Programs & Examples On #Fat32

FAT32 is a filesystem format that is used on flash drives and older systems. It is the only filesystem that is fully supported by all three major operating systems (Windows, Mac OS X, and Linux).

What is the difference between VFAT and FAT32 file systems?

FAT32 along with FAT16 and FAT12 are File System Types, but vfat along with umsdos and msdos are drivers, used to mount the FAT file systems in Linux. The choosing of the driver determines how some of the features are applied to the file system, for example, systems mounted with msdos driver don't have long filenames (they are 8.3 format). vfat is the most common driver for mounting FAT32 file systems nowadays.

Source: this wikipedia article

Output of commands like df and lsblk indeed show vfat as the File System Type. But sudo file -sL /dev/<partition> shows FAT (32 bit) if a File System is FAT32.

You can confirm vfat is a module and not a File System Type by running modinfo vfat.

Symbol for any number of any characters in regex?


. is any char, * means repeated zero or more times.

no operator "<<" matches these operands

If you want to use std::string reliably, you must #include <string>.

Angular 2 : No NgModule metadata found

I had this issue when i cloned from a git repository and I had it resolved when I created a new project and re-inserted the src folder from the old project.

The src folder is the only folder needed when deploying your angular application but you must reconfigure the dev environment, using this solution.

How to include header files in GCC search path?

Try gcc -c -I/home/me/development/skia sample.c.

How to switch to other branch in Source Tree to commit the code?

  1. Go to the log view (to be able to go here go to View -> log view).
  2. Double click on the line with the branch label stating that branch. Automatically, it will switch branch. (A prompt will dropdown and say switching branch.)
  3. If you have two or more branches on the same line, it will ask you via prompt which branch you want to switch. Choose the specific branch from the dropdown and click ok.

To determine which branch you are now on, look at the side bar, under BRANCHES, you are in the branch that is in BOLD LETTERS.

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

I think you need use List or classes based on that.

For instance,

ArrayList<Integer> integers = new ArrayList<Integer>();
int j;

}while( (integers.get(j-1) >= 1) || (integers.get(j-1) <= 100) );

You could read this article for getting more information about how to use that.

Failed to start mongod.service: Unit mongod.service not found

In some cases for some security reasons the unit would be marked as masked. This state is much stronger than being disabled in which you cannot even start the service manually.

to check this, run the following command:

    systemctl list-unit-files | grep mongod

if you find out something like this:

    mongod.service                         masked

then you can unmask the unit by:

    sudo systemctl unmask mongod

then you may want to start the service:

    sudo systemctl start mongod

and to enable auto-start during system boot:

    sudo systemctl enable mongod

However if mongodb did not start again or was not masked at all, you have the option to reinstall it this way:

    sudo apt-get --purge mongo*
    sudo apt-get install mongodb-org

thanks to @jehanzeb-malik

How disable / remove android activity label and label bar?

Whenever I do rake run:android,

my Androidmenifest.xml file is built-up again so my changes done

for NoTitlebar no more persist.

Rather than user adroid_title: 0

This helped me.

edit your build.yml

  android_title: 0
  #rest of things 
  #you needed 

Rails 3 check if attribute changed

ActiveModel::Dirty didn't work for me because the @model.update_attributes() hid the changes. So this is how I detected changes it in an update method in a controller:

def update
  @model = Model.find(params[:id])

  if @model.update_attributes(params[:model])
    do_stuff if attr_changed?


def detect_changes
  @changed = []
  @changed << :attr if @model.attr != params[:model][:attr]

def attr_changed?
  @changed.include :attr

If you're trying to detect a lot of attribute changes it could get messy though. Probably shouldn't do this in a controller, but meh.

Unable to send email using Gmail SMTP server through PHPMailer, getting error: SMTP AUTH is required for message submission on port 587. How to fix?

this code working fine for me

    $mail = new PHPMailer;
    //Enable SMTP debugging. 
    $mail->SMTPDebug = 0;
    //Set PHPMailer to use SMTP.
    //Set SMTP host name                          
    $mail->Host = $hostname;
    //Set this to true if SMTP host requires authentication to send email
    $mail->SMTPAuth = true;
    //Provide username and password     
    $mail->Username = $sender;
    $mail->Password = $mail_password;
    //If SMTP requires TLS encryption then set it
    $mail->SMTPSecure = "ssl";
    //Set TCP port to connect to 
    $mail->Port = 465;
    $mail->From = $sender;  
    $mail->FromName = $sender_name;
    $mail->Subject = $Subject;
    $mail->Body = $Body;
    $mail->AltBody = "This is the plain text version of the email content";
    if (!$mail->send()) {
        echo "Mailer Error: " . $mail->ErrorInfo;
    else {
           echo 'Mail Sent Successfully';

Correct way to add external jars (lib/*.jar) to an IntelliJ IDEA project

Just copy-paste the .jar under the "libs" folder (or whole "libs" folder), right click on it and select 'Add as library' option from the list. It will do the rest...

enter image description here

How to clean project cache in Intellij idea like Eclipse's clean?

Depending on the version you are running. It is basically the same just go to
File -> Invalidate caches, then restart Intellij
File -> Invalidate caches / Restart

The main difference is that in older versions you had to manually restart as cache files are not removed until you restart. The newer versions will ask if you also want to restart.

Older versions Newer Versions

As seen here on this official Jetbrains help page

You can also try delete caches manually in the system folder for your installed version. The location of this folder depends on your OS and version installed.

Windows Vista, 7, 8, 10


Mac OS

Read this for more details on cache locations.

With CSS, how do I make an image span the full width of the page as a background image?

If you're hoping to use background-image: url(...);, I don't think you can. However, if you want to play with layering, you can do something like this:

<img class="bg" src="..." />

And then some CSS:

  width: 100%;
  z-index: 0;

You can now layer content above the stretched image by playing with z-indexes and such. One quick note, the image can't be contained in any other elements for the width: 100%; to apply to the whole page.

Here's a quick demo if you can't rely on background-size:

invalid command code ., despite escaping periods, using sed

If you are on a OS X, this probably has nothing to do with the sed command. On the OSX version of sed, the -i option expects an extension argument so your command is actually parsed as the extension argument and the file path is interpreted as the command code.

Try adding the -e argument explicitly and giving '' as argument to -i:

find ./ -type f -exec sed -i '' -e "s/" {} \;

See this.

Where is the file in a Spring Boot project?

You can create it manually but the default location of is here

enter image description here

How to upload, display and save images using node.js and express

First of all, you should make an HTML form containing a file input element. You also need to set the form's enctype attribute to multipart/form-data:

<form method="post" enctype="multipart/form-data" action="/upload">
    <input type="file" name="file">
    <input type="submit" value="Submit">

Assuming the form is defined in index.html stored in a directory named public relative to where your script is located, you can serve it this way:

const http = require("http");
const path = require("path");
const fs = require("fs");

const express = require("express");

const app = express();
const httpServer = http.createServer(app);

const PORT = process.env.PORT || 3000;

httpServer.listen(PORT, () => {
  console.log(`Server is listening on port ${PORT}`);

// put the HTML file containing your form in a directory named "public" (relative to where this script is located)
app.get("/", express.static(path.join(__dirname, "./public")));

Once that's done, users will be able to upload files to your server via that form. But to reassemble the uploaded file in your application, you'll need to parse the request body (as multipart form data).

In Express 3.x you could use express.bodyParser middleware to handle multipart forms but as of Express 4.x, there's no body parser bundled with the framework. Luckily, you can choose from one of the many available multipart/form-data parsers out there. Here, I'll be using multer:

You need to define a route to handle form posts:

const multer = require("multer");

const handleError = (err, res) => {
    .end("Oops! Something went wrong!");

const upload = multer({
  dest: "/path/to/temporary/directory/to/store/uploaded/files"
  // you might also want to set some limits:
  upload.single("file" /* name attribute of <file> element in your form */),
  (req, res) => {
    const tempPath = req.file.path;
    const targetPath = path.join(__dirname, "./uploads/image.png");

    if (path.extname(req.file.originalname).toLowerCase() === ".png") {
      fs.rename(tempPath, targetPath, err => {
        if (err) return handleError(err, res);

          .end("File uploaded!");
    } else {
      fs.unlink(tempPath, err => {
        if (err) return handleError(err, res);

          .end("Only .png files are allowed!");

In the example above, .png files posted to /upload will be saved to uploaded directory relative to where the script is located.

In order to show the uploaded image, assuming you already have an HTML page containing an img element:

<img src="/image.png" />

you can define another route in your express app and use res.sendFile to serve the stored image:

app.get("/image.png", (req, res) => {
  res.sendFile(path.join(__dirname, "./uploads/image.png"));

Using moment.js to convert date to string "MM/dd/yyyy"

StartDate = moment(StartDate).format('MM-YYYY');

...and MySQL date format:

StartDate = moment(StartDate).format('YYYY-MM-DD');

Django model "doesn't declare an explicit app_label"

After keep on running into this issue and keep on coming back to this question I thought I'd share what my problem was.

Everything that @Xeberdee is correct so follow that and see if that solves the issue, if not this was my issue:

In my this is what I had:

class AlgoExplainedConfig(AppConfig):
    name = 'algo_explained'
    verbose_name = "Explain_Algo"

And all I did was I added the project name in front of my app name like this:

class AlgoExplainedConfig(AppConfig):
name = '**algorithms_explained**.algo_explained'
verbose_name = "Explain_Algo"

and that solved my problem and I was able to run the makemigrations and migrate command after that! good luck

C++ terminate called without an active exception

When a thread object goes out of scope and it is in joinable state, the program is terminated. The Standard Committee had two other options for the destructor of a joinable thread. It could quietly join -- but join might never return if the thread is stuck. Or it could detach the thread (a detached thread is not joinable). However, detached threads are very tricky, since they might survive till the end of the program and mess up the release of resources. So if you don't want to terminate your program, make sure you join (or detach) every thread.

jQuery hyperlinks - href value?

$('a').click(function (event) 
     //here you can also do all sort of things 

Then you can put in every href whatever you want and jQuery will trigger the preventDefault() method and you will not be redirected to that place.

Styling Password Fields in CSS

The problem is that (as of 2016), for the password field, Firefox and Internet Explorer use the character "Black Circle" (?), which uses the Unicode code point 25CF, but Chrome uses the character "Bullet" (•), which uses the Unicode code point 2022.

As you can see, even in the StackOverflow font the two characters have different sizes.

The font you're using, "Lucida Sans Unicode", has an even greater disparity between the sizes of these two characters, leading to you noticing the difference.

The simple solution is to use a font in which both characters have similar sizes.

The fix could thus be to use a default font of the browser, which should render the characters in the password field just fine:

input[type="password"] {
    font-family: caption;

Set left margin for a paragraph in html

<p style="margin-left:5em;">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut lacinia vestibulum quam sit amet aliquet. Phasellus tempor nisi eget tellus venenatis tempus. Aliquam dapibus porttitor convallis. Praesent pretium luctus orci, quis ullamcorper lacus lacinia a. Integer eget molestie purus. Vestibulum porta mollis tempus. Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos himenaeos. </p>

That'll do it, there's a few improvements obviously, but that's the basics. And I use 'em' as the measurement, you may want to use other units, like 'px'.

EDIT: What they're describing above is a way of associating groups of styles, or classes, with elements on a web page. You can implement that in a few ways, here's one which may suit you:

In your HTML page, containing the <p> tagged content from your DB add in a new 'style' node and wrap the styles you want to declare in a class like so:

  <style type="text/css">
    p { margin-left:5em; /* Or another measurement unit, like px */ }
  <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut lacinia vestibulum quam sit amet aliquet.</p>

So above, all <p> elements in your document will have that style rule applied. Perhaps you are pumping your paragraph content into a container of some sort? Try this:

  <style type="text/css">
    .container p { margin-left:5em; /* Or another measurement unit, like px */ }
  <div class="container">
    <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut lacinia vestibulum quam sit amet aliquet.</p>
  <p>Vestibulum porta mollis tempus. Class aptent taciti sociosqu ad litora torquent per conubia nostra.</p>

In the example above, only the <p> element inside the div, whose class name is 'container', will have the styles applied - and not the <p> element outside the container.

In addition to the above, you can collect your styles together and remove the style element from the <head> tag, replacing it with a <link> tag, which points to an external CSS file. This external file is where you'd now put your <p> tag styles. This concept is known as 'seperating content from style' and is considered good practice, and is also an extendible way to create styles, and can help with low maintenance.

How to change Navigation Bar color in iOS 7?

It's actually easier than the answers I've seen here:

1) Just make sure you select the navigation bar on the Navigation control. 
2) Select the color you want in the bar tint.
3) You have other options too, and/or individually on each view (just play with it).

I hope this helps somebody. I didn't like the answers I saw. I like to keep my code as clean as possible. Not saying that it's wrong to do it programmatically, but there are people out there like me....this is for you guys. Changing color of the navigation bar

jQuery if statement, syntax

You can wrap jQuery calls inside normal JavaScript code. So, for example:

$(document).ready(function() {
    if (someCondition && someOtherCondition) {
        // Make some jQuery call.

Javascript how to split newline

Here is example with console.log instead of alert(). It is more convenient :)

var parse = function(){
  var str = $('textarea').val();
  var results = str.split("\n");
  $.each(results, function(index, element){

  $('button').on('click', parse);

You can try it here

Call Python script from bash with argument

I have a bash script that calls a small python routine to display a message window. As I need to use killall to stop the python script I can't use the above method as it would then mean running killall python which could take out other python programmes so I use "$argument" & # The & returns control straight to the bash script so must be outside the backticks. The preview of this message is showing it without "`" either side of the command for some reason.

As long as the python script will run from the cli by name rather than python this works within the script. If you need more than one argument just use a space between each one within the quotes.

IntelliJ IDEA "cannot resolve symbol" and "cannot resolve method"

For me, IntelliJ could autocomplete packages, but never seemed to admit there were actual classes at any level of the hierarchy. Neither re-choosing the SDK nor re-creating the project seemed to fix it.

What did fix it was to delete the per-user IDEA directory ( in my case ~/.IntelliJIdea2017.1/) which meant losing all my other customizations... But at least it made the issue go away.

fatal: Unable to create temporary file '/home/username/git/myrepo.git/./objects/pack/tmp_pack_XXXXXX': Permission denied

I resolved it by giving permission to the user on each of the directories that you're using, like so:

sudo chown user /home/user/git

and so on.

Quickest way to clear all sheet contents VBA

The .Cells range isn't limited to ones that are being used, so your code is clearing the content of 1,048,576 rows and 16,384 columns - 17,179,869,184 total cells. That's going to take a while. Just clear the UsedRange instead:


Alternately, you can delete the sheet and re-add it:

Application.DisplayAlerts = False
Application.DisplayAlerts = True
Dim sheet As Worksheet
Set sheet = Sheets.Add
sheet.Name = "Zeros"

SQL statement to get column type

Use this query to get Schema, Table, Column,Type, max_length, is_nullable

SELECT QUOTENAME(SCHEMA_NAME(tb.[schema_id])) AS 'Schema'
    ,C.NAME as 'Column'
    , AS 'Type'
FROM SYS.COLUMNS C INNER JOIN SYS.TABLES tb ON tb.[object_id] = C.[object_id]
    INNER JOIN SYS.TYPES T ON C.system_type_id = T.user_type_id
WHERE tb.[is_ms_shipped] = 0
ORDER BY tb.[Name]

Fast ceiling of an integer division in C / C++

How about this? (requires y non-negative, so don't use this in the rare case where y is a variable with no non-negativity guarantee)

q = (x > 0)? 1 + (x - 1)/y: (x / y);

I reduced y/y to one, eliminating the term x + y - 1 and with it any chance of overflow.

I avoid x - 1 wrapping around when x is an unsigned type and contains zero.

For signed x, negative and zero still combine into a single case.

Probably not a huge benefit on a modern general-purpose CPU, but this would be far faster in an embedded system than any of the other correct answers.

Numpy converting array from float to strings

If the main problem is the loss of precision when converting from a float to a string, one possible way to go is to convert the floats to the decimalS:

In python 2.7 and higher you can directly convert a float to a decimal object.

How do I include a JavaScript file in another JavaScript file?

So this is a edge case. But if you need to load the JavaScript from a remote source, most modern browsers might block your cross-site requests due to CORS or something similar. So normal

<script src=""></script>

Won't work. And doing the document.createElement('script').src = '...' won't cut it either. Instead, what you could do is load the java-script as a resource via standard GET request, and do this:

<script type="text/javascript">
    var script = document.createElement('script');
    script.type = 'text/javascript';

    let xhr = new XMLHttpRequest();"GET", '', true);
    xhr.onreadystatechange = function() {
        if (this.readyState === XMLHttpRequest.DONE && this.status === 200) {
            script.innerHTML = this.responseText; // <-- This one

By grabbing the content yourself, the browser won't notice malicious intents and allow you go do the request. Then you add it in <script>'s innerHTML instead. This still causes the browser (at least tested in Chrome) to parse/execute the script.

Again, this is a edge case use case. And you'll have no backwards compatibility or browser compliance probably. But fun/useful thing to know about.

What is the '.well' equivalent class in Bootstrap 4

Looking for a one line option:

    <div class="jumbotron bg-dark"> got a team? </div>

Replace text inside td using jQuery having td containing other elements

$('#demoTable td').contents().each(function() {
    if (this.nodeType === 3) {
        ? this.textContent = 'The text has been '
        : this.innerText  = 'The text has been '
    } else {
        this.innerHTML = 'changed';
        return false;

How can I verify if one list is a subset of another?

Assuming the items are hashable

>>> from collections import Counter
>>> not Counter([1, 2]) - Counter([1])
>>> not Counter([1, 2]) - Counter([1, 2])
>>> not Counter([1, 2, 2]) - Counter([1, 2])

If you don't care about duplicate items eg. [1, 2, 2] and [1, 2] then just use:

>>> set([1, 2, 2]).issubset([1, 2])

Is testing equality on the smaller list after an intersection the fastest way to do this?

.issubset will be the fastest way to do it. Checking the length before testing issubset will not improve speed because you still have O(N + M) items to iterate through and check.

What are OLTP and OLAP. What is the difference between them?

Here you will find a better solution OLTP vs. OLAP

  • OLTP (On-line Transaction Processing) is involved in the operation of a particular system. OLTP is characterized by a large number of short on-line transactions (INSERT, UPDATE, DELETE). The main emphasis for OLTP systems is put on very fast query processing, maintaining data integrity in multi-access environments and an effectiveness measured by number of transactions per second. In OLTP database there is detailed and current data, and schema used to store transactional databases is the entity model (usually 3NF). It involves Queries accessing individual record like Update your Email in Company database.

  • OLAP (On-line Analytical Processing) deals with Historical Data or Archival Data. OLAP is characterized by relatively low volume of transactions. Queries are often very complex and involve aggregations. For OLAP systems a response time is an effectiveness measure. OLAP applications are widely used by Data Mining techniques. In OLAP database there is aggregated, historical data, stored in multi-dimensional schemas (usually star schema). Sometime query need to access large amount of data in Management records like what was the profit of your company in last year.

What is the difference between 'protected' and 'protected internal'?

public - The members (Functions & Variables) declared as public can be accessed from anywhere.

private - Private members cannot be accessed from outside the class. This is the default access specifier for a member, i.e if you do not specify an access specifier for a member (variable or function), it will be considered as private. Therefore, string PhoneNumber; is equivalent to private string PhoneNumber.

protected - Protected members can be accessed only from the child classes.

internal - It can be accessed only within the same assembly.

protected internal - It can be accessed within the same assembly as well as in derived class.

How can I get the content of CKEditor using JQuery?

var value = CKEDITOR.instances['YourInstanceName'].getData()
 alert( value);

Replace YourInstanceName with the name of your instance and you will get the desired results.

Spring + Web MVC: dispatcher-servlet.xml vs. applicationContext.xml (plus shared security)

To add to Kevin's answer, I find that in practice nearly all of your non-trivial Spring MVC applications will require an application context (as opposed to only the spring MVC dispatcher servlet context). It is in the application context that you should configure all non-web related concerns such as:

  • Security
  • Persistence
  • Scheduled Tasks
  • Others?

To make this a bit more concrete, here's an example of the Spring configuration I've used when setting up a modern (Spring version 4.1.2) Spring MVC application. Personally, I prefer to still use a WEB-INF/web.xml file but that's really the only xml configuration in sight.


<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="" xmlns:xsi="" xsi:schemaLocation="" version="3.1">






@ComponentScan(basePackages = "")
public class WebConfig {

  public InternalResourceViewResolver getInternalResourceViewResolver() {
    InternalResourceViewResolver resolver = new InternalResourceViewResolver();
    return resolver;

@ComponentScan(basePackages = "")
@Import(value = {SecurityConfig.class, PersistenceConfig.class, ScheduleConfig.class})
public class AppConfig {
  // application domain @Beans here...

public class SecurityConfig extends WebSecurityConfigurerAdapter {
  private LdapUserDetailsMapper ldapUserDetailsMapper;

    protected void configure(HttpSecurity http) throws Exception {

    http.logout().logoutRequestMatcher(new AntPathRequestMatcher("/logout"));

    public void configureGlobal(AuthenticationManagerBuilder auth) throws Exception {
      .userSearchBase("OU=App Users")

  private LdapContextSource getLdapContextSource() {
    LdapContextSource cs = new LdapContextSource();
    return cs;

@EnableJpaRepositories(transactionManagerRef = "getTransactionManager", entityManagerFactoryRef = "getEntityManagerFactory", basePackages = "")
public class PersistenceConfig {

  public LocalContainerEntityManagerFactoryBean getEntityManagerFactory(DataSource dataSource) {
    LocalContainerEntityManagerFactoryBean lef = new LocalContainerEntityManagerFactoryBean();
    return lef;

  private HibernateJpaVendorAdapter getHibernateJpaVendorAdapter() {
    HibernateJpaVendorAdapter hibernateJpaVendorAdapter = new HibernateJpaVendorAdapter();
    return hibernateJpaVendorAdapter;

  public JndiObjectFactoryBean getDataSource() {
    JndiObjectFactoryBean jndiFactoryBean = new JndiObjectFactoryBean();
    return jndiFactoryBean;

  public JpaTransactionManager getTransactionManager(DataSource dataSource) {
    JpaTransactionManager jpaTransactionManager = new JpaTransactionManager();
    return jpaTransactionManager;

public class ScheduleConfig {
  private EmployeeSynchronizer employeeSynchronizer;

  // cron pattern: sec, min, hr, day-of-month, month, day-of-week, year (optional)
  @Scheduled(cron="0 0 0 * * *")
  public void employeeSync() {

As you can see, the web configuration is only a small part of the overall spring web application configuration. Most web applications I've worked with have many concerns that lie outside of the dispatcher servlet configuration that require a full-blown application context bootstrapped via the org.springframework.web.context.ContextLoaderListener in the web.xml.

Is there a destructor for Java?

Perhaps you can use a try ... finally block to finalize the object in the control flow at which you are using the object. Of course it doesn't happen automatically, but neither does destruction in C++. You often see closing of resources in the finally block.

MySQL ON DUPLICATE KEY UPDATE for multiple rows insert in single query

You can use Replace instead of INSERT ... ON DUPLICATE KEY UPDATE.

angular 2 sort and filter

This isn't added out of the box because the Angular team wants Angular 2 to run minified. OrderBy runs off of reflection which breaks with minification. Check out Miško Heverey's response on the matter.

I've taken the time to create an OrderBy pipe that supports both single and multi-dimensional arrays. It also supports being able to sort on multiple columns of the multi-dimensional array.

<li *ngFor="let person of people | orderBy : ['-lastName', 'age']">{{person.firstName}} {{person.lastName}}, {{person.age}}</li>

This pipe does allow for adding more items to the array after rendering the page, and still sort the arrays with the new items correctly.

I have a write up on the process here.

And here's a working demo: and

EDIT: Added new demo to

EDIT 2: Updated ngFor to new syntax

How to calculate growth with a positive and negative number?

=(This Year - Last Year) / (ABS(Last Year))

This only works reliably if this year and last year are always positive numbers.

For example last_year=-50 this_year = -1. You get -100% growth when in fact the numbers have improved a great deal.

Python: pandas merge multiple dataframes

If you are filtering by common date this will return it:

dfs = [df1, df2, df3]
checker = dfs[-1]
check = set(checker.loc[:, 0])

for df in dfs[:-1]:
    check = check.intersection(set(df.loc[:, 0]))

print(checker[checker.loc[:, 0].isin(check)])

Fastest way to check if a file exist using standard C++/C++11/C?

inline bool exist(const std::string& name)
    ifstream file(name);
    if(!file)            // If the file was not found, then file is 0, i.e. !file=1 or true.
        return false;    // The file was not found.
    else                 // If the file was found, then file is non-0.
        return true;     // The file was found.

SPA best practices for authentication and session management

I would go for the second, the token system.

Did you know about ember-auth or ember-simple-auth? They both use the token based system, like ember-simple-auth states:

A lightweight and unobtrusive library for implementing token based authentication in Ember.js applications.

They have session management, and are easy to plug into existing projects too.

There is also an Ember App Kit example version of ember-simple-auth: Working example of ember-app-kit using ember-simple-auth for OAuth2 authentication.

Django CSRF check failing with an Ajax POST request

Real solution

Ok, I managed to trace the problem down. It lies in the Javascript (as I suggested below) code.

What you need is this:

     beforeSend: function(xhr, settings) {
         function getCookie(name) {
             var cookieValue = null;
             if (document.cookie && document.cookie != '') {
                 var cookies = document.cookie.split(';');
                 for (var i = 0; i < cookies.length; i++) {
                     var cookie = jQuery.trim(cookies[i]);
                     // Does this cookie string begin with the name we want?
                     if (cookie.substring(0, name.length + 1) == (name + '=')) {
                         cookieValue = decodeURIComponent(cookie.substring(name.length + 1));
             return cookieValue;
         if (!(/^http:.*/.test(settings.url) || /^https:.*/.test(settings.url))) {
             // Only send the token to relative URLs i.e. locally.
             xhr.setRequestHeader("X-CSRFToken", getCookie('csrftoken'));

instead of the code posted in the official docs:

The working code, comes from this Django entry:

So the general solution is: "use ajaxSetup handler instead of ajaxSend handler". I don't know why it works. But it works for me :)

Previous post (without answer)

I'm experiencing the same problem actually.

It occurs after updating to Django 1.2.5 - there were no errors with AJAX POST requests in Django 1.2.4 (AJAX wasn't protected in any way, but it worked just fine).

Just like OP, I have tried the JavaScript snippet posted in Django documentation. I'm using jQuery 1.5. I'm also using the "django.middleware.csrf.CsrfViewMiddleware" middleware.

I tried to follow the the middleware code and I know that it fails on this:

request_csrf_token = request.META.get('HTTP_X_CSRFTOKEN', '')

and then

if request_csrf_token != csrf_token:
    return self._reject(request, REASON_BAD_TOKEN)

this "if" is true, because "request_csrf_token" is empty.

Basically it means that the header is NOT set. So is there anything wrong with this JS line:

xhr.setRequestHeader("X-CSRFToken", getCookie('csrftoken'));


I hope that provided details will help us in resolving the issue :)

Embed YouTube video - Refused to display in a frame because it set 'X-Frame-Options' to 'SAMEORIGIN'

The YouTube URL in src must have and use the embed endpoint instead of watch, so for instance let’s say you want to embed this YouTube video: (browser's URL).

You should use the embed endpoint, so the URL now should be something like Use this value as the URL in the src attribute inside the iframe tag in your HTML code, for example:

<iframe width="853" height="480" src="" frameborder="0" allowfullscreen ng-show="showvideo"></iframe>

So just replace with and of course check for your video's ID. In this sample, my video ID is P6N9782MzFQ.

bash: pip: command not found

What I did to overcome this was sudo apt install python-pip.

It turned out my virtual machine did not have pip installed yet. It's conceivable that other people could have this scenario too.

Immediate exit of 'while' loop in C++


   if (choice==99)

Python 'list indices must be integers, not tuple"

Why does the error mention tuples?

Others have explained that the problem was the missing ,, but the final mystery is why does the error message talk about tuples?

The reason is that your:

["pennies", '2.5', '50.0', '.01'] 
["nickles", '5.0', '40.0', '.05']

can be reduced to:

[][1, 2]

as mentioned by 6502 with the same error.

But then __getitem__, which deals with [] resolution, converts object[1, 2] to a tuple:

class C(object):
    def __getitem__(self, k):
        return k

# Single argument is passed directly.
assert C()[0] == 0

# Multiple indices generate a tuple.
assert C()[0, 1] == (0, 1)

and the implementation of __getitem__ for the list built-in class cannot deal with tuple arguments like that.

More examples of __getitem__ action at:

How to blur background images in Android

This is an easy way to blur Images Efficiently with Android's RenderScript that I found on this article

  1. Create a Class called BlurBuilder

    public class BlurBuilder {
      private static final float BITMAP_SCALE = 0.4f;
      private static final float BLUR_RADIUS = 7.5f;
      public static Bitmap blur(Context context, Bitmap image) {
        int width = Math.round(image.getWidth() * BITMAP_SCALE);
        int height = Math.round(image.getHeight() * BITMAP_SCALE);
        Bitmap inputBitmap = Bitmap.createScaledBitmap(image, width, height, false);
        Bitmap outputBitmap = Bitmap.createBitmap(inputBitmap);
        RenderScript rs = RenderScript.create(context);
        ScriptIntrinsicBlur theIntrinsic = ScriptIntrinsicBlur.create(rs, Element.U8_4(rs));
        Allocation tmpIn = Allocation.createFromBitmap(rs, inputBitmap);
        Allocation tmpOut = Allocation.createFromBitmap(rs, outputBitmap);
        return outputBitmap;
  2. Copy any image to your drawable folder

  3. Use BlurBuilder in your activity like this:

    protected void onCreate(Bundle savedInstanceState) {
        mContainerView = (LinearLayout) findViewById(;
        Bitmap originalBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.background);
        Bitmap blurredBitmap = BlurBuilder.blur( this, originalBitmap );
        mContainerView.setBackground(new BitmapDrawable(getResources(), blurredBitmap));
  4. Renderscript is included into support v8 enabling this answer down to api 8. To enable it using gradle include these lines into your gradle file (from this answer)

    defaultConfig {
        renderscriptTargetApi *your target api*
        renderscriptSupportModeEnabled true
  5. Result

enter image description here

remove legend title in ggplot

You were almost there : just add theme(legend.title=element_blank())

ggplot(df, aes(x, y, colour=g)) +
  geom_line(stat="identity") + 
  theme(legend.position="bottom") +

This page on Cookbook for R gives plenty of details on how to customize legends.

Python Turtle, draw text with on screen with larger font

To add bold, italic and underline, just add the following to the font argument:

font=("Arial", 8, 'normal', 'bold', 'italic', 'underline')

How do I detect if Python is running as a 64-bit application?

import platform

From the Python docs:

Queries the given executable (defaults to the Python interpreter binary) for various architecture information.

Returns a tuple (bits, linkage) which contain information about the bit architecture and the linkage format used for the executable. Both values are returned as strings.

How do I change db schema to dbo

ALTER SCHEMA dbo TRANSFER jonathan.MovieData;


Converting string to number in javascript/jQuery

It sounds like this in your code is not referring to your .btn element. Try referencing it explicitly with a selector:

var votevalue = parseInt($(".btn").data('votevalue'), 10);

Also, don't forget the radix.

How to convert a HTMLElement to a string

The most easy way to do is copy innerHTML of that element to tmp variable and make it empty, then append new element, and after that copy back tmp variable to it. Here is an example I used to add jquery script to top of head.

var imported = document.createElement('script');
imported.src = '';
var tmpHead = document.head.innerHTML;
document.head.innerHTML = "";
document.head.innerHTML += tmpHead;

That simple :)

Configure hibernate to connect to database via JNDI Datasource

Apparently, you did it right. But here is a list of things you'll need with examples from a working application:

1) A context.xml file in META-INF, specifying your data source:


2) web.xml which tells the container that you are using this resource:


3) Hibernate configuration which consumes the data source. In this case, it's a persistence.xml, but it's similar in hibernate.cfg.xml

<persistence-unit name="dswebapp">
        <property name="hibernate.dialect" value="org.hibernate.dialect.H2Dialect" />
        <property name="hibernate.connection.datasource" value="java:comp/env/jdbc/DsWebAppDB"/>

Replace all particular values in a data frame

Here are a couple dplyr options:


# all columns:
df %>% 
  mutate_all(~na_if(., ''))

# specific column types:
df %>% 
  mutate_if(is.factor, ~na_if(., ''))

# specific columns:  
df %>% 
  mutate_at(vars(A, B), ~na_if(., ''))

# or:
df %>% 
  mutate(A = replace(A, A == '', NA))

# replace can be used if you want something other than NA:
df %>% 
  mutate(A = as.character(A)) %>% 
  mutate(A = replace(A, A == '', 'used to be empty'))

Adding an image to a project in Visual Studio

You need to turn on Show All Files option on solution pane toolbar and include this file manually.

Java - What does "\n" mean?

\n is add a new line.

Please note java has method System.out.println("Write text here");

Notice the difference:


System.out.println("Text 1");
System.out.println("Text 2");


Text 1
Text 2


System.out.print("Text 1");
System.out.print("Text 2");


Text 1Text 2

Allow anonymous authentication for a single folder in web.config?

The first approach to take is to modify your web.config using the <location> configuration tag, and <allow users="?"/> to allow anonymous or <allow users="*"/> for all:

   <location path="Path/To/Public/Folder">
            <allow users="?"/>

If that approach doesn't work then you can take the following approach which requires making a small modification to the IIS applicationHost.config.

First, change the anonymousAuthentication section's overrideModeDefault from "Deny" to "Allow" in C:\Windows\System32\inetsrv\config\applicationHost.config:

<section name="anonymousAuthentication" overrideModeDefault="Allow" />

overrideMode is a security feature of IIS. If override is disallowed at the system level in applicationHost.config then there is nothing you can do in web.config to enable it. If you don't have this level of access on your target system you have to take up that discussion with your hosting provider or system administrator.

Second, after setting overrideModeDefault="Allow" then you can put the following in your web.config:

<location path="Path/To/Public/Folder">
        <anonymousAuthentication enabled="true" />

How do you format an unsigned long long int using printf?

Compile it as x64 with VS2005:

%llu works well.

VBA test if cell is in a range

I don't work with contiguous ranges all the time. My solution for non-contiguous ranges is as follows (includes some code from other answers here):

Sub test_inters()
    Dim rng1 As Range
    Dim rng2 As Range
    Dim inters As Range

    Set rng2 = Worksheets("Gen2").Range("K7")
    Set rng1 = ExcludeCell(Worksheets("Gen2").Range("K6:K8"), rng2)

    If ( = Then
        Dim ints As Range
        MsgBox rng1.Address & vbCrLf _
        & rng2.Address & vbCrLf _

        For Each cell In rng1
            MsgBox cell.Address
            Set ints = Application.Intersect(cell, rng2)
            If (Not (ints Is Nothing)) Then
                MsgBox "Yes intersection"
                MsgBox "No intersection"
            End If
        Next cell
    End If
End Sub

What is a None value?

The book you refer to is clearly trying to greatly simplify the meaning of None. Python variables don't have an initial, empty state – Python variables are bound (only) when they're defined. You can't create a Python variable without giving it a value.

>>> print(x)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'x' is not defined
>>> def test(x):
...   print(x)
>>> test()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: test() takes exactly 1 argument (0 given)
>>> def test():
...   print(x)
>>> test()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 2, in test
NameError: global name 'x' is not defined

but sometimes you want to make a function mean different things depending on whether a variable is defined or not. You can create an argument with a default value of None:

>>> def test(x=None):
...   if x is None:
...     print('no x here')
...   else:
...     print(x)
>>> test()
no x here
>>> test('x!')

The fact that this value is the special None value is not terribly important in this case. I could've used any default value:

>>> def test(x=-1):
...   if x == -1:
...     print('no x here')
...   else:
...     print(x)
>>> test()
no x here
>>> test('x!')

…but having None around gives us two benefits:

  1. We don't have to pick a special value like -1 whose meaning is unclear, and
  2. Our function may actually need to handle -1 as a normal input.
>>> test(-1)
no x here


So the book is a little misleading mostly in its use of the word reset – assigning None to a name is a signal to a programmer that that value isn't being used or that the function should behave in some default way, but to reset a value to its original, undefined state you must use the del keyword:

>>> x = 3
>>> x
>>> del x
>>> x
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'x' is not defined

How to create query parameters in Javascript?

We've just released arg.js, a project aimed at solving this problem once and for all. It's traditionally been so difficult but now you can do:

var querystring = Arg.url({name: "Mat", state: "CO"});

And reading works:

var name = Arg("name");

or getting the whole lot:

var params = Arg.all();

and if you care about the difference between ?query=true and #hash=true then you can use the Arg.query() and Arg.hash() methods.

Java Map equivalent in C#

You can index Dictionary, you didn't need 'get'.

Dictionary<string,string> example = new Dictionary<string,string>();

An efficient way to test/get values is TryGetValue (thanx to Earwicker):

if (otherExample.TryGetValue("key", out value))
    otherExample["key"] = value + 1;

With this method you can fast and exception-less get values (if present).



Try Get Value

Difference between javacore, thread dump and heap dump in Websphere

JVM head dump is a snapshot of a JVM heap memory in a given time. So its simply a heap representation of JVM. That is the state of the objects.

JVM thread dump is a snapshot of a JVM threads at a given time. So thats what were threads doing at any given time. This is the state of threads. This helps understanding such as locked threads, hanged threads and running threads.

Head dump has more information of java class level information than a thread dump. For example Head dump is good to analyse JVM heap memory issues and OutOfMemoryError errors. JVM head dump is generated automatically when there is something like OutOfMemoryError has taken place. Heap dump can be created manually by killing the process using kill -3 . Generating a heap dump is a intensive computing task, which will probably hang your jvm. so itsn't a methond to use offetenly. Heap can be analysed using tools such as eclipse memory analyser.

Core dump is a os level memory usage of objects. It has more informaiton than a head dump. core dump is not created when we kill a process purposely.

Negative weights using Dijkstra's Algorithm

you did not use S anywhere in your algorithm (besides modifying it). the idea of dijkstra is once a vertex is on S, it will not be modified ever again. in this case, once B is inside S, you will not reach it again via C.

this fact ensures the complexity of O(E+VlogV) [otherwise, you will repeat edges more then once, and vertices more then once]

in other words, the algorithm you posted, might not be in O(E+VlogV), as promised by dijkstra's algorithm.

Java FileWriter how to write to next Line

You can call the method newLine() provided by java, to insert the new line in to a file.

For more refernce -

Disable-web-security in Chrome 48+

Mac OS:

open -a Google\ Chrome --args --disable-web-security --user-data-dir=

UPD: add = to --user-data-dir because newer chrome versions require it in order to work

How do I best silence a warning about unused variables?

Using an UNREFERENCED_PARAMETER(p) could work. I know it is defined in WinNT.h for Windows systems and can easily be defined for gcc as well (if it doesn't already have it).


#define UNREFERENCED_PARAMETER(P)          (P)

in WinNT.h.

Classes vs. Functions

Before answering your question:

If you do not have a Person class, first you must consider whether you want to create a Person class. Do you plan to reuse the concept of a Person very often? If so, you should create a Person class. (You have access to this data in the form of a passed-in variable and you don't care about being messy and sloppy.)

To answer your question:

You have access to their birthyear, so in that case you likely have a Person class with a someperson.birthdate field. In that case, you have to ask yourself, is someperson.age a value that is reusable?

The answer is yes. We often care about age more than the birthdate, so if the birthdate is a field, age should definitely be a derived field. (A case where we would not do this: if we were calculating values like someperson.chanceIsFemale or someperson.positionToDisplayInGrid or other irrelevant values, we would not extend the Person class; you just ask yourself, "Would another program care about the fields I am thinking of extending the class with?" The answer to that question will determine if you extend the original class, or make a function (or your own class like PersonAnalysisData or something).)

Find an object in array?

You can filter the array and then just pick the first element, as shown in Find Object with Property in Array.

Or you define a custom extension

extension Array {

    // Returns the first element satisfying the predicate, or `nil`
    // if there is no matching element.
    func findFirstMatching<L : BooleanType>(predicate: T -> L) -> T? {
        for item in self {
            if predicate(item) {
                return item // found
        return nil // not found

Usage example:

struct T {
    var name : String

let array = [T(name: "bar"), T(name: "baz"), T(name: "foo")]

if let item = array.findFirstMatching( { $ == "foo" } ) {
    // item is the first matching array element
} else {
    // not found

In Swift 3 you can use the existing first(where:) method (as mentioned in a comment):

if let item = array.first(where: { $ == "foo" }) {
    // item is the first matching array element
} else {
    // not found

Adding values to an array in java

  • First line : array created.
  • Third line loop started from j = 1 to j = 28123
  • Fourth line you give the variable x value (0) each time the loop is accessed.
  • Fifth line you put the value of j in the index 0.
  • Sixth line you do increment to the value x by 1.(but it will be reset to 0 at line 4)

How do I use Assert to verify that an exception has been thrown?

The helper provided by @Richiban above works great except it doesn't handle the situation where an exception is thrown, but not the type expected. The following addresses that:

using System;
using Microsoft.VisualStudio.TestTools.UnitTesting;

namespace YourProject.Tests
    public static class MyAssert
        /// <summary>
        /// Helper for Asserting that a function throws an exception of a particular type.
        /// </summary>
        public static void Throws<T>( Action func ) where T : Exception
            Exception exceptionOther = null;
            var exceptionThrown = false;
            catch ( T )
                exceptionThrown = true;
            catch (Exception e) {
                exceptionOther = e;

            if ( !exceptionThrown )
                if (exceptionOther != null) {
                    throw new AssertFailedException(
                        String.Format("An exception of type {0} was expected, but not thrown. Instead, an exception of type {1} was thrown.", typeof(T), exceptionOther.GetType()),

                throw new AssertFailedException(
                    String.Format("An exception of type {0} was expected, but no exception was thrown.", typeof(T))

What are the advantages and disadvantages of recursion?

For the most part recursion is slower, and takes up more of the stack as well. The main advantage of recursion is that for problems like tree traversal it make the algorithm a little easier or more "elegant". Check out some of the comparisons:


How to get Android application id?

I am not sure what you need the app/installation ID for, but you can review the existing possibilities in a great article from Android developers:

To sum up:

  • UUID.randomUUID() for creating id on the first time an app runs after installation and simple retrieval afterwards
  • TelephonyManager.getDeviceId() for actual device identifier
  • Settings.Secure.ANDROID_ID on relatively modern devices

ASP.NET MVC: Custom Validation by DataAnnotation

A bit late to answer, but for who is searching. You can easily do this by using an extra property with the data annotation:

public string foo { get; set; }
public string bar { get; set; }

[MinLength(20, ErrorMessage = "too short")]
public string foobar 
        return foo + bar;

That's all that is too it really. If you really want to display in a specific place the validation error as well, you can add this in your view:

@Html.ValidationMessage("foobar", "your combined text is too short")

doing this in the view can come in handy if you want to do localization.

Hope this helps!

Validate phone number using javascript


Assuming you are validating US phone numbers, this will do the trick.

First, we allow 0 or 1 open parentheses to start \(?

Then, we allow 3 consecutive digits between 0-9 [0-9]{3}

After, we repeat the first step and allow 0 or 1 closing parentheses \)?

For the second grouping, we start by allowing a space or a hyphen 0 or 1 times ((\s|\-){1})?

This is repeated between the second and third grouping of numbers, and we check for 3 consecutive digits then four consecutive digits to end it. For US phone numbers I think this covers the bases for a lot of different ways that people might format the number, but is restrictive enough that they can't pass an unreasonable string.

Close Bootstrap modal on form submit

If you do not want to use jQuery, make the button type a normal button and add a click listener pointing to the function you would like to execute, and send the form in as a parameter. The button would be as follows:

<button (click)="yourSubmitFunction(yourForm)" [disabled]="!yourForm.valid" type="button" class="btn btn-primary" data-dismiss="modal">Save changes</button>

Remember to remove: (ngSubmit)="yourSubmitFunction(yourForm)" from the form div if you use this method.

For loop in multidimensional javascript array

An efficient way to loop over an Array is the built-in array method .map()

For a 1-dimensional array it would look like this:

function HandleOneElement( Cuby ) {
} ; // the map function will pass each element

for 2-dimensional array: function( cubeRow ) { HandleOneElement ) } )

for an n-dimensional array of any form:

Function.prototype.ArrayFunction = function(param) {
  if (param instanceof Array) {
    return Function.prototype.ArrayFunction, this ) ;
  else return (this)(param) ;
HandleOneElement.ArrayFunction(cubes) ;

Confirmation dialog on ng-click - AngularJS

I created a module for this very thing that relies on the Angular-UI $modal service.

Does HTML5 <video> playback support the .avi format?

Short answer: No. Use WebM or Ogg instead.

This article covers just about everything you need to know about the <video> element, including which browsers support which container formats and codecs.

Inline functions in C#?

C# does not support inline methods (or functions) in the way dynamic languages like python do. However anonymous methods and lambdas can be used for similar purposes including when you need to access a variable in the containing method like in the example below.

static void Main(string[] args)
    int a = 1;

    Action inline = () => a++;
    //here a = 2

Java generics - get class?

Short answer: You can't.

Long answer:

Due to the way generics is implemented in Java, the generic type T is not kept at runtime. Still, you can use a private data member:

public class Foo<T> 
    private Class<T> type;

    public Foo(Class<T> type) { this.type = type; } 

Usage example:

Foo<Integer> test = new Foo<Integer>(Integer.class);

nginx missing sites-available directory

If you'd prefer a more direct approach, one that does NOT mess with symlinking between /etc/nginx/sites-available and /etc/nginx/sites-enabled, do the following:

  1. Locate your nginx.conf file. Likely at /etc/nginx/nginx.conf
  2. Find the http block.
  3. Somewhere in the http block, write include /etc/nginx/conf.d/*.conf; This tells nginx to pull in any files in the conf.d directory that end in .conf. (I know: it's weird that a directory can have a . in it.)
  4. Create the conf.d directory if it doesn't already exist (per the path in step 3). Be sure to give it the right permissions/ownership. Likely root or www-data.
  5. Move or copy your separate config files (just like you have in /etc/nginx/sites-available) into the directory conf.d.
  6. Reload or restart nginx.
  7. Eat an ice cream cone.

Any .conf files that you put into the conf.d directory from here on out will become active as long as you reload/restart nginx after.

Note: You can use the conf.d and sites-enabled + sites-available method concurrently if you wish. I like to test on my dev box using conf.d. Feels faster than symlinking and unsymlinking.

check if a string matches an IP address pattern in python?

We do not need any import to do this. This also works much faster

def is_valid_ip(str_ip_addr):
   :return: returns true if IP is valid, else returns False
   ip_blocks = str(str_ip_addr).split(".")
   if len(ip_blocks) == 4:
       for block in ip_blocks:
           # Check if number is digit, if not checked before calling this function
           if not block.isdigit():
               return False
           tmp = int(block)
           if 0 > tmp > 255:
               return False
       return True
    return False

Add comma to numbers every three digits

This is not jQuery, but it works for me. Taken from this site.

function addCommas(nStr) {
    nStr += '';
    x = nStr.split('.');
    x1 = x[0];
    x2 = x.length > 1 ? '.' + x[1] : '';
    var rgx = /(\d+)(\d{3})/;
    while (rgx.test(x1)) {
        x1 = x1.replace(rgx, '$1' + ',' + '$2');
    return x1 + x2;

stdcall and cdecl

Raymond Chen gives a nice overview of what __stdcall and __cdecl does.

(1) The caller "knows" to clean up the stack after calling a function because the compiler knows the calling convention of that function and generates the necessary code.

void __stdcall StdcallFunc() {}

void __cdecl CdeclFunc()
    // The compiler knows that StdcallFunc() uses the __stdcall
    // convention at this point, so it generates the proper binary
    // for stack cleanup.

It is possible to mismatch the calling convention, like this:

LRESULT MyWndProc(HWND hwnd, UINT msg,
    WPARAM wParam, LPARAM lParam);
// ...
// Compiler usually complains but there's this cast here...
windowClass.lpfnWndProc = reinterpret_cast<WNDPROC>(&MyWndProc);

So many code samples get this wrong it's not even funny. It's supposed to be like this:

// CALLBACK is #define'd as __stdcall
    WPARAM wParam, LPARAM lParam);
// ...
windowClass.lpfnWndProc = &MyWndProc;

However, assuming the programmer doesn't ignore compiler errors, the compiler will generate the code needed to clean up the stack properly since it'll know the calling conventions of the functions involved.

(2) Both ways should work. In fact, this happens quite frequently at least in code that interacts with the Windows API, because __cdecl is the default for C and C++ programs according to the Visual C++ compiler and the WinAPI functions use the __stdcall convention.

(3) There should be no real performance difference between the two.

How to know which is running in Jupyter notebook?

import sys

will give you the interpreter. You can select the interpreter you want when you create a new notebook. Make sure the path to your anaconda interpreter is added to your path (somewhere in your bashrc/bash_profile most likely).

For example I used to have the following line in my .bash_profile, that I added manually :

export PATH="$HOME/anaconda3/bin:$PATH"

EDIT: As mentioned in a comment, this is not the proper way to add anaconda to the path. Quoting Anaconda's doc, this should be done instead after install, using conda init:

Should I add Anaconda to the macOS or Linux PATH?

We do not recommend adding Anaconda to the PATH manually. During installation, you will be asked “Do you wish the installer to initialize Anaconda3 by running conda init?” We recommend “yes”. If you enter “no”, then conda will not modify your shell scripts at all. In order to initialize after the installation process is done, first run source <path to conda>/bin/activate and then run conda init

Set NA to 0 in R

To add to James's example, it seems you always have to create an intermediate when performing calculations on NA-containing data frames.

For instance, adding two columns (A and B) together from a data frame dfr:

temp.df <- data.frame(dfr) # copy the original
temp.df[] <- 0
dfr$C <- temp.df$A + temp.df$B # or any other calculation

When I do this I throw away the intermediate afterwards with remove/rm.

Render Content Dynamically from an array map function in React Native

lapsList() {

    return => {
      return (

You forgot to return the map. this code will resolve the issue.

How to make "if not true condition"?

On Unix systems that supports it (not macOS it seems):

if getent passwd "$username" >/dev/null; then
    printf 'User %s exists\n' "$username"
    printf 'User %s does not exist\n' "$username"

This has the advantage that it will query any directory service that may be in use (YP/NIS or LDAP etc.) and the local password database file.

The issue with grep -q "$username" /etc/passwd is that it will give a false positive when there is no such user, but something else matches the pattern. This could happen if there is a partial or exact match somewhere else in the file.

For example, in my passwd file, there is a line saying

build:*:21:21:base and xenocara build:/var/empty:/bin/ksh

This would provoke a valid match on things like cara and enoc etc., even though there are no such users on my system.

For a grep solution to be correct, you will need to properly parse the /etc/passwd file:

if cut -d ':' -f 1 /etc/passwd | grep -qxF "$username"; then
    # found
    # not found

... or any other similar test against the first of the :-delimited fields.

How do I evenly add space between a label and the input field regardless of length of text?

You can use a table

<table class="formcontrols" >   
            <label for="firstName">FirstName:</label>
        <td  style="padding-left:10px;">
            <input id="firstName" name="firstName" value="John">
            <label for="Test">Last name:</label>
        <td  style="padding-left:10px;">
            <input id="lastName" name="lastName" value="Travolta">

The result would be: ImageResult

Eclipse reported "Failed to load JNI shared library"

Installing a 64-bit version of Java will solve the issue. Go to page Java Downloads for All Operating Systems

This is a problem due to the incompatibility of the Java version and the Eclipse version both should be 64 bit if you are using a 64-bit system.

Alternative to itoa() for converting integer to string C++?

Note that all of the stringstream methods may involve locking around the use of the locale object for formatting. This may be something to be wary of if you're using this conversion from multiple threads...

See here for more. Convert a number to a string with specified length in C++

Open source PDF library for C/C++ application?

PDF Hummus. see for - contains all required features for manipulation with PDF files except rendering.

How do we update URL or query strings using javascript/jQuery without reloading the page?

Define a new URL object, assign it the current url, append your parameter(s) to that URL object and finally push it to your browsers state.

var url = new URL(window.location.href);
//var url = new URL(window.location.origin + window.location.pathname) <- flush existing parameters
url.searchParams.append("order", orderId);
window.history.pushState(null, null, url);

Share link on Google+

No, you cannot. Google Plus has been discontinued. Clicking any link for any answer here brings me to this text:

Google+ is no longer available for consumer (personal) and brand accounts

From all of us on the Google+ team,

thank you for making Google+ such a special place.

There is one section that reads that the product is continued for "G Suite," but as of Feb., 2020, the chat and social service listed for G Suite is Hangouts, not Google+.

The format was documented at, but this documentation has since been removed, probably because no part of Google+ continues in development. If you are feeling nostalgic, you can see what the API used to say with an link.

How do I specify unique constraint for multiple columns in MySQL?

For PostgreSQL... It didn't work for me with index; it gave me an error, so I did this:

alter table table_name
add unique(column_name_1,column_name_2);

PostgreSQL gave unique index its own name. I guess you can change the name of index in the options for the table, if it is needed to be changed...

Android Studio Could not initialize class org.codehaus.groovy.runtime.InvokerHelper

I face this issue when I was Building my Flutter Application. This error is due to the gradle version that you are using in your Android Project. Follow the below steps:

distributionUrl =

Now Save the File (Ctrl + S), Go to the console and run the command

flutter run

It will take some time, but the issue that you were facing will be solved.

How to insert a timestamp in Oracle?

First of all you need to make the field Nullable, then after that so simple - instead of putting a value put this code CURRENT_TIMESTAMP.

How to import an existing X.509 certificate and private key in Java keystore to use in SSL?

Keytool in Java 6 does have this capability: Importing private keys into a Java keystore using keytool

Here are the basic details from that post.

  1. Convert the existing cert to a PKCS12 using OpenSSL. A password is required when asked or the 2nd step will complain.

    openssl pkcs12 -export -in [my_certificate.crt] -inkey [my_key.key] -out [keystore.p12] -name [new_alias] -CAfile [my_ca_bundle.crt] -caname root
  2. Convert the PKCS12 to a Java Keystore File.

    keytool -importkeystore -deststorepass [new_keystore_pass] -destkeypass [new_key_pass] -destkeystore [keystore.jks] -srckeystore [keystore.p12] -srcstoretype PKCS12 -srcstorepass [pass_used_in_p12_keystore] -alias [alias_used_in_p12_keystore]

How to recursively list all the files in a directory in C#?

In Framework 2.0 you can use (It list files of root folder, it's best the most popular answer):

static void DirSearch(string dir)
        foreach (string f in Directory.GetFiles(dir))
        foreach (string d in Directory.GetDirectories(dir))

    catch (System.Exception ex)

Setting background colour of Android layout element

If you want to change a color quickly (and you don't have Hex numbers memorized) android has a few preset colors you can access like this:


There are 15 colors you can choose from which is nice for testing things out quickly, and you don't need to set up additional files.

Setting up a values/colors.xml file and using straight Hex like explained above will still work.

Change div width live with jQuery

You can use, which will be triggered when the window resizes.

$( window ).bind("resize", function(){
    // Change the width of the div
    $("#yourdiv").width( 600 );

If you want a DIV width as percentage of the screen, just use CSS width : 80%;.

Delete statement in SQL is very slow

I read this article it was really helpful for troubleshooting any kind of inconveniences

this is a case of waitresource KEY: 16:72057595075231744 (ab74b4daaf17)

-- First SQL Provider to find the SPID (Session ID)

-- Second Identify problem, check Status, Open_tran, Lastwaittype, waittype, and waittime
-- iMPORTANT Waitresource select * from sys.sysprocesses where spid = 57

select * from sys.databases where database_id=16

-- with Waitresource check this to obtain object id 
select * from sys.partitions where hobt_id=72057595075231744

select * from sys.objects where object_id=2105058535

Run an exe from C# code

I know this is well answered, but if you're interested, I wrote a library that makes executing commands much easier.

Check it out here:

Getting Google+ profile picture url with user_id

Tried everything possible.. here is final piece of working code. Hope it helps someone who is looking for it.

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_PROXYPORT, 3128);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 0);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 0);
$response = curl_exec($ch);
$d = json_decode($response);
$avatar_url = $d->{'image'}->{'url'};
echo $avatar_url;

How do I find out if the GPS of an Android device is enabled

Yes you can check below is the code:

public boolean isGPSEnabled (Context mContext){
    LocationManager locationManager = (LocationManager)
    return locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);

How to convert an XML file to nice pandas dataframe?

You can easily use xml (from the Python standard library) to convert to a pandas.DataFrame. Here's what I would do (when reading from a file replace xml_data with the name of your file or file object):

import pandas as pd
import xml.etree.ElementTree as ET
import io

def iter_docs(author):
    author_attr = author.attrib
    for doc in author.iter('document'):
        doc_dict = author_attr.copy()
        doc_dict['data'] = doc.text
        yield doc_dict

xml_data = io.StringIO(u'''\
<author type="XXX" language="EN" gender="xx" feature="xx" web="">
    <documents count="N">
        <document KEY="e95a9a6c790ecb95e46cf15bee517651" web=""><![CDATA[A large text with lots of strings and punctuations symbols [...]
        <document KEY="bc360cfbafc39970587547215162f0db" web=""><![CDATA[A large text with lots of strings and punctuations symbols [...]
        <document KEY="19e71144c50a8b9160b3f0955e906fce" web=""><![CDATA[A large text with lots of strings and punctuations symbols [...]
        <document KEY="21d4af9021a174f61b884606c74d9e42" web=""><![CDATA[A large text with lots of strings and punctuations symbols [...]
        <document KEY="28a45eb2460899763d709ca00ddbb665" web=""><![CDATA[A large text with lots of strings and punctuations symbols [...]
        <document KEY="a0c0712a6a351f85d9f5757e9fff8946" web=""><![CDATA[A large text with lots of strings and punctuations symbols [...]
        <document KEY="626726ba8d34d15d02b6d043c55fe691" web=""><![CDATA[A large text with lots of strings and punctuations symbols [...]
        <document KEY="2cb473e0f102e2e4a40aa3006e412ae4" web=""><![CDATA[A large text with lots of strings and punctuations symbols [...] [...]

etree = ET.parse(xml_data) #create an ElementTree object 
doc_df = pd.DataFrame(list(iter_docs(etree.getroot())))

If there are multiple authors in your original document or the root of your XML is not an author, then I would add the following generator:

def iter_author(etree):
    for author in etree.iter('author'):
        for row in iter_docs(author):
            yield row

and change doc_df = pd.DataFrame(list(iter_docs(etree.getroot()))) to doc_df = pd.DataFrame(list(iter_author(etree)))

Have a look at the ElementTree tutorial provided in the xml library documentation.

How to unblock with mysqladmin flush hosts

You can easily restart your MySql service. This kicks the error off.

JSONObject - How to get a value?

You can try the below function to get value from JSON string,

public static String GetJSONValue(String JSONString, String Field)
       return JSONString.substring(JSONString.indexOf(Field), JSONString.indexOf("\n", JSONString.indexOf(Field))).replace(Field+"\": \"", "").replace("\"", "").replace(",","");   

How to change permissions for a folder and its subfolders/files in one step?

You can change permission by using following commands

sudo chmod go=rwx /opt/lampp/htdocs

estimating of testing effort as a percentage of development time

Gartner in Oct 2006 states that testing typically consumes between 10% and 35% of work on a system integration project. I assume that it applies to the waterfall method. This is quite a wide range - but there are many dependencies on the amount of customisations to a standard product and the number of systems to be integrated.

change background image in body

If you're page has an Open Graph image, commonly used for social sharing, you can use it to set the background image at runtime with vanilla JavaScript like so:

  const meta = document.querySelector('[property="og:image"]');
  const body = document.querySelector("body"); = `url(${meta.content})`;

The above uses document.querySelector and Attribute Selectors to assign meta the first Open Graph image it selects. A similar task is performed to get the body. Finally, string interpolation is used to assign body the the value of the path to the Open Graph image.

If you want the image to cover the entire viewport and stay fixed set background-size like so: = `url(${meta.content}) center center no-repeat fixed`; = 'cover';

Using this approach you can set a low-quality background image placeholder using CSS and swap with a high-fidelity image later using an image onload event, thereby reducing perceived latency.

What is the use of DesiredCapabilities in Selenium WebDriver?

When you run selenium WebDriver, the WebDriver opens a remote server in your computer's local host. Now, this server, called the Selenium Server, is used to interpret your code into actions to run or "drive" the instance of a real browser known as either chromebrowser, ie broser, ff browser, etc.

So, the Selenium Server can interact with different browser properties and hence it has many "capabilities".

Now what capabilities do you desire? Consider a scenario where you are validating if files have been downloaded properly in your app but, however, you do not have a desktop automation tool. In the case where you click the download link and a desktop pop up shows up to ask where to save and/or if you want to download. Your next route to bypass that would be to suppress that pop up. How? Desired Capabilities.

There are other such examples. In summary, Selenium Server can do a lot, use Desired Capabilities to tailor it to your need.

How to generate a random alpha-numeric string

Java supplies a way of doing this directly. If you don't want the dashes, they are easy to strip out. Just use uuid.replace("-", "")

import java.util.UUID;

public class randomStringGenerator {
    public static void main(String[] args) {

    public static String generateString() {
        String uuid = UUID.randomUUID().toString();
        return "uuid = " + uuid;


uuid = 2d7428a6-b58c-4008-8575-f05549f16316

Finding local IP addresses using Python's stdlib

netifaces is available via pip and easy_install. (I know, it's not in base, but it could be worth the install.)

netifaces does have some oddities across platforms:

  • The localhost/loop-back interface may not always be included (Cygwin).
  • Addresses are listed per-protocol (e.g., IPv4, IPv6) and protocols are listed per-interface. On some systems (Linux) each protocol-interface pair has its own associated interface (using the interface_name:n notation) while on other systems (Windows) a single interface will have a list of addresses for each protocol. In both cases there is a protocol list, but it may contain only a single element.

Here's some netifaces code to play with:

import netifaces

PROTO = netifaces.AF_INET   # We want only IPv4, for now at least

# Get list of network interfaces
# Note: Can't filter for 'lo' here because Windows lacks it.
ifaces = netifaces.interfaces()

# Get all addresses (of all kinds) for each interface
if_addrs = [netifaces.ifaddresses(iface) for iface in ifaces]

# Filter for the desired address type
if_inet_addrs = [addr[PROTO] for addr in if_addrs if PROTO in addr]

iface_addrs = [s['addr'] for a in if_inet_addrs for s in a if 'addr' in s]
# Can filter for '' here.

The above code doesn't map an address back to its interface name (useful for generating ebtables/iptables rules on the fly). So here's a version that keeps the above information with the interface name in a tuple:

import netifaces

PROTO = netifaces.AF_INET   # We want only IPv4, for now at least

# Get list of network interfaces
ifaces = netifaces.interfaces()

# Get addresses for each interface
if_addrs = [(netifaces.ifaddresses(iface), iface) for iface in ifaces]

# Filter for only IPv4 addresses
if_inet_addrs = [(tup[0][PROTO], tup[1]) for tup in if_addrs if PROTO in tup[0]]

iface_addrs = [(s['addr'], tup[1]) for tup in if_inet_addrs for s in tup[0] if 'addr' in s]

And, no, I'm not in love with list comprehensions. It's just the way my brain works these days.

The following snippet will print it all out:

from __future__ import print_function  # For 2.x folks
from pprint import pprint as pp

print('\nifaces = ', end='')

print('\nif_addrs = ', end='')

print('\nif_inet_addrs = ', end='')

print('\niface_addrs = ', end='')


HTTP post XML data in C#

AlliterativeAlice's example helped me tremendously. In my case, though, the server I was talking to didn't like having single quotes around utf-8 in the content type. It failed with a generic "Server Error" and it took hours to figure out what it didn't like:

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

Store JSON object in data attribute in HTML jQuery

There's a better way of storing JSON in the HTML:


<script id="some-data" type="application/json">{"param_1": "Value 1", "param_2": "Value 2"}</script>



Trigger a keypress/keydown/keyup event in JS/jQuery?

First of all, I need to say that sample from Sionnach733 worked flawlessly. Some users complain about absent of actual examples. Here is my two cents. I've been working on mouse click simulation when using this site: You can open any video and try run this code. It performs switch to next video.

function triggerEvent(el, type, keyCode) {
    if ('createEvent' in document) {
            // modern browsers, IE9+
            var e = document.createEvent('HTMLEvents');
            e.keyCode = keyCode;
            e.initEvent(type, false, true);
    } else {
        // IE 8
        var e = document.createEventObject();
        e.keyCode = keyCode;
        e.eventType = type;
        el.fireEvent('on'+e.eventType, e);

var nextButton = document.getElementsByClassName('icon-player-next')[0];
triggerEvent(nextButton, 'keyup', 13); // simulate mouse/enter key press

Detecting negative numbers

I believe this is what you were looking for:

class Expression {
    protected $expression;
    protected $result;

    public function __construct($expression) {
        $this->expression = $expression;

    public function evaluate() {
        $this->result = eval("return ".$this->expression.";");
        return $this;

    public function getResult() {
        return $this->result;

class NegativeFinder {
    protected $expressionObj;

    public function __construct(Expression $expressionObj) {
        $this->expressionObj = $expressionObj;

    public function isItNegative() {
        $result = $this->expressionObj->evaluate()->getResult();

        if($this->hasMinusSign($result)) {
            return true;
        } else {
            return false;

    protected function hasMinusSign($value) {
        return (substr(strval($value), 0, 1) == "-");


$soldPrice = 1;
$boughtPrice = 2;
$negativeFinderObj = new NegativeFinder(new Expression("$soldPrice - $boughtPrice"));

echo ($negativeFinderObj->isItNegative()) ? "It is negative!" : "It is not negative :(";

Do however note that eval is a dangerous function, therefore use it only if you really, really need to find out if a number is negative.


How to find foreign key dependencies in SQL Server?

Because your question is geared towards a single table, you can use this:

EXEC sp_fkeys 'TableName'

I found it on SO here:

I found the information I needed pretty quickly. It lists the foreign key's table, column and name.


Here's a link to the documentation that details the different parameters that can be used:

YouTube iframe embed - full screen

Putting allowfullscreen inside iframe tag without setting it to true is already deprecated. The updated answer for this issue which is fullscreen is not available with embedded YouTube videos is to set allowfullscreen to true inside tag:

   src="URL here" 

Tested and working for all browsers without issues.

IIS URL Rewrite and Web.config

Just wanted to point out one thing missing in LazyOne's answer (I would have just commented under the answer but don't have enough rep)

In rule #2 for permanent redirect there is thing missing:


So rule #2 should look like this:

            <rule name="SpecificRedirect" stopProcessing="true">
                <match url="^page$" />
                <action type="Redirect" url="/page.html" redirectType="Permanent" />


For more information on how to use the URL Rewrite Module see this excellent documentation: URL Rewrite Module Configuration Reference

In response to @kneidels question from the comments; To match the url: topic.php?id=39 something like the following could be used:

      <rule name="SpecificRedirect" stopProcessing="true">
        <match url="^topic.php$" />
        <conditions logicalGrouping="MatchAll">
          <add input="{QUERY_STRING}" pattern="(?:id)=(\d{2})" />
        <action type="Redirect" url="/newpage/{C:1}" appendQueryString="false" redirectType="Permanent" />

This will match topic.php?id=ab where a is any number between 0-9 and b is also any number between 0-9. It will then redirect to /newpage/xy where xy comes from the original url. I have not tested this but it should work.

python inserting variable string as file name

Even better are f-strings in python 3!

f = open(f'{name}.csv', 'wb')

What is the difference between public, private, and protected?

For me, this is the most useful way to understand the three property types:

Public: Use this when you are OK with this variable being directly accessed and changed from anywhere in your code.

Example usage from outside of the class:

$myObject = new MyObject()
$myObject->publicVar = 'newvalue';
$pubVar = $myObject->publicVar;

Protected: Use this when you want to force other programmers (and yourself) to use getters/setters outside of the class when accessing and setting variables (but you should be consistent and use the getters and setters inside the class as well). This or private tend to be the default way you should set up all class properties.

Why? Because if you decide at some point in the future (maybe even in like 5 minutes) that you want to manipulate the value that is returned for that property or do something with it before getting/setting, you can do that without refactoring everywhere you have used it in your project.

Example usage from outside of the class:

$myObject = new MyObject()
$protectedVar = $myObject->getProtectedVar();

Private: private properties are very similar to protected properties. But the distinguishing feature/difference is that making it private also makes it inaccessible to child classes without using the parent class's getter or setter.

So basically, if you are using getters and setters for a property (or if it is used only internally by the parent class and it isn't meant to be accessible anywhere else) you might as well make it private, just to prevent anyone from trying to use it directly and introducing bugs.

Example usage inside a child class (that extends MyObject):

$privateVar = $this->getPrivateVar();

How to use PowerShell select-string to find more than one pattern in a file?

If you want to match the two words in either order, use:

gci C:\Logs| select-string -pattern '(VendorEnquiry.*Failed)|(Failed.*VendorEnquiry)'

If Failed always comes after VendorEnquiry on the line, just use:

gci C:\Logs| select-string -pattern '(VendorEnquiry.*Failed)'

Bootstrap 3 Gutter Size

Bootstrap 3 introduced row-no-gutters in v3.4.0

You could make a row without gutters, and have a row with gutters inside it for the parts you do want to have a gutter.

Remove all constraints affecting a UIView

In Swift:

import UIKit

extension UIView {

     Removes all constrains for this view
    func removeConstraints() {

        let constraints = self.superview?.constraints.filter{
            $0.firstItem as? UIView == self || $0.secondItem as? UIView == self
        } ?? []


How to scroll to top of the page in AngularJS?

You can use

$window.scrollTo(x, y);

where x is the pixel along the horizontal axis and y is the pixel along the vertical axis.

  1. Scroll to top

    $window.scrollTo(0, 0);
  2. Focus on element

    $window.scrollTo(0, angular.element('put here your element').offsetTop);   



Also you can use $anchorScroll


How to change the plot line color from blue to black?

The usual way to set the line color in matplotlib is to specify it in the plot command. This can either be done by a string after the data, e.g. "r-" for a red line, or by explicitely stating the color argument.

import matplotlib.pyplot as plt

plt.plot([1,2,3], [2,3,1], "r-") # red line
plt.plot([1,2,3], [5,5,3], color="blue") # blue line

See also the plot command's documentation.

In case you already have a line with a certain color, you can change that with the lines2D.set_color() method.

line, = plt.plot([1,2,3], [4,5,3], color="blue")

Setting the color of a line in a pandas plot is also best done at the point of creating the plot:

import matplotlib.pyplot as plt
import pandas as pd

df = pd.DataFrame({ "x" : [1,2,3,5], "y" : [3,5,2,6]})
df.plot("x", "y", color="r") #plot red line

If you want to change this color later on, you can do so by


This will get you the first (possibly the only) line of the current active axes.
In case you have more axes in the plot, you could loop through them

for ax in plt.gcf().axes:

and if you have more lines you can loop over them as well.

Specify sudo password for Ansible

Very simple, and only add in the variable file:


$ vim group_vars/all

And add these:

Ansible_connection: ssh
Ansible_ssh_user: rafael
Ansible_ssh_pass: password123
Ansible_become_pass: password123

Getting Error "Form submission canceled because the form is not connected"

A thing to look out for if you see this in React, is that the <form> still has to render in the DOM while it's submitting. i.e, this will fail

{ this.state.submitting ? 
     <div>Form is being submitted</div> :
     <form onSubmit={()=>this.setState({submitting: true}) ...>
         <button ...>

So when the form is submitted, state.submitting gets set and the "submitting..." message renders instead of the form, then this error happens.

Moving the form tag outside the conditional ensured that it was always there when needed, i.e.

<form onSubmit={...} ...>
  { this.state.submitting ? 
     <div>Form is being submitted</div> :
     <button ...>

What is the iOS 6 user agent string?

Some more:

Mozilla/5.0 (iPhone; CPU iPhone OS 6_1_3 like Mac OS X) AppleWebKit/536.26 (KHTML, like Gecko) Version/6.0 Mobile/10B329 Safari/8536.25

Mozilla/5.0 (iPhone; CPU iPhone OS 6_1_4 like Mac OS X) AppleWebKit/536.26 (KHTML, like Gecko) Version/6.0 Mobile/10B350 Safari/8536.25

Performing Breadth First Search recursively

Here is short Scala solution:

  def bfs(nodes: List[Node]): List[Node] = {
    if (nodes.nonEmpty) {
      nodes ++ bfs(nodes.flatMap(_.children))
    } else {

Idea of using return value as accumulator is well suited. Can be implemented in other languages in similar way, just make sure that your recursive function process list of nodes.

Test code listing (using @marco test tree):

import org.scalatest.FlatSpec

import scala.collection.mutable

class Node(val value: Int) {

  private val _children: mutable.ArrayBuffer[Node] = mutable.ArrayBuffer.empty

  def add(child: Node): Unit = _children += child

  def children = _children.toList

  override def toString: String = s"$value"

class BfsTestScala extends FlatSpec {

  //            1
  //          / | \
  //        2   3   4
  //      / |       | \
  //    5   6       7  8
  //  / |           | \
  // 9  10         11  12
  def tree(): Node = {
    val root = new Node(1)
    root.add(new Node(2))
    root.add(new Node(3))
    root.add(new Node(4))
    root.children(0).add(new Node(5))
    root.children(0).add(new Node(6))
    root.children(2).add(new Node(7))
    root.children(2).add(new Node(8))
    root.children(0).children(0).add(new Node(9))
    root.children(0).children(0).add(new Node(10))
    root.children(2).children(0).add(new Node(11))
    root.children(2).children(0).add(new Node(12))

  def bfs(nodes: List[Node]): List[Node] = {
    if (nodes.nonEmpty) {
      nodes ++ bfs(nodes.flatMap(_.children))
    } else {

  "BFS" should "work" in {


List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)

warning: assignment makes integer from pointer without a cast

The warning comes from the fact that you're dereferencing src in the assignment. The expression *src has type char, which is an integral type. The expression "anotherstring" has type char [14], which in this particular context is implicitly converted to type char *, and its value is the address of the first character in the array. So, you wind up trying to assign a pointer value to an integral type, hence the warning. Drop the * from *src, and it should work as expected:

src = "anotherstring";

since the type of src is char *.

Losing scope when using ng-include

As @Renan mentioned, ng-include creates a new child scope. This scope prototypically inherits (see dashed lines below) from the HomeCtrl scope. ng-model="lineText" actually creates a primitive scope property on the child scope, not HomeCtrl's scope. This child scope is not accessible to the parent/HomeCtrl scope:

ng-include scope

To store what the user typed into HomeCtrl's $scope.lines array, I suggest you pass the value to the addLine function:

 <form ng-submit="addLine(lineText)">

In addition, since lineText is owned by the ngInclude scope/partial, I feel it should be responsible for clearing it:

 <form ng-submit="addLine(lineText); lineText=''">

Function addLine() would thus become:

$scope.addLine = function(lineText) {
        text: lineText



  • define an object property on HomeCtrl's $scope, and use that in the partial: ng-model="someObj.lineText; fiddle
  • not recommended, this is more of a hack: use $parent in the partial to create/access a lineText property on the HomeCtrl $scope:  ng-model="$parent.lineText"; fiddle

It is a bit involved to explain why the above two alternatives work, but it is fully explained here: What are the nuances of scope prototypal / prototypical inheritance in AngularJS?

I don't recommend using this in the addLine() function. It becomes much less clear which scope is being accessed/manipulated.

How to retry after exception?

I prefer to limit the number of retries, so that if there's a problem with that specific item you will eventually continue onto the next one, thus:

for i in range(100):
  for attempt in range(10):
      # do thing
      # perhaps reconnect, etc.
    # we failed all the attempts - deal with the consequences.

R plot: size and resolution

A reproducible example:

the_plot <- function()
  x <- seq(0, 1, length.out = 100)
  y <- pbeta(x, 1, 10)
    xlab = "False Positive Rate",
    ylab = "Average true positive rate",
    type = "l"

James's suggestion of using pointsize, in combination with the various cex parameters, can produce reasonable results.

  width     = 3.25,
  height    = 3.25,
  units     = "in",
  res       = 1200,
  pointsize = 4
  mar      = c(5, 5, 2, 2),
  xaxs     = "i",
  yaxs     = "i",
  cex.axis = 2,
  cex.lab  = 2

Of course the better solution is to abandon this fiddling with base graphics and use a system that will handle the resolution scaling for you. For example,


ggplot_alternative <- function()
  the_data <- data.frame(
    x <- seq(0, 1, length.out = 100),
    y = pbeta(x, 1, 10)

ggplot(the_data, aes(x, y)) +
    geom_line() +
    xlab("False Positive Rate") +
    ylab("Average true positive rate") +
    coord_cartesian(0:1, 0:1)

  width = 3.25,
  height = 3.25,
  dpi = 1200

jQuery to remove an option from drop down list, given option's text/value

I have used the above option to .hide entries from 2 drops down boxes (first you select the city, then you selected the area within that city). It works fine on screen but the hidden options are still selectable via keyboard inputs.

converting a base 64 string to an image and saving it

Here is what I ended up going with.

    private void SaveByteArrayAsImage(string fullOutputPath, string base64String)
        byte[] bytes = Convert.FromBase64String(base64String);

        Image image;
        using (MemoryStream ms = new MemoryStream(bytes))
            image = Image.FromStream(ms);

        image.Save(fullOutputPath, System.Drawing.Imaging.ImageFormat.Png);

How to get the fields in an Object via reflection?

Here's a quick and dirty method that does what you want in a generic way. You'll need to add exception handling and you'll probably want to cache the BeanInfo types in a weakhashmap.

public Map<String, Object> getNonNullProperties(final Object thingy) {
    final Map<String, Object> nonNullProperties = new TreeMap<String, Object>();
    try {
        final BeanInfo beanInfo = Introspector.getBeanInfo(thingy
        for (final PropertyDescriptor descriptor : beanInfo
                .getPropertyDescriptors()) {
            try {
                final Object propertyValue = descriptor.getReadMethod()
                if (propertyValue != null) {
            } catch (final IllegalArgumentException e) {
                // handle this please
            } catch (final IllegalAccessException e) {
                // and this also
            } catch (final InvocationTargetException e) {
                // and this, too
    } catch (final IntrospectionException e) {
        // do something sensible here
    return nonNullProperties;

See these references:

Open a URL without using a browser from a batch file

You can use the HH command to open any website.

hh <http://url>

For example,


Though it will not open the website in the browser, but this will open the website in an HTML help window.

Convert categorical data in pandas dataframe

One of the simplest ways to convert the categorical variable into dummy/indicator variables is to use get_dummies provided by pandas. Say for example we have data in which sex is a categorical value (male & female) and you need to convert it into a dummy/indicator here is how to do it.

tranning_data = pd.read_csv("../titanic/train.csv")
features = ["Age", "Sex", ] //here sex is catagorical value
X_train = pd.get_dummies(tranning_data[features])

Age Sex_female Sex_male
20    0          1
33    1          0
40    1          0
22    1          0
54    0          1

Side-by-side list items as icons within a div (css)

I would recommend that you use display: inline;. float is screwed up in IE. Here is an example of how I would approach it:

<ul class="side-by-side">
  <li>item 1<li>
  <li>item 2<li>
  <li>item 3<li>

and here's the css:

.side-by-side {
  width: 100%;
  border: 1px solid black;

.side-by-side li {
  display: inline;

Also, if you use floats the ul will not wrap around the li's and will instead have a hight of 0 in this example:

.side-by-side li {
  float: left;

Difference between -XX:+UseParallelGC and -XX:+UseParNewGC

Parallel GC

  • XX:+UseParallelGC Use parallel garbage collection for scavenges. (Introduced in 1.4.1)
  • XX:+UseParallelOldGC Use parallel garbage collection for the full collections. Enabling this option automatically sets -XX:+UseParallelGC. (Introduced in 5.0 update 6.)


UseParNewGC A parallel version of the young generation copying collector is used with the concurrent collector (i.e. if -XX:+ UseConcMarkSweepGC is used on the command line then the flag UseParNewGC is also set to true if it is not otherwise explicitly set on the command line).

Perhaps the easiest way to understand was combinations of garbage collection algorithms made by Alexey Ragozin

<table border="1" style="width:100%">_x000D_
    <td align="center">Young collector</td>_x000D_
    <td align="center">Old collector</td>_x000D_
    <td align="center">JVM option</td>_x000D_
    <td>Serial (DefNew)</td>_x000D_
    <td>Serial Mark-Sweep-Compact</td>_x000D_
    <td>Parallel scavenge (PSYoungGen)</td>_x000D_
    <td>Serial Mark-Sweep-Compact (PSOldGen)</td>_x000D_
    <td>Parallel scavenge (PSYoungGen)</td>_x000D_
    <td>Parallel Mark-Sweep-Compact (ParOldGen)</td>_x000D_
    <td>Serial (DefNew)</td>_x000D_
    <td>Concurrent Mark Sweep</td>_x000D_
    <td>Parallel (ParNew)</td>_x000D_
    <td>Concurrent Mark Sweep</td>_x000D_
    <td colspan="2">G1</td>_x000D_


  1. Apply -XX:+UseParallelGC when you require parallel collection method over YOUNG generation ONLY, (but still) use serial-mark-sweep method as OLD generation collection
  2. Apply -XX:+UseParallelOldGC when you require parallel collection method over YOUNG generation (automatically sets -XX:+UseParallelGC) AND OLD generation collection
  3. Apply -XX:+UseParNewGC & -XX:+UseConcMarkSweepGC when you require parallel collection method over YOUNG generation AND require CMS method as your collection over OLD generation memory
  4. You can't apply -XX:+UseParallelGC or -XX:+UseParallelOldGC with -XX:+UseConcMarkSweepGC simultaneously, that's why your require -XX:+UseParNewGC to be paired with CMS otherwise use -XX:+UseSerialGC explicitly OR -XX:-UseParNewGC if you wish to use serial method against young generation

How can I change image source on click with jQuery?

It switches back because by default, when you click a link, it follows the link and loads the page. In your case, you don't want that. You can prevent it either by doing e.preventDefault(); (like Neal mentioned) or by returning false :

$(function() {
   return false;

Interesting question on the differences between prevent default and return false.

In this case, return false will work just fine because the event doesn't need to be propagated.

How do you convert between 12 hour time and 24 hour time in PHP?

// 24-hour time to 12-hour time 
$time_in_12_hour_format  = date("g:i a", strtotime("13:30"));

// 12-hour time to 24-hour time 
$time_in_24_hour_format  = date("H:i", strtotime("1:30 PM"));

Access-Control-Allow-Origin error sending a jQuery Post to Google API's

There is a little hack with php. And it works not only with Google, but with any website you don't control and can't add Access-Control-Allow-Origin *

We need to create PHP-file (ex. getContentFromUrl.php) on our webserver and make a little trick.



$ext_url = $_POST['ext_url'];

echo file_get_contents($ext_url);



    method: 'POST',
    url: 'getContentFromUrl.php', // link to your PHP file
    data: {
        // url where our server will send request which can't be done by AJAX
        'ext_url': ''
    success: function(data) {
        // we can find any data on external url, cause we've got all page
        var $h1 = $(data).find('h1').html();

    error:function() {

How it works:

  1. Your browser with the help of JS will send request to your server
  2. Your server will send request to any other server and get reply from another server (any website)
  3. Your server will send this reply to your JS

And we can make events onClick, put this event on some button. Hope this will help!

How can I prevent the TypeError: list indices must be integers, not tuple when copying a python list to a numpy array?

Just if someone is having this issue and hadn't done list[index, sub-index], you could be having the problem because you're missing a comma between two arrays in an array of arrays (It happened to me).

declaring a priority_queue in c++ with a custom comparator

One can also use a lambda function.

auto Compare = [](Node &a, Node &b) { //compare };
std::priority_queue<Node, std::vector<Node>, decltype(Compare)> openset(Compare);

CMake is not able to find BOOST libraries

I'm using this to set up boost from cmake in my CMakeLists.txt. Try something similar (make sure to update paths to your installation of boost).

SET (BOOST_ROOT "/opt/boost/boost_1_57_0")
SET (BOOST_INCLUDEDIR "/opt/boost/boost-1.57.0/include")
SET (BOOST_LIBRARYDIR "/opt/boost/boost-1.57.0/lib")

if (NOT Boost_FOUND)
  message(FATAL_ERROR "Fatal error: Boost (version >= 1.55) required.")
  message(STATUS "Setting up BOOST")
  message(STATUS " Includes - ${Boost_INCLUDE_DIRS}")
  message(STATUS " Library  - ${Boost_LIBRARY_DIRS}")
endif (NOT Boost_FOUND)

This will either search default paths (/usr, /usr/local) or the path provided through the cmake variables (BOOST_ROOT, BOOST_INCLUDEDIR, BOOST_LIBRARYDIR). It works for me on cmake > 2.6.

Read Post Data submitted to ASP.Net Form

if (!string.IsNullOrEmpty(Request.Form["username"])) { ... }

username is the name of the input on the submitting page. The password can be obtained the same way. If its not null or empty, it exists, then log in the user (I don't recall the exact steps for ASP.NET Membership, assuming that's what you're using).

How to locate the php.ini file (xampp)

as KingCrunch pointed out, using phpinfo you can see what config file is in action in the "Loaded Configuration File" row. in my case in was in C:\xampp\apache\bin note that there is a php.ini also in C:\xampp\php which seems to be redundant and irrelevant

Date query with ISODate in mongodb doesn't seem to work

Although $date is a part of MongoDB Extended JSON and that's what you get as default with mongoexport I don't think you can really use it as a part of the query.

If try exact search with $date like below:{dt: {"$date": "2012-01-01T15:00:00.000Z"}})

you'll get error:

error: { "$err" : "invalid operator: $date", "code" : 10068 }

Try this:

    "dt" : {"$gte": new Date("2013-10-01T00:00:00.000Z")}

or (following comments by @user3805045):

    "dt" : {"$gte": ISODate("2013-10-01T00:00:00.000Z")}

ISODate may be also required to compare dates without time (noted by @MattMolnar).

According to Data Types in the mongo Shell both should be equivalent:

The mongo shell provides various methods to return the date, either as a string or as a Date object:

  • Date() method which returns the current date as a string.
  • new Date() constructor which returns a Date object using the ISODate() wrapper.
  • ISODate() constructor which returns a Date object using the ISODate() wrapper.

and using ISODate should still return a Date object.

{"$date": "ISO-8601 string"} can be used when strict JSON representation is required. One possible example is Hadoop connector.

get specific row from spark dataframe

This Works for me in PySpark"column").collect()[0][0]

How to escape double quotes in JSON

When and where to use \\\" instead. OK if you are like me you will feel just as silly as I did when I realized what I was doing after I found this thread.

If you're making a .json text file/stream and importing the data from there then the main stream answer of just one backslash before the double quotes:\" is the one you're looking for.

However if you're like me and you're trying to get the "Tryit Editor" to have a double quotes in the output of the JSON.parse(text), then the one you're looking for is the triple backslash double quotes \\\". This is because you're building your text string within an HTML <script> block, and the first double backslash inserts a single backslash into the string variable then the following backslash double quote inserts the double quote into the string so that the resulting script string contains the \" from the standard answer and the JSON parser will parse this as just the double quotes.

  var text="{";
  text += '"quip":"\\\"If nobody is listening, then you\'re likely talking to the wrong audience.\\\""';
  text += "}";
  var obj=JSON.parse(text);

+1: since it's a JavaScript text string, a double backslash double quote \\" would work too; because the double quote does not need escaped within a single quoted string eg '\"' and '"' result in the same JS string.

Jenkins - how to build a specific branch

enter image description here

There will be an option in configure under Build Triggers

Check the GitHub Branches

A hook will be created and then you can build any branch you like from Jenkins when you select github Branches enter image description here

Hope it helps :)

plain count up timer in javascript

Check this:

var minutesLabel = document.getElementById("minutes");_x000D_
var secondsLabel = document.getElementById("seconds");_x000D_
var totalSeconds = 0;_x000D_
setInterval(setTime, 1000);_x000D_
function setTime() {_x000D_
  secondsLabel.innerHTML = pad(totalSeconds % 60);_x000D_
  minutesLabel.innerHTML = pad(parseInt(totalSeconds / 60));_x000D_
function pad(val) {_x000D_
  var valString = val + "";_x000D_
  if (valString.length < 2) {_x000D_
    return "0" + valString;_x000D_
  } else {_x000D_
    return valString;_x000D_
<label id="minutes">00</label>:<label id="seconds">00</label>

Get key from a HashMap using the value

You have it reversed. The 100 should be the first parameter (it's the key) and the "one" should be the second parameter (it's the value).

Read the javadoc for HashMap and that might help you: HashMap

To get the value, use hashmap.get(100).

How to fix Subversion lock error

Subversion supports a command named "Cleanup"; it is used to release the locks on a projectenter image description here

How can I get npm start at a different directory?

I came here from google so it might be relevant to others: for yarn you could use:

yarn --cwd /path/to/your/app run start 

How to select an element inside "this" in jQuery?

$( this ).find( '' ).css("border", "3px double red");


$( this ).children( '' ).css("border", "3px double red");

Use children for immediate descendants, or find for deeper elements.

C#: How to access an Excel cell?

If you are trying to automate Excel, you probably shouldn't be opening a Word document and using the Word automation ;)

Check this out, it should get you started,

And here is some code. It is taken from some of my code and has a lot of stuff deleted, so it doesn't do anything and may not compile or work exactly, but it should get you going. It is oriented toward reading, but should point you in the right direction.

Microsoft.Office.Interop.Excel.Worksheet sheet = newWorkbook.ActiveSheet;

if ( sheet != null )
    Microsoft.Office.Interop.Excel.Range range = sheet.UsedRange;
    if ( range != null )
        int nRows = usedRange.Rows.Count;
        int nCols = usedRange.Columns.Count;
        foreach ( Microsoft.Office.Interop.Excel.Range row in usedRange.Rows )
            string value = row.Cells[0].FormattedValue as string;

You can also do

Microsoft.Office.Interop.Excel.Sheets sheets = newWorkbook.ExcelSheets;

if ( sheets != null )
     foreach ( Microsoft.Office.Interop.Excel.Worksheet sheet in sheets )
          // Do Stuff

And if you need to insert rows/columns

// Inserts a new row at the beginning of the sheet
Microsoft.Office.Interop.Excel.Range a1 = sheet.get_Range( "A1", Type.Missing );
a1.EntireRow.Insert( Microsoft.Office.Interop.Excel.XlInsertShiftDirection.xlShiftDown, Type.Missing );

Git: How to find a deleted file in the project commit history?

Get a list of the deleted files and copy the full path of the deleted file

git log --diff-filter=D --summary | grep delete

Execute the next command to find commit id of that commit and copy the commit id

git log --all -- FILEPATH

Show diff of deleted file


Remember, you can write output to a file using > like

git show COMMIT_ID -- FILE_PATH > deleted.diff

PostgreSQL function for last inserted ID

Try this:

select nextval('my_seq_name');  // Returns next value

If this return 1 (or whatever is the start_value for your sequence), then reset the sequence back to the original value, passing the false flag:

select setval('my_seq_name', 1, false);


select setval('my_seq_name', nextValue - 1, true);

This will restore the sequence value to the original state and "setval" will return with the sequence value you are looking for.

How to make div background color transparent in CSS

Opacity gives you translucency or transparency. See an example Fiddle here.

-ms-filter: "progid:DXImageTransform.Microsoft.Alpha(Opacity=50)";       /* IE 8 */
filter: alpha(opacity=50);  /* IE 5-7 */
-moz-opacity: 0.5;          /* Netscape */
-khtml-opacity: 0.5;        /* Safari 1.x */
opacity: 0.5;               /* Good browsers */

Note: these are NOT CSS3 properties


Generate random numbers following a normal distribution in C/C++

Here's a C++ example, based on some of the references. This is quick and dirty, you are better off not re-inventing and using the boost library.

#include "math.h" // for RAND, and rand
double sampleNormal() {
    double u = ((double) rand() / (RAND_MAX)) * 2 - 1;
    double v = ((double) rand() / (RAND_MAX)) * 2 - 1;
    double r = u * u + v * v;
    if (r == 0 || r > 1) return sampleNormal();
    double c = sqrt(-2 * log(r) / r);
    return u * c;

You can use a Q-Q plot to examine the results and see how well it approximates a real normal distribution (rank your samples 1..x, turn the ranks into proportions of total count of x ie. how many samples, get the z-values and plot them. An upwards straight line is the desired result).

How to create windows service from java jar?

I've been experimenting with Apache Commons Daemon. It's supports windows (Procrun) and unix (Jsvc). Advanced Installer has a Java Service tutorial with an example project to download. If you get their javaservice.jar running as a windows service you can test it by using "telnet 4444". I used their example because my focus was on getting a java windows service running, not writing java.

Why am I getting "(304) Not Modified" error on some links when using HttpWebRequest?

I think you have not installed these features. see below in picture.

enter image description here

I also suffered from this problem some days ago. After installing this feature then I solved it. If you have not installed this feature then installed it.

Install Process:

  1. go to android studio
  2. Tools
  3. Android
  4. SDK Manager
  5. Appearance & Behavior
  6. Android SDK

Tree view of a directory/folder in Windows?

In the Windows command prompt you can use "tree /F" to view a tree of the current folder and all descending files & folders.

In File Explorer under Windows 8.1:

  • Select folder
  • Press Shift, right-click mouse, and select "Open command window here"
  • Type tree /f > tree.txt and press Enter
  • Use MS Word to open "tree.txt"
  • The dialog box "File Conversion - tree.txt" will open
  • For "Text encoding" tick the "MS-DOS" option

You now have an editable tree structure file.

This works for versions of Windows from Windows XP to Windows 8.1.


There's no need for "else" in this case:

IF EXISTS(SELECT *  FROM  table1  WHERE Name='John' ) return 1
return 0

SQL - How to find the highest number in a column?

If you're talking MS SQL, here's the most efficient way. This retrieves the current identity seed from a table based on whatever column is the identity.

select IDENT_CURRENT('TableName') as LastIdentity

Using MAX(id) is more generic, but for example I have an table with 400 million rows that takes 2 minutes to get the MAX(id). IDENT_CURRENT is nearly instantaneous...

What does principal end of an association means in 1:1 relationship in Entity framework

You can also use the [Required] data annotation attribute to solve this:

public class Foo
    public string FooId { get; set; }

    public Boo Boo { get; set; }

public class Boo
    public string BooId { get; set; }

    public Foo Foo {get; set; }

Foo is required for Boo.

How to call base.base.method()?

In cases where you do not have access to the derived class source, but need all the source of the derived class besides the current method, then I would recommended you should also do a derived class and call the implementation of the derived class.

Here is an example:

//No access to the source of the following classes
public class Base
     public virtual void method1(){ Console.WriteLine("In Base");}
public class Derived : Base
     public override void method1(){ Console.WriteLine("In Derived");}
     public void method2(){ Console.WriteLine("Some important method in Derived");}

//Here should go your classes
//First do your own derived class
public class MyDerived : Base

//Then derive from the derived class 
//and call the bass class implementation via your derived class
public class specialDerived : Derived
     public override void method1()
          MyDerived md = new MyDerived();
          //This is actually the base.base class implementation

std::string to float or double

As to why atof() isn't working in the original question: the fact that it's cast to double makes me suspicious. The code shouldn't compile without #include <stdlib.h>, but if the cast was added to solve a compile warning, then atof() is not correctly declared. If the compiler assumes atof() returns an int, casting it will solve the conversion warning, but it will not cause the return value to be recognized as a double.

#include <stdlib.h>
#include <string>

  std::string num = "0.6";
  double temp = atof(num.c_str());

should work without warnings.

SQL 'LIKE' query using '%' where the search criteria contains '%'

The easiest solution is to dispense with "like" altogether:

Select * 
from table
where charindex(search_criteria, name) > 0

I prefer charindex over like. Historically, it had better performance, but I'm not sure if it makes much of difference now.

CR LF notepad++ removal

Please find the below screenshot

enter image description here

enter image description here

How can I ping a server port with PHP?

socket_create needs to be run as root on a UNIX system with;

$socket = socket_create(AF_UNIX, SOCK_STREAM, 0);

How to convert comma separated string into numeric array in javascript

You can use split() to get string array from comma separated string. If you iterate and perform mathematical operation on element of string array then that element will be treated as number by run-time cast but still you have string array. To convert comma separated string int array see the edit.

arr = strVale.split(',');

Live Demo

var strVale = "130,235,342,124";
arr = strVale.split(',');
for(i=0; i < arr.length; i++)
    console.log(arr[i] + " * 2 = " + (arr[i])*2);


130 * 2 = 260
235 * 2 = 470
342 * 2 = 684
124 * 2 = 248

Edit, Comma separated string to int Array In the above example the string are casted to numbers in expression but to get the int array from string array you need to convert it to number.

var strVale = "130,235,342,124";
var strArr = strVale.split(',');
var intArr = [];
for(i=0; i < strArr.length; i++)

SQL Server - Return value after INSERT

The best and most sure solution is using SCOPE_IDENTITY().

Just you have to get the scope identity after every insert and save it in a variable because you can call two insert in the same scope.

ident_current and @@identity may be they work but they are not safe scope. You can have issues in a big application

  declare @duplicataId int
  select @duplicataId =   (SELECT SCOPE_IDENTITY())

More detail is here Microsoft docs

Resize UIImage and change the size of UIImageView

This is the Swift equivalent for Rajneesh071's answer, using extensions

UIImage {
  func scaleToSize(aSize :CGSize) -> UIImage {
    if (CGSizeEqualToSize(self.size, aSize)) {
      return self

    UIGraphicsBeginImageContextWithOptions(aSize, false, 0.0)
    self.drawInRect(CGRectMake(0.0, 0.0, aSize.width, aSize.height))
    let image = UIGraphicsGetImageFromCurrentImageContext()
    return image


let image = UIImage(named: "Icon")
item.icon = image?.scaleToSize(CGSize(width: 30.0, height: 30.0))

Why does the PHP json_encode function convert UTF-8 strings to hexadecimal entities?

Is this the expected behavior?

the json_encode() only works with UTF-8 encoded data.

maybe you can get an answer to convert it here: cyrillic-characters-in-phps-json-encode

How often should you use git-gc?

You don't have to use git gc very often, because git gc (Garbage collection) is run automatically on several frequently used commands:

git pull
git merge
git rebase
git commit

Source: git gc best practices and FAQS

Random / noise functions for GLSL

There is also a nice implementation described here by McEwan and @StefanGustavson that looks like Perlin noise, but "does not require any setup, i.e. not textures nor uniform arrays. Just add it to your shader source code and call it wherever you want".

That's very handy, especially given that Gustavson's earlier implementation, which @dep linked to, uses a 1D texture, which is not supported in GLSL ES (the shader language of WebGL).

How to hide underbar in EditText

Programmatically use : editText.setBackground(null)

From xml use: android:background="@null"

How to get input text value on click in ReactJS

There are two ways to go about doing this.

  1. Create a state in the constructor that contains the text input. Attach an onChange event to the input box that updates state each time. Then onClick you could just alert the state object.

  2. handleClick: function() { alert(this.refs.myInput.value); },

response.sendRedirect() from Servlet to JSP does not seem to work

You can use this:

response.sendRedirect(String.format("%s%s", request.getContextPath(), "/views/equipment/createEquipment.jsp"));

The last part is your path in your web-app

Error type 3 Error: Activity class {} does not exist

After all these solve suggestions i still had not solved my this problem. And then i remembered my phone has 2 ANDROID User Interface. One of them is using in casual, another is private things of yours. When i download my projects to phone, downloads both of them. I deleted my project in casual one but had not private one. Everything works fine when i delete the private one. So If you have 2 android ui, you should delete all of them and download again.

'uint32_t' does not name a type

just navigate to /usr/include/x86_64-linux-gnu/bits open stdint-uintn.h and add these lines

typedef __uint8_t uint8_t;
typedef __uint16_t uint16_t;
typedef __uint32_t uint32_t;
typedef __uint64_t uint64_t;

again open stdint-intn.h and add

typedef __int8_t int8_t;
typedef __int16_t int16_t;
typedef __int32_t int32_t;
typedef __int64_t int64_t;

note these lines are already present just copy and add the missing lines cheerss..