Programs & Examples On #Reverse proxy

A reverse proxy server usually refers to an HTTP accelerator or load-balancer which proxies requests on behalf of the actual clients to one or more backend HTTP servers.

Error during SSL Handshake with remote server

Faced the same problem as OP:

  • Tomcat returned response when accessing directly via SOAP UI
  • Didn't load html files
  • When used Apache properties mentioned by the previous answer, web-page appeared but AngularJS couldn't get HTTP response

Tomcat SSL certificate was expired while a browser showed it as secure - Apache certificate was far from expiration. Updating Tomcat KeyStore file solved the problem.

nginx - read custom header from upstream server


You can write some-thing like

set my_header $http_MY_CUSTOM_HEADER;
if($my_header != 'some-value') {
#do some thing;

Proxy with express.js

I found a shorter and very straightforward solution which works seamlessly, and with authentication as well, using express-http-proxy:

const url = require('url');
const proxy = require('express-http-proxy');

// New hostname+path as specified by question:
const apiProxy = proxy('', {
    proxyReqPathResolver: req => url.parse(req.baseUrl).path

And then simply:

app.use('/api/*', apiProxy);

Note: as mentioned by @MaxPRafferty, use req.originalUrl in place of baseUrl to preserve the querystring:

    forwardPath: req => url.parse(req.baseUrl).path

Update: As mentioned by Andrew (thank you!), there's a ready-made solution using the same principle:

npm i --save http-proxy-middleware

And then:

const proxy = require('http-proxy-middleware')
var apiProxy = proxy('/api', {target: ''});

Documentation: http-proxy-middleware on Github

I know I'm late to join this party, but I hope this helps someone.

What's the difference between a proxy server and a reverse proxy server?

A pair of simple definitions would be:

Forward Proxy: Acting on behalf of a requestor (or service consumer)

Reverse Proxy: Acting on behalf of service/content producer.

How to serve all existing static files directly with NGINX, but proxy the rest to a backend server.

Try this:

location / {
    root /path/to/root;
    expires 30d;
    access_log off;

location ~* ^.*\.php$ {
    if (!-f $request_filename) {
        return 404;
    proxy_set_header X-Real-IP  $remote_addr;
    proxy_set_header Host $host;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;

Hopefully it works. Regular expressions have higher priority than plain strings, so all requests ending in .php should be forwared to Apache if only a corresponding .php file exists. Rest will be handled as static files. The actual algorithm of evaluating location is here.

From inside of a Docker container, how do I connect to the localhost of the machine?

Here is my solution : it works for my case

  • set local mysql server to public access by comment #bind-address = in /etc/mysql/mysql.conf.d

  • restart mysql server sudo /etc/init.d/mysql restart

  • run the following command to open user root access any host mysql -uroot -proot GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' IDENTIFIED BY 'root' WITH GRANT OPTION; FLUSH PRIVILEGES;

  • create sh script :


    HOSTIP=`ip -4 addr show scope global dev eth0 | grep inet | awk '{print \$2}' | cut -d / -f 1`

      docker run -it -d --name web-app \
                  --add-host=local:${HOSTIP} \
                  -p 8080:8080 \
                  -e DATABASE_HOST=${HOSTIP} \
                  -e DATABASE_PORT=3306 \
                  -e DATABASE_NAME=demo \
                  -e DATABASE_USER=root \
                  -e DATABASE_PASSWORD=root \

  • run with docker-composer

    version: '2.1'

    tomcatwar: extra_hosts: - "local:" image: sopheamak/springboot_docker_mysql
    ports: - 8080:8080 environment: - DATABASE_HOST=local - DATABASE_USER=root - DATABASE_PASSWORD=root - DATABASE_NAME=demo - DATABASE_PORT=3306

Nginx reverse proxy causing 504 Gateway Timeout

If nginx_ajp_module is used, try adding ajp_read_timeout 10m; in nginx.conf file.

Configure Nginx with proxy_pass

Give this a try...

server {
    listen   80;
    access_log off;
    location / {
        proxy_pass http://IP:8080;
        proxy_set_header    Host            $host;
        proxy_set_header    X-Real-IP       $remote_addr;
        proxy_set_header    X-Forwarded-for $remote_addr;
        port_in_redirect off;
        proxy_redirect   http://IP:8080/jira  /;
        proxy_connect_timeout 300;

    location ~ ^/stash {
        proxy_pass http://IP:7990;
        proxy_set_header    Host            $host;
        proxy_set_header    X-Real-IP       $remote_addr;
        proxy_set_header    X-Forwarded-for $remote_addr;
        port_in_redirect off;
        proxy_redirect   http://IP:7990/  /stash;
        proxy_connect_timeout 300;

    error_page   500 502 503 504  /50x.html;
    location = /50x.html {
        root   /usr/local/nginx/html;

Java: how do I initialize an array size if it's unknown?

int i,largest = 0;
Scanner scan = new Scanner(;
System.out.println("Enter the number of numbers in the list");
i = scan.nextInt();
int arr[] = new int[i];
System.out.println("Enter the list of numbers:");
for(int j=0;j<i;j++){
    arr[j] = scan.nextInt();

The above code works well. I have taken the input of the number of elements in the list and initialized the array accordingly.

what is the difference between $_SERVER['REQUEST_URI'] and $_GET['q']?

Given this example url:

$_SERVER['REQUEST_URI'] will give you:


Whereas $_GET['q'] will give you:


In other words, $_SERVER['REQUEST_URI'] will hold the full request path including the querystring. And $_GET['q'] will give you the value of parameter q in the querystring.

unbound method f() must be called with fibo_ instance as first argument (got classobj instance instead)

In Python 2 (3 has different syntax):

What if you can't instantiate your Parent class before you need to call one of its methods?

Use super(ChildClass, self).method() to access parent methods.

class ParentClass(object):
    def method_to_call(self, arg_1):
        print arg_1

class ChildClass(ParentClass):
    def do_thing(self):
        super(ChildClass, self).method_to_call('my arg')

Scanner doesn't read whole sentence - difference between next() and nextLine() of scanner class

next() can read the input only till the space. It can't read two words separated by space. Also, next() places the cursor in the same line after reading the input.

nextLine() reads input including space between the words (that is, it reads till the end of line \n). Once the input is read, nextLine() positions the cursor in the next line.

for reading the entire line you can use nextLine()

How to get the system uptime in Windows?

Two ways to do that..

Option 1:

1.  Go to "Start" -> "Run".

2.  Write "CMD" and press on "Enter" key.

3.  Write the command "net statistics server" and press on "Enter" key.

4.  The line that start with "Statistics since …" provides the time that the server was up from.

  The command "net stats srv" can be use instead.

Option 2:

Uptime.exe Tool Allows You to Estimate Server Availability with Windows NT 4.0 SP4 or Higher

Hope it helped you!!

SMTP server response: 530 5.7.0 Must issue a STARTTLS command first

I had a false response for the following:

fputs($connection, 'STARTTLS'.$newLine);

turns out I use the wrong connection variable, so I just had to change it to:

fputs($smtpConnect, 'STARTTLS'.$newLine);

If using TLS remember to put HELO before and after:

fputs($smtpConnect, 'HELO '.$localhost . $newLine);
$response = fgets($smtpConnect, 515);
if($secure == 'tls')
    fputs($smtpConnect, 'STARTTLS'.$newLine);
    $response = fgets($smtpConnect, 515);
stream_socket_enable_crypto($smtpConnect, true, STREAM_CRYPTO_METHOD_TLS_CLIENT);

// Say hello again!
    fputs($smtpConnect, 'HELO '.$localhost . $newLine);
    $response = fgets($smtpConnect, 515);

Content Type application/soap+xml; charset=utf-8 was not supported by service

As suggested by others this happens due to service client mismatch.

I ran into the same problem, when was debugging got to know that there is a mismatch in the binding. Instead of WSHTTPBinding I was referring to BasicHttpBinding. In my case I am referring both BasicHttp and WsHttp. I was dynamically assigning the binding based on the reference. So check your service constructor as shown below

Refer this image

How can I initialise a static Map?

Map.of in Java 9+

private static final Map<Integer, String> MY_MAP = Map.of(1, "one", 2, "two");

See JEP 269 for details. JDK 9 reached general availability in September 2017.

How to call a function, PostgreSQL

For Postgresql you can use PERFORM. PERFORM is only valid within PL/PgSQL procedure language.

    PERFORM "saveUser"(3, 'asd','asd','asd','asd','asd');
END $$;

The suggestion from the postgres team:

HINT: If you want to discard the results of a SELECT, use PERFORM instead.


Here's one working syntax for SQL Server 2017:

USE [<yourdb-name>]

FROM <table1-name>
SELECT * FROM <table2-name>

Grouping functions (tapply, by, aggregate) and the *apply family

First start with Joran's excellent answer -- doubtful anything can better that.

Then the following mnemonics may help to remember the distinctions between each. Whilst some are obvious, others may be less so --- for these you'll find justification in Joran's discussions.


  • lapply is a list apply which acts on a list or vector and returns a list.
  • sapply is a simple lapply (function defaults to returning a vector or matrix when possible)
  • vapply is a verified apply (allows the return object type to be prespecified)
  • rapply is a recursive apply for nested lists, i.e. lists within lists
  • tapply is a tagged apply where the tags identify the subsets
  • apply is generic: applies a function to a matrix's rows or columns (or, more generally, to dimensions of an array)

Building the Right Background

If using the apply family still feels a bit alien to you, then it might be that you're missing a key point of view.

These two articles can help. They provide the necessary background to motivate the functional programming techniques that are being provided by the apply family of functions.

Users of Lisp will recognise the paradigm immediately. If you're not familiar with Lisp, once you get your head around FP, you'll have gained a powerful point of view for use in R -- and apply will make a lot more sense.

Free tool to Create/Edit PNG Images?

I use Pixlr - an online photo editor, it has great filters and user friendly interface.

Cannot deserialize the current JSON array (e.g. [1,2,3]) into type

For array type Please try this one.

 List<MyStok> myDeserializedObjList = (List<MyStok>)Newtonsoft.Json.JsonConvert.DeserializeObject(sc), typeof(List<MyStok>));

Please See here for details to deserialise Json


Use requests library. Try this solution, or just add https:// before the URL:

import requests
from bs4 import BeautifulSoup
import re

pages = set()
def getLinks(pageUrl):
    global pages
    html = requests.get(""+pageUrl, verify=False).text
    bsObj = BeautifulSoup(html)
    for link in bsObj.findAll("a", href=re.compile("^(/wiki/)")):
        if 'href' in link.attrs:
            if link.attrs['href'] not in pages:
                #We have encountered a new page
                newPage = link.attrs['href']

Check if this works for you

Can't create handler inside thread which has not called Looper.prepare()

All the answers above are correct, but I think this is the easiest example possible:

public class ExampleActivity extends Activity {
    private Handler handler;
    private ProgressBar progress;

    public void onCreate(Bundle savedInstanceState) {
        progress = (ProgressBar) findViewById(;
        handler = new Handler();

    public void clickAButton(View view) {
        // Do something that takes a while
        Runnable runnable = new Runnable() {
            public void run() {
       Runnable() { // This thread runs in the UI
                    public void run() {
                        progress.setProgress("anything"); // Update the UI
        new Thread(runnable).start();

What this does is update a progress bar in the UI thread from a completely different thread passed through the post() method of the handler declared in the activity.

Hope it helps!

Input group - two inputs close to each other

To show more than one inputs inline without using "form-inline" class you can use the next code:

<div class="input-group">
    <input type="text" class="form-control" value="First input" />
    <span class="input-group-btn"></span>
    <input type="text" class="form-control" value="Second input" />

Then using CSS selectors:

/* To remove space between text inputs */
.input-group > .input-group-btn:empty {
    width: 0px;

Basically you have to insert an empty span tag with "input-group-btn" class between input tags.

If you want to see more examples of input groups and bootstrap-select groups take a look at this URL:

How to align 3 divs (left/center/right) inside another div?

I like my bars tight and dynamic. This is for CSS 3 & HTML 5

  1. First, setting the Width to 100px is limiting. Don't do it.

  2. Second, setting the container's width to 100% will work ok, until were talking about it being a header/footer bar for the whole app, like a navigation or credits/copyright bar. Use right: 0; instead for that scenario.

  3. You are using id's (hash #container, #left, etc) instead of classes (.container, .left, etc), which is fine, unless you want to repeat your style pattern elsewhere in your code. I'd consider using classes instead.

  4. For HTML, no need to swap order for: left, center, & right. display: inline-block; fixes this, returning your code to something cleaner and logically in order again.

  5. Lastly, you need to clear the floats all up so that it doesn't mess with future <div>. You do this with the clear: both;

To summarize:


<div class="container">
  <div class="left"></div>
  <div class="center"></div>
  <div class="right"></div>
  <div class="clear"></div>


.container {right: 0; text-align: center;}

.container .left, .container .center, .container .right { display: inline-block; }

.container .left { float: left; }
.container .center { margin: 0 auto; }
.container .right { float: right; }
.clear { clear: both; }

Bonus point if using HAML and SASS ;)




.container {
  right: 0;
  text-align: center;

  .left, .center, .right { display: inline-block; }

  .left { float: left; }
  .center { margin: 0 auto; }
  .right { float: right; }
  .clear { clear: both; }

Can I write into the console in a unit test? If yes, why doesn't the console window open?

There are several ways to write output from a Visual Studio unit test in C#:

  • Console.Write - The Visual Studio test harness will capture this and show it when you select the test in the Test Explorer and click the Output link. Does not show up in the Visual Studio Output Window when either running or debugging a unit test (arguably this is a bug).
  • Debug.Write - The Visual Studio test harness will capture this and show it in the test output. Does appear in the Visual Studio Output Window when debugging a unit test, unless Visual Studio Debugging options are configured to redirect Output to the Immediate Window. Nothing will appear in the Output (or Immediate) Window if you simply run the test without debugging. By default only available in a Debug build (that is, when DEBUG constant is defined).
  • Trace.Write - The Visual Studio test harness will capture this and show it in the test output. Does appear in the Visual Studio Output (or Immediate) Window when debugging a unit test (but not when simply running the test without debugging). By default available in both Debug and Release builds (that is, when TRACE constant is defined).

Confirmed in Visual Studio 2013 Professional.

How do I interpret precision and scale of a number in a database?

Precision of a number is the number of digits.

Scale of a number is the number of digits after the decimal point.

What is generally implied when setting precision and scale on field definition is that they represent maximum values.

Example, a decimal field defined with precision=5 and scale=2 would allow the following values:

  • 123.45 (p=5,s=2)
  • 12.34 (p=4,s=2)
  • 12345 (p=5,s=0)
  • 123.4 (p=4,s=1)
  • 0 (p=0,s=0)

The following values are not allowed or would cause a data loss:

  • 12.345 (p=5,s=3) => could be truncated into 12.35 (p=4,s=2)
  • 1234.56 (p=6,s=2) => could be truncated into 1234.6 (p=5,s=1)
  • 123.456 (p=6,s=3) => could be truncated into 123.46 (p=5,s=2)
  • 123450 (p=6,s=0) => out of range

Note that the range is generally defined by the precision: |value| < 10^p ...

How to calculate sum of a formula field in crystal Reports?

The only reason that I know of why a formula wouldn't be available to summarize on is if it didn't reference any database fields or whose value wasn't dynamic throughout sections of the report. For example, if you have a formula that returns a constant it won't be available. Or if it only references a field that is set throughout the report and returns a value based on that field, like "if {parameter}=1 then 1" would not be available either.

In general, the formula's value should not be static through the sections of the report you're summarizing over (Though the way Crystal determines this is beyond me and this doesn't seem to be a hard and fast rule)

EDIT: One other reason why a formula wouldn't be available is if you're already using a summary function in that formula. Only one level of summaries at a time!

(13: Permission denied) while connecting to upstream:[nginx]

I’ve run into this problem too. Another solution is to toggle the SELinux boolean value for httpd network connect to on (Nginx uses the httpd label).

setsebool httpd_can_network_connect on

To make the change persist use the -P flag.

setsebool httpd_can_network_connect on -P

You can see a list of all available SELinux booleans for httpd using

getsebool -a | grep httpd

Build Android Studio app via command line

1. Install Gradle and the Android SDK


  • Install these however you see fit
  • Run ./gradlew, or gradlew.bat if on Windows
    • chmod +x ./gradlew may be necessary

From this point onwards, gradle refers to running Gradle whichever way you've chosen. Substitute accordingly.

2. Setup the Android SDK

  • If you've manually installed the SDK

    • export ANDROID_HOME=<install location>
    • You may want to put that in your ~/.profile if it's not done automatically
  • Accept the licenses: yes | sdkmanager --licenses

    • sdkmanager can be found in $ANDROID_HOME/tools/bin
    • sdkmanager may have to be run as root
  • Try running gradle

    • If there are complaints about licenses or SDKs not being found, fix the directory permissions
      • chown -R user:group $ANDROID_HOME
      • If you're reckless and/or the only user: chmod 777 -R $ANDROID_HOME

3. Building

  • gradle tasks lists all tasks that can be run
  • :app:[appname] is the prefix of all tasks, which you'll see in the Gradle logs when you're building
    • This can be excluded when running a task

Some essential tasks

  • gradle assemble: build all variants of your app
    • Resulting .apks are in app/[appname]/build/outputs/apk/[debug/release]
  • gradle assembleDebug or assembleRelease: build just the debug or release versions
  • gradle installDebug or installRelease build and install to an attached device
    • Have adb installed
    • Attach a device with USB debugging and USB file transfer enabled
    • Run adb devices, check that your device is listed and device is beside it

Automatically build and install upon changes

This avoids having to continuously run the same commands

gradle -t --continue installDebug
  • -t: aka --continuous, automatically re-runs the task after a file is changed
  • --continue: Continue after errors. Prevents stopping when errors occur

Run gradle -h for more help

Iterate a list with indexes in Python

python enumerate function will be satisfied your requirements

result = list(enumerate([1,3,7,12]))
print result


[(0, 1), (1, 3), (2, 7),(3,12)]

Using generic std::function objects with member functions in one class

Either you need

std::function<void(Foo*)> f = &Foo::doSomething;

so that you can call it on any instance, or you need to bind a specific instance, for example this

std::function<void(void)> f = std::bind(&Foo::doSomething, this);

Where is Python language used?

With a few exceptions, Python is used pretty much wherever a programmer who knows Python wants to focus on solving a problem instead of struggling with implementation details. You'll find it in games, web applications, network servers, scientific computing, media tools, application scripting, etc. (There's a somewhat old list of some organizations that use it here.) People who know it well tend to love it because it strikes a very rare balance of conciseness and clarity, and (perhaps to a lesser extent) because it has a rich set of useful libraries.

Some places where Python isn't used as much:

  • Web browser scripts (because browsers implement JavaScript, not Python, though there are ways around that)
  • Large GUI applications (perhaps because good GUI bindings are relatively new)
  • Graphics engines (for performance reasons, but note that Python is sometimes used for the controlling logic that makes use of a graphics engine)
  • Small embedded devices (although some folks have had success with compact, stripped-down and special-purpose implementations of Python, and we're starting to see python tools for building applications on smart phones and tablets.)

Twitter bootstrap scrollable table

All above solutions make table header scroll too... If you want to scroll tbody only then apply this:

tbody {
    height: 100px !important;
    overflow: scroll;

Stack, Static, and Heap in C++

Stack memory allocation (function variables, local variables) can be problematic when your stack is too "deep" and you overflow the memory available to stack allocations. The heap is for objects that need to be accessed from multiple threads or throughout the program lifecycle. You can write an entire program without using the heap.

You can leak memory quite easily without a garbage collector, but you can also dictate when objects and memory is freed. I have run in to issues with Java when it runs the GC and I have a real time process, because the GC is an exclusive thread (nothing else can run). So if performance is critical and you can guarantee there are no leaked objects, not using a GC is very helpful. Otherwise it just makes you hate life when your application consumes memory and you have to track down the source of a leak.

Clearing an HTML file upload field via JavaScript

For compatibility when ajax is not available, set .val('') or it will resend the last ajax-uploaded file that is still present in the input. The following should properly clear the input whilst retaining .on() events:

var input = $("input[type='file']");

How can I see an the output of my C programs using Dev-C++?

i think you should link your project in console mode

just press Ctrl+h and in General tab select console.

Converting Long to Date in Java returns 1970

The Date constructor (click the link!) accepts the time as long in milliseconds, not seconds. You need to multiply it by 1000 and make sure that you supply it as long.

Date d = new Date(1220227200L * 1000);

This shows here

Sun Aug 31 20:00:00 GMT-04:00 2008

Oracle SQL Query for listing all Schemas in a DB

Either of the following SQL will return all schema in Oracle DB.

  1. select owner FROM all_tables group by owner;
  2. select distinct owner FROM all_tables;

Removing App ID from Developer Connection

As @AlexanderN pointed out, you can now delete App IDs.

  1. In your Member Center go to the Certificates, Identifiers & Profiles section.
  2. Go to Identifiers folder.
  3. Select the App ID you want to delete and click Settings
  4. Scroll down and click Delete.

How do I set the time zone of MySQL?

If anyone is using GoDaddy Shared Hosting, you can try for following solution, worked for me.

When starting DB connection, set the time_zone command in my PDO object e.g.:

$pdo = new PDO($dsn, $user, $pass, $opt);
$pdo->exec("SET time_zone='+05:30';");

Where "+05:30" is the TimeZone of India. You can change it as per your need.

After that; all the MySQL processes related to Date and Time are set with required timezone.

Source :

Adding multiple columns AFTER a specific column in MySQL

This one is correct:

    ADD COLUMN `count` SMALLINT(6) NOT NULL AFTER `lastname`,
    ADD COLUMN `log` VARCHAR(12) NOT NULL AFTER `count`,

Getting "error": "unsupported_grant_type" when trying to get a JWT by calling an OWIN OAuth secured Web Api via Postman

try to add this in your payload


overlay opaque div over youtube iframe

Note that the wmode=transparent fix only works if it's first so


Java: how do I check if a Date is within a certain range?

  public class TestDate {

    public static void main(String[] args) {
    // TODO Auto-generated method stub

    String fromDate = "18-FEB-2018";
    String toDate = "20-FEB-2018";

    String requestDate = "19/02/2018";  
    System.out.println(checkBetween(requestDate,fromDate, toDate));

public static boolean checkBetween(String dateToCheck, String startDate, String endDate) {
    boolean res = false;
    SimpleDateFormat fmt1 = new SimpleDateFormat("dd-MMM-yyyy"); //22-05-2013
    SimpleDateFormat fmt2 = new SimpleDateFormat("dd/MM/yyyy"); //22-05-2013
    try {
     Date requestDate = fmt2.parse(dateToCheck);
     Date fromDate = fmt1.parse(startDate);
     Date toDate = fmt1.parse(endDate);
     res = requestDate.compareTo(fromDate) >= 0 && requestDate.compareTo(toDate) <=0;
    }catch(ParseException pex){
    return res;

How to convert int to QString?

Use QString::number():

int i = 42;
QString s = QString::number(i);

Invalid application path

I had a similar issue today. It was caused by skype! A recent update to skype had re-enabled port 80 and 443 as alternatives to incoming connections.

H/T :

To disable, go to skype > options > Advanced > Connections and uncheck "Use port 80 and 443 as alternatives to incoming connections"

Compiling C++11 with g++

If you want to keep the GNU compiler extensions, use -std=gnu++0x rather than -std=c++0x. Here's a quote from the man page:

The compiler can accept several base standards, such as c89 or c++98, and GNU dialects of those standards, such as gnu89 or gnu++98. By specifying a base standard, the compiler will accept all programs following that standard and those using GNU extensions that do not contradict it. For example, -std=c89 turns off certain features of GCC that are incompatible with ISO C90, such as the "asm" and "typeof" keywords, but not other GNU extensions that do not have a meaning in ISO C90, such as omitting the middle term of a "?:" expression. On the other hand, by specifying a GNU dialect of a standard, all features the compiler support are enabled, even when those features change the meaning of the base standard and some strict-conforming programs may be rejected. The particular standard is used by -pedantic to identify which features are GNU extensions given that version of the standard. For example-std=gnu89 -pedantic would warn about C++ style // comments, while -std=gnu99 -pedantic would not.

How do I start Mongo DB from Windows?

Actually windows way to use service, from the official documentation:

  • Find out where is your executable is installed, path may be like this:

    "C:\Program Files\MongoDB\Server\3.4\bin\mongod.exe"

  • Create config file with such content (yaml format), path may be like this:

    "C:\Program Files\MongoDB\Server\3.4\mongod.cfg"

    destination: file
    path: c:\data\log\mongod.log
    dbPath: c:\data\db
  • Execute as admin the next command (run command line as admin):
C:\...\mongod.exe --config C:\...\mongod.cfg --install

Where paths is reduced with dots, see above.

The key --install say to mongo to install itself as windows service.

Now you can start, stop, restart mongo server as usual windows service choose your favorite way from this:

  • from Control Panel -> Administration -> Services -> MongoDB
  • by command execution from command line as admin: (net start MongoDB)

Check log file specified in config file if any problems.

CSS: Position text in the middle of the page

Even though you've accepted an answer, I want to post this method. I use jQuery to center it vertically instead of css (although both of these methods work). Here is a fiddle, and I'll post the code here anyways.


<h1>Hello world!</h1>

Javascript (jQuery):

  $('h1').css({ 'width':'100%', 'text-align':'center' });
  var h1 = $('h1').height();
  var h = h1/2;
  var w1 = $(window).height();
  var w = w1/2;
  var m = w - h
  $('h1').css("margin-top",m + "px")

This takes the height of the viewport, divides it by two, subtracts half the height of the h1, and sets that number to the margin-top of the h1. The beauty of this method is that it works on multiple-line h1s.

EDIT: I modified it so that it centered it every time the window is resized.

Using "label for" on radio buttons

Either structure is valid and accessible, but the for attribute should be equal to the id of the input element:

<input type="radio" ... id="r1" /><label for="r1">button text</label>


<label for="r1"><input type="radio" ... id="r1" />button text</label>

The for attribute is optional in the second version (label containing input), but IIRC there were some older browsers that didn't make the label text clickable unless you included it. The first version (label after input) is easier to style with CSS using the adjacent sibling selector +:

input[type="radio"]:checked+label {font-weight:bold;}

Difference between Hive internal tables and external tables?

In Hive We can also create an external table. It tells Hive to refer to the data that is at an existing location outside the warehouse directory. Dropping External tables will delete metadata but not the data.

Android: How to programmatically access the device serial number shown in the AVD manager (API Version 8)

Build.SERIAL can be empty or sometimes return a different value (proof 1, proof 2) than what you can see in your device's settings.

If you want a more complete and robust solution, I've compiled every possible solution I could found in a single gist. Here's a simplified version of it :

public static String getSerialNumber() {
    String serialNumber;

    try {
        Class<?> c = Class.forName("android.os.SystemProperties");
        Method get = c.getMethod("get", String.class);

        serialNumber = (String) get.invoke(c, "gsm.sn1");
        if (serialNumber.equals(""))
            serialNumber = (String) get.invoke(c, "ril.serialnumber");
        if (serialNumber.equals(""))
            serialNumber = (String) get.invoke(c, "ro.serialno");
        if (serialNumber.equals(""))
            serialNumber = (String) get.invoke(c, "sys.serialnumber");
        if (serialNumber.equals(""))
            serialNumber = Build.SERIAL;

        // If none of the methods above worked
        if (serialNumber.equals(""))
            serialNumber = null;
    } catch (Exception e) {
        serialNumber = null;

    return serialNumber;

I try to update the gist regularly whenever I can test on a new device or Android version. Contributions are welcome too.

Calculating the position of points in a circle

Here's a solution using C#:

void DrawCirclePoints(int points, double radius, Point center)
    double slice = 2 * Math.PI / points;
    for (int i = 0; i < points; i++)
        double angle = slice * i;
        int newX = (int)(center.X + radius * Math.Cos(angle));
        int newY = (int)(center.Y + radius * Math.Sin(angle));
        Point p = new Point(newX, newY);

Sample output from DrawCirclePoints(8, 10, new Point(0,0));:


Good luck!

Multiple file-extensions searchPattern for System.IO.Directory.GetFiles

var filteredFiles = Directory
    .GetFiles(path, "*.*")
    .Where(file => file.ToLower().EndsWith("aspx") || file.ToLower().EndsWith("ascx"))

Edit 2014-07-23

You can do this in .NET 4.5 for a faster enumeration:

var filteredFiles = Directory
    .EnumerateFiles(path) //<--- .NET 4.5
    .Where(file => file.ToLower().EndsWith("aspx") || file.ToLower().EndsWith("ascx"))

Directory.EnumerateFiles in MSDN

Why doesn't height: 100% work to expand divs to the screen height?

In order for a percentage value to work for height, the parent's height must be determined. The only exception is the root element <html>, which can be a percentage height. .

So, you've given all of your elements height, except for the <html>, so what you should do is add this:

html {
    height: 100%;

And your code should work fine.

* { padding: 0; margin: 0; }_x000D_
html, body, #fullheight {_x000D_
    min-height: 100% !important;_x000D_
    height: 100%;_x000D_
#fullheight {_x000D_
    width: 250px;_x000D_
    background: blue;_x000D_
<div id=fullheight>_x000D_
  Lorem Ipsum        _x000D_

JsFiddle example.

Extract a substring using PowerShell

PS> $a = "-----start-------Hello World------end-------"
PS> $a.substring(17, 11)
PS> $a.Substring($a.IndexOf('H'), 11)

$a.Substring(argument1, argument2) --> Here argument1 = Starting position of the desired alphabet and argument2 = Length of the substring you want as output.

Here 17 is the index of the alphabet 'H' and since we want to Print till Hello World, we provide 11 as the second argument

How to convert the system date format to dd/mm/yy in SQL Server 2008 R2?

   SELECT CONVERT(varchar(11),getdate(),101)  -- mm/dd/yyyy

   SELECT CONVERT(varchar(11),getdate(),103)  -- dd/mm/yyyy

Check this . I am assuming D30.SPGD30_TRACKED_ADJUSTMENT_X is of datetime datatype .
That is why i am using CAST() function to make it as an character expression because CHARINDEX() works on character expression.
Also I think there is no need of OR condition.

select case when CHARINDEX('-',cast(D30.SPGD30_TRACKED_ADJUSTMENT_X as varchar )) > 0 

then 'Score Calculation - '+CONVERT(VARCHAR(11), D30.SPGD30_TRACKED_ADJUSTMENT_X, 103)


select case when CHARINDEX('-',D30.SPGD30_TRACKED_ADJUSTMENT_X) > 0 
then 'Score Calculation - '+

See this link for conversion to other date formats:

Switch statement: must default be the last case?

There are cases when you are converting ENUM to a string or converting string to enum in case where you are writing/reading to/from a file.

You sometimes need to make one of the values default to cover errors made by manually editing files.

case ModeTiled:
    // write to a file "tiled"

case ModeStretched:
    // write to a file "stretched"

Visual Studio move project to a different folder

This worked for me vb2019. I copied my source project folder. I then pasted the project, and renamed the the folder to whatever. In order to break the ties back to the source project folder, I temporarily renamed the source folder. I opened my destination project. The paths to the forms and modules were re-discovered in the local folder. I went through all my forms and modules to make sure they were working. I ran the project. I closed the project. I renamed the source project folder back to is't original name. I can open both projects at the same time without errors.

Iterating through populated rows

I'm going to make a couple of assumptions in my answer. I'm assuming your data starts in A1 and there are no empty cells in the first column of each row that has data.

This code will:

  1. Find the last row in column A that has data
  2. Loop through each row
  3. Find the last column in current row with data
  4. Loop through each cell in current row up to last column found.

This is not a fast method but will iterate through each one individually as you suggested is your intention.

Sub iterateThroughAll()
    ScreenUpdating = False
    Dim wks As Worksheet
    Set wks = ActiveSheet

    Dim rowRange As Range
    Dim colRange As Range

    Dim LastCol As Long
    Dim LastRow As Long
    LastRow = wks.Cells(wks.Rows.Count, "A").End(xlUp).Row

    Set rowRange = wks.Range("A1:A" & LastRow)

    'Loop through each row
    For Each rrow In rowRange
        'Find Last column in current row
        LastCol = wks.Cells(rrow, wks.Columns.Count).End(xlToLeft).Column
        Set colRange = wks.Range(wks.Cells(rrow, 1), wks.Cells(rrow, LastCol))

        'Loop through all cells in row up to last col
        For Each cell In colRange
            'Do something to each cell
            Debug.Print (cell.Value)
        Next cell
    Next rrow
    ScreenUpdating = True
End Sub

What is the perfect counterpart in Python for "while not EOF"

Loop over the file to read lines:

with open('somefile') as openfileobject:
    for line in openfileobject:

File objects are iterable and yield lines until EOF. Using the file object as an iterable uses a buffer to ensure performant reads.

You can do the same with the stdin (no need to use raw_input():

import sys

for line in sys.stdin:

To complete the picture, binary reads can be done with:

from functools import partial

with open('somefile', 'rb') as openfileobject:
    for chunk in iter(partial(, 1024), b''):

where chunk will contain up to 1024 bytes at a time from the file, and iteration stops when starts returning empty byte strings.

Can Json.NET serialize / deserialize to / from a stream?

The current version of does not allow you to use the accepted answer code. A current alternative is:

public static object DeserializeFromStream(Stream stream)
    var serializer = new JsonSerializer();

    using (var sr = new StreamReader(stream))
    using (var jsonTextReader = new JsonTextReader(sr))
        return serializer.Deserialize(jsonTextReader);

Documentation: Deserialize JSON from a file stream

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

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

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

ProcÚdure PL/SQL terminÚe avec succÞs.

SQL> print x;


jQuery remove selected option from this

this isn't a css selector. you can avoid spelling the id of this by passing it as a context:

$('option:selected', this).remove();

Can't find System.Windows.Media namespace?

The System.Windows.Media.Imaging namespace is part of PresentationCore.dll (if you are using Visual Studio 2008 then the WPF application template will automatically add this reference). Note that this namespace is not a direct wrapping of the WIC library, although a large proportion of the more common uses are still available and it is relatively obvious how these map to the WIC versions. For more information on the classes in this namespace check out

pointer to array c++

The parenthesis are superfluous in your example. The pointer doesn't care whether there's an array involved - it only knows that its pointing to an int

  int g[] = {9,8};
  int (*j) = g;

could also be rewritten as

  int g[] = {9,8};
  int *j = g;

which could also be rewritten as

  int g[] = {9,8};
  int *j = &g[0];

a pointer-to-an-array would look like

  int g[] = {9,8};
  int (*j)[2] = &g;

  //Dereference 'j' and access array element zero
  int n = (*j)[0];

There's a good read on pointer declarations (and how to grok them) at this link here:

Padding between ActionBar's home icon and title

This is how I was able to set the padding between the home icon and the title.

ImageView view = (ImageView)findViewById(;
view.setPadding(left, top, right, bottom);

I couldn't find a way to customize this via the ActionBar xml styles though. That is, the following XML doesn't work:

<style name="ActionBar" parent="android:style/Widget.Holo.Light.ActionBar">        
    <item name="android:titleTextStyle">@style/ActionBarTitle</item>
    <item name="android:icon">@drawable/ic_action_home</item>        

<style name="ActionBarTitle" parent="android:style/TextAppearance.Holo.Widget.ActionBar.Title">
    <item name="android:textSize">18sp</item>
    <item name="android:paddingLeft">12dp</item>   <!-- Can't get this padding to work :( -->

However, if you are looking to achieve this through xml, these two links might help you find a solution:

(This is the actual layout used to display the home icon in an action bar)

What is (x & 1) and (x >>= 1)?

x & 1 is equivalent to x % 2.

x >> 1 is equivalent to x / 2

So, these things are basically the result and remainder of divide by two.

Allow a div to cover the whole page instead of the area within the container

Apply a css-reset to reset all the margins and paddings like this


v2.0 | 20110126 License: none (public domain) */

html, body, div, span, applet, object, iframe,
h1, h2, h3, h4, h5, h6, p, blockquote, pre,
a, abbr, acronym, address, big, cite, code,
del, dfn, em, img, ins, kbd, q, s, samp,
small, strike, strong, sub, sup, tt, var,
b, u, i, center,
dl, dt, dd, ol, ul, li,
fieldset, form, label, legend,
table, caption, tbody, tfoot, thead, tr, th, td,
article, aside, canvas, details, embed, 
figure, figcaption, footer, header, hgroup, 
menu, nav, output, ruby, section, summary,
time, mark, audio, video {
margin: 0;
padding: 0;
border: 0;
font-size: 100%;
font: inherit;
vertical-align: baseline;
/* HTML5 display-role reset for older browsers */
article, aside, details, figcaption, figure, 
footer, header, hgroup, menu, nav, section {
display: block;
body {
line-height: 1;
ol, ul {
list-style: none;
blockquote, q {
quotes: none;
blockquote:before, blockquote:after,
q:before, q:after {
content: '';
content: none;
table {
border-collapse: collapse;
border-spacing: 0;

You can use various css-resets as you need, normal and use in css

  margin: 0px;
 padding: 0px;

margin: 0px;
padding: 0px;

Difference in make_shared and normal shared_ptr in C++

The difference is that std::make_shared performs one heap-allocation, whereas calling the std::shared_ptr constructor performs two.

Where do the heap-allocations happen?

std::shared_ptr manages two entities:

  • the control block (stores meta data such as ref-counts, type-erased deleter, etc)
  • the object being managed

std::make_shared performs a single heap-allocation accounting for the space necessary for both the control block and the data. In the other case, new Obj("foo") invokes a heap-allocation for the managed data and the std::shared_ptr constructor performs another one for the control block.

For further information, check out the implementation notes at cppreference.

Update I: Exception-Safety

NOTE (2019/08/30): This is not a problem since C++17, due to the changes in the evaluation order of function arguments. Specifically, each argument to a function is required to fully execute before evaluation of other arguments.

Since the OP seem to be wondering about the exception-safety side of things, I've updated my answer.

Consider this example,

void F(const std::shared_ptr<Lhs> &lhs, const std::shared_ptr<Rhs> &rhs) { /* ... */ }

F(std::shared_ptr<Lhs>(new Lhs("foo")),
  std::shared_ptr<Rhs>(new Rhs("bar")));

Because C++ allows arbitrary order of evaluation of subexpressions, one possible ordering is:

  1. new Lhs("foo"))
  2. new Rhs("bar"))
  3. std::shared_ptr<Lhs>
  4. std::shared_ptr<Rhs>

Now, suppose we get an exception thrown at step 2 (e.g., out of memory exception, Rhs constructor threw some exception). We then lose memory allocated at step 1, since nothing will have had a chance to clean it up. The core of the problem here is that the raw pointer didn't get passed to the std::shared_ptr constructor immediately.

One way to fix this is to do them on separate lines so that this arbitary ordering cannot occur.

auto lhs = std::shared_ptr<Lhs>(new Lhs("foo"));
auto rhs = std::shared_ptr<Rhs>(new Rhs("bar"));
F(lhs, rhs);

The preferred way to solve this of course is to use std::make_shared instead.

F(std::make_shared<Lhs>("foo"), std::make_shared<Rhs>("bar"));

Update II: Disadvantage of std::make_shared

Quoting Casey's comments:

Since there there's only one allocation, the pointee's memory cannot be deallocated until the control block is no longer in use. A weak_ptr can keep the control block alive indefinitely.

Why do instances of weak_ptrs keep the control block alive?

There must be a way for weak_ptrs to determine if the managed object is still valid (eg. for lock). They do this by checking the number of shared_ptrs that own the managed object, which is stored in the control block. The result is that the control blocks are alive until the shared_ptr count and the weak_ptr count both hit 0.

Back to std::make_shared

Since std::make_shared makes a single heap-allocation for both the control block and the managed object, there is no way to free the memory for control block and the managed object independently. We must wait until we can free both the control block and the managed object, which happens to be until there are no shared_ptrs or weak_ptrs alive.

Suppose we instead performed two heap-allocations for the control block and the managed object via new and shared_ptr constructor. Then we free the memory for the managed object (maybe earlier) when there are no shared_ptrs alive, and free the memory for the control block (maybe later) when there are no weak_ptrs alive.

Using arrays or std::vectors in C++, what's the performance gap?

If you do not need to dynamically adjust the size, you have the memory overhead of saving the capacity (one pointer/size_t). That's it.

Write-back vs Write-Through caching?

The benefit of write-through to main memory is that it simplifies the design of the computer system. With write-through, the main memory always has an up-to-date copy of the line. So when a read is done, main memory can always reply with the requested data.

If write-back is used, sometimes the up-to-date data is in a processor cache, and sometimes it is in main memory. If the data is in a processor cache, then that processor must stop main memory from replying to the read request, because the main memory might have a stale copy of the data. This is more complicated than write-through.

Also, write-through can simplify the cache coherency protocol because it doesn't need the Modify state. The Modify state records that the cache must write back the cache line before it invalidates or evicts the line. In write-through a cache line can always be invalidated without writing back since memory already has an up-to-date copy of the line.

One more thing - on a write-back architecture software that writes to memory-mapped I/O registers must take extra steps to make sure that writes are immediately sent out of the cache. Otherwise writes are not visible outside the core until the line is read by another processor or the line is evicted.

@Autowired - No qualifying bean of type found for dependency at least 1 bean

You forgot @Service annotation in your service class.

Best Practice for Forcing Garbage Collection in C#

Not sure if it is a best practice, but when working with large amounts of images in a loop (i.e. creating and disposing a lot of Graphics/Image/Bitmap objects), i regularly let the GC.Collect.

I think I read somewhere that the GC only runs when the program is (mostly) idle, and not in the middle of a intensive loop, so that could look like an area where manual GC could make sense.

Observable.of is not a function

For me (Angular 5 & RxJS 5) the autocomplete import suggested:

import { Observable } from '../../../../../node_modules/rxjs/Observable';

while to should be (with all static operators from, of, e.c.t working fine:

import { Observable } from 'rxjs/Observable';

How to get GMT date in yyyy-mm-dd hh:mm:ss in PHP

You don't have to repeat those format identifiers . For yyyy you just need to have Y, etc.

gmdate('Y-m-d h:i:s \G\M\T', time());

In fact you don't even need to give it a default time if you want current time

gmdate('Y-m-d h:i:s \G\M\T');  // This is fine for your purpose


You can get that list of identifiers Here

Reset par to the default values at startup

From Quick-R

par()              # view current settings
opar <- par()      # make a copy of current settings
par(col.lab="red") # red x and y labels 
hist(mtcars$mpg)   # create a plot with these new settings 
par(opar)          # restore original settings

What is console.log in jQuery?

it will print log messages in your developer console (firebug/webkit dev tools/ie dev tools)

Correct format specifier for double in printf

"%f" is the (or at least one) correct format for a double. There is no format for a float, because if you attempt to pass a float to printf, it'll be promoted to double before printf receives it1. "%lf" is also acceptable under the current standard -- the l is specified as having no effect if followed by the f conversion specifier (among others).

Note that this is one place that printf format strings differ substantially from scanf (and fscanf, etc.) format strings. For output, you're passing a value, which will be promoted from float to double when passed as a variadic parameter. For input you're passing a pointer, which is not promoted, so you have to tell scanf whether you want to read a float or a double, so for scanf, %f means you want to read a float and %lf means you want to read a double (and, for what it's worth, for a long double, you use %Lf for either printf or scanf).

1. C99, § "If the expression that denotes the called function has a type that does not include a prototype, the integer promotions are performed on each argument, and arguments that have type float are promoted to double. These are called the default argument promotions." In C++ the wording is somewhat different (e.g., it doesn't use the word "prototype") but the effect is the same: all the variadic parameters undergo default promotions before they're received by the function.

How to call a VbScript from a Batch File without opening an additional command prompt

If you want to fix vbs associations type

regsvr32 vbscript.dll
regsvr32 jscript.dll
regsvr32 wshext.dll
regsvr32 wshom.ocx
regsvr32 wshcon.dll
regsvr32 scrrun.dll

Also if you can't use vbs due to management then convert your script to a program which is designed to be easy, is easy, and takes 5 minutes.

Big difference is functions and subs are both called using brackets rather than just functions.

So the compilers are installed on all computers with .NET installed.

See this article here on how to make a .NET exe. Note the sample is for a scripting host. You can't use this, you have to put your vbs code in as .NET code.

How can I convert a VBScript to an executable (EXE) file?

Angular.js programmatically setting a form field to dirty

If you have access to the NgModelController (you can only get access to it from a directive) then you can call

ngModel.$setViewValue("your new view value");
// or to keep the view value the same and just change it to dirty

Handle Button click inside a row in RecyclerView

You can check if you have any similar entries first, if you get a collection with size 0, start a new query to save.


more professional and faster way. create a cloud trigger (before save)

check out this answer

Access a URL and read Data with R

Beside of read.csv(url("...")) you also can use read.table("http://...").


> sample <- read.table("")
> sample
                V1   V2   V3   V4 V5
1        Rochester 19.0 20.6 15.0  E
2         Syracuse 17.0 15.6 20.2  E
43         Atlanta  4.2 70.6 32.6  S

Algorithm for Determining Tic Tac Toe Game Over

I like this algorithm as it uses a 1x9 vs 3x3 representation of the board.

private int[] board = new int[9];
private static final int[] START = new int[] { 0, 3, 6, 0, 1, 2, 0, 2 };
private static final int[] INCR  = new int[] { 1, 1, 1, 3, 3, 3, 4, 2 };
private static int SIZE = 3;
 * Determines if there is a winner in tic-tac-toe board.
 * @return {@code 0} for draw, {@code 1} for 'X', {@code -1} for 'Y'
public int hasWinner() {
    for (int i = 0; i < START.length; i++) {
        int sum = 0;
        for (int j = 0; j < SIZE; j++) {
            sum += board[START[i] + j * INCR[i]];
        if (Math.abs(sum) == SIZE) {
            return sum / SIZE;
    return 0;

Easy way to prevent Heroku idling?

I have an app that only needs to run from monday to friday around lunchtime. I just added the following script to the crontab at work:

# script to unidle heroku installation for the use with cronjob
# usage in crontab:
# */5 11-15 * * 1-5 /usr/local/bin/
# The command /usr/local/bin/ will execute every 5th minute of 11am through 3pm Mondays through Fridays in every month.
# resources:
echo url to unidle: $1
echo [UPTIMER]: waking up at:
curl $1
echo [UPTIMER]: awake at:

So for any app just drop another line in your crontab like:

*/5 11-15 * * 1-5 /usr/local/bin/

ValueError: object too deep for desired array while using convolution

np.convolve needs a flattened array as one of it's inputs, you can use numpy.ndarray.flatten() which is quite fast, find it here.

How to serve up a JSON response using Go?

In framework I got it to work like this:

// say we are in some resource Show action
// some code is omitted
user := &models.User{}
if c.Request().Header.Get("Content-type") == "application/json" {
    return c.Render(200, r.JSON(user))
} else {
    // Make user available inside the html template
    c.Set("user", user)
    return c.Render(200, r.HTML("users/show.html"))

and then when I want to get JSON response for that resource I have to set "Content-type" to "application/json" and it works.

I think Rails has more convenient way to handle multiple response types, I didn't see the same in gobuffalo so far.

How to use regex in String.contains() method in Java

matcher.find() does what you needed. Example:


React: how to update state.item[1] in state using setState?

As none of the above options was ideal to me I ended up using map:

this.setState({items:,idx)=> idx!==1 ?item :{...item,name:'new_name'}) })

Sum values from multiple rows using vlookup or index/match functions

You should use Ctrl+shift+enter when using the =SUM(VLOOKUP(A9,A1:D5,{2,3,4,},FALSE)) that results in {=SUM(VLOOKUP(A9,A1:D5,{2,3,4,},FALSE))} en also works.

Can I have onScrollListener for a ScrollView?

This might be very useful. Use NestedScrollView instead of ScrollView. Support Library 23.1 introduced an OnScrollChangeListener to NestedScrollView. So you can do something like this.

 myScrollView.setOnScrollChangeListener(new NestedScrollView.OnScrollChangeListener() {
        public void onScrollChange(NestedScrollView v, int scrollX, int scrollY, int oldScrollX, int oldScrollY) {
            //Do something

jQuery Ajax error handling, show custom exception messages

Although it has been many years since this question is asked, I still don't find xhr.responseText as the answer I was looking for. It returned me string in the following format:

"{"error":true,"message":"The user name or password is incorrect"}"

which I definitely don't want to show to the users. What I was looking for is something like below:


xhr.responseJSON.message gives me the exact message from the Json Object which can be shown to the users.

Android SDK location should not contain whitespace, as this cause problems with NDK tools

As long as you aren't using the NDK you can just ignore that warning.

By the way: This warning has nothing to do with parallel installations.

byte array to pdf

You shouldn't be using the BinaryFormatter for this - that's for serializing .Net types to a binary file so they can be read back again as .Net types.

If it's stored in the database, hopefully, as a varbinary - then all you need to do is get the byte array from that (that will depend on your data access technology - EF and Linq to Sql, for example, will create a mapping that makes it trivial to get a byte array) and then write it to the file as you do in your last line of code.

With any luck - I'm hoping that fileContent here is the byte array? In which case you can just do

System.IO.File.WriteAllBytes("hello.pdf", fileContent);

Hiding a form and showing another when a button is clicked in a Windows Forms application

The While statement will not execute until after form1 is closed - as it is outside the main message loop.

Remove it and change the first bit of code to:

private void button1_Click_1(object sender, EventArgs e)  
    if (richTextBox1.Text != null)  
        Form2 form2 = new Form2();;
    else MessageBox.Show("Insert Attributes First !");  


This is not the best way to achieve what you are looking to do though. Instead consider the Wizard design pattern.

Alternatively you could implement a custom ApplicationContext that handles the lifetime of both forms. An example to implement a splash screen is here, which should set you on the right path.

Java: Multiple class declarations in one file

javac doesn't actively prohibit this, but it does have a limitation that pretty much means that you'd never want to refer to a top-level class from another file unless it has the same name as the file it's in.

Suppose you have two files, and contains:

  • public class Foo contains:

  • public class Bar
  • class Baz

Let's also say that all of the classes are in the same package (and the files are in the same directory).

What happens if refers to Baz but not Bar and we try to compile The compilation fails with an error like this: cannot find symbol
symbol  : class Baz
location: class Foo
  private Baz baz;
1 error

This makes sense if you think about it. If refers to Baz, but there is no (or Baz.class), how can javac know what source file to look in?

If you instead tell javac to compile and at the same time, or even if you had previously compiled (leaving the Baz.class where javac can find it) then this error goes away. This makes your build process feel very unreliable and flaky, however.

Because the actual limitation, which is more like "don't refer to a top-level class from another file unless it has the same name as the file it's in or you're also referring to a class that's in that same file that's named the same thing as the file" is kind of hard to follow, people usually go with the much more straightforward (though stricter) convention of just putting one top-level class in each file. This is also better if you ever change your mind about whether a class should be public or not.

Sometimes there really is a good reason why everybody does something in a particular way.

How do I make a checkbox required on an ASP.NET form?

Scott's answer will work for classes of checkboxes. If you want individual checkboxes, you have to be a little sneakier. If you're just doing one box, it's better to do it with IDs. This example does it by specific check boxes and doesn't require jQuery. It's also a nice little example of how you can get those pesky control IDs into your Javascript.

The .ascx:

<script type="text/javascript">

    function checkAgreement(source, args)
        var elem = document.getElementById('<%= chkAgree.ClientID %>');
        if (elem.checked)
            args.IsValid = true;
            args.IsValid = false;

    function checkAge(source, args)
        var elem = document.getElementById('<%= chkAge.ClientID %>');
        if (elem.checked)
            args.IsValid = true;
            args.IsValid = false;


<asp:CheckBox ID="chkAgree" runat="server" />
<asp:Label AssociatedControlID="chkAgree" runat="server">I agree to the</asp:Label>
<asp:HyperLink ID="lnkTerms" runat="server">Terms & Conditions</asp:HyperLink>
<asp:Label AssociatedControlID="chkAgree" runat="server">.</asp:Label>
<br />

<asp:CustomValidator ID="chkAgreeValidator" runat="server" Display="Dynamic"
    You must agree to the terms and conditions.

<asp:CheckBox ID="chkAge" runat="server" />
<asp:Label AssociatedControlID="chkAge" runat="server">I certify that I am at least 18 years of age.</asp:Label>        
<asp:CustomValidator ID="chkAgeValidator" runat="server" Display="Dynamic"
    You must be 18 years or older to continue.

And the codebehind:

Protected Sub chkAgreeValidator_ServerValidate(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.ServerValidateEventArgs) _
Handles chkAgreeValidator.ServerValidate
    e.IsValid = chkAgree.Checked
End Sub

Protected Sub chkAgeValidator_ServerValidate(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.ServerValidateEventArgs) _
Handles chkAgeValidator.ServerValidate
    e.IsValid = chkAge.Checked
End Sub

Maven plugins can not be found in IntelliJ

Enabling "use plugin registry" and Restart project after invalidate cash solved my problem

to Enabling "use plugin registry" >>> (intelij) File > Setting > Maven > enable the option from the option list of maven

To invalidate cash >>> file > invalidate cash

That's it...

Float to String format specifier

You can pass a format string to the ToString method, like so:

ToString("N4"); // 4 decimal points Number

If you want to see more modifiers, take a look at MSDN - Standard Numeric Format Strings

Set start value for column with autoincrement

In the Table Designer on SQL Server Management Studio you can set the where the auto increment will start. Right-click on the table in Object Explorer and choose Design, then go to the Column Properties for the relevant column:

Here the autoincrement will start at 760

Including JavaScript class definition from another file in Node.js

I just want to point out that most of the answers here don't work, I am new to NodeJS and IDK if throughout time the "module.exports.yourClass" method changed, or if people just entered the wrong answer.

// MyClass

module.exports.Ninja = class Ninja{
        console.log('TESTING 1... 2... 3...');
//Using MyClass in seprate File

const ninjaFw = require('./NinjaFw');

let ninja = new ninjaFw.Ninja();

  • This is the method I am currently using. I like this syntax, becuase module.exports sits on the same line as the class declaration and that cleans the code up a little imo. The other way you can do it is like this:
//  Ninja Framework File

class Ninja{
        console.log('TESTING 1... 2... 3...');

module.exports.Ninja = Ninja;

  • Two different syntax but, in the end, the same result. Just a matter of syntax anesthetics.

Python add item to the tuple

#1 form

a = ('x', 'y')
b = a + ('z',)

#2 form

a = ('x', 'y')
b = a + tuple('b')

How to find serial number of Android device?

As Dave Webb mentions, the Android Developer Blog has an article that covers this.

I spoke with someone at Google to get some additional clarification on a few items. Here's what I discovered that's NOT mentioned in the aforementioned blog post:

  • ANDROID_ID is the preferred solution. ANDROID_ID is perfectly reliable on versions of Android <=2.1 or >=2.3. Only 2.2 has the problems mentioned in the post.
  • Several devices by several manufacturers are affected by the ANDROID_ID bug in 2.2.
  • As far as I've been able to determine, all affected devices have the same ANDROID_ID, which is 9774d56d682e549c. Which is also the same device id reported by the emulator, btw.
  • Google believes that OEMs have patched the issue for many or most of their devices, but I was able to verify that as of the beginning of April 2011, at least, it's still quite easy to find devices that have the broken ANDROID_ID.

Based on Google's recommendations, I implemented a class that will generate a unique UUID for each device, using ANDROID_ID as the seed where appropriate, falling back on TelephonyManager.getDeviceId() as necessary, and if that fails, resorting to a randomly generated unique UUID that is persisted across app restarts (but not app re-installations).

import android.content.Context;
import android.content.SharedPreferences;
import android.provider.Settings.Secure;
import android.telephony.TelephonyManager;

import java.util.UUID;

public class DeviceUuidFactory {

    protected static final String PREFS_FILE = "device_id.xml";
    protected static final String PREFS_DEVICE_ID = "device_id";
    protected static volatile UUID uuid;

    public DeviceUuidFactory(Context context) {
        if (uuid == null) {
            synchronized (DeviceUuidFactory.class) {
                if (uuid == null) {
                    final SharedPreferences prefs = context
                            .getSharedPreferences(PREFS_FILE, 0);
                    final String id = prefs.getString(PREFS_DEVICE_ID, null);
                    if (id != null) {
                        // Use the ids previously computed and stored in the
                        // prefs file
                        uuid = UUID.fromString(id);
                    } else {
                        final String androidId = Secure.getString(
                            context.getContentResolver(), Secure.ANDROID_ID);
                        // Use the Android ID unless it's broken, in which case
                        // fallback on deviceId,
                        // unless it's not available, then fallback on a random
                        // number which we store to a prefs file
                        try {
                            if (!"9774d56d682e549c".equals(androidId)) {
                                uuid = UUID.nameUUIDFromBytes(androidId
                            } else {
                                final String deviceId = ((TelephonyManager) 
                                uuid = deviceId != null ? UUID
                                                .getBytes("utf8")) : UUID
                        } catch (UnsupportedEncodingException e) {
                            throw new RuntimeException(e);
                        // Write the value out to the prefs file
                                .putString(PREFS_DEVICE_ID, uuid.toString())

     * Returns a unique UUID for the current android device. As with all UUIDs,
     * this unique ID is "very highly likely" to be unique across all Android
     * devices. Much more so than ANDROID_ID is.
     * The UUID is generated by using ANDROID_ID as the base key if appropriate,
     * falling back on TelephonyManager.getDeviceID() if ANDROID_ID is known to
     * be incorrect, and finally falling back on a random UUID that's persisted
     * to SharedPreferences if getDeviceID() does not return a usable value.
     * In some rare circumstances, this ID may change. In particular, if the
     * device is factory reset a new device ID may be generated. In addition, if
     * a user upgrades their phone from certain buggy implementations of Android
     * 2.2 to a newer, non-buggy version of Android, the device ID may change.
     * Or, if a user uninstalls your app on a device that has neither a proper
     * Android ID nor a Device ID, this ID may change on reinstallation.
     * Note that if the code falls back on using TelephonyManager.getDeviceId(),
     * the resulting ID will NOT change after a factory reset. Something to be
     * aware of.
     * Works around a bug in Android 2.2 for many devices when using ANDROID_ID
     * directly.
     * @see
     * @return a UUID that may be used to uniquely identify your device for most
     *         purposes.
    public UUID getDeviceUuid() {
        return uuid;

Failed to load the JNI shared Library (JDK)

I'm not sure why but I had the jre installed into my c:\windows directory and java.exe and javaw.exe inside my windows\system32 directory.

Obviously these directories were getting priority even AFTER adding the -vm flag to my eclipse.ini file.

Delete them from here fixed the issue for me.

Save the plots into a PDF

If someone ends up here from google, looking to convert a single figure to a .pdf (that was what I was looking for):

import matplotlib.pyplot as plt

f = plt.figure()
plt.plot(range(10), range(10), "o")

f.savefig("foo.pdf", bbox_inches='tight')

How to retrieve current workspace using Jenkins Pipeline Groovy script?

A quick note for anyone who is using bat in the job and needs to access Workspace:

It won't work.

$WORKSPACE as mentioned here only works with PowerShell. So your code should have powershell for execution

 stage('Verifying Workspace') {
  powershell label: '', script: 'dir $WORKSPACE'

Is there an equivalent to the SUBSTRING function in MS Access SQL?

I have worked alot with msaccess vba. I think you are looking for MID function


    dim myReturn as string
    myreturn = mid("bonjour tout le monde",9,4)

will give you back the value "tout"

Session TimeOut in web.xml


In the above code "60" stands for the minutes. The session will expired after 60 minutes. So if you want to more time. For Example -1 that is described your session never expires.

How do I center align horizontal <UL> menu?

i use jquery code for this. (Alternative solution)

    $(document).ready(function() { 
       var margin = $(".topmenu-design").width()-$("#topmenu").width();

How to search in a List of Java object

Using Java 8

With Java 8 you can simply convert your list to a stream allowing you to write:

import java.util.List;

List<Sample> list = new ArrayList<Sample>();
List<Sample> result =
    .filter(a -> Objects.equals(a.value3, "three"))

Note that

  • a -> Objects.equals(a.value3, "three") is a lambda expression
  • result is a List with a Sample type
  • It's very fast, no cast at every iteration
  • If your filter logic gets heavier, you can do list.parallelStream() instead of (read this)

Apache Commons

If you can't use Java 8, you can use Apache Commons library and write:

import org.apache.commons.collections.CollectionUtils;
import org.apache.commons.collections.Predicate;

Collection result =, new Predicate() {
     public boolean evaluate(Object a) {
         return Objects.equals(((Sample) a).value3, "three");

// If you need the results as a typed array:
Sample[] resultTyped = (Sample[]) result.toArray(new Sample[result.size()]);

Note that:

  • There is a cast from Object to Sample at each iteration
  • If you need your results to be typed as Sample[], you need extra code (as shown in my sample)

Bonus: A nice blog article talking about how to find element in list.

How to get root directory in yii2

Use "getAlias" in Yii2


PHP Pass variable to next page

try this code

using hidden field we can pass php varibale to another page


<?php $myVariable = "Some text";?>
<form method="post" action="page2.php">
 <input type="hidden" name="text" value="<?php echo $myVariable; ?>">
 <button type="submit">Submit</button>

pass php variable to hidden field value so you can access this variable into another page


 echo $text;

Writing a Python list of lists to a csv file

You could use pandas:

In [1]: import pandas as pd

In [2]: a = [[1.2,'abc',3],[1.2,'werew',4],[1.4,'qew',2]]

In [3]: my_df = pd.DataFrame(a)

In [4]: my_df.to_csv('my_csv.csv', index=False, header=False)

Convert a video to MP4 (H.264/AAC) with ffmpeg

You need to recompile ffmpeg (from source) so that it supports x264. If you follow the instructions in this page, then you will be able to peform any kind of conversion you want.

How to read a configuration file in Java

Create a configuration file and put your entries there.


You can load this file using Properties.load(fileName) and retrieved values you get(key);

error code 1292 incorrect date value mysql

I happened to be working in localhost , in windows 10, using WAMP, as it turns out, Wamp has a really accessible configuration interface to change the MySQL configuration. You just need to go to the Wamp panel, then to MySQL, then to settings and change the mode to sql-mode: none.(essentially disabling the strict mode) The following picture illustrates this.

enter image description here

Java integer list

If you want to rewrite a line on console, print a control character \r (carriage return).

List<Integer> myCoords = new ArrayList<Integer>();
Iterator<Integer> myListIterator = myCoords.iterator(); 
while (myListIterator.hasNext()) {
    Integer coord =;     

How do I convert an array object to a string in PowerShell?

You could specify type like this:

[string[]] $a = "This", "Is", "a", "cat"

Checking the type:



    IsPublic IsSerial Name                                     BaseType
    -------- -------- ----                                     --------
    True     True     String[]                                 System.Array

Outputting $a:

PS C:\> $a 

Eclipse error: R cannot be resolved to a variable

I had a fully working project to which I was doing a minor change when this occured after updateting the SDK. Eclipse updated the SDK and the ADT but I could still not build the project. Exlipse said there were no further updates available.

The problem persisted until I manually uninstalled the ADT from eclipse and re-installed it. Only then would my project build. I had restarted eclipse inbetween each step.

Java: convert seconds to minutes, hours and days

You should try this

import java.util.Scanner;

public class Time_converter {

    public static void main(String[] args) {

        Scanner input = new Scanner (;
        int seconds;
        int minutes ;
        int hours;
        System.out.print("Enter the number of seconds : ");
        seconds = input.nextInt();
        hours = seconds / 3600;
        minutes = (seconds%3600)/60;
        int seconds_output = (seconds% 3600)%60;

        System.out.println("The time entered in hours,minutes and seconds is:");
        System.out.println(hours  + " hours :" + minutes + " minutes:" + seconds_output +" seconds"); 


How can I select the record with the 2nd highest salary in database Oracle?

select Max(Salary) as SecondHighestSalary from Employee where Salary not in (select max(Salary) from Employee)

What is the best way to prevent session hijacking?

Try Secure Cookie protocol described in this paper by Liu, Kovacs, Huang, and Gouda:

As stated in document:

A secure cookie protocol that runs between a client and a server needs to provide the following four services: authentication, confidentiality, integrity and anti-replay.

As for ease of deployment:

In terms of efficiency, our protocol does not involve any database lookup or public key cryptography. In terms of deployability, our protocol can be easily deployed on an existing web server, and it does not require any change to the Internet cookie specication.

In short: it is secure, lightweight, works for me just great.

Getting json body in aws Lambda via API gateway

There are two different Lambda integrations you can configure in API Gateway, such as Lambda integration and Lambda proxy integration. For Lambda integration, you can customise what you are going to pass to Lambda in the payload that you don't need to parse the body, but when you are using Lambda Proxy integration in API Gateway, API Gateway will proxy everything to Lambda in payload like this,

    "message": "Hello me!",
    "input": {
        "path": "/test/hello",
        "headers": {
            "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8",
            "Accept-Encoding": "gzip, deflate, lzma, sdch, br",
            "Accept-Language": "en-US,en;q=0.8",
            "CloudFront-Forwarded-Proto": "https",
            "CloudFront-Is-Desktop-Viewer": "true",
            "CloudFront-Is-Mobile-Viewer": "false",
            "CloudFront-Is-SmartTV-Viewer": "false",
            "CloudFront-Is-Tablet-Viewer": "false",
            "CloudFront-Viewer-Country": "US",
            "Host": "",
            "Upgrade-Insecure-Requests": "1",
            "User-Agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/52.0.2743.82 Safari/537.36 OPR/39.0.2256.48",
            "Via": "1.1 (CloudFront)",
            "X-Amz-Cf-Id": "nBsWBOrSHMgnaROZJK1wGCZ9PcRcSpq_oSXZNQwQ10OTZL4cimZo3g==",
            "X-Forwarded-For": ",",
            "X-Forwarded-Port": "443",
            "X-Forwarded-Proto": "https"
        "pathParameters": {"proxy": "hello"},
        "requestContext": {
            "accountId": "123456789012",
            "resourceId": "us4z18",
            "stage": "test",
            "requestId": "41b45ea3-70b5-11e6-b7bd-69b5aaebc7d9",
            "identity": {
                "cognitoIdentityPoolId": "",
                "accountId": "",
                "cognitoIdentityId": "",
                "caller": "",
                "apiKey": "",
                "sourceIp": "",
                "cognitoAuthenticationType": "",
                "cognitoAuthenticationProvider": "",
                "userArn": "",
                "userAgent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/52.0.2743.82 Safari/537.36 OPR/39.0.2256.48",
                "user": ""
            "resourcePath": "/{proxy+}",
            "httpMethod": "GET",
            "apiId": "wt6mne2s9k"
        "resource": "/{proxy+}",
        "httpMethod": "GET",
        "queryStringParameters": {"name": "me"},
        "stageVariables": {"stageVarName": "stageVarValue"},
        "body": "{\"foo\":\"bar\"}",
        "isBase64Encoded": false

For the example you are referencing, it is not getting the body from the original request. It is constructing the response body back to API Gateway. It should be in this format,

    "statusCode": httpStatusCode,
    "headers": { "headerName": "headerValue", ... },
    "body": "...",
    "isBase64Encoded": false

PDF to image using Java

You will need a PDF renderer. There are a few more or less good ones on the market (ICEPdf, pdfrenderer), but without, you will have to rely on external tools. The free PDF renderers also cannot render embedded fonts, and so will only be good for creating thumbnails (what you eventually want).

My favorite external tool is Ghostscript, which can convert PDFs to images with a single command line invocation.

This converts Postscript (and PDF?) files to bmp for us, just as a guide to modify for your needs (Know you need the env vars for gs to work!):


Set BIN_DIR=C:\Program Files\IKOffice_ACME\bin
Set GS=C:\Program Files\IKOffice_ACME\gs
Set GS_DLL=%GS%\gs8.54\bin\gsdll32.dll
Set GS_LIB=%GS%\gs8.54\lib;%GS%\gs8.54\Resource;%GS%\fonts
Set Path=%Path%;%GS%\gs8.54\bin
Set Path=%Path%;%GS%\gs8.54\lib

call "%GS%\gs8.54\bin\gswin32c.exe" -q -dSAFER -dNOPAUSE -dBATCH -sDEVICE#bmpmono -r600x600 -sOutputFile#%2 -f %1


UPDATE: pdfbox is now able to embed fonts, so no need for Ghostscript anymore.

Python time measure function

My way of doing it:

from time import time

def printTime(start):
    end = time()
    duration = end - start
    if duration < 60:
        return "used: " + str(round(duration, 2)) + "s."
        mins = int(duration / 60)
        secs = round(duration % 60, 2)
        if mins < 60:
            return "used: " + str(mins) + "m " + str(secs) + "s."
            hours = int(duration / 3600)
            mins = mins % 60
            return "used: " + str(hours) + "h " + str(mins) + "m " + str(secs) + "s."

Set a variable as start = time() before execute the function/loops, and printTime(start) right after the block.

and you got the answer.

Removing empty lines in Notepad++

There is now a built-in way to do this as of version 6.5.2

Edit -> Line Operations -> Remove Empty Lines or Remove Empty Lines (Containing Blank characters)

Screenshot of removing empty lines

Scroll to a specific Element Using html

Should you want to resort to using a plug-in, malihu-custom-scrollbar-plugin, could do the job. It performs an actual scroll, not just a jump. You can even specify the speed/momentum of scroll. It also lets you set up a menu (list of links to scroll to), which have their CSS changed based on whether the anchors-to-scroll-to are in viewport, and other useful features.

There are demo on the author's site and let our company site serve as a real-world example too.

Simple way to create matrix of random numbers

When you say "a matrix of random numbers", you can use numpy as Pavel mentioned above, in this case I'm assuming to you it is irrelevant what distribution these (pseudo) random numbers adhere to.

However, if you require a particular distribution (I imagine you are interested in the uniform distribution), numpy.random has very useful methods for you. For example, let's say you want a 3x2 matrix with a pseudo random uniform distribution bounded by [low,high]. You can do this like so:


Note, you can replace uniform by any number of distributions supported by this library.

Further reading:

How to get bitmap from a url in android?

This should do the trick:

public static Bitmap getBitmapFromURL(String src) {
    try {
        URL url = new URL(src);
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        InputStream input = connection.getInputStream();
        Bitmap myBitmap = BitmapFactory.decodeStream(input);
        return myBitmap;
    } catch (IOException e) {
        return null;
} // Author: silentnuke

Don't forget to add the internet permission in your manifest.

.ssh directory not being created

Is there a step missing?

Yes. You need to create the directory:

mkdir ${HOME}/.ssh

Additionally, SSH requires you to set the permissions so that only you (the owner) can access anything in ~/.ssh:

% chmod 700 ~/.ssh

Should the .ssh dir be generated when I use the ssh-keygen command?

No. This command generates an SSH key pair but will fail if it cannot write to the required directory:

% ssh-keygen
Generating public/private rsa key pair.
Enter file in which to save the key (/Users/xxx/.ssh/id_rsa): /Users/tmp/does_not_exist
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
open /Users/tmp/does_not_exist failed: No such file or directory.
Saving the key failed: /Users/tmp/does_not_exist.

Once you've created your keys, you should also restrict who can read those key files to just yourself:

% chmod -R go-wrx ~/.ssh/*

Can you use Microsoft Entity Framework with Oracle?

DevArt's OraDirect provider now supports entity framework. See

What is the meaning of git reset --hard origin/master?

git reset --hard origin/master

says: throw away all my staged and unstaged changes, forget everything on my current local branch and make it exactly the same as origin/master.

You probably wanted to ask this before you ran the command. The destructive nature is hinted at by using the same words as in "hard reset".

Finding square root without using sqrt function?

Remove your nCount altogether (as there are some roots that this algorithm will take many iterations for).

double SqrtNumber(double num)
    double lower_bound=0; 
    double upper_bound=num;
    double temp=0;

    while(fabs(num - (temp * temp)) > SOME_SMALL_VALUE)
           temp = (lower_bound+upper_bound)/2;
           if (temp*temp >= num)
                   upper_bound = temp;
                   lower_bound = temp;
    return temp;

How do I convert a string to a double in Python?

Be aware that if your string number contains more than 15 significant digits float(s) will round it.In those cases it is better to use Decimal

Here is an explanation and some code samples:

php function mail() isn't working

I think you are not configured properly,

if you are using XAMPP then you can easily send mail from localhost.

for example you can configure C:\xampp\php\php.ini and c:\xampp\sendmail\sendmail.ini for gmail to send mail.

in C:\xampp\php\php.ini find extension=php_openssl.dll and remove the semicolon from the beginning of that line to make SSL working for gmail for localhost.

in php.ini file find [mail function] and change
sendmail_from = [email protected]
sendmail_path = "C:\xampp\sendmail\sendmail.exe -t"

(use the above send mail path only and it will work)

Now Open C:\xampp\sendmail\sendmail.ini. Replace all the existing code in sendmail.ini with following code

[email protected]
[email protected]

Now you have done!! create php file with mail function and send mail from localhost.


First, make sure you PHP installation has SSL support (look for an "openssl" section in the output from phpinfo()).

You can set the following settings in your PHP.ini:


Adjusting and image Size to fit a div (bootstrap)

Simply add the class img-responsive to your img tag, it is applicable in bootstrap 3 onward!

Javascript - How to show escape characters in a string?

JavaScript uses the \ (backslash) as an escape characters for:

  • \' single quote
  • \" double quote
  • \ backslash
  • \n new line
  • \r carriage return
  • \t tab
  • \b backspace
  • \f form feed
  • \v vertical tab (IE < 9 treats '\v' as 'v' instead of a vertical tab ('\x0B'). If cross-browser compatibility is a concern, use \x0B instead of \v.)
  • \0 null character (U+0000 NULL) (only if the next character is not a decimal digit; else it’s an octal escape sequence)

Note that the \v and \0 escapes are not allowed in JSON strings.

Linux command for extracting war file?


jar xvf myproject.war

How can I search (case-insensitive) in a column using LIKE wildcard?


SELECT * FROM trees WHERE trees.`title` ILIKE '%elm%';

it worked for me !!

How to generate graphs and charts from mysql database in php

I use Google Chart Tools It's well documented and the charts look great. Being javascript, you can feed it json data via ajax.

Is there a way to check for both `null` and `undefined`?

I always write it like this:

var foo:string;


This will work fine and I think it's very readable.

Adding a Time to a DateTime in C#

If you are using two DateTime objects, one to store the date the other the time, you could do the following:

var date = new DateTime(2016,6,28);

var time = new DateTime(1,1,1,13,13,13);

var combinedDateTime = date.AddTicks(time.TimeOfDay.Ticks);

An example of this can be found here

C++ -- expected primary-expression before ' '


int wordLength = wordLengthFunction(string word);


int wordLength = wordLengthFunction(word);

I just had to Clean my project and then it built successfully afterwards.

Creating a very simple 1 username/password login in php

Your code could look more like:

$errorMsg = "";
$validUser = $_SESSION["login"] === true;
if(isset($_POST["sub"])) {
  $validUser = $_POST["username"] == "admin" && $_POST["password"] == "password";
  if(!$validUser) $errorMsg = "Invalid username or password.";
  else $_SESSION["login"] = true;
if($validUser) {
   header("Location: /login-success.php"); die();
<!DOCTYPE html>
  <meta http-equiv="content-type" content="text/html;charset=utf-8" />
  <form name="input" action="" method="post">
    <label for="username">Username:</label><input type="text" value="<?= $_POST["username"] ?>" id="username" name="username" />
    <label for="password">Password:</label><input type="password" value="" id="password" name="password" />
    <div class="error"><?= $errorMsg ?></div>
    <input type="submit" value="Home" name="sub" />

Now, when the page is redirected based on the header('LOCATION:wherever.php), put session_start() at the top of the page and test to make sure $_SESSION['login'] === true. Remember that == would be true if $_SESSION['login'] == 1 as well. Of course, this is a bad idea for security reasons, but my example may teach you a different way of using PHP.

"UserWarning: Matplotlib is currently using agg, which is a non-GUI backend, so cannot show the figure." when plotting figure with pyplot on Pycharm

This worked with R reticulate. Found it here.

1: matplotlib.use( 'tkagg' ) or 2: matplotlib$use( 'tkagg' )

For example:

import numpy as np
import matplotlib.pyplot as plt
from matplotlib import style

import matplotlib
matplotlib.use( 'tkagg' )

from sklearn import svm

x = [1, 5, 1.5, 8, 1, 9]
y = [2, 8, 1.8, 8, 0.6, 11]


Sublime 3 - Set Key map for function Goto Definition

If you want to see how to do a proper definition go into Sublime Text->Preferences->Key Bindings - Default and search for the command you want to override.

{ "keys": ["f12"], "command": "goto_definition" },
{ "keys": ["super+alt+down"], "command": "goto_definition" }

Those are two that show in my Default.

On Mac I copied the second to override.

in Sublime Text -> Preferences -> Key Bindings - User I added this

/* Beginning of File */

        "keys": ["super+shift+i"], "command": "goto_definition" 

/* End of File */

This binds it to the Command + Shift + 1 combination on mac.

How to access parent Iframe from JavaScript

I would recommend using the postMessage API.

In your iframe, call:

window.parent.postMessage({message: 'Hello world'}, 'http://localhost/');

In the page you're including the iframe you can listen for events like this:

window.addEventListener('message', function(event) {
      if(event.origin === 'http://localhost/')
        alert('Received message: ' +;
        alert('Origin not allowed!');

    }, false);

By the way, it is also possible to do calls to other windows, and not only iframes.

Read more about the postMessage API on John Resigs blog here

Sorting options elements alphabetically using jQuery

None of the answers worked for me. For some strange reason, when looping through the options, each option returns nothing when text() is called. Instead, I was forced to retrieve the option's label via attr('label')

 * Sort the options of the target select list
 * alphabetically by label. For some reason, when
 * we call detach(), the returned options have no
 * text() and instead we're forced to get the option's
 * label via the 'label' attribute.
 * @param select jQuery selector
function sort_multi_select(select) {
    var options = select.find('option');
    options.detach().sort(function (a, b) {
        var at = $(a).attr('label'), //label, not text()
            bt = $(b).attr('label');
        return at > bt ? 1 : at < bt ? -1 : 0;


How to parse date string to Date?

A parse exception is a checked exception, so you must catch it with a try-catch when working with parsing Strings to Dates, as @miku suggested...

How to remove spaces from a string using JavaScript?


str = str.replace(/\s/g, '');


var str = '/var/www/site/Brand new document.docx';_x000D_
document.write( str.replace(/\s/g, '') );

Update: Based on this question, this:

str = str.replace(/\s+/g, '');

is a better solution. It produces the same result, but it does it faster.

The Regex

\s is the regex for "whitespace", and g is the "global" flag, meaning match ALL \s (whitespaces).

A great explanation for + can be found here.

As a side note, you could replace the content between the single quotes to anything you want, so you can replace whitespace with any other string.

How to determine when Fragment becomes visible in ViewPager

setUserVisibleHint(boolean visible) is now deprecated So this is the correct solution

FragmentPagerAdapter(fragmentManager, BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT)

In ViewPager2 and ViewPager from version androidx.fragment:fragment:1.1.0 you can just use onPause() and onResume() to determine which fragment is currently visible for the user. onResume() is called when the fragment became visible and onPause when it stops to be visible.

To enable this behavior in the first ViewPager you have to pass FragmentPagerAdapter.BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT parameter as the second argument of the FragmentPagerAdapter constructor.

JQuery, select first row of table

jQuery is not necessary, you can use only javascript.

<table id="table">

The table object has a collection of all rows.

var myTable = document.getElementById('table');
var rows =  myTable.rows;
var firstRow = rows[0];

How to insert a newline in front of a pattern?

In vi on Red Hat, I was able to insert carriage returns using just the \r character. I believe this internally executes 'ex' instead of 'sed', but it's similar, and vi can be another way to do bulk edits such as code patches. For example. I am surrounding a search term with an if statement that insists on carriage returns after the braces:


Note that I also had it insert some tabs to make things align better.

How to loop an object in React?

The problem is the way you're using forEach(), as it will always return undefined. You're probably looking for the map() method, which returns a new array:

var tifOptions = Object.keys(tifs).map(function(key) {
    return <option value={key}>{tifs[key]}</option>

If you still want to use forEach(), you'd have to do something like this:

var tifOptions = [];

Object.keys(tifs).forEach(function(key) {
    tifOptions.push(<option value={key}>{tifs[key]}</option>);


If you're writing ES6, you can accomplish the same thing a bit neater using an arrow function:

const tifOptions = Object.keys(tifs).map(key => 
    <option value={key}>{tifs[key]}</option>

Here's a fiddle showing all options mentioned above:

How to have conditional elements and keep DRY with Facebook React's JSX?

Simple, create a function.

renderBanner: function() {
  if (!this.state.banner) return;
  return (
    <div id="banner">{this.state.banner}</div>

render: function () {
  return (
    <div id="page">
      <div id="other-content">
        blah blah blah...

This is a pattern I personally follow all the time. Makes code really clean and easy to understand. What's more it allows you to refactor Banner into its own component if it gets too large (or re-used in other places).

What are the differences between git remote prune, git prune, git fetch --prune, etc

I don't blame you for getting frustrated about this. The best way to look at is this. There are potentially three versions of every remote branch:

  1. The actual branch on the remote repository
    (e.g., remote repo at, refs/heads/master)
  2. Your snapshot of that branch locally (stored under refs/remotes/...)
    (e.g., local repo, refs/remotes/origin/master)
  3. And a local branch that might be tracking the remote branch
    (e.g., local repo, refs/heads/master)

Let's start with git prune. This removes objects that are no longer being referenced, it does not remove references. In your case, you have a local branch. That means there's a ref named random_branch_I_want_deleted that refers to some objects that represent the history of that branch. So, by definition, git prune will not remove random_branch_I_want_deleted. Really, git prune is a way to delete data that has accumulated in Git but is not being referenced by anything. In general, it doesn't affect your view of any branches.

git remote prune origin and git fetch --prune both operate on references under refs/remotes/... (I'll refer to these as remote references). It doesn't affect local branches. The git remote version is useful if you only want to remove remote references under a particular remote. Otherwise, the two do exactly the same thing. So, in short, git remote prune and git fetch --prune operate on number 2 above. For example, if you deleted a branch using the git web GUI and don't want it to show up in your local branch list anymore (git branch -r), then this is the command you should use.

To remove a local branch, you should use git branch -d (or -D if it's not merged anywhere). FWIW, there is no git command to automatically remove the local tracking branches if a remote branch disappears.

Find full path of the Python interpreter?

There are a few alternate ways to figure out the currently used python in Linux is:

  1. which python command.
  2. command -v python command
  3. type python command

Similarly On Windows with Cygwin will also result the same.

kuvivek@HOSTNAME ~
$ which python

kuvivek@HOSTNAME ~
$ whereis python
python: /usr/bin/python /usr/bin/python3.4 /usr/lib/python2.7 /usr/lib/python3.4        /usr/include/python2.7 /usr/include/python3.4m /usr/share/man/man1/python.1.gz

kuvivek@HOSTNAME ~
$ which python3

kuvivek@HOSTNAME ~
$ command -v python

kuvivek@HOSTNAME ~
$ type python
python is hashed (/usr/bin/python)

If you are already in the python shell. Try anyone of these. Note: This is an alternate way. Not the best pythonic way.

>>> import os
>>> os.popen('which python').read()
>>> os.popen('type python').read()
'python is /usr/bin/python\n'
>>> os.popen('command -v python').read()

If you are not sure of the actual path of the python command and is available in your system, Use the following command.

pi@osboxes:~ $ which python
pi@osboxes:~ $ readlink -f $(which python)
pi@osboxes:~ $ 
pi@osboxes:~ $ which python3
pi@osboxes:~ $ 
pi@osboxes:~ $ readlink -f $(which python3)
pi@osboxes:~ $ 

What is the correct format to use for Date/Time in an XML file

EDIT: This is bad advice. Use "o", as above. "s" does the wrong thing.

I always use this:


This is correct if your schema looks like this:

<xs:element name="startdate" type="xs:dateTime"/>

Which would result in:


You can get more information here:

Docker can't connect to docker daemon

Try to change the Docker configuration file, docker or docker-network in /etc/sysconfig:

(... ~ v1.17)

docker file:

OPTIONS= -H fd://

or (v1.18):

docker-network file:

DOCKER_NETWORK_OPTIONS= -H unix:///var/run/docker.sock

Why use double indirection? or Why use pointers to pointers?

One thing I use them for constantly is when I have an array of objects and I need to perform lookups (binary search) on them by different fields.
I keep the original array...

int num_objects;
OBJECT *original_array = malloc(sizeof(OBJECT)*num_objects);

Then make an array of sorted pointers to the objects.

int compare_object_by_name( const void *v1, const void *v2 ) {
  OBJECT *o1 = *(OBJECT **)v1;
  OBJECT *o2 = *(OBJECT **)v2;
  return (strcmp(o1->name, o2->name);

OBJECT **object_ptrs_by_name = malloc(sizeof(OBJECT *)*num_objects);
  int i = 0;
  for( ; i<num_objects; i++)
    object_ptrs_by_name[i] = original_array+i;
  qsort(object_ptrs_by_name, num_objects, sizeof(OBJECT *), compare_object_by_name);

You can make as many sorted pointer arrays as you need, then use a binary search on the sorted pointer array to access the object you need by the data you have. The original array of objects can stay unsorted, but each pointer array will be sorted by their specified field.

Split Java String by New Line

The above answers did not help me on Android, thanks to the Pshemo response that worked for me on Android. I will leave some of Pshemo's answer here :


Convert string to variable name in python

You can use a Dictionary to keep track of the keys and values.

For instance...

dictOfStuff = {} ##Make a Dictionary

x = "Buffalo" ##OR it can equal the input of something, up to you.

dictOfStuff[x] = 4 ##Get the dict spot that has the same key ("name") as what X is equal to. In this case "Buffalo". and set it to 4. Or you can set it to  what ever you like

print(dictOfStuff[x]) ##print out the value of the spot in the dict that same key ("name") as the dictionary.

A dictionary is very similar to a real life dictionary. You have a word and you have a definition. You can look up the word and get the definition. So in this case, you have the word "Buffalo" and it's definition is 4. It can work with any other word and definition. Just make sure you put them into the dictionary first.

Convert Base64 string to an image file?

This code worked for me.

$decoded = base64_decode($base64);_x000D_
$file = 'invoice.pdf';_x000D_
file_put_contents($file, $decoded);_x000D_
if (file_exists($file)) {_x000D_
    header('Content-Description: File Transfer');_x000D_
    header('Content-Type: application/octet-stream');_x000D_
    header('Content-Disposition: attachment; filename="'.basename($file).'"');_x000D_
    header('Expires: 0');_x000D_
    header('Cache-Control: must-revalidate');_x000D_
    header('Pragma: public');_x000D_
    header('Content-Length: ' . filesize($file));_x000D_

How to asynchronously call a method in Java

You can use Future-AsyncResult for this.

public Future<Page> findPage(String page) throws InterruptedException {
    System.out.println("Looking up " + page);
    Page results = restTemplate.getForObject("" + page, Page.class);
    return new AsyncResult<Page>(results);


How do I modify fields inside the new PostgreSQL JSON datatype?

With Postgresql 9.5 it can be done by following-

SET data = data - 'a' || '{"a":5}'
WHERE data->>'b' = '2';


SET data = jsonb_set(data, '{a}', '5'::jsonb);

Somebody asked how to update many fields in jsonb value at once. Suppose we create a table:


Then we INSERT a experimental row:

INSERT INTO testjsonb
VALUES (DEFAULT, '{"a":"one", "b":"two", "c":{"c1":"see1","c2":"see2","c3":"see3"}}');

Then we UPDATE the row:

UPDATE testjsonb SET object = object - 'b' || '{"a":1,"d":4}';

Which does the following:

  1. Updates the a field
  2. Removes the b field
  3. Add the d field

Selecting the data:

SELECT jsonb_pretty(object) FROM testjsonb;

Will result in:

 {                      +
     "a": 1,            +
     "c": {             +
         "c1": "see1",  +
         "c2": "see2",  +
         "c3": "see3",  +
     },                 +
     "d": 4             +
(1 row)

To update field inside, Dont use the concat operator ||. Use jsonb_set instead. Which is not simple:

UPDATE testjsonb SET object =
jsonb_set(jsonb_set(object, '{c,c1}','"seeme"'),'{c,c2}','"seehim"');

Using the concat operator for {c,c1} for example:

UPDATE testjsonb SET object = object || '{"c":{"c1":"seedoctor"}}';

Will remove {c,c2} and {c,c3}.

For more power, seek power at postgresql json functions documentation. One might be interested in the #- operator, jsonb_set function and also jsonb_insert function.

Animate scroll to ID on page load

There is a jquery plugin for this. It scrolls document to a specific element, so that it would be perfectly in the middle of viewport. It also supports animation easings so that the scroll effect would look super smooth. Check this link.

In your case the code is

$("#title1").animatedScroll({easing: "easeOutExpo"});

How to check if a list is empty in Python?

I like Zarembisty's answer. Although, if you want to be more explicit, you can always do:

if len(my_list) == 0:
    print "my_list is empty"

Passing enum or object through an intent (the best solution)

You can pass an enum through as a string.

public enum CountType {

private CountType count;
count = ONE;

String countString =;

CountType countToo = CountType.valueOf(countString);

Given strings are supported you should be able to pass the value of the enum around with no problem.

Webdriver findElements By xpath

The XPath turns into this:

Get me all of the div elements that have an id equal to container.

As for getting the first etc, you have two options.

Turn it into a .findElement() - this will just return the first one for you anyway.


To explicitly do this in XPath, you'd be looking at:


for the first one, for the second etc:


Then XPath has a special indexer, called last, which would (you guessed it) get you the last element found:


Worth mentioning that XPath indexers will start from 1 not 0 like they do in most programming languages.

As for getting the parent 'node', well, you can use parent:


That would get the div's direct parent.

You could then go further and say I want the first *div* with an id of container, and I want his parent:


Hope that helps!

What is a method group in C#?

You can cast a method group into a delegate.

The delegate signature selects 1 method out of the group.

This example picks the ToString() overload which takes a string parameter:

Func<string,string> fn = 123.ToString;

This example picks the ToString() overload which takes no parameters:

Func<string> fn = 123.ToString;

formatFloat : convert float number to string

Try this

package main

import "fmt"
import "strconv"

func FloatToString(input_num float64) string {
    // to convert a float number to a string
    return strconv.FormatFloat(input_num, 'f', 6, 64)

func main() {

If you just want as many digits precision as possible, then the special precision -1 uses the smallest number of digits necessary such that ParseFloat will return f exactly. Eg

strconv.FormatFloat(input_num, 'f', -1, 64)

Personally I find fmt easier to use. (Playground link)

fmt.Printf("x = %.6f\n", 21312421.213123)

Or if you just want to convert the string

fmt.Sprintf("%.6f", 21312421.213123)

How do I convert a String object into a Hash object?

I prefer to abuse ActiveSupport::JSON. Their approach is to convert the hash to yaml and then load it. Unfortunately the conversion to yaml isn't simple and you'd probably want to borrow it from AS if you don't have AS in your project already.

We also have to convert any symbols into regular string-keys as symbols aren't appropriate in JSON.

However, its unable to handle hashes that have a date string in them (our date strings end up not being surrounded by strings, which is where the big issue comes in):

string = '{'last_request_at' : 2011-12-28 23:00:00 UTC }' ActiveSupport::JSON.decode(string.gsub(/:([a-zA-z])/,'\\1').gsub('=>', ' : '))

Would result in an invalid JSON string error when it tries to parse the date value.

Would love any suggestions on how to handle this case

Binary search (bisection) in Python

While there's no explicit binary search algorithm in Python, there is a module - bisect - designed to find the insertion point for an element in a sorted list using a binary search. This can be "tricked" into performing a binary search. The biggest advantage of this is the same advantage most library code has - it's high-performing, well-tested and just works (binary searches in particular can be quite difficult to implement successfully - particularly if edge cases aren't carefully considered).

Basic Types

For basic types like Strings or ints it's pretty easy - all you need is the bisect module and a sorted list:

>>> import bisect
>>> names = ['bender', 'fry', 'leela', 'nibbler', 'zoidberg']
>>> bisect.bisect_left(names, 'fry')
>>> keyword = 'fry'
>>> x = bisect.bisect_left(names, keyword)
>>> names[x] == keyword
>>> keyword = 'arnie'
>>> x = bisect.bisect_left(names, keyword)
>>> names[x] == keyword

You can also use this to find duplicates:

>>> names = ['bender', 'fry', 'fry', 'fry', 'leela', 'nibbler', 'zoidberg']
>>> keyword = 'fry'
>>> leftIndex = bisect.bisect_left(names, keyword)
>>> rightIndex = bisect.bisect_right(names, keyword)
>>> names[leftIndex:rightIndex]
['fry', 'fry', 'fry']

Obviously you could just return the index rather than the value at that index if desired.


For custom types or objects, things are a little bit trickier: you have to make sure to implement rich comparison methods to get bisect to compare correctly.

>>> import bisect
>>> class Tag(object):  # a simple wrapper around strings
...     def __init__(self, tag):
...         self.tag = tag
...     def __lt__(self, other):
...         return self.tag < other.tag
...     def __gt__(self, other):
...         return self.tag > other.tag
>>> tags = [Tag('bender'), Tag('fry'), Tag('leela'), Tag('nibbler'), Tag('zoidbe
>>> key = Tag('fry')
>>> leftIndex = bisect.bisect_left(tags, key)
>>> rightIndex = bisect.bisect_right(tags, key)
>>> print([tag.tag for tag in tags[leftIndex:rightIndex]])

This should work in at least Python 2.7 -> 3.3

How to select option in drop down using Capybara

In Capybara you can use only find with xpath

find(:xpath, "//*[@id='organizationSelect']/option[2]").click

and method click

Xcode error "Could not find Developer Disk Image"

My problem was with Xcode 7 and Xcode 6.4 beta and iOS 8.4 - device not compatible.

In case of the same problem for better understanding how to fix, do next:

  1. Go to /Applications/
  2. Go to
  3. Copy folder iOS 8.4 in another folder

Enter image description here

  1. Restart Xcode

Like Operator in Entity Framework?

You can use a real like in Link to Entities quite easily


    <Function Name="String_Like" ReturnType="Edm.Boolean">
      <Parameter Name="searchingIn" Type="Edm.String" />
      <Parameter Name="lookingFor" Type="Edm.String" />
        searchingIn LIKE lookingFor

to your EDMX in this tag:


Also remember the namespace in the <schema namespace="" /> attribute

Then add an extension class in the above namespace:

public static class Extensions
    [EdmFunction("DocTrails3.Net.Database.Models", "String_Like")]
    public static Boolean Like(this String searchingIn, String lookingFor)
        throw new Exception("Not implemented");

This extension method will now map to the EDMX function.

More info here:

Changing the tmp folder of mysql

This is answered in the documentation:

Where MySQL Stores Temporary Files

On Unix, MySQL uses the value of the TMPDIR environment variable as the path name of the directory in which to store temporary files. If TMPDIR is not set, MySQL uses the system default, which is usually /tmp, /var/tmp, or /usr/tmp.

On Windows, Netware and OS2, MySQL checks in order the values of the TMPDIR, TEMP, and TMP environment variables. For the first one found to be set, MySQL uses it and does not check those remaining. If none of TMPDIR, TEMP, or TMP are set, MySQL uses the Windows system default, which is usually C:\windows\temp.

Build query string for System.Net.HttpClient get

Thanks to "Darin Dimitrov", This is the extension methods.

 public static partial class Ext
    public static Uri GetUriWithparameters(this Uri uri,Dictionary<string,string> queryParams = null,int port = -1)
        var builder = new UriBuilder(uri);
        builder.Port = port;
        if(null != queryParams && 0 < queryParams.Count)
            var query = HttpUtility.ParseQueryString(builder.Query);
            foreach(var item in queryParams)
                query[item.Key] = item.Value;
            builder.Query = query.ToString();
        return builder.Uri;

    public static string GetUriWithparameters(string uri,Dictionary<string,string> queryParams = null,int port = -1)
        var builder = new UriBuilder(uri);
        builder.Port = port;
        if(null != queryParams && 0 < queryParams.Count)
            var query = HttpUtility.ParseQueryString(builder.Query);
            foreach(var item in queryParams)
                query[item.Key] = item.Value;
            builder.Query = query.ToString();
        return builder.Uri.ToString();

Activity <App Name> has leaked ServiceConnection <ServiceConnection Name>@438030a8 that was originally bound here

You mention the user switching between Activities pretty quickly. Could it be that you're calling unbindService before the service connection has been established? This may have the effect of failing to unbind, then leaking the binding.

Not entirely sure how you could handle this... Perhaps when onServiceConnected is called you could call unbindService if onDestroy has already been called. Not sure if that'll work though.

If you haven't already, you could add an onUnbind method to your service. That way you can see exactly when your classes unbind from it, and it might help with debugging.

public boolean onUnbind(Intent intent) {
    Log.d(this.getClass().getName(), "UNBIND");
    return true;

Disable/enable an input with jQuery?

    // Disable #x
    $( "#x" ).prop( "disabled", true );
    // Enable #x
    $( "#x" ).prop( "disabled", false );

Sometimes you need to disable/enable the form element like input or textarea. Jquery helps you to easily make this with setting disabled attribute to "disabled". For e.g.:

  //To disable 
  $('.someElement').attr('disabled', 'disabled');

To enable disabled element you need to remove "disabled" attribute from this element or empty it's string. For e.g:

//To enable 

// OR you can set attr to "" 
$('.someElement').attr('disabled', '');

refer :

Convert Text to Date?

Blast from the past but I think I found an easy answer to this. The following worked for me. I think it's the equivalent of selecting the cell hitting F2 and then hitting enter, which makes Excel recognize the text as a date.

Selection.Value = Selection.Value

SQL Server 2008 Insert with WHILE LOOP

Assuming that ID is an identity column:

INSERT INTO TheTable(HospitalID, Email, Description)
SELECT 32, Email, Description FROM TheTable
WHERE HospitalID <> 32

Try to avoid loops with SQL. Try to think in terms of sets instead.

Display SQL query results in php

You need to fetch the data from each row of the resultset obtained from the query. You can use mysql_fetch_array() for this.

// Process all rows
while($row = mysql_fetch_array($result)) {
    echo $row['column_name']; // Print a single column data
    echo print_r($row);       // Print the entire row data

Change your code to this :

$sql="SELECT * FROM  modul1open WHERE idM1O>=(SELECT FLOOR( MAX( idM1O ) * RAND( ) )  FROM  modul1open) 

$result = mysql_query($sql);
while($row = mysql_fetch_array($result)) {
    echo $row['fieldname']; 

enable/disable zoom in Android WebView

The solution you posted seems to work in stopping the zoom controls from appearing when the user drags, however there are situations where a user will pinch zoom and the zoom controls will appear. I've noticed that there are 2 ways that the webview will accept pinch zooming, and only one of them causes the zoom controls to appear despite your code:

User Pinch Zooms and controls appear:

getSettings().setBuiltInZoomControls(false); getSettings().setSupportZoom(false);
getSettings().setBuiltInZoomControls(true); getSettings().setSupportZoom(true);
ACTION_MOVE (Repeat several times, as the user moves their fingers)

User Pinch Zoom and Controls don't appear:

getSettings().setBuiltInZoomControls(false); getSettings().setSupportZoom(false);
getSettings().setBuiltInZoomControls(true); getSettings().setSupportZoom(true);
ACTION_MOVE (Repeat several times, as the user moves their fingers)

Can you shed more light on your solution?

Trigger function when date is selected with jQuery UI datepicker

If the datepicker is in a row of a grid, try something like

editoptions : {
    dataInit : function (e) {
            onSelect : function (ev) {
                // here your code

rails simple_form - hidden field - create?

try this

= f.input :title, :as => :hidden, :input_html => { :value => "some value" }

setting JAVA_HOME & CLASSPATH in CentOS 6

I created a folder named a in /home/prasanth and copied your code to a file named I compiled from /home/prasanth as javac a/ and run javac a.A. I got output as


Java maximum memory on Windows XP

Here is how to increase the Paging size

  1. right click on mycomputer--->properties--->Advanced
  2. in the performance section click settings
  3. click Advanced tab
  4. in Virtual memory section, click change. It will show ur current paging size.
  5. Select Drive where HDD space is available.
  6. Provide initial size and max size ...e.g. initial size 0 MB and max size 4000 MB. (As much as you will require)

document.getElementById("remember").visibility = "hidden"; not working on a checkbox

There are two problems in your code:

  • The property is called visibility and not visiblity.
  • It is not a property of the element itself but of its .style property.

It's easy to fix. Simple replace this:


with this:


How do MySQL indexes work?

I want to add my 2 cents. I am far from being a database expert, but I've recently read up a bit on this topic; enough for me to try and give an ELI5. So, here's may layman's explanation.

I understand it as such that an index is like a mini-mirror of your table, pretty much like an associative array. If you feed it with a matching key then you can just jump to that row in one "command".

But if you didn't have that index / array, the query interpreter must use a for-loop to go through all rows and check for a match (the full-table scan).

Having an index has the "downside" of extra storage (for that mini-mirror), in exchange for the "upside" of looking up content faster.

Note that (in dependence of your db engine) creating primary, foreign or unique keys automatically sets up a respective index as well. That same principle is basically why and how those keys work.

How to access the last value in a vector?

Package data.table includes last function

# [1] 10

TypeError: Missing 1 required positional argument: 'self'

You can also get this error by prematurely taking PyCharm's advice to annotate a method @staticmethod. Remove the annotation.

How do I make a newline after a twitter bootstrap element?

Like KingCronus mentioned in the comments you can use the row class to make the list or heading on its own line. You could use the row class on either or both elements:

<ul class="nav nav-tabs span2 row">
  <li><a href="./index.html"><i class="icon-black icon-music"></i></a></li>
  <li><a href="./about.html"><i class="icon-black icon-eye-open"></i></a></li>
  <li><a href="./team.html"><i class="icon-black icon-user"></i></a></li>
  <li><a href="./contact.html"><i class="icon-black icon-envelope"></i></a></li>

<div class="well span6 row">
  <h3>I wish this appeared on the next line without having to gratuitously use BR!</h3>

How can I disable ReSharper in Visual Studio and enable it again?

Now Resharper supports Suspend & Resume argument at devenv.exe

(ReSharper 2019.2.3)

Run VS & Suspend R#:

devenv.exe /ReSharper.Suspend

Run VS & Resume R#:

devenv.exe /ReSharper.Resume

Here's an example usage:

enter image description here

How to blur background images in Android

You can have a view with Background color as black and set alpha for the view as 0.7 or whatever as per your requirement.

<RelativeLayout xmlns:android=""


Excel VBA - Range.Copy transpose paste

Worksheets("Sheet2").Range("A1").PasteSpecial Transpose:=True

Create a day-of-week column in a Pandas dataframe using Python

Pandas 0.23+

Use pandas.Series.dt.day_name(), since pandas.Timestamp.weekday_name has been deprecated:

import pandas as pd

df = pd.DataFrame({'my_dates':['2015-01-01','2015-01-02','2015-01-03'],'myvals':[1,2,3]})
df['my_dates'] = pd.to_datetime(df['my_dates'])

df['day_of_week'] = df['my_dates'].dt.day_name()


    my_dates  myvals day_of_week
0 2015-01-01       1    Thursday
1 2015-01-02       2      Friday
2 2015-01-03       3    Saturday

Pandas 0.18.1+

As user jezrael points out below, dt.weekday_name was added in version 0.18.1 Pandas Docs

import pandas as pd

df = pd.DataFrame({'my_dates':['2015-01-01','2015-01-02','2015-01-03'],'myvals':[1,2,3]})
df['my_dates'] = pd.to_datetime(df['my_dates'])
df['day_of_week'] = df['my_dates'].dt.weekday_name


    my_dates  myvals day_of_week
0 2015-01-01       1    Thursday
1 2015-01-02       2      Friday
2 2015-01-03       3    Saturday

Original Answer:

Use this:

See this:

Get weekday/day-of-week for Datetime column of DataFrame

If you want a string instead of an integer do something like this:

import pandas as pd

df = pd.DataFrame({'my_dates':['2015-01-01','2015-01-02','2015-01-03'],'myvals':[1,2,3]})
df['my_dates'] = pd.to_datetime(df['my_dates'])
df['day_of_week'] = df['my_dates'].dt.dayofweek

days = {0:'Mon',1:'Tues',2:'Weds',3:'Thurs',4:'Fri',5:'Sat',6:'Sun'}

df['day_of_week'] = df['day_of_week'].apply(lambda x: days[x])


    my_dates  myvals day_of_week
0 2015-01-01       1       Thurs
1 2015-01-02       2         Fri
2 2015-01-01       3       Thurs

How to check if div element is empty

Using plain javascript

 var isEmpty = document.getElementById('cartContent').innerHTML === "";

And if you are using jquery it can be done like

 var isEmpty = $("#cartContent").html() === "";

Colorplot of 2D array matplotlib

I'm afraid your posted example is not working, since X and Y aren't defined. So instead of pcolormesh let's use imshow:

import numpy as np
import matplotlib.pyplot as plt

H = np.array([[1, 2, 3, 4],
              [5, 6, 7, 8],
              [9, 10, 11, 12],
              [13, 14, 15, 16]])  # added some commas and array creation code

fig = plt.figure(figsize=(6, 3.2))

ax = fig.add_subplot(111)

cax = fig.add_axes([0.12, 0.1, 0.78, 0.8])

Getting 404 Not Found error while trying to use ErrorDocument

When we apply local url, ErrorDocument directive expect the full path from DocumentRoot. There fore,

 ErrorDocument 404 /yourfoldernames/errors/404.html