to reflect the new PHP version. For instance:

In your nginx site config file (here: /etc/nginx/sites-available), change

fastcgi_pass unix:/var/run/php5-fpm.sock;


fastcgi_pass unix:/var/run/php/php5.6-fpm.sock;

CSS endless rotation animation

@-webkit-keyframes rotating /* Safari and Chrome */ {_x000D_
  from {_x000D_
    -webkit-transform: rotate(0deg);_x000D_
    -o-transform: rotate(0deg);_x000D_
    transform: rotate(0deg);_x000D_
  to {_x000D_
    -webkit-transform: rotate(360deg);_x000D_
    -o-transform: rotate(360deg);_x000D_
    transform: rotate(360deg);_x000D_
@keyframes rotating {_x000D_
  from {_x000D_
    -ms-transform: rotate(0deg);_x000D_
    -moz-transform: rotate(0deg);_x000D_
    -webkit-transform: rotate(0deg);_x000D_
    -o-transform: rotate(0deg);_x000D_
    transform: rotate(0deg);_x000D_
  to {_x000D_
    -ms-transform: rotate(360deg);_x000D_
    -moz-transform: rotate(360deg);_x000D_
    -webkit-transform: rotate(360deg);_x000D_
    -o-transform: rotate(360deg);_x000D_
    transform: rotate(360deg);_x000D_
.rotating {_x000D_
  -webkit-animation: rotating 2s linear infinite;_x000D_
  -moz-animation: rotating 2s linear infinite;_x000D_
  -ms-animation: rotating 2s linear infinite;_x000D_
  -o-animation: rotating 2s linear infinite;_x000D_
  animation: rotating 2s linear infinite;_x000D_
<div _x000D_
  style="width: 100px; height: 100px; line-height: 100px; text-align: center;" _x000D_

Removing the textarea border in HTML

Add this to your <head>:

<style type="text/css">
    textarea { border: none; }

Or do it directly on the textarea:

<textarea style="border: none"></textarea>

How to use phpexcel to read data and insert into database?

In order to read data from microsoft excel 2007 by codeigniter just create a helper function excel_helper.php and add the following in:

      require_once APPPATH.'libraries/phpexcel/PHPExcel.php';
      require_once APPPATH.'libraries/phpexcel/PHPExcel/IOFactory.php';
      in controller add the following code to read spread sheet by active sheet
     //initialize php excel first  
     //define cachemethod
     $cacheMethod   = PHPExcel_CachedObjectStorageFactory::cache_to_phpTemp;
     $cacheSettings = array('memoryCacheSize' => '20MB');
     //set php excel settings

    $arrayLabel = array("A","B","C","D","E");
    //=== set object reader
    $objectReader = PHPExcel_IOFactory::createReader('Excel2007');

    $objPHPExcel = $objectReader->load("./forms/test.xlsx");
    $objWorksheet = $objPHPExcel->setActiveSheetIndexbyName('Sheet1');

    $starting = 1;
    $end      = 3;
    for($i = $starting;$i<=$end; $i++)

           //== display each cell value
           echo $objWorksheet->getCell($arrayLabel[$j].$i)->getValue();
     //or dump data
     $sheetData = $objPHPExcel->getActiveSheet()->toArray(null,true,true,true);

     //see also the following link
     ----------- import in another style around 5000 records ------
    //=== change php ini limits. =====
    $cacheMethod = PHPExcel_CachedObjectStorageFactory:: cache_to_phpTemp;
    $cacheSettings = array( ' memoryCacheSize ' => '50MB');
    PHPExcel_Settings::setCacheStorageMethod($cacheMethod, $cacheSettings);
    //==== create excel object of reader
    $objReader = PHPExcel_IOFactory::createReader('Excel2007');
    //==== load forms tashkil where the file exists
    $objPHPExcel = $objReader->load("./forms/5000records.xlsx");
    //==== set active sheet to read data
    $worksheet  = $objPHPExcel->setActiveSheetIndexbyName('Sheet1');

    $highestRow         = $worksheet->getHighestRow(); // e.g. 10
    $highestColumn      = $worksheet->getHighestColumn(); // e.g 'F'
    $highestColumnIndex = PHPExcel_Cell::columnIndexFromString($highestColumn);
    $nrColumns          = ord($highestColumn) - 64;
    $worksheetTitle     = $worksheet->getTitle();

    echo "<br>The worksheet ".$worksheetTitle." has ";
    echo $nrColumns . ' columns (A-' . $highestColumn . ') ';
    echo ' and ' . $highestRow . ' row.';
    echo '<br>Data: <table border="1"><tr>';
    //----- loop from all rows -----
    for ($row = 1; $row <= $highestRow; ++ $row) 
        echo '<tr>';
        echo "<td>".$row."</td>";
        //--- read each excel column for each row ----
        for ($col = 0; $col < $highestColumnIndex; ++ $col) 
            if($row == 1)
                // show column name with the title
                 //----- get value ----
                $cell = $worksheet->getCellByColumnAndRow($col, $row);
                $val = $cell->getValue();
                //$dataType = PHPExcel_Cell_DataType::dataTypeForValue($val);
                echo '<td>' . $val ."(".$row." X ".$col.")".'</td>';
                if($col == 9)
                    //----- get value ----
                    $cell = $worksheet->getCellByColumnAndRow($col, $row);
                    $val = $cell->getValue();
                    //$dataType = PHPExcel_Cell_DataType::dataTypeForValue($val);
                    echo '<td>zone ' . $val .'</td>';
                else if($col == 13)
                    $date = PHPExcel_Shared_Date::ExcelToPHPObject($worksheet->getCellByColumnAndRow($col, $row)->getValue())->format('Y-m-d');
                    echo '<td>' .dateprovider($date,'dr') .'</td>';
                     //----- get value ----
                    $cell = $worksheet->getCellByColumnAndRow($col, $row);
                    $val = $cell->getValue();
                    //$dataType = PHPExcel_Cell_DataType::dataTypeForValue($val);
                    echo '<td>' . $val .'</td>';
        echo '</tr>';
    echo '</table>';

    echo "Total time:".$this->benchmark->elapsed_time('code_start', 'code_end');     

Reading a registry key in C#

string InstallPath = (string)Registry.GetValue(@"HKEY_LOCAL_MACHINE\SOFTWARE\MyApplication\AppPath", "Installed", null);    
if (InstallPath != null)
    // Do stuff

That code should get your value. You'll need to be

using Microsoft.Win32;

for that to work though.

creating triggers for After Insert, After Update and After Delete in SQL

(Update: overlooked a fault in the matter, I have corrected)

(Update2: I wrote from memory the code screwed up, repaired it)

(Update3: check on SQLFiddle)

create table Derived_Values
    BusinessUnit nvarchar(100) not null
    ,Questions nvarchar(100) not null
    ,Answer nvarchar(100)


ALTER TABLE Derived_Values ADD CONSTRAINT PK_Derived_Values
PRIMARY KEY CLUSTERED (BusinessUnit, Questions);

create table Derived_Values_Test
    BusinessUnit nvarchar(150)
    ,Questions nvarchar(100)
    ,Answer nvarchar(100)


CREATE TRIGGER trgAfterUpdate ON  [Derived_Values]
    declare @BusinessUnit nvarchar(50)
    set @BusinessUnit = 'Updated Record -- After Update Trigger.'

    insert into 
        --(BusinessUnit,Questions, Answer) 
        @BusinessUnit + i.BusinessUnit, i.Questions, i.Answer
        inserted i
        inner join deleted d on i.BusinessUnit = d.BusinessUnit


CREATE TRIGGER trgAfterDelete ON  [Derived_Values]
    declare @BusinessUnit nvarchar(50)
    set @BusinessUnit = 'Deleted Record -- After Delete Trigger.'

    insert into 
        --(BusinessUnit,Questions, Answer) 
        @BusinessUnit + d.BusinessUnit, d.Questions, d.Answer
        deleted d


insert Derived_Values (BusinessUnit,Questions, Answer) values ('BU1', 'Q11', 'A11')
insert Derived_Values (BusinessUnit,Questions, Answer) values ('BU1', 'Q12', 'A12')
insert Derived_Values (BusinessUnit,Questions, Answer) values ('BU2', 'Q21', 'A21')
insert Derived_Values (BusinessUnit,Questions, Answer) values ('BU2', 'Q22', 'A22')

UPDATE Derived_Values SET Answer='Updated Answers A11' from Derived_Values WHERE (BusinessUnit = 'BU1') AND (Questions = 'Q11');
UPDATE Derived_Values SET Answer='Updated Answers A12' from Derived_Values WHERE (BusinessUnit = 'BU1') AND (Questions = 'Q12');
UPDATE Derived_Values SET Answer='Updated Answers A21' from Derived_Values WHERE (BusinessUnit = 'BU2') AND (Questions = 'Q21');
UPDATE Derived_Values SET Answer='Updated Answers A22' from Derived_Values WHERE (BusinessUnit = 'BU2') AND (Questions = 'Q22');

delete Derived_Values;

and then:

SELECT * FROM Derived_Values;

select * from Derived_Values_Test;

Record Count: 0;

Updated Record -- After Update Trigger.BU1  Q11 Updated Answers A11
Deleted Record -- After Delete Trigger.BU1  Q11 A11
Updated Record -- After Update Trigger.BU1  Q12 Updated Answers A12
Deleted Record -- After Delete Trigger.BU1  Q12 A12
Updated Record -- After Update Trigger.BU2  Q21 Updated Answers A21
Deleted Record -- After Delete Trigger.BU2  Q21 A21
Updated Record -- After Update Trigger.BU2  Q22 Updated Answers A22
Deleted Record -- After Delete Trigger.BU2  Q22 A22

(Update4: If you want to sync: SQLFiddle)

create table Derived_Values
    BusinessUnit nvarchar(100) not null
    ,Questions nvarchar(100) not null
    ,Answer nvarchar(100)


ALTER TABLE Derived_Values ADD CONSTRAINT PK_Derived_Values
PRIMARY KEY CLUSTERED (BusinessUnit, Questions);

create table Derived_Values_Test
    BusinessUnit nvarchar(150) not null
    ,Questions nvarchar(100) not null
    ,Answer nvarchar(100)


ALTER TABLE Derived_Values_Test ADD CONSTRAINT PK_Derived_Values_Test
PRIMARY KEY CLUSTERED (BusinessUnit, Questions);

CREATE TRIGGER trgAfterInsert ON  [Derived_Values]
        i.BusinessUnit, i.Questions, i.Answer
        inserted i


CREATE TRIGGER trgAfterUpdate ON  [Derived_Values]
    declare @BusinessUnit nvarchar(50)
    set @BusinessUnit = 'Updated Record -- After Update Trigger.'

        --BusinessUnit = i.BusinessUnit
        --,Questions = i.Questions
        Answer = i.Answer
        inner join inserted i 
        [Derived_Values].BusinessUnit = i.BusinessUnit
        [Derived_Values].Questions = i.Questions


CREATE TRIGGER trgAfterDelete ON  [Derived_Values]
        inner join deleted d 
        [Derived_Values_Test].BusinessUnit = d.BusinessUnit
        [Derived_Values_Test].Questions = d.Questions


insert Derived_Values (BusinessUnit,Questions, Answer) values ('BU1', 'Q11', 'A11')
insert Derived_Values (BusinessUnit,Questions, Answer) values ('BU1', 'Q12', 'A12')
insert Derived_Values (BusinessUnit,Questions, Answer) values ('BU2', 'Q21', 'A21')
insert Derived_Values (BusinessUnit,Questions, Answer) values ('BU2', 'Q22', 'A22')

UPDATE Derived_Values SET Answer='Updated Answers A11' from Derived_Values WHERE (BusinessUnit = 'BU1') AND (Questions = 'Q11');
UPDATE Derived_Values SET Answer='Updated Answers A12' from Derived_Values WHERE (BusinessUnit = 'BU1') AND (Questions = 'Q12');
UPDATE Derived_Values SET Answer='Updated Answers A21' from Derived_Values WHERE (BusinessUnit = 'BU2') AND (Questions = 'Q21');
UPDATE Derived_Values SET Answer='Updated Answers A22' from Derived_Values WHERE (BusinessUnit = 'BU2') AND (Questions = 'Q22');

--delete Derived_Values;

And then:

SELECT * FROM Derived_Values;

select * from Derived_Values_Test;

BU1 Q11 Updated Answers A11
BU1 Q12 Updated Answers A12
BU2 Q21 Updated Answers A21
BU2 Q22 Updated Answers A22

BU1 Q11 Updated Answers A11
BU1 Q12 Updated Answers A12
BU2 Q21 Updated Answers A21
BU2 Q22 Updated Answers A22

How to use global variables in React Native?

The way you should be doing it in React Native (as I understand it), is by saving your 'global' variable in your index.js, for example. From there you can then pass it down using props.


    class MainComponent extends Component {

        componentDidMount() {
            //Define some variable in your component
            this.variable = "What's up, I'm a variable";
        render () {
                renderScene={(() => {
                                //Pass the variable you want to be global through here

    class SceneComponent extends Component {

        render() {


How do you connect to a MySQL database using Oracle SQL Developer?

My experience with windows client and linux/mysql server:

When sqldev is used in a windows client and mysql is installed in a linux server meaning, sqldev network access to mysql.

Assuming mysql is already up and running and the databases to be accessed are up and functional:

• Ensure the version of sqldev (32 or 64). If 64 and to avoid dealing with path access copy a valid 64 version of msvcr100.dll into directory ~\sqldeveloper\jdev\bin.

a. Open the file msvcr100.dll in notepad and search for first occurrence of “PE “

 i. “PE  d” it is 64.

ii. “PE  L” it is 32.

b. Note: if sqldev is 64 and msvcr100.dll is 32, the application gets stuck at startup.

• For sqldev to work with mysql there is need of the JDBC jar driver. Download it from mysql site.

a. Driver name = mysql-connector-java-x.x.xx

b. Copy it into someplace related to your sqldeveloper directory.

c. Set it up in menu sqldev Tools/Preferences/Database/Third Party JDBC Driver (add entry)

• In Linux/mysql server change file /etc/mysql/mysql.conf.d/mysqld.cnf look for

bind-address = (this linux localhost)

and change to

bind-address = (this linux server real IP or machine name if DNS is up)

• Enter to linux mysql and grant needed access for example

# mysql –u root -p

GRANT ALL ON . to root@'yourWindowsClientComputerName' IDENTIFIED BY 'mysqlPasswd';

flush privileges;

restart mysql - sudo /etc/init.d/mysql restart

• Start sqldev and create a new connection

a. user = root

b. pass = (your mysql pass)

c. Choose MySql tab

 i.   Hostname = the linux IP hostname

 ii.  Port     = 3306 (default for mysql)

 iii. Choose Database = (from pull down the mysql database you want to use)

 iv.  save and connect

That is all I had to do in my case.

Thank you,


How do you add an SDK to Android Studio?

You can change from the "build.gradle" file the line:

compileSdkVersion 18

to the sdk that you want to be used.

Context.startForegroundService() did not then call Service.startForeground()

Even after calling the startForeground in Service, It crashes on some devices if we call stopService just before onCreate is called. So, I fixed this issue by Starting the service with an additional flag:

Intent intent = new Intent(context, YourService.class);
intent.putExtra("request_stop", true);

and added a check in onStartCommand to see if it was started to stop:

public int onStartCommand(Intent intent, int flags, int startId) {
    //call startForeground first
    if (intent != null) {
        boolean stopService = intent.getBooleanExtra("request_stop", false);
        if (stopService) {

    //Continue with the background task
    return START_STICKY;

P.S. If the service were not running, it would start the service first, which is an overhead.

Angularjs dynamic ng-pattern validation

This is an interesting problem, complex Angular validation. The following fiddle implements what you want:


I created a new directive, rpattern, that is a mix of Angular's ng-required and the ng-pattern code from input[type=text]. What it does is watch the required attribute of the field and take that into account when validating with regexp, i.e. if not required mark field as valid-pattern.


  • Most of the code is from Angular, tailored to the needs of this.
  • When the checkbox is checked, the field is required.
  • The field is not hidden when the required checkbox is false.
  • The regular expression is simplified for the demo (valid is 3 digits).

A dirty (but smaller) solution, if you do not want a new directive, would be something like:

$scope.phoneNumberPattern = (function() {
    var regexp = /^\(?(\d{3})\)?[ .-]?(\d{3})[ .-]?(\d{4})$/;
    return {
        test: function(value) {
            if( $scope.requireTel === false ) {
                return true;
            return regexp.test(value);

And in HTML no changes would be required:

<input type="text" ng-model="..." ng-required="requireTel"
    ng-pattern="phoneNumberPattern" />

This actually tricks angular into calling our test() method, instead of RegExp.test(), that takes the required into account.

Html.fromHtml deprecated in Android N

I had a lot of these warnings and I always use FROM_HTML_MODE_LEGACY so I made a helper class called HtmlCompat containing the following:

   public static Spanned fromHtml(String source) {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
            return Html.fromHtml(source, Html.FROM_HTML_MODE_LEGACY);
        } else {
            return Html.fromHtml(source);

How to get number of rows using SqlDataReader in C#

If you do not need to retrieve all the row and want to avoid to make a double query, you can probably try something like that:

using (var sqlCon = new SqlConnection("Server=;Database=MyDb;User Id=Me;Password=glop;"))

        var com = sqlCon.CreateCommand();
        com.CommandText = "select * from BigTable";
        using (var reader = com.ExecuteReader())
            //here you retrieve what you need

        com.CommandText = "select @@ROWCOUNT";
        var totalRow = com.ExecuteScalar();


You may have to add a transaction not sure if reusing the same command will automatically add a transaction on it...

How to Convert a Text File into a List in Python


crimefile = open(fileName, 'r')
yourResult = [line.split(',') for line in crimefile.readlines()]

If "0" then leave the cell blank

An example of an IF Statement that can be used to add a calculation into the cell you wish to hide if value = 0 but displayed upon another cell value reference.

=IF(/Your reference cell/=0,"",SUM(/Here you put your SUM/))

sql: check if entry in table A exists in table B

This also works

FROM tableB

Disabling Strict Standards in PHP 5.4

If you would need to disable E_DEPRACATED also, use:

php_value error_reporting 22527

In my case CMS Made Simple was complaining "E_STRICT is enabled in the error_reporting" as well as "E_DEPRECATED is enabled". Adding that one line to .htaccess solved both misconfigurations.

How to use custom packages

For this kind of folder structure:


The simplest way is to use this:

import (

How can I specify a local gem in my Gemfile?

You can also reference a local gem with git if you happen to be working on it.

gem 'foo',
  :git => '/Path/to/local/git/repo',
  :branch => 'my-feature-branch'

Then, if it changes I run

bundle exec gem uninstall foo
bundle update foo

But I am not sure everyone needs to run these two steps.

How can I build a recursive function in python?

Recursive function example:

def recursive(string, num):
    print "#%s - %s" % (string, num)
    recursive(string, num+1)

Run it with:

recursive("Hello world", 0)

Access a JavaScript variable from PHP

I'm looking at this and thinking, if you can only get variables into php in a form, why not just make a form and put a hidden input in the thing so it doesn't show on screen, and then put the value from your javascript into the hidden input and POST that into the php? It would sure be a lot less hassle than some of this other stuff right?

HTML.ActionLink vs Url.Action in ASP.NET Razor

@HTML.ActionLink generates a HTML anchor tag. While @Url.Action generates a URL for you. You can easily understand it by;

// 1. <a href="/ControllerName/ActionMethod">Item Definition</a>
@HTML.ActionLink("Item Definition", "ActionMethod", "ControllerName")

// 2. /ControllerName/ActionMethod
@Url.Action("ActionMethod", "ControllerName")

// 3. <a href="/ControllerName/ActionMethod">Item Definition</a>
<a href="@Url.Action("ActionMethod", "ControllerName")"> Item Definition</a>

Both of these approaches are different and it totally depends upon your need.

How to remove an element from a list by index

Use the del statement:

del listName[-N]

For example, if you want to remove the last 3 items, your code should be:

del listName[-3:]

For example, if you want to remove the last 8 items, your code should be:

del listName[-8:]

draw diagonal lines in div background with CSS

Here is how I did this using the css clip-path property alongside relative and absolute positioning to create a more fancy cross.

.cross {_x000D_
  height: 150px;_x000D_
  border: 2px solid #555;_x000D_
  border-radius: 5px;_x000D_
  position: relative;_x000D_
  background: #efefef;_x000D_
.cross .diag1{_x000D_
  position: absolute;_x000D_
  width:100%; height:100%;_x000D_
  clip-path: polygon(90% 0, 100% 0%, 10% 100%, 0% 100%);_x000D_
  background: #311B92;_x000D_
.cross .diag2{_x000D_
  position: absolute;_x000D_
  width:100%; height:100%;_x000D_
  clip-path: polygon(0 0, 10% 0, 100% 100%, 90% 100%);_x000D_
  background: #1B5E20;_x000D_
<div class="cross">_x000D_
  <div class="diag1"></div>_x000D_
  <div class="diag2"></div>_x000D_

Here is a link to the code on codepen if you'd like to tweak it.

Displaying standard DataTables in MVC

While I tried the approach above, it becomes a complete disaster with mvc. Your controller passing a model and your view using a strongly typed model become too difficult to work with.

Get your Dataset into a List ..... I have a repository pattern and here is an example of getting a dataset from an old school asmx web service private readonly CISOnlineSRVDEV.ServiceSoapClient _ServiceSoapClient;

    public Get_Client_Repository()
        : this(new CISOnlineSRVDEV.ServiceSoapClient())

    public Get_Client_Repository(CISOnlineSRVDEV.ServiceSoapClient serviceSoapClient)
        _ServiceSoapClient = serviceSoapClient;

    public IEnumerable<IClient> GetClient(IClient client)
        // ****  Calling teh web service with passing in the clientId and returning a dataset
        DataSet dataSet = _ServiceSoapClient.get_clients(client.RbhaId,
                                                        "");//client.BirthDate.ToString());  //TODO: NEED TO FIX

        // USE LINQ to go through the dataset to make it easily available for the Model to display on the View page
        List<IClient> clients = (from c in dataSet.Tables[0].AsEnumerable()
                                 select new Client()
                                     RbhaId = c[5].ToString(),
                                     ClientId = c[2].ToString(),
                                     AhcccsId = c[6].ToString(),
                                     LastName = c[0].ToString(), // Add another field called   Sex M/F  c[4]
                                     FirstName = c[1].ToString(),
                                     BirthDate = c[3].ToDateTime()  //extension helper  ToDateTime()

        return clients;


Then in the Controller I'm doing this

IClient client = (IClient)TempData["Client"];

// Instantiate and instance of the repository 
var repository = new Get_Client_Repository();
// Set a model object to return the dynamic list from repository method call passing in the parameter data
var model = repository.GetClient(client);

// Call the View up passing in the data from the list
return View(model);

Then in the View it is easy :

@model IEnumerable<CISOnlineMVC.DAL.IClient>



        <th>Last Name</th>
        <th>First Name</th>
        <th>Client ID</th>
        <th>RBHA ID</th>
        <th>AHCCCS ID</th>

@foreach (var item in Model) {
            @Html.ActionLink("Select", "ClientDetails", "Cis", new { id = item.ClientId }, null) |
            Gender @* ADD in*@


PersistentObjectException: detached entity passed to persist thrown by JPA and Hibernate

Remove cascading from the child entity Transaction, it should be just:

@Entity class Transaction {
    @ManyToOne // no cascading here!
    private Account account;

(FetchType.EAGER can be removed as well as it's the default for @ManyToOne)

That's all!

Why? By saying "cascade ALL" on the child entity Transaction you require that every DB operation gets propagated to the parent entity Account. If you then do persist(transaction), persist(account) will be invoked as well.

But only transient (new) entities may be passed to persist (Transaction in this case). The detached (or other non-transient state) ones may not (Account in this case, as it's already in DB).

Therefore you get the exception "detached entity passed to persist". The Account entity is meant! Not the Transaction you call persist on.

You generally don't want to propagate from child to parent. Unfortunately there are many code examples in books (even in good ones) and through the net, which do exactly that. I don't know, why... Perhaps sometimes simply copied over and over without much thinking...

Guess what happens if you call remove(transaction) still having "cascade ALL" in that @ManyToOne? The account (btw, with all other transactions!) will be deleted from the DB as well. But that wasn't your intention, was it?

How do you merge two Git repositories?

I had a similar challenge, but in my case, we had developed one version of the codebase in repo A, then cloned that into a new repo, repo B, for the new version of the product. After fixing some bugs in repo A, we needed to FI the changes into repo B. Ended up doing the following:

  1. Adding a remote to repo B that pointed to repo A (git remote add...)
  2. Pulling the current branch (we were not using master for bug fixes) (git pull remoteForRepoA bugFixBranch)
  3. Pushing merges to github

Worked a treat :)

How to pause javascript code execution for 2 seconds

There's no (safe) way to pause execution. You can, however, do something like this using setTimeout:

function writeNext(i)

    if(i == 5)

        writeNext(i + 1);

    }, 2000);


What is the difference between instanceof and Class.isAssignableFrom(...)?

instanceof can only be used with reference types, not primitive types. isAssignableFrom() can be used with any class objects:

a instanceof int  // syntax error
3 instanceof Foo  // syntax error
int.class.isAssignableFrom(int.class)  // true


How to test if a DataSet is empty?

If I understand correctly, this should work for you

if (ds.Tables[0].Rows.Count == 0)

How to mock void methods with Mockito

First of all: you should always import mockito static, this way the code will be much more readable (and intuitive):

import static org.mockito.Mockito.*;

For partial mocking and still keeping original functionality on the rest mockito offers "Spy".

You can use it as follows:

private World world = spy(new World());

To eliminate a method from being executed you could use something like this:


to give some custom behaviour to a method use "when" with an "thenReturn":


For more examples please find the excellent mockito samples in the doc.

Git - how delete file from remote repository

The easiest thing to do is to move the file from your local directory temporarily, then commit changes to your remote repo. Then add it back to your local repo, make sure to update .gitignore so it doesn't commit to remote again

How to get the <td> in HTML tables to fit content, and let a specific <td> fill in the rest

Define width of .absorbing-column

Set table-layout to auto and define an extreme width on .absorbing-column.

Here I have set the width to 100% because it ensures that this column will take the maximum amount of space allowed, while the columns with no defined width will reduce to fit their content and no further.

This is one of the quirky benefits of how tables behave. The table-layout: auto algorithm is mathematically forgiving.

You may even choose to define a min-width on all td elements to prevent them from becoming too narrow and the table will behave nicely.

table {_x000D_
    table-layout: auto;_x000D_
    border-collapse: collapse;_x000D_
    width: 100%;_x000D_
table td {_x000D_
    border: 1px solid #ccc;_x000D_
table .absorbing-column {_x000D_
    width: 100%;_x000D_
      <th>Column A</th>_x000D_
      <th>Column B</th>_x000D_
      <th>Column C</th>_x000D_
      <th class="absorbing-column">Column D</th>_x000D_
      <td>Data A.1 lorem</td>_x000D_
      <td>Data B.1 ip</td>_x000D_
      <td>Data C.1 sum l</td>_x000D_
      <td>Data D.1</td>_x000D_
      <td>Data A.2 ipsum</td>_x000D_
      <td>Data B.2 lorem</td>_x000D_
      <td>Data C.2 some data</td>_x000D_
      <td>Data D.2 a long line of text that is long</td>_x000D_
      <td>Data A.3</td>_x000D_
      <td>Data B.3</td>_x000D_
      <td>Data C.3</td>_x000D_
      <td>Data D.3</td>_x000D_

Get resultset from oracle stored procedure

    FOR c_invoice IN 
       SELECT CodeInvoice, NameClient FROM Invoice
       WHERE NameClient = p_nameClient
        dbms_output.put_line('Code Invoice: ' || c_invoice.CodeInvoice);
        dbms_output.put_line('Name Client : ' ||  c_invoice.NameClient );

Executing in SQL Developer:

    SP_Invoices('Perico de los palotes');
-- Or:
EXEC SP_Invoices('Perico de los palotes');


> Code Invoice: 1 
> Name Client : Perico de los palotes
> Code Invoice: 2 
> Name Client : Perico de los palotes

How do I return clean JSON from a WCF Service?

When you are using GET Method the contract must be this.

[WebGet(UriTemplate = "/", BodyStyle = WebMessageBodyStyle.Bare, ResponseFormat = WebMessageFormat.Json)]
List<User> Get();

with this we have a json without the boot parameter

Aldo Flores @alduar

How to show one layout on top of the other programmatically in my case?

FrameLayout is not the better way to do this:

Use RelativeLayout instead. You can position the elements anywhere you like. The element that comes after, has the higher z-index than the previous one (i.e. it comes over the previous one).


<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android=""
    android:layout_width="match_parent" android:layout_height="match_parent">

        android:text="This is a text."

enter image description here

Detect Safari browser

As other people have already noted, feature detection is preferred over checking for a specific browser. One reason is that the user agent string can be altered. Another reason is that the string may change and break your code in newer versions.

If you still want to do it and test for any Safari version, I'd suggest using this

var isSafari = navigator.vendor && navigator.vendor.indexOf('Apple') > -1 &&
               navigator.userAgent &&
               navigator.userAgent.indexOf('CriOS') == -1 &&
               navigator.userAgent.indexOf('FxiOS') == -1;

This will work with any version of Safari across all devices: Mac, iPhone, iPod, iPad.


To test in your current browser:

Edit 2

Updated according to Chrome docs to detect Chrome on iOS correctly

It's worth noting that all Browsers on iOS are just wrappers for Safari and use the same engine. See's comment on his own answer in this thread.

Edit 3

Updated according to Firefox docs to detect Firefox on iOS correctly

How to detect window.print() finish

This Actually worked for me in chrome. I was pretty suprised.

jQuery(document).bind("keyup keydown", function(e){
    if(e.ctrlKey && e.keyCode == 80){
         Print(); e.preventDefault();

Where Print is a function I wrote that calls window.print(); It also works as a pure blocker if you disable Print();

As noted here by user3017502

window.print() will pause so you can add an onPrintFinish or onPrintBegin like this

function Print(){

Laravel Eloquent get results grouped by days

You could also solve this problem in following way:

$totalView =  View::select(DB::raw('Date(read_at) as date'), DB::raw('count(*) as Views'))

Turn off axes in subplots

import matplotlib.pyplot as plt

fig, ax = plt.subplots(2, 2)

To turn off axes for all subplots, do either:

[axi.set_axis_off() for axi in ax.ravel()]


map(lambda axi: axi.set_axis_off(), ax.ravel())

".addEventListener is not a function" why does this error occur?

document.getElementsByClassName returns an array of elements. so may be you want to target a specific index of them: var comment = document.getElementsByClassName('button')[0]; should get you what you want.

Update #1:

var comments = document.getElementsByClassName('button');
var numComments = comments.length;

function showComment() {
  var place = document.getElementById('textfield');
  var commentBox = document.createElement('textarea');

for (var i = 0; i < numComments; i++) {
  comments[i].addEventListener('click', showComment, false);

Update #2: (with removeEventListener incorporated as well)

var comments = document.getElementsByClassName('button');
var numComments = comments.length;

function showComment(e) {
  var place = document.getElementById('textfield');
  var commentBox = document.createElement('textarea');
  for (var i = 0; i < numComments; i++) {
    comments[i].removeEventListener('click', showComment, false);

for (var i = 0; i < numComments; i++) {
  comments[i].addEventListener('click', showComment, false);

Multiple Buttons' OnClickListener() android

I had a similar issue and what I did is: Create a array of Buttons

Button buttons[] = new Button[10];

Then to implement on click listener and reference xml id's I used a loop like this

for (int i = 0; i < 10; i++) {      
String buttonID = "button" + i;
        int resID = getResources().getIdentifier(buttonID, "id",
                "your package name here");
        buttons[i] = (Button) findViewById(resID);

But calling them up remains same as in Prag's answer point 4. PS- If anybody has a better method to call up all the button's onClick, please do comment.

Retain precision with double in Java

        0.8                     1.2
        0.7                     1.3
        0.7000000000000002      2.3
        0.7999999999999998      4.2
        double adjust = fToInt + 1.0 - orgV;
        // The following two lines works for me. 
        String s = String.format("%.2f", adjust);
        double val = Double.parseDouble(s);

        System.out.println(val); // output: 0.8, 0.7, 0.7, 0.8

How do I measure time elapsed in Java?

Unfortunately, none of the ten answers posted so far are quite right.

If you are measuring elapsed time, and you want it to be correct, you must use System.nanoTime(). You cannot use System.currentTimeMillis(), unless you don't mind your result being wrong.

The purpose of nanoTime is to measure elapsed time, and the purpose of currentTimeMillis is to measure wall-clock time. You can't use the one for the other purpose. The reason is that no computer's clock is perfect; it always drifts and occasionally needs to be corrected. This correction might either happen manually, or in the case of most machines, there's a process that runs and continually issues small corrections to the system clock ("wall clock"). These tend to happen often. Another such correction happens whenever there is a leap second.

Since nanoTime's purpose is to measure elapsed time, it is unaffected by any of these small corrections. It is what you want to use. Any timings currently underway with currentTimeMillis will be off -- possibly even negative.

You may say, "this doesn't sound like it would ever really matter that much," to which I say, maybe not, but overall, isn't correct code just better than incorrect code? Besides, nanoTime is shorter to type anyway.

Previously posted disclaimers about nanoTime usually having only microsecond precision are valid. Also it can take more than a whole microsecond to invoke, depending on circumstances (as can the other one), so don't expect to time very very small intervals correctly.

printf, wprintf, %s, %S, %ls, char* and wchar*: Errors not announced by a compiler warning?

I suspect GCC (mingw) has custom code to disable the checks for the wide printf functions on Windows. This is because Microsoft's own implementation (MSVCRT) is badly wrong and has %s and %ls backwards for the wide printf functions; since GCC can't be sure whether you will be linking with MS's broken implementation or some corrected one, the least-obtrusive thing it can do is just shut off the warning.

How can I find the length of a number?

You have to make the number to string in order to take length

var num = 123;

alert((num + "").length);



how to find all indexes and their columns for tables, views and synonyms in oracle

SELECT * FROM user_cons_columns WHERE table_name = 'table_name';

Does a favicon have to be 32x32 or 16x16?

I don't see any up to date info listed here, so here goes:

To answer this question now, 2 favicons will not do it if you want your icon to look great everywhere. See the sizes below:

16 x 16 – Standard size for browsers
24 x 24 – IE9 pinned site size for user interface
32 x 32 – IE new page tab, Windows 7+ taskbar button, Safari Reading List sidebar
48 x 48 – Windows site
57 x 57 – iPod touch, iPhone up to 3G
60 x 60 – iPhone touch up to iOS7
64 x 64 – Windows site, Safari Reader List sidebar in HiDPI/Retina
70 x 70 – Win 8.1 Metro tile
72 x 72 – iPad touch up to iOS6
76 x 76 – iOS7
96 x 96 – GoogleTV
114 x 114 – iPhone retina touch up to iOS6
120 x 120 – iPhone retina touch iOS7
128 x 128 – Chrome Web Store app, Android
144 x 144 – IE10 Metro tile for pinned site, iPad retina up to iOS6
150 x 150 – Win 8.1 Metro tile
152 x 152 – iPad retina touch iOS7
196 x 196 – Android Chrome
310 x 150 – Win 8.1 wide Metro tile
310 x 310 – Win 8.1 Metro tile

Remove leading and trailing spaces?

Starting file:

     line 1
   line 2
line 3  
      line 4 


with open("filename.txt", "r") as f:
    lines = f.readlines()
    for line in lines:
        stripped = line.strip()


line 1
line 2
line 3
line 4

Frame Buster Buster ... buster code needed

Came up with this, and it seems to work at least in Firefox and the Opera browser.

if(top != self) {
 top.onbeforeunload = function() {};

Is it possible to have SSL certificate for IP address, not domain name?

The answer is yes. In short, it is a subject alternative name (SAN) certificate that contains IPs where you would typically see DNS entries. The certificate type is not limited to Public IPs - that restriction is only imposed by a signing authority rather than the technology. I just wanted to clarify that point. I suspect you really just want to get rid of that pesky insecure prompt on your internal websites and devices without the cost and hassle of giving them DNS names then paying for a CA to issue a cert every year or two. You should NOT be trying to convince the world that your IP address is a reputable website and folks should feel comfortable providing their payment information. Now that we have established why no reputable organization wants to issue this type of certificate, lets just do it ourselves with a self signed SAN certificate. Internally I have a trusted certificate that is deployed to all of our hosts, then I sign this type of certificate with it and all devices become trusted. Doing that here is beyond the scope of the question but I think it relevant to the discussion as the question and solution go hand in hand. To be concise, here is how to generate an individual self signed SAN certificate with IP addresses. Expand the IP list to include your entire subnet and use one cert for everything.

#using: OpenSSL 1.1.1c FIPS  28 May 2019 / CentOS Linux release 8.2.2004

C=US ; ST=Confusion ; L=Anywhere ; O=Private\ Subnet ; [email protected]

openssl genrsa -out ip.key $BITS


cp /etc/pki/tls/openssl.cnf /tmp/openssl.cnf
echo -e "$SAN" >> /tmp/openssl.cnf

openssl req -subj "$SUBJ" -new -x509 -days 10950 \
    -key ip.key -out ip.crt -batch \
    -set_serial 168933982 \
    -config /tmp/openssl.cnf \
    -extensions SAN

openssl x509 -in ip.crt -noout -text

How to check if running in Cygwin, Mac or Linux?

Here is the bash script I used to detect three different OS type (GNU/Linux, Mac OS X, Windows NT)

Pay attention

  • In your bash script, use #!/usr/bin/env bash instead of #!/bin/sh to prevent the problem caused by /bin/sh linked to different default shell in different platforms, or there will be error like unexpected operator, that's what happened on my computer (Ubuntu 64 bits 12.04).
  • Mac OS X 10.6.8 (Snow Leopard) do not have expr program unless you install it, so I just use uname.


  1. Use uname to get the system information (-s parameter).
  2. Use expr and substr to deal with the string.
  3. Use if elif fi to do the matching job.
  4. You can add more system support if you want, just follow the uname -s specification.


#!/usr/bin/env bash

if [ "$(uname)" == "Darwin" ]; then
    # Do something under Mac OS X platform        
elif [ "$(expr substr $(uname -s) 1 5)" == "Linux" ]; then
    # Do something under GNU/Linux platform
elif [ "$(expr substr $(uname -s) 1 10)" == "MINGW32_NT" ]; then
    # Do something under 32 bits Windows NT platform
elif [ "$(expr substr $(uname -s) 1 10)" == "MINGW64_NT" ]; then
    # Do something under 64 bits Windows NT platform


  • Linux (Ubuntu 12.04 LTS, Kernel 3.2.0) tested OK.
  • OS X (10.6.8 Snow Leopard) tested OK.
  • Windows (Windows 7 64 bit) tested OK.

What I learned

  1. Check for both opening and closing quotes.
  2. Check for missing parentheses and braces {}


Get data from fs.readFile

var content;
fs.readFile('./Index.html', function read(err, data) {
    if (err) {
        throw err;
    content = data;

This is just because node is asynchronous and it will not wait for the read function and as soon as the program starts it will console the value as undefined, Which is actually true because there is no value assigned to content variable. To handle we can use promises, generators etc. We can use promise in this way.

new Promise((resolve,reject)=>{
    fs.readFile('./index.html','utf-8',(err, data)=>{
        if (err) {
            reject(err); // in the case of error, control flow goes to the catch block with the error occured.
            resolve(data);  // in the case of success, control flow goes to the then block with the content of the file.
    console.log(data); // use your content of the file here (in this then).    
    throw err; //  handle error here.

How to add a class with React.js?

Taken from their site.

render() {
  let className = 'menu';
  if (this.props.isActive) {
    className += ' menu-active';
  return <span className={className}>Menu</span>

Could not calculate build plan: Plugin org.apache.maven.plugins:maven-resources-plugin:2.6 or one of its dependencies could not be resolved

I had a similar problem in spring tool suite(sts). THE .m2 repository was not completely downloaded in the local system which is the reason why I was getting this error. So I reinstalled sts and deleted the old .m2 repository from the system and created a new maven project in sts which downloaded the complete .m2 repository. It worked for me.

How to get all Windows service names starting with a common word?

sc queryex type= service state= all | find /i "NATION"
  • use /i for case insensitive search
  • the white space after type=is deliberate and required

Split comma-separated values

Lamba expression aren't included in c# 2.0

maybe you could refert to this post here on SO

Create a tar.xz in one command

Try this: tar -cf file.tar file-to-compress ; xz -z file.tar


  1. tar.gz and tar.xz are not the same; xz provides better compression.
  2. Don't use pipe | because this runs commands simultaneously. Using ; or & executes commands one after another.

Good way to encapsulate Integer.parseInt()

After reading the answers to the question I think encapsulating or wrapping the parseInt method is not necessary, maybe even not a good idea.

You could return 'null' as Jon suggested, but that's more or less replacing a try/catch construct by a null-check. There's just a slight difference on the behaviour if you 'forget' error handling: if you don't catch the exception, there's no assignment and the left hand side variable keeps it old value. If you don't test for null, you'll probably get hit by the JVM (NPE).

yawn's suggestion looks more elegant to me, because I do not like returning null to signal some errors or exceptional states. Now you have to check referential equality with a predefined object, that indicates a problem. But, as others argue, if again you 'forget' to check and a String is unparsable, the program continous with the wrapped int inside your 'ERROR' or 'NULL' object.

Nikolay's solution is even more object orientated and will work with parseXXX methods from other wrapper classes aswell. But in the end, he just replaced the NumberFormatException by an OperationNotSupported exception - again you need a try/catch to handle unparsable inputs.

So, its my conclusion to not encapsulate the plain parseInt method. I'd only encapsulate if I could add some (application depended) error handling as well.

Removing "bullets" from unordered list <ul>

In your css file add following.

 list-style-type: none;

Getting the actual usedrange

I use the following vba code to determine the entire used rows range for the worksheet to then shorten the selected range of a column:

    Set rUsedRowRange = Selection.Worksheet.UsedRange.Columns( _
    Selection.Column - Selection.Worksheet.UsedRange.Column + 1)

Also works the other way around:

    Set rUsedColumnRange = Selection.Worksheet.UsedRange.Rows( _
    Selection.Row - Selection.Worksheet.UsedRange.Row + 1)

.crx file install in chrome

In case Chrome tells you "This can only be added from the Chrome Web Store", you can try the following:

  • Go to the webstore and try to add the extension
  • It will fail and give you a download instead
  • Rename the downloaded file to .zip and unpack it to a directory (you might get a warning about a corrupt zip header, but most unpacker will continue anyway)
  • Go to Settings -> Tools -> Extensions
  • Enable developer mode
  • Click "Load unpacked extention"
  • Browse to the unpacked folder and install your extention

Converting from byte to int in java

Bytes are transparently converted to ints.

Just say

int i= rno[0];

Exiting from python Command Line

I recommend you exit the Python interpreter with Ctrl-D. This is the old ASCII code for end-of-file or end-of-transmission.

Real-world examples of recursion

You have an organization tree that is N levels deep. Several of the nodes are checked, and you want to expand out to only those nodes that have been checked.

This is something that I actually coded. Its nice and easy with recursion.

Subtracting Number of Days from a Date in PL/SQL

Use sysdate-1 to subtract one day from system date.

select sysdate, sysdate -1 from dual;


-------- ---------
22-10-13 21-10-13 

Artificially create a connection timeout error

Connect to a non-routable IP address, such as

Change Circle color of radio button


All button will change color, the circle box and the central check.

psql: could not connect to server: No such file or directory (Mac OS X)

I faced the same problem for psql (PostgreSQL) 9.6.11.

what worked for me -

remove -- rm /usr/local/var/[email protected]/

restart postgres -- brew services restart [email protected]

If doesn't exist or the above process doesn't work then run --

sudo chmod 700 /usr/local/var/[email protected]

Floating point exception( core dump

Floating Point Exception happens because of an unexpected infinity or NaN. You can track that using gdb, which allows you to see what is going on inside your C program while it runs. For more details:

In a nutshell, these commands might be useful...

gcc -g myprog.c

gdb a.out

gdb core a.out

ddd a.out

Declaring a python function with an array parameters and passing an array argument to the function call?

Maybe you want unpack elements of array, I don't know if I got it, but below a example:

def my_func(*args):
    for a in args:
        print a

my_list = ['a','b','c']

Print "\n" or newline characters as part of the output on terminal

Use repr

>>> string = "abcd\n"
>>> print(repr(string))

msvcr110.dll is missing from computer error while installing PHP

I was missing the MSVCR110.dll. Which I corrected. I could run php from the command line but not the web server. Then I clicked on php-cgi.exe and it gave me the answer. The php5.dll was missing (I downloaded the wrong copy). So for my 2012 IIS box I re-installed using php's x86 non thread safe zip.

What's the difference between display:inline-flex and display:flex?

Open in Full page for better understanding

.item {_x000D_
  width : 100px;_x000D_
  height : 100px;_x000D_
  margin: 20px;_x000D_
  border: 1px solid blue;_x000D_
  background-color: yellow;_x000D_
  text-align: center;_x000D_
  line-height: 99px;_x000D_
.flex-con {_x000D_
  flex-wrap: wrap;_x000D_
  /* <A>    */_x000D_
  display: flex;_x000D_
  /* 1. uncomment below 2 lines by commenting above 1 line */_x000D_
  /* <B>   */_x000D_
/*   display: inline-flex; */_x000D_
.label {_x000D_
  padding-bottom: 20px;_x000D_
.flex-inline-play {_x000D_
  padding: 20px;_x000D_
  border: 1px dashed green;_x000D_
/*  <C> */_x000D_
  width: 1000px;_x000D_
/*   <D> */_x000D_
  display: flex;_x000D_
     <h1>Flex vs inline-flex</h1>_x000D_
    <cite>This pen is understand difference between_x000D_
    flex and inline-flex. Follow along to understand this basic property of css</cite>_x000D_
      <li>Follow #1 in CSS:_x000D_
          <li>Comment <code>display: flex</code></li>_x000D_
          <li>Un-comment <code>display: inline-flex</code></li>_x000D_
        Hope you would have understood till now. This is very similar to situation of `inline-block` vs `block`. Lets go beyond and understand usecase to apply learning. Now lets play with combinations of A, B, C & D by un-commenting only as instructed:_x000D_
     <li>A with D -- does this do same job as <code>display: inline-flex</code>. Umm, you may be right, but not its doesnt do always, keep going !</li>_x000D_
          <li>A with C</li>_x000D_
          <li>A with C & D -- Something wrong ? Keep going !</li>_x000D_
          <li>B with C</li>_x000D_
          <li>B with C & D -- Still same ? Did you learn something ? inline-flex is useful if you have space to occupy in parent of 2 flexboxes <code>.flex-con</code>. That's the only usecase</li>_x000D_
 <div class="label">Playground:</div>_x000D_
<div class="flex-inline-play">_x000D_
  <div class="flex-con">_x000D_
    <div class="item">1</div>_x000D_
    <div class="item">2</div>_x000D_
    <div class="item">3</div>_x000D_
    <div class="item">4</div>_x000D_
  <div class="flex-con">_x000D_
    <div class="item">X</div>_x000D_
    <div class="item">Y</div>_x000D_
    <div class="item">Z</div>_x000D_
    <div class="item">V</div>_x000D_
    <div class="item">W</div>_x000D_

C# function to return array

return Labels; should do the trick!

public static ArtworkData[] GetDataRecords(int UsersID)
    ArtworkData[] Labels;
    Labels = new ArtworkData[3];

    return Labels;

How to use find command to find all files with extensions from list?

find -E /path/to -regex ".*\.(jpg|gif|png|jpeg)" > log

The -E saves you from having to escape the parens and pipes in your regex.

PHP Session data not being saved

Check the value of "views" when before you increment it. If, for some bizarre reason, it's getting set to a string, then when you add 1 to it, it'll always return 1.

if (isset($_SESSION['views'])) {
    if (!is_numeric($_SESSION['views'])) {
        echo "CRAP!";
} else {
    $_SESSION['views'] = 1;

Passing an array by reference

It is a syntax. In the function arguments int (&myArray)[100] parenthesis that enclose the &myArray are necessary. if you don't use them, you will be passing an array of references and that is because the subscript operator [] has higher precedence over the & operator.

E.g. int &myArray[100] // array of references

So, by using type construction () you tell the compiler that you want a reference to an array of 100 integers.

E.g int (&myArray)[100] // reference of an array of 100 ints

The 'json' native gem requires installed build tools

I have found that the error is sometimes caused by a missing library.

so If you install RDOC first by running

gem install rdoc

then install rails with:

gem install rails

then go back and install the devtools as mentioned before with:

1) Extract DevKit to path C:\Ruby193\DevKit
2) cd C:\Ruby192\DevKit
3) ruby dk.rb init
4) ruby dk.rb review
5) ruby dk.rb install

then try installing json

which culminate with you finally being able to run

rails new project_name - without errors.

good luck

No @XmlRootElement generated by JAXB

@XmlRootElement is not needed for unmarshalling - if one uses the 2 parameter form of Unmarshaller#unmarshall.

So, if instead of doing:

UserType user = (UserType) unmarshaller.unmarshal(new StringReader(responseString));

one should do:

JAXBElement<UserType> userElement = unmarshaller.unmarshal(someSource, UserType.class);
UserType user = userElement.getValue();

The latter code will not require @XmlRootElement annotation at UserType class level.

How can I compile and run c# program without using visual studio?

If you have a project ready and just want to change some code and then build. Check out MSBuild which is located in the Microsoft.Net under windows directory.

C:\Windows\Microsoft.NET\Framework\v4.0.30319\msbuild "C:\Projects\MyProject.csproj" /p:Configuration=Debug;DeployOnBuild=True;PackageAsSingleFile=False;outdir=C:\Projects\MyProjects\Publish\

(Please do not edit, leave as a single line)

... The line above broken up for readability

C:\Windows\Microsoft.NET\Framework\v4.0.30319\msbuild "C:\Projects\MyProject.csproj"

Checking for empty queryset in Django

I disagree with the predicate

if not orgs:

It should be

if not orgs.count():

I was having the same issue with a fairly large result set (~150k results). The operator is not overloaded in QuerySet, so the result is actually unpacked as a list before the check is made. In my case execution time went down by three orders.

Android: Test Push Notification online (Google Cloud Messaging)

Pushwatch is a free to use online GCM and APNS push notification tester developed by myself in Django/Python as I have found myself in a similar situation while working on multiple projects. It can send both GCM and APNS notifications and also support JSON messages for extra arguments. Following are the links to the testers.

Please let me know if you have any questions or face issues using it.

How to prompt for user input and read command-line arguments

As of Python 3.2 2.7, there is now argparse for processing command line arguments.

How to do constructor chaining in C#

I have a diary class and so i am not writing setting the values again and again

public Diary() {
    this.Like = defaultLike;
    this.Dislike = defaultDislike;

public Diary(string title, string diary): this()
    this.Title = title;
    this.DiaryText = diary;

public Diary(string title, string diary, string category): this(title, diary) {
    this.Category = category;

public Diary(int id, string title, string diary, string category)
    : this(title, diary, category)
    this.DiaryID = id;

Hello World in Python

print("Hello, World!")

You are probably using Python 3.0, where print is now a function (hence the parenthesis) instead of a statement.

What is [Serializable] and when should I use it?

Since the original question was about the SerializableAttribute, it should be noted that this attribute only applies when using the BinaryFormatter or SoapFormatter.

It is a bit confusing, unless you really pay attention to the details, as to when to use it and what its actual purpose is.

It has NOTHING to do with XML or JSON serialization.

Used with the SerializableAttribute are the ISerializable Interface and SerializationInfo Class. These are also only used with the BinaryFormatter or SoapFormatter.

Unless you intend to serialize your class using Binary or Soap, do not bother marking your class as [Serializable]. XML and JSON serializers are not even aware of its existence.

What primitive data type is time_t?

Unfortunately, it's not completely portable. It's usually integral, but it can be any "integer or real-floating type".

UnsupportedClassVersionError unsupported major.minor version 51.0 unable to load class

Try adding the following to your eclipse.ini file:

C:\Program Files\Java\jdk1.7.0_01\bin\java.exe

You might also have to change the Dosgi.requiredJavaVersion to 1.7 in the same file.

Filter by Dates in SQL

WHERE dates BETWEEN (convert(datetime, '2012-12-12',110) AND (convert(datetime, '2012-12-12',110))

What is the best IDE to develop Android apps in?

Unfortunately, there is no perfect IDE for Android. Eclipse has more features as it is the only IDE google developed plugin for. However, if you are just like me, tired of crashes and weired debug/develop mode swithes, Use Netbeans plugin from

get current date with 'yyyy-MM-dd' format in Angular 4

You can use DatePipe for formatting Date in Angular.

In ts if you want to format date then you can inject DatePipe as Service in constructor like this

import { DatePipe } from '@angular/common';

    templateUrl: './name.component.html',
    styleUrls: ['./name.component.scss'],
    providers: [DatePipe]

myDate = new Date();
constructor(private datePipe: DatePipe){
    this.myDate = this.datePipe.transform(this.myDate, 'yyyy-MM-dd');

And if you want to format in html file, 'Shortdate' will return date of type MM/DD/YY

{{myDate | date: 'shortDate' }}

As of Angular 6, this also works,

import {formatDate} from '@angular/common';

formatDate(new Date(), 'yyyy/MM/dd', 'en');

Import pandas dataframe column as string not int

Since pandas 1.0 it became much more straightforward. This will read column 'ID' as dtype 'string':


As we can see in this Getting started guide, 'string' dtype has been introduced (before strings were treated as dtype 'object').

Button Width Match Parent

The most basic approach is using Container by define its width to infinite. See below example of code

    width: double.infinity,
        onPressed: () {
            //your action here
        child: Text("Button"),


YouTube embedded video: set different thumbnail

There's a nice workaround for this in the sitepoint forums:

<div onclick="'block';'none'">
   <img src="my_thumbnail.png" style="cursor:pointer" />
<div style="display:none">
    <!-- Embed code here -->

Note: To prevent having to click twice to make the video play, use autoplay=1 in the video embed code. It will start playing when the second div is displayed.

HTTP post XML data in C#

In General:

An example of an easy way to post XML data and get the response (as a string) would be the following function:

public string postXMLData(string destinationUrl, string requestXml)
    HttpWebRequest request = (HttpWebRequest)WebRequest.Create(destinationUrl);
    byte[] bytes;
    bytes = System.Text.Encoding.ASCII.GetBytes(requestXml);
    request.ContentType = "text/xml; encoding='utf-8'";
    request.ContentLength = bytes.Length;
    request.Method = "POST";
    Stream requestStream = request.GetRequestStream();
    requestStream.Write(bytes, 0, bytes.Length);
    HttpWebResponse response;
    response = (HttpWebResponse)request.GetResponse();
    if (response.StatusCode == HttpStatusCode.OK)
        Stream responseStream = response.GetResponseStream();
        string responseStr = new StreamReader(responseStream).ReadToEnd();
        return responseStr;
    return null;

In your specific situation:

Instead of:

request.ContentType = "application/x-www-form-urlencoded";


request.ContentType = "text/xml; encoding='utf-8'";

Also, remove:

string postData = "XMLData=" + Sendingxml;

And replace:

byte[] byteArray = Encoding.UTF8.GetBytes(postData);


byte[] byteArray = Encoding.UTF8.GetBytes(Sendingxml.ToString());

What is simplest way to read a file into String?

From Java 7 (API Description) onwards you can do:

new String(Files.readAllBytes(Paths.get(filePath)), StandardCharsets.UTF_8);

Where filePath is a String representing the file you want to load.

How do I convert a file path to a URL in ASP.NET

The simple solution seems to be to have a temporary location within the website that you can access easily with URL and then you can move files to the physical location when you need to save them.

Select Tag Helper in ASP.NET Core MVC

You can also use IHtmlHelper.GetEnumSelectList.

    // Summary:
    //     Returns a select list for the given TEnum.
    // Type parameters:
    //   TEnum:
    //     Type to generate a select list for.
    // Returns:
    //     An System.Collections.Generic.IEnumerable`1 containing the select list for the
    //     given TEnum.
    // Exceptions:
    //   T:System.ArgumentException:
    //     Thrown if TEnum is not an System.Enum or if it has a System.FlagsAttribute.
    IEnumerable<SelectListItem> GetEnumSelectList<TEnum>() where TEnum : struct;

What do we mean by Byte array?

A byte is 8 bits (binary data).

A byte array is an array of bytes (tautology FTW!).

You could use a byte array to store a collection of binary data, for example, the contents of a file. The downside to this is that the entire file contents must be loaded into memory.

For large amounts of binary data, it would be better to use a streaming data type if your language supports it.

CMake error at CMakeLists.txt:30 (project): No CMAKE_C_COMPILER could be found

For me it worked to use the Developer Command Prompt that comes with Visual Studio and then just cd to your/jcef/dir and run cmake -G "Visual Studio 14 Win64" ..

Database Structure for Tree Data Structure

If you have to use Relational DataBase to organize tree data structure then Postgresql has cool ltree module that provides data type for representing labels of data stored in a hierarchical tree-like structure. You can get the idea from there.(For more information see:

In common LDAP is used to organize records in hierarchical structure.

android: how to change layout on button click?

The logcat shows the error, you should call super.onCreate(savedInstanceState) :

public void onCreate(Bundle savedInstanceState){
    //... your code

Calling pylab.savefig without display in ipython

This is a matplotlib question, and you can get around this by using a backend that doesn't display to the user, e.g. 'Agg':

import matplotlib
import matplotlib.pyplot as plt


EDIT: If you don't want to lose the ability to display plots, turn off Interactive Mode, and only call when you are ready to display the plots:

import matplotlib.pyplot as plt

# Turn interactive plotting off

# Create a new figure, plot into it, then close it so it never gets displayed
fig = plt.figure()

# Create a new figure, plot into it, then don't close it so it does get displayed

# Display all "open" (non-closed) figures

how to take user input in Array using java?

You can do the following:

    import java.util.Scanner;

    public class Test {

            public static void main(String[] args) {

            int arr[];
            Scanner scan = new Scanner(;
            // If you want to take 5 numbers for user and store it in an int array
            for(int i=0; i<5; i++) {
                System.out.print("Enter number " + (i+1) + ": ");
                arr[i] = scan.nextInt();    // Taking user input

            // For printing those numbers
            for(int i=0; i<5; i++) 
                System.out.println("Number " + (i+1) + ": " + arr[i]);

How can I match multiple occurrences with a regex in JavaScript similar to PHP's preg_match_all()?

If someone (like me) needs Tomalak's method with array support (ie. multiple select), here it is:

function getUrlParams(url) {
  var re = /(?:\?|&(?:amp;)?)([^=&#]+)(?:=?([^&#]*))/g,
      match, params = {},
      decode = function (s) {return decodeURIComponent(s.replace(/\+/g, " "));};

  if (typeof url == "undefined") url = document.location.href;

  while (match = re.exec(url)) {
    if( params[decode(match[1])] ) {
        if( typeof params[decode(match[1])] != 'object' ) {
            params[decode(match[1])] = new Array( params[decode(match[1])], decode(match[2]) );
        } else {
        params[decode(match[1])] = decode(match[2]);
  return params;
var urlParams = getUrlParams(;

input ?my=1&my=2&my=things

result 1,2,things (earlier returned only: things)

Trigger to fire only if a condition is met in SQL Server

Your where clause should have worked. I am at a loss as to why it didn't. Let me show you how I would have figured out the problem with the where clause as it might help you for the future.

When I create triggers, I start at the query window by creating a temp table called #inserted (and or #deleted) with all the columns of the table. Then I popultae it with typical values (Always multiple records and I try to hit the test cases in the values)

Then I write my triggers logic and I can test without it actually being in a trigger. In a case like your where clause not doing what was expected, I could easily test by commenting out the insert to see what the select was returning. I would then probably be easily able to see what the problem was. I assure you that where clasues do work in triggers if they are written correctly.

Once I know that the code works properly for all the cases, I global replace #inserted with inserted and add the create trigger code around it and voila, a tested trigger.

AS I said in a comment, I have a concern that the solution you picked will not work properly in a multiple record insert or update. Triggers should always be written to account for that as you cannot predict if and when they will happen (and they do happen eventually to pretty much every table.)

SQL Server insert if not exists best practice

Another option is to left join your Results table with your existing competitors Table and find the new competitors by filtering the distinct records that don´t match int the join:

INSERT Competitors (cName)
FROM    CompResults cr left join
        Competitors c on cr.Name = c.cName
where   c.cName is null

New syntax MERGE also offer a compact, elegant and efficient way to do that:

MERGE INTO Competitors AS Target
USING (SELECT DISTINCT Name FROM CompResults) AS Source ON Target.Name = Source.Name
    INSERT (Name) VALUES (Source.Name);

Routing with Multiple Parameters using ASP.NET MVC

Starting with MVC 5, you can also use Attribute Routing to move the URL parameter configuration to your controllers.

A detailed discussion is available here:


First you enable attribute routing

 public class RouteConfig 
     public static void RegisterRoutes(RouteCollection routes)


Then you can use attributes to define parameters and optionally data types

public class BooksController : Controller
    // eg: /books
    // eg: /books/1430210079
    public ActionResult View(string isbn)

Gradient of n colors ranging from color 1 and color 2

Try the following:

color.gradient <- function(x, colors=c("red","yellow","green"), colsteps=100) {
  return( colorRampPalette(colors) (colsteps) [ findInterval(x, seq(min(x),max(x), length.out=colsteps)) ] )
x <- c((1:100)^2, (100:1)^2)
plot(x,col=color.gradient(x), pch=19,cex=2)

enter image description here

Best way to compare dates in Android

Kotlin supports operators overloading

In Kotlin you can easily compare dates with compare operators. Because Kotlin already support operators overloading. So to compare date objects :

firstDate: Date = // your first date
secondDate: Date = // your second date

if(firstDate < secondDate){
// fist date is before second date

and if you're using calendar objects, you can easily compare like this:

if(cal1.time < cal2.time){
// cal1 date is before cal2 date

How to remove duplicate objects in a List<MyObject> without equals/hashcode?

If you can't edit the source of the class (why not?), then you need to iterate over the list and compare each item based on the four criteria mentioned ("title, author, url and description").

To do this in a performant way, I would create a new class, something like BlogKey which contains those four elements and which properly implements equals() and hashCode(). You can then iterate over the original list, constructing a BlogKey for each and adding to a HashMap:

Map<BlogKey, Blog> map = new HashMap<BlogKey, Blog>();
for (Blog blog : blogs) {
     BlogKey key = createKey(blog);
     if (!map.containsKey(key)) {
          map.put(key, blog);
Collection<Blog> uniqueBlogs = map.values();

However the far simplest thing is to just edit the original source code of Blog so that it correctly implements equals() and hashCode().

Access a global variable in a PHP function

It's a matter of scope. In short, global variables should be avoided so:

You either need to pass it as a parameter:

$data = 'My data';

function menugen($data)
    echo $data;

Or have it in a class and access it

class MyClass
    private $data = "";

    function menugen()
        echo this->data;


See @MatteoTassinari answer as well, as you can mark it as global to access it, but global variables are generally not required, so it would be wise to re-think your coding.

how to upload a file to my server using html

On top of what the others have already stated, some sort of server-side scripting is necessary in order for the server to read and save the file.

Using PHP might be a good choice, but you're free to use any server-side scripting language. may be of use on that end.

Tensorflow installation error: not a supported wheel on this platform

I faced the same issue and tried all the solutions that folks suggested here and other links (like

It was so frustrating because using print(wheel.pep425tags.get_supported()) I could see that my ubuntu supported ('cp37', 'cp37m', 'linux_x86_64') and that was exactly what I was trying to install (from

What at the end fixed it was to simply download the package first and then

pip install tensorflow-1.14.0-cp37-cp37m-linux_x86_64.whl

How can I create an error 404 in PHP?

What you're doing will work, and the browser will receive a 404 code. What it won't do is display the "not found" page that you might be expecting, e.g.:

Not Found

The requested URL /test.php was not found on this server.

That's because the web server doesn't send that page when PHP returns a 404 code (at least Apache doesn't). PHP is responsible for sending all its own output. So if you want a similar page, you'll have to send the HTML yourself, e.g.:

header($_SERVER["SERVER_PROTOCOL"]." 404 Not Found", true, 404);

You could configure Apache to use the same page for its own 404 messages, by putting this in httpd.conf:

ErrorDocument 404 /notFound.php

Python Serial: How to use the read or readline function to read more than 1 character at a time

Serial sends data 8 bits at a time, that translates to 1 byte and 1 byte means 1 character.

You need to implement your own method that can read characters into a buffer until some sentinel is reached. The convention is to send a message like 12431\n indicating one line.

So what you need to do is to implement a buffer that will store X number of characters and as soon as you reach that \n, perform your operation on the line and proceed to read the next line into the buffer.

Note you will have to take care of buffer overflow cases i.e. when a line is received that is longer than your buffer etc...


import serial

ser = serial.Serial(

print("connected to: " + ser.portstr)

#this will store the line
line = []

while True:
    for c in
        if c == '\n':
            print("Line: " + ''.join(line))
            line = []


Building a fat jar using maven

You can use the onejar-maven-plugin for packaging. Basically, it assembles your project and its dependencies in as one jar, including not just your project jar file, but also all external dependencies as a "jar of jars", e.g.


Note 1: Configuration options is available at the project home page.

Note 2: For one reason or the other, the onejar-maven-plugin project is not published at Maven Central. However tracks the original project and publishes it to with the groupId com.jolira.

How to limit file upload type file size in PHP?

Hope This useful...


<form action="check.php" method="post" enctype="multipart/form-data">
<label>Upload An Image</label>
<input type="file" name="file_upload" />
<input type="submit" name="upload"/>


        $error_1='File Size too large';
        echo '<script>alert("'.$error_1.'")</script>';
        $error_2='Invalid File';
        echo '<script>alert("'.$error_2.'")</script>';
        $error_3='Format Not Supported.Only .jpeg files are accepted';
        echo '<script>alert("'.$error_3.'")</script>';

            $target_dir = "uploads/";
            $target_file = $target_dir . basename($_FILES["file_upload"]["name"]);
            if(move_uploaded_file($_FILES["file_upload"]["tmp_name"], $target_file)){ 
            echo "The file ". basename($_FILES["file_upload"]["name"]). " has been uploaded.";
                echo "sorry";

How to fix Invalid AES key length?

I was facing the same issue then i made my key 16 byte and it's working properly now. Create your key exactly 16 byte. It will surely work.

How can I delete a query string parameter in JavaScript?

Glad you scrolled here.

I would suggest you to resolve this task by next possible solutions:

  1. You need to support only modern browsers (Edge >= 17) - use URLSearchParams.delete() API. It is native and obviously is the most convenient way of solving this task.
  2. If this is not an option, you may want to write a function to do this. Such a function does
    • do not change URL if a parameter is not present
    • remove URL parameter without a value, like
    • remove URL parameter with a value, like
    • remove URL parameter if is it in URL twice, like
    • Does not use for loop and not modify array during looping over it
    • is more functional
    • is more readable than regexp solutions
    • Before using make sure your URL is not encoded

Works in IE > 9 (ES5 version)

function removeParamFromUrl(url, param) {  // url: string, param: string_x000D_
  var urlParts = url.split('?'),_x000D_
      preservedQueryParams = '';_x000D_
  if (urlParts.length === 2) {_x000D_
    preservedQueryParams = urlParts[1]_x000D_
      .filter(function(queryParam) {_x000D_
        return !(queryParam === param || queryParam.indexOf(param + '=') === 0)_x000D_
  return urlParts[0] +  (preservedQueryParams && '?' + preservedQueryParams); _x000D_

Fancy ES6 version

function removeParamFromUrlEs6(url, param) {_x000D_
  const [path, queryParams] = url.split('?');_x000D_
 let preservedQueryParams = '';_x000D_
  if (queryParams) {_x000D_
    preservedQueryParams = queryParams_x000D_
      .filter(queryParam => !(queryParam === param || queryParam.startsWith(`${param}=`)))_x000D_
  return `${path}${preservedQueryParams && `?${preservedQueryParams}`}`;  _x000D_

See how it works here

Creating an array of objects in Java

You are correct. Aside from that if we want to create array of specific size filled with elements provided by some "factory", since Java 8 (which introduces stream API) we can use this one-liner:

A[] a = Stream.generate(() -> new A()).limit(4).toArray(A[]::new);
  • Stream.generate(() -> new A()) is like factory for separate A elements created in a way described by lambda, () -> new A() which is implementation of Supplier<A> - it describe how each new A instances should be created.
  • limit(4) sets amount of elements which stream will generate
  • toArray(A[]::new) (can also be rewritten as toArray(size -> new A[size])) - it lets us decide/describe type of array which should be returned.

For some primitive types you can use DoubleStream, IntStream, LongStream which additionally provide generators like range rangeClosed and few others.

Warning: The method assertEquals from the type Assert is deprecated

When I use Junit4, import junit.framework.Assert; import junit.framework.TestCase; the warning info is :The type of Assert is deprecated

when import like this: import org.junit.Assert; import org.junit.Test; the warning has disappeared

possible duplicate of differences between 2 JUnit Assert classes

Application Loader stuck at "Authenticating with the iTunes store" when uploading an iOS app

There is no magic fix. Itunes is just working bad. Lately is having more and more issues and it takes more and more to update and send an ipa to the store. I had this issue with AppLoader and Xcode organiser too and after trying multiple times it just went through.

How to retrieve the LoaderException property?

Another Alternative for those who are probing around and/or in interactive mode:


Note: [0] grabs the most recent Error from the stack

Adding Git-Bash to the new Windows Terminal

If you want to display an icon and are using a dark theme. Which means the icon provided above doesn't look that great. Then you can find the icon here

C:\Program Files\Git\mingw64\share\git\git-for-windows I copied it into.


and named it git-bash_32px as suggested above.

Control the opacity with CTRL + SHIFT + scrolling.

            "acrylicOpacity" : 0.75,
            "closeOnExit" : true,
            "colorScheme" : "Campbell",
            "commandline" : "\"%PROGRAMFILES%\\git\\usr\\bin\\bash.exe\" -i -l",
            "cursorColor" : "#FFFFFF",
            "cursorShape" : "bar",
            "fontFace" : "Consolas",
            "fontSize" : 10,
            "guid" : "{73225108-7633-47ae-80c1-5d00111ef646}",
            "historySize" : 9001,
            "icon" : "ms-appdata:///roaming/git-bash_32px.ico",
            "name" : "Bash",
            "padding" : "0, 0, 0, 0",
            "snapOnInput" : true,
            "startingDirectory" : "%USERPROFILE%",
            "useAcrylic" : true

CSS to keep element at "fixed" position on screen

The easiest way is to use position: fixed:

.element {
  position: fixed;
  bottom: 0;
  right: 0;

(note that position fixed is buggy / doesn't work on ios and android browsers)

How to mark a method as obsolete or deprecated?

The shortest way is by adding the ObsoleteAttribute as an attribute to the method. Make sure to include an appropriate explanation:

[Obsolete("Method1 is deprecated, please use Method2 instead.")]
public void Method1()
{ … }

You can also cause the compilation to fail, treating the usage of the method as an error instead of warning, if the method is called from somewhere in code like this:

[Obsolete("Method1 is deprecated, please use Method2 instead.", true)]

Checking whether a variable is an integer or not

I've had this problem before, if your type to use it in a if statement, and let's just say you wanted it to return true, you would enter this into a line, (The bottom line in all that is really needed to be looked at):

In [1]: test = 1

In [2]: test2 = 1.0

In [3]: type(test) == int
Out[3]: True

In [4]: type(test2) == int
Out[4]: False

In [5]: if type(x) == int is True:

You can do the same thing to check if it's a float, if it's true or false, and use to assign a name, (like x if you know what I mean.)

Why doesn't Dijkstra's algorithm work for negative weight edges?

Recall that in Dijkstra's algorithm, once a vertex is marked as "closed" (and out of the open set) -it assumes that any node originating from it will lead to greater distance so, the algorithm found the shortest path to it, and will never have to develop this node again, but this doesn't hold true in case of negative weights.

Get current cursor position

GetCursorPos() will return to you the x/y if you pass in a pointer to a POINT structure.

Hiding the cursor can be done with ShowCursor().

system("pause"); - Why is it wrong?

As listed on the other answers, there are many reasons you can find to avoid this. It all boils down to one reason that makes the rest moot. The System() function is inherently insecure/untrusted, and should not be introduced into a program unless necessary.

For a student assignment, this condition was never met, and for this reason I would fail an assignment without even running the program if a call to this method was present. (This was made clear from the start.)

How to crop a CvMat in OpenCV?

I understand this question has been answered but perhaps this might be useful to someone...

If you wish to copy the data into a separate cv::Mat object you could use a function similar to this:

void ExtractROI(Mat& inImage, Mat& outImage, Rect roi){
    /* Create the image */
    outImage = Mat(roi.height, roi.width, inImage.type(), Scalar(0));

    /* Populate the image */
    for (int i = roi.y; i < (roi.y+roi.height); i++){
        uchar* inP = inImage.ptr<uchar>(i);
        uchar* outP = outImage.ptr<uchar>(i-roi.y);
        for (int j = roi.x; j < (roi.x+roi.width); j++){
            outP[j-roi.x] = inP[j];

It would be important to note that this would only function properly on single channel images.

Pointers in C: when to use the ampersand and the asterisk?

Yeah that can be quite complicated since the * is used for many different purposes in C/C++.

If * appears in front of an already declared variable/function, it means either that:

  • a) * gives access to the value of that variable (if the type of that variable is a pointer type, or overloaded the * operator).
  • b) * has the meaning of the multiply operator, in that case, there has to be another variable to the left of the *

If * appears in a variable or function declaration it means that that variable is a pointer:

int int_value = 1;
int * int_ptr; //can point to another int variable
int   int_array1[10]; //can contain up to 10 int values, basically int_array1 is an pointer as well which points to the first int of the array
//int   int_array2[]; //illegal, without initializer list..
int int_array3[] = {1,2,3,4,5};  // these two
int int_array4[5] = {1,2,3,4,5}; // are identical

void func_takes_int_ptr1(int *int_ptr){} // these two are identical
void func_takes_int_ptr2(int int_ptr[]){}// and legal

If & appears in a variable or function declaration, it generally means that that variable is a reference to a variable of that type.

If & appears in front of an already declared variable, it returns the address of that variable

Additionally you should know, that when passing an array to a function, you will always have to pass the array size of that array as well, except when the array is something like a 0-terminated cstring (char array).

see if two files have the same content in python

Yes, I think hashing the file would be the best way if you have to compare several files and store hashes for later comparison. As hash can clash, a byte-by-byte comparison may be done depending on the use case.

Generally byte-by-byte comparison would be sufficient and efficient, which filecmp module already does + other things too.

See e.g.

>>> import filecmp
>>> filecmp.cmp('file1.txt', 'file1.txt')
>>> filecmp.cmp('file1.txt', 'file2.txt')

Speed consideration: Usually if only two files have to be compared, hashing them and comparing them would be slower instead of simple byte-by-byte comparison if done efficiently. e.g. code below tries to time hash vs byte-by-byte

Disclaimer: this is not the best way of timing or comparing two algo. and there is need for improvements but it does give rough idea. If you think it should be improved do tell me I will change it.

import random
import string
import hashlib
import time

def getRandText(N):
    return  "".join([random.choice(string.printable) for i in xrange(N)])

randText1 = getRandText(N)
randText2 = getRandText(N)

def cmpHash(text1, text2):
    hash1 = hashlib.md5()
    hash1 = hash1.hexdigest()

    hash2 = hashlib.md5()
    hash2 = hash2.hexdigest()

    return  hash1 == hash2

def cmpByteByByte(text1, text2):
    return text1 == text2

for cmpFunc in (cmpHash, cmpByteByByte):
    st = time.time()
    for i in range(10):
        cmpFunc(randText1, randText2)
    print cmpFunc.func_name,time.time()-st

and the output is

cmpHash 0.234999895096
cmpByteByByte 0.0

Styling every 3rd item of a list using CSS?

You can use the :nth-child selector for that

li:nth-child(3n) {
 /* your rules here */

What’s the difference between “{}” and “[]” while declaring a JavaScript array?

When you declare

var a=[];

you are declaring a empty array.

But when you are declaring

var a={};

you are declaring a Object .

Although Array is also Object in Javascript but it is numeric key paired values. Which have all the functionality of object but Added some few method of Array like Push,Splice,Length and so on.

So if you want Some values where you need to use numeric keys use Array. else use object. you can Create object like:

var a={name:"abc",age:"14"}; 

And can access values like


Start index for iterating Python list

Why are people using list slicing (slow because it copies to a new list), importing a library function, or trying to rotate an array for this?

Use a normal for-loop with range(start, stop, step) (where start and step are optional arguments).

For example, looping through an array starting at index 1:

for i in range(1, len(arr)):

AngularJS not detecting Access-Control-Allow-Origin header?

If you guys are having this problem in sails.js just set your cors.js to include Authorization as the allowed header

  *                                                                          *_x000D_
  * Which headers should be allowed for CORS requests? This is only used in  *_x000D_
  * response to preflight requests.                                          *_x000D_
  *                                                                          *_x000D_
  headers: 'Authorization' // this line here

javascript set cookie with expire time

Here's a function I wrote another application. Feel free to reuse:

function writeCookie (key, value, days) {
    var date = new Date();

    // Default at 365 days.
    days = days || 365;

    // Get unix milliseconds at current time plus number of days
    date.setTime(+ date + (days * 86400000)); //24 * 60 * 60 * 1000

    window.document.cookie = key + "=" + value + "; expires=" + date.toGMTString() + "; path=/";

    return value;

C++11 introduced a standardized memory model. What does it mean? And how is it going to affect C++ programming?

The above answers get at the most fundamental aspects of the C++ memory model. In practice, most uses of std::atomic<> "just work", at least until the programmer over-optimizes (e.g., by trying to relax too many things).

There is one place where mistakes are still common: sequence locks. There is an excellent and easy-to-read discussion of the challenges at Sequence locks are appealing because the reader avoids writing to the lock word. The following code is based on Figure 1 of the above technical report, and it highlights the challenges when implementing sequence locks in C++:

atomic<uint64_t> seq; // seqlock representation
int data1, data2;     // this data will be protected by seq

T reader() {
    int r1, r2;
    unsigned seq0, seq1;
    while (true) {
        seq0 = seq;
        r1 = data1; // INCORRECT! Data Race!
        r2 = data2; // INCORRECT!
        seq1 = seq;

        // if the lock didn't change while I was reading, and
        // the lock wasn't held while I was reading, then my
        // reads should be valid
        if (seq0 == seq1 && !(seq0 & 1))
    use(r1, r2);

void writer(int new_data1, int new_data2) {
    unsigned seq0 = seq;
    while (true) {
        if ((!(seq0 & 1)) && seq.compare_exchange_weak(seq0, seq0 + 1))
            break; // atomically moving the lock from even to odd is an acquire
    data1 = new_data1;
    data2 = new_data2;
    seq = seq0 + 2; // release the lock by increasing its value to even

As unintuitive as it seams at first, data1 and data2 need to be atomic<>. If they are not atomic, then they could be read (in reader()) at the exact same time as they are written (in writer()). According to the C++ memory model, this is a race even if reader() never actually uses the data. In addition, if they are not atomic, then the compiler can cache the first read of each value in a register. Obviously you wouldn't want that... you want to re-read in each iteration of the while loop in reader().

It is also not sufficient to make them atomic<> and access them with memory_order_relaxed. The reason for this is that the reads of seq (in reader()) only have acquire semantics. In simple terms, if X and Y are memory accesses, X precedes Y, X is not an acquire or release, and Y is an acquire, then the compiler can reorder Y before X. If Y was the second read of seq, and X was a read of data, such a reordering would break the lock implementation.

The paper gives a few solutions. The one with the best performance today is probably the one that uses an atomic_thread_fence with memory_order_relaxed before the second read of the seqlock. In the paper, it's Figure 6. I'm not reproducing the code here, because anyone who has read this far really ought to read the paper. It is more precise and complete than this post.

The last issue is that it might be unnatural to make the data variables atomic. If you can't in your code, then you need to be very careful, because casting from non-atomic to atomic is only legal for primitive types. C++20 is supposed to add atomic_ref<>, which will make this problem easier to resolve.

To summarize: even if you think you understand the C++ memory model, you should be very careful before rolling your own sequence locks.

MySQL - Trigger for updating same table after insert






Can't start Eclipse - Java was started but returned exit code=13

The strangest fix ever. Look at your Eclipse path, and make sure you do not have strange characters (like !, #, and @). It worked for me.

How to draw vectors (physical 2D/3D vectors) in MATLAB?

I'm not sure of a way to do this in 3D, but in 2D you can use the compass command.

Android Webview gives net::ERR_CACHE_MISS message

Answers assembled! I wanted to just combine all the answers into one comprehensive one.

1. Check if <uses-permission android:name="android.permission.INTERNET" /> is present in manifest.xml. Make sure that it is nested under <manifest> and not <application>. Thanks to sajid45 and Liyanis Velazquez

2. Ensure that you are using <uses-permission android:name="android.permission.INTERNET"/> instead of the deprecated <uses-permission android:name="android.permission.internet"/>. Much thanks to alan_shi and creos.

3. If minimum version is below KK, check that you have

if (18 < Build.VERSION.SDK_INT ){
    //18 = JellyBean MR2, KITKAT=19


if (Build.VERSION.SDK_INT >= 19) {

because proper webview is only added in KK (SDK 19). Thanks to Devavrata, Mike ChanSeong Kim and Liyanis Velazquez

4. Ensure that you don't have webView.getSettings().setBlockNetworkLoads (false);. Thanks to TechNikh for pointing this out.

5. If all else fails, make sure that your Android Studio, Android SDK and the emulator image (if you are using one) is updated. And if you are still meeting the problem, just open a new question and make a comment below to your URL.

How to get the Power of some Integer in Swift language?

Swift 4.x version

precedencegroup ExponentiationPrecedence {
  associativity: right
  higherThan: MultiplicationPrecedence

infix operator ^^: ExponentiationPrecedence
public func ^^ (radix: Float, power: Float) -> Float {
  return pow((radix), (power))

public func ^^ (radix: Double, power: Double) -> Double {
  return pow((radix), (power))

public func ^^ (radix: Int, power: Int) -> Int {
  return NSDecimalNumber(decimal: pow(Decimal(radix), power)).intValue

Git clone without .git directory

Alternatively, if you have Node.js installed, you can use the following command:

npx degit GIT_REPO

npx comes with Node, and it allows you to run binary node-based packages without installing them first (alternatively, you can first install degit globally using npm i -g degit).

Degit is a tool created by Rich Harris, the creator of Svelte and Rollup, which he uses to quickly create a new project by cloning a repository without keeping the git folder. But it can also be used to clone any repo once...

Python Socket Receive Large Amount of Data

Disclaimer: There are very rare cases in which you really need to do this. If possible use an existing application layer protocol or define your own eg. precede each message with a fixed length integer indicating the length of data that follows or terminate each message with a '\n' character. (Adam Rosenfield's answer does a really good job at explaining that)

With that said, there is a way to read all of the data available on a socket. However, it is a bad idea to rely on this kind of communication as it introduces the risk of loosing data. Use this solution with extreme caution and only after reading the explanation below.

def recvall(sock):
    BUFF_SIZE = 4096
    data = bytearray()
    while True:
        packet = sock.recv(BUFF_SIZE)
        if not packet:  # Important!!
    return data

Now the if not packet: line is absolutely critical! Many answers here suggested using a condition like if len(packet) < BUFF_SIZE: which is broken and will most likely cause you to close your connection prematurely and loose data. It wrongly assumes that one send on one end of a TCP socket corresponds to one receive of sent number of bytes on the other end. It does not. There is a very good chance that sock.recv(BUFF_SIZE) will return a chunk smaller than BUFF_SIZE even if there's still data waiting to be received. There is a good explanation of the issue here and here.

By using the above solution you are still risking data loss if the other end of the connection is writing data slower than you are reading. You may just simply consume all data on your end and exit when more is on the way. There are ways around it that require the use of concurrent programming, but that's another topic of its own.

Running CMD command in PowerShell

Try this:

& "C:\Program Files (x86)\Microsoft Configuration Manager\AdminConsole\bin\i386\CmRcViewer.exe" PCNAME

To PowerShell a string "..." is just a string and PowerShell evaluates it by echoing it to the screen. To get PowerShell to execute the command whose name is in a string, you use the call operator &.

Set Background cell color in PHPExcel

You can easily apply colours on cell and rows.

$sheet->cell(1, function($row) 

$sheet->row(1, ['Col 1', 'Col 2', 'Col 3']); 
$sheet->row(1, function($row) 

Tool to compare directories (Windows 7)

The tool that richardtz suggests is excellent.

Another one that is amazing and comes with a 30 day free trial is Araxis Merge. This one does a 3 way merge and is much more feature complete than winmerge, but it is a commercial product.

You might also like to check out Scott Hanselman's developer tool list, which mentions a couple more in addition to winmerge

HttpWebRequest using Basic authentication

I finally got it!

string url = @"";
WebRequest request = WebRequest.Create(url);
request.Credentials = GetCredential();
request.PreAuthenticate = true;

and this is GetCredential()

private CredentialCache GetCredential()
    string url = @"";
    ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3;
    CredentialCache credentialCache = new CredentialCache();
    credentialCache.Add(new System.Uri(url), "Basic", new NetworkCredential(ConfigurationManager.AppSettings["ead_username"], ConfigurationManager.AppSettings["ead_password"]));
    return credentialCache;


How can I escape white space in a bash loop list?

Just had a simple variant problem... Convert files of typed .flv to .mp3 (yawn).

for file in read `find . *.flv`; do ffmpeg -i ${file} -acodec copy ${file}.mp3;done

recursively find all the Macintosh user flash files and turn them into audio (copy, no transcode) ... it's like the while above, noting that read instead of just 'for file in ' will escape.

Edit In Place Content Editing

I was looking for a inline editing solution and I found a plunker that seemed promising, but it didn't work for me out of the box. After some tinkering with the code I got it working. Kudos to the person who made the initial effort to code this piece.

The example is available here

Here goes the code:

app.controller('MainCtrl', function($scope) {

  $scope.updateTodo = function(indx) {

  $scope.cancelEdit = function(value) {
    console.log('Canceled editing', value);

  $scope.todos = [
    {id:123, title: 'Lord of the things'},
    {id:321, title: 'Hoovering heights'},
    {id:231, title: 'Watership brown'}

// On esc event
app.directive('onEsc', function() {
  return function(scope, elm, attr) {
    elm.bind('keydown', function(e) {
      if (e.keyCode === 27) {

// On enter event
app.directive('onEnter', function() {
  return function(scope, elm, attr) {
    elm.bind('keypress', function(e) {
      if (e.keyCode === 13) {

// Inline edit directive
app.directive('inlineEdit', function($timeout) {
  return {
    scope: {
      model: '=inlineEdit',
      handleSave: '&onSave',
      handleCancel: '&onCancel'
    link: function(scope, elm, attr) {
      var previousValue;

      scope.edit = function() {
        scope.editMode = true;
        previousValue = scope.model;

        $timeout(function() {
        }, 0, false);
      }; = function() {
        scope.editMode = false;
        scope.handleSave({value: scope.model});
      scope.cancel = function() {
        scope.editMode = false;
        scope.model = previousValue;
        scope.handleCancel({value: scope.model});
    templateUrl: 'inline-edit.html'

Directive template:

  <input type="text" on-enter="save()" on-esc="cancel()" ng-model="model" ng-show="editMode">
  <button ng-click="cancel()" ng-show="editMode">cancel</button>
  <button ng-click="save()" ng-show="editMode">save</button>
  <span ng-mouseenter="showEdit = true" ng-mouseleave="showEdit = false">
    <span ng-hide="editMode" ng-click="edit()">{{model}}</span>
    <a ng-show="showEdit" ng-click="edit()">edit</a>

To use it just add water:

<div ng-repeat="todo in todos" 


Another option is to use the readymade Xeditable for AngularJS:

How to tell if a connection is dead in python

Short answer:

use a non-blocking recv(), or a blocking recv() / select() with a very short timeout.

Long answer:

The way to handle socket connections is to read or write as you need to, and be prepared to handle connection errors.

TCP distinguishes between 3 forms of "dropping" a connection: timeout, reset, close.

Of these, the timeout can not really be detected, TCP might only tell you the time has not expired yet. But even if it told you that, the time might still expire right after.

Also remember that using shutdown() either you or your peer (the other end of the connection) may close only the incoming byte stream, and keep the outgoing byte stream running, or close the outgoing stream and keep the incoming one running.

So strictly speaking, you want to check if the read stream is closed, or if the write stream is closed, or if both are closed.

Even if the connection was "dropped", you should still be able to read any data that is still in the network buffer. Only after the buffer is empty will you receive a disconnect from recv().

Checking if the connection was dropped is like asking "what will I receive after reading all data that is currently buffered ?" To find that out, you just have to read all data that is currently bufferred.

I can see how "reading all buffered data", to get to the end of it, might be a problem for some people, that still think of recv() as a blocking function. With a blocking recv(), "checking" for a read when the buffer is already empty will block, which defeats the purpose of "checking".

In my opinion any function that is documented to potentially block the entire process indefinitely is a design flaw, but I guess it is still there for historical reasons, from when using a socket just like a regular file descriptor was a cool idea.

What you can do is:

  • set the socket to non-blocking mode, but than you get a system-depended error to indicate the receive buffer is empty, or the send buffer is full
  • stick to blocking mode but set a very short socket timeout. This will allow you to "ping" or "check" the socket with recv(), pretty much what you want to do
  • use select() call or asyncore module with a very short timeout. Error reporting is still system-specific.

For the write part of the problem, keeping the read buffers empty pretty much covers it. You will discover a connection "dropped" after a non-blocking read attempt, and you may choose to stop sending anything after a read returns a closed channel.

I guess the only way to be sure your sent data has reached the other end (and is not still in the send buffer) is either:

  • receive a proper response on the same socket for the exact message that you sent. Basically you are using the higher level protocol to provide confirmation.
  • perform a successful shutdow() and close() on the socket

The python socket howto says send() will return 0 bytes written if channel is closed. You may use a non-blocking or a timeout socket.send() and if it returns 0 you can no longer send data on that socket. But if it returns non-zero, you have already sent something, good luck with that :)

Also here I have not considered OOB (out-of-band) socket data here as a means to approach your problem, but I think OOB was not what you meant.

SQL Server® 2016, 2017 and 2019 Express full download

Download the developer edition. There you can choose Express as license when installing.

enter image description here

Adding Only Untracked Files

It's easy with git add -i. Type a (for "add untracked"), then * (for "all"), then q (to quit) and you're done.

To do it with a single command: echo -e "a\n*\nq\n"|git add -i

The request failed or the service did not respond in a timely fashion?

If you recently changed the password associated with the service account:

  1. Start SQL Server Configuration Manager.
  2. Select SQL Server Services in the left pane.
  3. Right click the service you are trying to start in the right pane and click Properties.
  4. Enter the new Password and Confirm password.

Ruby: How to get the first character of a string

For completeness sake, since Ruby 1.9 String#chr returns the first character of a string. Its still available in 2.0 and 2.1.

"Smith".chr    #=> "S"

What's the difference between django OneToOneField and ForeignKey?

The easiest way to draw a relationship between items is by understanding them in plain languages. Example

A user can have many cars but then a car can have just one owner. After establishing this, the foreign key should be used on the item with the many relationship. In this case the car. Meaning you'll include user as a foreign key in cars

And a one on one relationship is quite simple. Say a man and a heart. A man has only one heart and a heart can belong to just one man

How can I create an object based on an interface file definition in TypeScript?

You can set default values using Class.

Without Class Constructor:

interface IModal {
  content: string;
  form: string;
  href: string;
  isPopup: boolean;

class Modal implements IModal {
  content = "";
  form = "";
  href: string;  // will not be added to object
  isPopup = true;

const myModal = new Modal();
console.log(myModal); // output: {content: "", form: "", isPopup: true}

With Class Constructor

interface IModal {
  content: string;
  form: string;
  href: string;
  isPopup: boolean;

class Modal implements IModal {
  constructor() {
    this.content = "";
    this.form = "";
    this.isPopup = true;

  content: string;

  form: string;

  href: string; // not part of constructor so will not be added to object

  isPopup: boolean;

const myModal = new Modal();
console.log(myModal); // output: {content: "", form: "", isPopup: true}

AngularJS passing data to $http.get request

Starting from AngularJS v1.4.8, you can use get(url, config) as follows:

var data = {

var config = {
 params: data,
 headers : {'Accept' : 'application/json'}

$http.get(user.details_path, config).then(function(response) {
   // process response here..
 }, function(response) {

Center content in responsive bootstrap navbar

from the bootstrap official site (and, almost, like Eric S. Bullington said.

the example navbar looks like:

<nav class="navbar navbar-default">
    <div class="container-fluid">
        <!-- Brand and toggle get grouped for better mobile display -->
        <div class="navbar-header">

to center the nav, that what i've done:

<div class="container-fluid" id="nav_center">


@media (min-width:768px) { /* don't break navbar on small screen */
    #nav_center {
        width: 700px /* need to found your width according to your entry*/

work with class="container" and navbar-right or left, and of course you can replace id by class. :D

How to install Boost on Ubuntu

Installing Boost on Ubuntu with an example of using boost::array:

Install libboost-all-dev and aptitude:

sudo apt install libboost-all-dev

sudo apt install aptitude

aptitude search boost

Then paste this into a C++ file called main.cpp:

#include <iostream>
#include <boost/array.hpp>

using namespace std;
int main(){
  boost::array<int, 4> arr = {{1,2,3,4}};
  cout << "hi" << arr[0];
  return 0;

Compile like this:

g++ -o s main.cpp

Run it like this:


Program prints:


How to import functions from different js file in a Vue+webpack+vue-loader project

I like the answer of Anacrust, though, by the fact "console.log" is executed twice, I would like to do a small update for src/mylib.js:

let test = {
  foo () { return 'foo' },
  bar () { return 'bar' },
  baz () { return 'baz' }

export default test

All other code remains the same...

What's the difference between a null pointer and a void pointer?

A null pointer is guaranteed to not compare equal to a pointer to any object. It's actual value is system dependent and may vary depending on the type. To get a null int pointer you would do

int* p = 0;

A null pointer will be returned by malloc on failure.

We can test if a pointer is null, i.e. if malloc or some other function failed simply by testing its boolean value:

if (p) {
    /* Pointer is not null */
} else {
    /* Pointer is null */

A void pointer can point to any type and it is up to you to handle how much memory the referenced objects consume for the purpose of dereferencing and pointer arithmetic.

How to change button color with tkinter

When you do self.button = Button(...).grid(...), what gets assigned to self.button is the result of the grid() command, not a reference to the Button object created.

You need to assign your self.button variable before packing/griding it. It should look something like this:

self.button = Button(self,text="Click Me",command=self.color_change,bg="blue")
self.button.grid(row = 2, column = 2, sticky = W)

Setting button text via javascript

Use textContent instead of value to set the button text.

Typically the value attribute is used to associate a value with the button when it's submitted as form data.

Note that while it's possible to set the button text with innerHTML, using textContext should be preferred because it's more performant and it can prevent cross-site scripting attacks as its value is not parsed as HTML.


var b = document.createElement('button');
b.setAttribute('content', 'test content');
b.setAttribute('class', 'btn');  
b.textContent = 'test value';

var wrapper = document.getElementById("divWrapper");

Produces this in the DOM:

<div id="divWrapper">
    <button content="test content" class="btn">test value</button>


Reading serial data in realtime in Python

You can use inWaiting() to get the amount of bytes available at the input queue.

Then you can use read() to read the bytes, something like that:

While True:
    bytesToRead = ser.inWaiting()

Why not to use readline() at this case from Docs:

Read a line which is terminated with end-of-line (eol) character (\n by default) or until timeout.

You are waiting for the timeout at each reading since it waits for eol. the serial input Q remains the same it just a lot of time to get to the "end" of the buffer, To understand it better: you are writing to the input Q like a race car, and reading like an old car :)

How to redirect cin and cout to files?

Just write

#include <cstdio>
#include <iostream>
using namespace std;

int main()
    cout<<"write in file";
    return 0;

How to get the device's IMEI/ESN programmatically in android?

I use the following code to get the IMEI or use Secure.ANDROID_ID as an alternative, when the device doesn't have phone capabilities:

 * Returns the unique identifier for the device
 * @return unique identifier for the device
public String getDeviceIMEI() {
    String deviceUniqueIdentifier = null;
    TelephonyManager tm = (TelephonyManager) this.getSystemService(Context.TELEPHONY_SERVICE);
    if (null != tm) {
        deviceUniqueIdentifier = tm.getDeviceId();
    if (null == deviceUniqueIdentifier || 0 == deviceUniqueIdentifier.length()) {
        deviceUniqueIdentifier = Settings.Secure.getString(this.getContentResolver(), Settings.Secure.ANDROID_ID);
    return deviceUniqueIdentifier;

Navigate to another page with a button in angular 2

Having the router link on the button seems to work fine for me:

<button class="nav-link" routerLink="/" (click)="hideMenu()">
     <i class="fa fa-home"></i> 

Git reset single file in feature branch to be the same as in master

you are almost there; you just need to give the reference to master; since you want to get the file from the master branch:

git checkout master -- filename

Note that the differences will be cached; so if you want to see the differences you obtained; use

git diff --cached

How do I get the serial key for Visual Studio Express?

The question is about VS 2008 Express.

Microsoft's web page for registering Visual Studio 2008 Express has been dead (404) for some time, so registering it is not possible.

Instead, as a workaround, you can temporarily remove the requirement to register VS2008Exp by deleting (or renaming) the registry key:


To ensure that this is working beforehand, click Help -> register product within VS2008.

You should see text like

"You have not yet registered your copy of Visual C++ 2008 Express Edition. This product will run for 10 more days before you will be required to register it."

Close the application, delete that key, reopen, click help->register product.

The text should now say

"You have not yet registered your copy of Visual C++ 2008 Express Edition. This product will run for 30 more days before you will be required to register it."

So you have two options - delete that key manually every 30 days, or run it from a batch file that also contains a line like:

reg delete HKCU\Software\Microsoft\VCExpress\9.0\Registration /f

[Edit: User @i486 confirms on testing that this workaround works even after the expiration period has expired]

[Edit2: User @Wyatt8740 has a much more elegant way to prevent the value from reappearing.]

How to delete an item in a list if it exists?

Here's another one-liner approach to throw out there:

next((some_list.pop(i) for i, l in enumerate(some_list) if l == thing), None)

It doesn't create a list copy, doesn't make multiple passes through the list, doesn't require additional exception handling, and returns the matched object or None if there isn't a match. Only issue is that it makes for a long statement.

In general, when looking for a one-liner solution that doesn't throw exceptions, next() is the way to go, since it's one of the few Python functions that supports a default argument.

What is the difference between OFFLINE and ONLINE index rebuild in SQL Server?

In ONLINE mode the new index is built while the old index is accessible to reads and writes. any update on the old index will also get applied to the new index. An antimatter column is used to track possible conflicts between the updates and the rebuild (ie. delete of a row which was not yet copied). See Online Index Operations. When the process is completed the table is locked for a brief period and the new index replaces the old index. If the index contains LOB columns, ONLINE operations are not supported in SQL Server 2005/2008/R2.

In OFFLINE mode the table is locked upfront for any read or write, and then the new index gets built from the old index, while holding a lock on the table. No read or write operation is permitted on the table while the index is being rebuilt. Only when the operation is done is the lock on the table released and reads and writes are allowed again.

Note that in SQL Server 2012 the restriction on LOBs was lifted, see Online Index Operations for indexes containing LOB columns.


From [Hive Language Manual][1]:

COALESCE (T v1, T v2, ...)

Will return the first value that is not NULL, or NULL if all values's are NULL

How to use Git for Unity3D source control?

I thought that I might post a simpler .gitignore for anyone that is interested:

# Ignore Everything

# Except for these: