Programs & Examples On #Arabic

The Arabic tag is for issues relating to displaying user interfaces and managing data in Arabic written language.

HTML - Arabic Support

Won't you need the ensure the area where you display the Arabic is Right-to-Left orientated also?


<p dir="rtl">

Filtering array of objects with lodash based on property value

let myArr = [_x000D_
    { name: "john", age: 23 },_x000D_
    { name: "john", age: 43 },_x000D_
    { name: "jim", age: 101 },_x000D_
    { name: "bob", age: 67 },_x000D_
let list = _.filter(myArr, item => === "john");

Send File Attachment from Form Using phpMailer and PHP

In my own case, i was using serialize() on the form, Hence the files were not being sent to php. If you are using jquery, use FormData(). For example

<form id='form'>
<input type='file' name='file' />
<input type='submit' />

Using jquery,

$('#form').submit(function (e) {
var formData = new FormData(this); // grab all form contents including files
//you can then use formData and pass to ajax


Best practice for REST token-based authentication with JAX-RS and Jersey

How token-based authentication works

In token-based authentication, the client exchanges hard credentials (such as username and password) for a piece of data called token. For each request, instead of sending the hard credentials, the client will send the token to the server to perform authentication and then authorization.

In a few words, an authentication scheme based on tokens follow these steps:

  1. The client sends their credentials (username and password) to the server.
  2. The server authenticates the credentials and, if they are valid, generate a token for the user.
  3. The server stores the previously generated token in some storage along with the user identifier and an expiration date.
  4. The server sends the generated token to the client.
  5. The client sends the token to the server in each request.
  6. The server, in each request, extracts the token from the incoming request. With the token, the server looks up the user details to perform authentication.
    • If the token is valid, the server accepts the request.
    • If the token is invalid, the server refuses the request.
  7. Once the authentication has been performed, the server performs authorization.
  8. The server can provide an endpoint to refresh tokens.

Note: The step 3 is not required if the server has issued a signed token (such as JWT, which allows you to perform stateless authentication).

What you can do with JAX-RS 2.0 (Jersey, RESTEasy and Apache CXF)

This solution uses only the JAX-RS 2.0 API, avoiding any vendor specific solution. So, it should work with JAX-RS 2.0 implementations, such as Jersey, RESTEasy and Apache CXF.

It is worthwhile to mention that if you are using token-based authentication, you are not relying on the standard Java EE web application security mechanisms offered by the servlet container and configurable via application's web.xml descriptor. It's a custom authentication.

Authenticating a user with their username and password and issuing a token

Create a JAX-RS resource method which receives and validates the credentials (username and password) and issue a token for the user:

public class AuthenticationEndpoint {

    public Response authenticateUser(@FormParam("username") String username, 
                                     @FormParam("password") String password) {

        try {

            // Authenticate the user using the credentials provided
            authenticate(username, password);

            // Issue a token for the user
            String token = issueToken(username);

            // Return the token on the response
            return Response.ok(token).build();

        } catch (Exception e) {
            return Response.status(Response.Status.FORBIDDEN).build();

    private void authenticate(String username, String password) throws Exception {
        // Authenticate against a database, LDAP, file or whatever
        // Throw an Exception if the credentials are invalid

    private String issueToken(String username) {
        // Issue a token (can be a random String persisted to a database or a JWT token)
        // The issued token must be associated to a user
        // Return the issued token

If any exceptions are thrown when validating the credentials, a response with the status 403 (Forbidden) will be returned.

If the credentials are successfully validated, a response with the status 200 (OK) will be returned and the issued token will be sent to the client in the response payload. The client must send the token to the server in every request.

When consuming application/x-www-form-urlencoded, the client must to send the credentials in the following format in the request payload:


Instead of form params, it's possible to wrap the username and the password into a class:

public class Credentials implements Serializable {

    private String username;
    private String password;

    // Getters and setters omitted

And then consume it as JSON:

public Response authenticateUser(Credentials credentials) {

    String username = credentials.getUsername();
    String password = credentials.getPassword();

    // Authenticate the user, issue a token and return a response

Using this approach, the client must to send the credentials in the following format in the payload of the request:

  "username": "admin",
  "password": "123456"

Extracting the token from the request and validating it

The client should send the token in the standard HTTP Authorization header of the request. For example:

Authorization: Bearer <token-goes-here>

The name of the standard HTTP header is unfortunate because it carries authentication information, not authorization. However, it's the standard HTTP header for sending credentials to the server.

JAX-RS provides @NameBinding, a meta-annotation used to create other annotations to bind filters and interceptors to resource classes and methods. Define a @Secured annotation as following:

@Target({TYPE, METHOD})
public @interface Secured { }

The above defined name-binding annotation will be used to decorate a filter class, which implements ContainerRequestFilter, allowing you to intercept the request before it be handled by a resource method. The ContainerRequestContext can be used to access the HTTP request headers and then extract the token:

public class AuthenticationFilter implements ContainerRequestFilter {

    private static final String REALM = "example";
    private static final String AUTHENTICATION_SCHEME = "Bearer";

    public void filter(ContainerRequestContext requestContext) throws IOException {

        // Get the Authorization header from the request
        String authorizationHeader =

        // Validate the Authorization header
        if (!isTokenBasedAuthentication(authorizationHeader)) {

        // Extract the token from the Authorization header
        String token = authorizationHeader

        try {

            // Validate the token

        } catch (Exception e) {

    private boolean isTokenBasedAuthentication(String authorizationHeader) {

        // Check if the Authorization header is valid
        // It must not be null and must be prefixed with "Bearer" plus a whitespace
        // The authentication scheme comparison must be case-insensitive
        return authorizationHeader != null && authorizationHeader.toLowerCase()
                    .startsWith(AUTHENTICATION_SCHEME.toLowerCase() + " ");

    private void abortWithUnauthorized(ContainerRequestContext requestContext) {

        // Abort the filter chain with a 401 status code response
        // The WWW-Authenticate header is sent along with the response
                                AUTHENTICATION_SCHEME + " realm=\"" + REALM + "\"")

    private void validateToken(String token) throws Exception {
        // Check if the token was issued by the server and if it's not expired
        // Throw an Exception if the token is invalid

If any problems happen during the token validation, a response with the status 401 (Unauthorized) will be returned. Otherwise the request will proceed to a resource method.

Securing your REST endpoints

To bind the authentication filter to resource methods or resource classes, annotate them with the @Secured annotation created above. For the methods and/or classes that are annotated, the filter will be executed. It means that such endpoints will only be reached if the request is performed with a valid token.

If some methods or classes do not need authentication, simply do not annotate them:

public class ExampleResource {

    public Response myUnsecuredMethod(@PathParam("id") Long id) {
        // This method is not annotated with @Secured
        // The authentication filter won't be executed before invoking this method

    public Response mySecuredMethod(@PathParam("id") Long id) {
        // This method is annotated with @Secured
        // The authentication filter will be executed before invoking this method
        // The HTTP request must be performed with a valid token

In the example shown above, the filter will be executed only for the mySecuredMethod(Long) method because it's annotated with @Secured.

Identifying the current user

It's very likely that you will need to know the user who is performing the request agains your REST API. The following approaches can be used to achieve it:

Overriding the security context of the current request

Within your ContainerRequestFilter.filter(ContainerRequestContext) method, a new SecurityContext instance can be set for the current request. Then override the SecurityContext.getUserPrincipal(), returning a Principal instance:

final SecurityContext currentSecurityContext = requestContext.getSecurityContext();
requestContext.setSecurityContext(new SecurityContext() {

        public Principal getUserPrincipal() {
            return () -> username;

    public boolean isUserInRole(String role) {
        return true;

    public boolean isSecure() {
        return currentSecurityContext.isSecure();

    public String getAuthenticationScheme() {

Use the token to look up the user identifier (username), which will be the Principal's name.

Inject the SecurityContext in any JAX-RS resource class:

SecurityContext securityContext;

The same can be done in a JAX-RS resource method:

public Response myMethod(@PathParam("id") Long id, 
                         @Context SecurityContext securityContext) {

And then get the Principal:

Principal principal = securityContext.getUserPrincipal();
String username = principal.getName();

Using CDI (Context and Dependency Injection)

If, for some reason, you don't want to override the SecurityContext, you can use CDI (Context and Dependency Injection), which provides useful features such as events and producers.

Create a CDI qualifier:

public @interface AuthenticatedUser { }

In your AuthenticationFilter created above, inject an Event annotated with @AuthenticatedUser:

Event<String> userAuthenticatedEvent;

If the authentication succeeds, fire the event passing the username as parameter (remember, the token is issued for a user and the token will be used to look up the user identifier):;

It's very likely that there's a class that represents a user in your application. Let's call this class User.

Create a CDI bean to handle the authentication event, find a User instance with the correspondent username and assign it to the authenticatedUser producer field:

public class AuthenticatedUserProducer {

    private User authenticatedUser;

    public void handleAuthenticationEvent(@Observes @AuthenticatedUser String username) {
        this.authenticatedUser = findUser(username);

    private User findUser(String username) {
        // Hit the the database or a service to find a user by its username and return it
        // Return the User instance

The authenticatedUser field produces a User instance that can be injected into container managed beans, such as JAX-RS services, CDI beans, servlets and EJBs. Use the following piece of code to inject a User instance (in fact, it's a CDI proxy):

User authenticatedUser;

Note that the CDI @Produces annotation is different from the JAX-RS @Produces annotation:

Be sure you use the CDI @Produces annotation in your AuthenticatedUserProducer bean.

The key here is the bean annotated with @RequestScoped, allowing you to share data between filters and your beans. If you don't wan't to use events, you can modify the filter to store the authenticated user in a request scoped bean and then read it from your JAX-RS resource classes.

Compared to the approach that overrides the SecurityContext, the CDI approach allows you to get the authenticated user from beans other than JAX-RS resources and providers.

Supporting role-based authorization

Please refer to my other answer for details on how to support role-based authorization.

Issuing tokens

A token can be:

  • Opaque: Reveals no details other than the value itself (like a random string)
  • Self-contained: Contains details about the token itself (like JWT).

See details below:

Random string as token

A token can be issued by generating a random string and persisting it to a database along with the user identifier and an expiration date. A good example of how to generate a random string in Java can be seen here. You also could use:

Random random = new SecureRandom();
String token = new BigInteger(130, random).toString(32);

JWT (JSON Web Token)

JWT (JSON Web Token) is a standard method for representing claims securely between two parties and is defined by the RFC 7519.

It's a self-contained token and it enables you to store details in claims. These claims are stored in the token payload which is a JSON encoded as Base64. Here are some claims registered in the RFC 7519 and what they mean (read the full RFC for further details):

  • iss: Principal that issued the token.
  • sub: Principal that is the subject of the JWT.
  • exp: Expiration date for the token.
  • nbf: Time on which the token will start to be accepted for processing.
  • iat: Time on which the token was issued.
  • jti: Unique identifier for the token.

Be aware that you must not store sensitive data, such as passwords, in the token.

The payload can be read by the client and the integrity of the token can be easily checked by verifying its signature on the server. The signature is what prevents the token from being tampered with.

You won't need to persist JWT tokens if you don't need to track them. Althought, by persisting the tokens, you will have the possibility of invalidating and revoking the access of them. To keep the track of JWT tokens, instead of persisting the whole token on the server, you could persist the token identifier (jti claim) along with some other details such as the user you issued the token for, the expiration date, etc.

When persisting tokens, always consider removing the old ones in order to prevent your database from growing indefinitely.

Using JWT

There are a few Java libraries to issue and validate JWT tokens such as:

To find some other great resources to work with JWT, have a look at

Handling token revocation with JWT

If you want to revoke tokens, you must keep the track of them. You don't need to store the whole token on server side, store only the token identifier (that must be unique) and some metadata if you need. For the token identifier you could use UUID.

The jti claim should be used to store the token identifier on the token. When validating the token, ensure that it has not been revoked by checking the value of the jti claim against the token identifiers you have on server side.

For security purposes, revoke all the tokens for a user when they change their password.

Additional information

  • It doesn't matter which type of authentication you decide to use. Always do it on the top of a HTTPS connection to prevent the man-in-the-middle attack.
  • Take a look at this question from Information Security for more information about tokens.
  • In this article you will find some useful information about token-based authentication.

How to do an INNER JOIN on multiple columns

something like....

      , as from
      , as to
FROM flights f
INNER JOIN airports a1
ON f.fairport = a1. code
INNER JOIN airports a2
ON f.tairport = a2. code

Git push existing repo to a new and different remote repo server?

Here is a manual way to do git remote set-url origin [new repo URL]:

  1. Clone the repository: git clone <old remote>
  2. Create a GitHub repository
  3. Open <repository>/.git/config

    $ git config -e
        repositoryformatversion = 0
        filemode = false
        bare = false
        logallrefupdates = true
        symlinks = false
        ignorecase = true
    [remote "origin"]
        url = <old remote>
        fetch = +refs/heads/*:refs/remotes/origin/*
    [branch "master"]
        remote = origin
        merge = refs/heads/master

    and change the remote (the url option)

    [remote "origin"]
        url = <new remote>
        fetch = +refs/heads/*:refs/remotes/origin/*
  4. Push the repository to GitHub: git push

You can also use both/multiple remotes.

Order discrete x scale by frequency/value

Hadley has been developing a package called forcats. This package makes the task so much easier. You can exploit fct_infreq() when you want to change the order of x-axis by the frequency of a factor. In the case of the mtcars example in this post, you want to reorder levels of cyl by the frequency of each level. The level which appears most frequently stays on the left side. All you need is the fct_infreq().


ggplot(mtcars, aes(fct_infreq(factor(cyl)))) +
geom_bar() +
labs(x = "cyl")

If you wanna go the other way around, you can use fct_rev() along with fct_infreq().

ggplot(mtcars, aes(fct_rev(fct_infreq(factor(cyl))))) +
geom_bar() +
labs(x = "cyl") 

enter image description here

In Java, what purpose do the keywords `final`, `finally` and `finalize` fulfil?

  • "Final" denotes that something cannot be changed. You usually want to use this on static variables that will hold the same value throughout the life of your program.
  • "Finally" is used in conjunction with a try/catch block. Anything inside of the "finally" clause will be executed regardless of if the code in the 'try' block throws an exception or not.
  • "Finalize" is called by the JVM before an object is about to be garbage collected.

How to choose an AWS profile when using boto3 to connect to CloudFront

Just add profile to session configuration before client call. boto3.session.Session(profile_name='YOUR_PROFILE_NAME').client('cloudwatch')

How to get the input from the Tkinter Text Widget?

Here is how I did it with python 3.5.2:

from tkinter import *
def retrieve_input():

textBox=Text(root, height=2, width=10)
buttonCommit=Button(root, height=1, width=10, text="Commit", 
                    command=lambda: retrieve_input())
#command=lambda: retrieve_input() >>> just means do this when i press the button


with that, when i typed "blah blah" in the text widget and pressed the button, whatever i typed got printed out. So i think that is the answer for storing user input from Text widget to variable.

AWS : The config profile (MyName) could not be found

Working with profiles is little tricky. Documentation can be found at: (But you need to pay attention on env variables like AWS_PROFILE)

Using profile with aws cli requires a config file (default at ~/.aws/config or set using AWS_CONFIG_FILE). A sample config file for reference: `

[profile PROFILE_NAME]


Env variable AWS_PROFILE informs AWS cli about the profile to use from AWS config. It is not an alternate of config file like AWS_ACCESS_KEY_ID/AWS_SECRET_ACCESS_KEY are for ~/.aws/credentials.

Another interesting fact is if AWS_PROFILE is set and the AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY environment variables are set, then the credentials provided by AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY will override the credentials located in the profile provided by AWS_PROFILE.

How can I escape a double quote inside double quotes?

A simple example of escaping quotes in the shell:

$ echo 'abc'\''abc'
$ echo "abc"\""abc"

It's done by finishing an already-opened one ('), placing the escaped one (\'), and then opening another one (').


$ echo 'abc'"'"'abc'
$ echo "abc"'"'"abc"

It's done by finishing already opened one ('), placing a quote in another quote ("'"), and then opening another one (').

More examples: Escaping single-quotes within single-quoted strings

How to create a .jar file or export JAR in IntelliJ IDEA (like Eclipse Java archive export)?

For Intellij IDEA version 11.0.2

File | Project Structure | Artifacts then you should press alt+insert or click the plus icon and create new artifact choose --> jar --> From modules with dependencies.

Next goto Build | Build artifacts --> choose your artifact.


what is trailing whitespace and how can I handle this?

Trailing whitespace:

It is extra spaces (and tabs) at the end of line      
                                                 ^^^^^ here

Strip them:

#!/usr/bin/env python2
strip trailing whitespace from file
usage: <file>

import sys

if len(sys.argv[1:]) != 1:

content = ''
outsize = 0
inp = outp = sys.argv[1]
with open(inp, 'rb') as infile:
  content =
with open(outp, 'wb') as output:
  for line in content.splitlines():
    newline = line.rstrip(" \t")
    outsize += len(newline) + 1
    output.write(newline + '\n')

print("Done. Stripped %s bytes." % (len(content)-outsize))

Django DateField default options

This is why you should always import the base datetime module: import datetime, rather than the datetime class within that module: from datetime import datetime.

The other mistake you have made is to actually call the function in the default, with the (). This means that all models will get the date at the time the class is first defined - so if your server stays up for days or weeks without restarting Apache, all elements will get same the initial date.

So the field should be:

import datetime
date = models.DateField(_("Date"),

PHP memcached Fatal error: Class 'Memcache' not found

I went into wp-config/ and deleted the object-cache.php and advanced-cache.php and it worked fine for me.

Tensorflow import error: No module named 'tensorflow'

I had same issues on Windows 64-bit processor but manage to solve them. Check if your Python is for 32- or 64-bit installation. If it is for 32-bit, then you should download the executable installer (for e.g. you can choose latest Python version - for me is 3.7.3) -> Scroll to the bottom in Files section and select “Windows x86-64 executable installer”. Download and install it.

The tensorflow installation steps check here : . I hope this helps somehow ...

Create array of regex matches

(4castle's answer is better than the below if you can assume Java >= 9)

You need to create a matcher and use that to iteratively find matches.

 import java.util.regex.Matcher;
 import java.util.regex.Pattern;


 List<String> allMatches = new ArrayList<String>();
 Matcher m = Pattern.compile("your regular expression here")
 while (m.find()) {

After this, allMatches contains the matches, and you can use allMatches.toArray(new String[0]) to get an array if you really need one.

You can also use MatchResult to write helper functions to loop over matches since Matcher.toMatchResult() returns a snapshot of the current group state.

For example you can write a lazy iterator to let you do

for (MatchResult match : allMatches(pattern, input)) {
  // Use match, and maybe break without doing the work to find all possible matches.

by doing something like this:

public static Iterable<MatchResult> allMatches(
      final Pattern p, final CharSequence input) {
  return new Iterable<MatchResult>() {
    public Iterator<MatchResult> iterator() {
      return new Iterator<MatchResult>() {
        // Use a matcher internally.
        final Matcher matcher = p.matcher(input);
        // Keep a match around that supports any interleaving of hasNext/next calls.
        MatchResult pending;

        public boolean hasNext() {
          // Lazily fill pending, and avoid calling find() multiple times if the
          // clients call hasNext() repeatedly before sampling via next().
          if (pending == null && matcher.find()) {
            pending = matcher.toMatchResult();
          return pending != null;

        public MatchResult next() {
          // Fill pending if necessary (as when clients call next() without
          // checking hasNext()), throw if not possible.
          if (!hasNext()) { throw new NoSuchElementException(); }
          // Consume pending so next call to hasNext() does a find().
          MatchResult next = pending;
          pending = null;
          return next;

        /** Required to satisfy the interface, but unsupported. */
        public void remove() { throw new UnsupportedOperationException(); }

With this,

for (MatchResult match : allMatches(Pattern.compile("[abc]"), "abracadabra")) {
  System.out.println( + " at " + match.start());


a at 0
b at 1
a at 3
c at 4
a at 5
a at 7
b at 8
a at 10

How do you remove duplicates from a list whilst preserving order?

An in-place method

This method is quadratic, because we have a linear lookup into the list for every element of the list (to that we have to add the cost of rearranging the list because of the del s).

That said, it is possible to operate in place if we start from the end of the list and proceed toward the origin removing each term that is present in the sub-list at its left

This idea in code is simply

for i in range(len(l)-1,0,-1): 
    if l[i] in l[:i]: del l[i] 

A simple test of the implementation

In [91]: from random import randint, seed                                                                                            
In [92]: seed('20080808') ; l = [randint(1,6) for _ in range(12)] # Beijing Olympics                                                                 
In [93]: for i in range(len(l)-1,0,-1): 
    ...:     print(l) 
    ...:     print(i, l[i], l[:i], end='') 
    ...:     if l[i] in l[:i]: 
    ...:          print( ': remove', l[i]) 
    ...:          del l[i] 
    ...:     else: 
    ...:          print() 
    ...: print(l)
[6, 5, 1, 4, 6, 1, 6, 2, 2, 4, 5, 2]
11 2 [6, 5, 1, 4, 6, 1, 6, 2, 2, 4, 5]: remove 2
[6, 5, 1, 4, 6, 1, 6, 2, 2, 4, 5]
10 5 [6, 5, 1, 4, 6, 1, 6, 2, 2, 4]: remove 5
[6, 5, 1, 4, 6, 1, 6, 2, 2, 4]
9 4 [6, 5, 1, 4, 6, 1, 6, 2, 2]: remove 4
[6, 5, 1, 4, 6, 1, 6, 2, 2]
8 2 [6, 5, 1, 4, 6, 1, 6, 2]: remove 2
[6, 5, 1, 4, 6, 1, 6, 2]
7 2 [6, 5, 1, 4, 6, 1, 6]
[6, 5, 1, 4, 6, 1, 6, 2]
6 6 [6, 5, 1, 4, 6, 1]: remove 6
[6, 5, 1, 4, 6, 1, 2]
5 1 [6, 5, 1, 4, 6]: remove 1
[6, 5, 1, 4, 6, 2]
4 6 [6, 5, 1, 4]: remove 6
[6, 5, 1, 4, 2]
3 4 [6, 5, 1]
[6, 5, 1, 4, 2]
2 1 [6, 5]
[6, 5, 1, 4, 2]
1 5 [6]
[6, 5, 1, 4, 2]

In [94]:                                                                                                                             

Python non-greedy regexes

Do you want it to match "(b)"? Do as Zitrax and Paolo have suggested. Do you want it to match "b"? Do

>>> x = "a (b) c (d) e"
>>>"\((.*?)\)", x).group(1)

python mpl_toolkits installation issue

It doesn't work on Ubuntu 16.04, it seems that some libraries have been forgotten in the python installation package on this one. You should use package manager instead.


Uninstall matplotlib from pip then install it again with apt-get

python 2:

sudo pip uninstall matplotlib
sudo apt-get install python-matplotlib

python 3:

sudo pip3 uninstall matplotlib
sudo apt-get install python3-matplotlib

Getting all types in a namespace via reflection

Get all classes by part of Namespace name in just one row:

var allClasses = Assembly.GetExecutingAssembly().GetTypes().Where(a => a.IsClass && a.Namespace != null && a.Namespace.Contains(@"..your namespace...")).ToList();

When should an Excel VBA variable be killed or set to Nothing?

VB6/VBA uses deterministic approach to destoying objects. Each object stores number of references to itself. When the number reaches zero, the object is destroyed.

Object variables are guaranteed to be cleaned (set to Nothing) when they go out of scope, this decrements the reference counters in their respective objects. No manual action required.

There are only two cases when you want an explicit cleanup:

  1. When you want an object to be destroyed before its variable goes out of scope (e.g., your procedure is going to take long time to execute, and the object holds a resource, so you want to destroy the object as soon as possible to release the resource).

  2. When you have a circular reference between two or more objects.

    If objectA stores a references to objectB, and objectB stores a reference to objectA, the two objects will never get destroyed unless you brake the chain by explicitly setting objectA.ReferenceToB = Nothing or objectB.ReferenceToA = Nothing.

The code snippet you show is wrong. No manual cleanup is required. It is even harmful to do a manual cleanup, as it gives you a false sense of more correct code.

If you have a variable at a class level, it will be cleaned/destroyed when the class instance is destructed. You can destroy it earlier if you want (see item 1.).

If you have a variable at a module level, it will be cleaned/destroyed when your program exits (or, in case of VBA, when the VBA project is reset). You can destroy it earlier if you want (see item 1.).

Access level of a variable (public vs. private) does not affect its life time.

How to wait until an element exists?

You can listen to DOMNodeInserted or DOMSubtreeModified events which fire whenever a new element is added to the DOM.

There is also LiveQuery jQuery plugin which would detect when a new element is created:

    //element created

How to change HTML Object element data attribute value in javascript

and in jquery:

$('element').attr('some attribute','some attributes value')



TypeScript: correct way to do string equality?

If you know x and y are both strings, using === is not strictly necessary, but is still good practice.

Assuming both variables actually are strings, both operators will function identically. However, TS often allows you to pass an object that meets all the requirements of string rather than an actual string, which may complicate things.

Given the possibility of confusion or changes in the future, your linter is probably correct in demanding ===. Just go with that.

Change value of input and submit form in JavaScript

Here is simple code. You must set an id for your input. Here call it 'myInput':

var myform = document.getElementById('myform');
myform.onsubmit = function(){
    document.getElementById('myInput').value = '1';

Convert JSON String to JSON Object c#

string result = await resp.Content.ReadAsStringAsync(); List _Resp = JsonConvert.DeserializeObject<List>(result); //List _objList = new List((IEnumerable)_Resp);

            IList usll = _Resp.Select(a => a.lttsdata).ToList();
            // List<ListViewClass> _objList = new List<ListViewClass>((IEnumerable<ListViewClass>)_Resp);
            //IList usll = _objList.OrderBy(a=> a.ReqID).ToList();
            Lv.ItemsSource = usll;

Importing CSV File to Google Maps

For generating the KML file from your CSV file (or XLS), you can use MyGeodata online GIS Data Converter. Here is the CSV to KML How-To.

How to create loading dialogs in Android?

It's a ProgressDialog, with setIndeterminate(true).


ProgressDialog dialog =, "", 
                    "Loading. Please wait...", true);

An indeterminate progress bar doesn't actually show a bar, it shows a spinning activity circle thing. I'm sure you know what I mean :)

MySQL: Delete all rows older than 10 minutes

The answer is right in the MYSQL manual itself.

"DELETE FROM `table_name` WHERE `time_col` < ADDDATE(NOW(), INTERVAL -1 HOUR)"

How to Make Laravel Eloquent "IN" Query?

Here is how you do in Eloquent

$users = User::whereIn('id', array(1, 2, 3))->get();

And if you are using Query builder then :

$users = DB::table('users')->whereIn('id', array(1, 2, 3))->get();

understanding private setters

A private setter is useful if you have a read only property and don't want to explicitly declare the backing variable.


public int MyProperty
    get; private set;

is the same as:

private int myProperty;
public int MyProperty
    get { return myProperty; }

For non auto implemented properties it gives you a consistent way of setting the property from within your class so that if you need validation etc. you only have it one place.

To answer your final question the MSDN has this to say on private setters:

However, for small classes or structs that just encapsulate a set of values (data) and have little or no behaviors, it is recommended to make the objects immutable by declaring the set accessor as private.

From the MSDN page on Auto Implemented properties

Convert this string to datetime

The Problem is with your code formatting,

inorder to use strtotime() You should replace '06/Oct/2011:19:00:02' with 06/10/2011 19:00:02 and date('d/M/Y:H:i:s', $date); with date('d/M/Y H:i:s', $date);. Note the spaces in between.

So the final code looks like this

$s = '06/10/2011 19:00:02';
$date = strtotime($s);
echo date('d/M/Y H:i:s', $date);

Git stash pop- needs merge, unable to refresh index

Its much simpler than the accepted answer. You need to:

  1. Check git status and unmerged paths under it. Fix the conflicts. You can skip this step if you'd rather do it later.

  2. Add all these files under unmerged paths to index using git add <filename>.

  3. Now do git stash pop. If you get any conflicts these will again need to be resolved.

Request UAC elevation from within a Python script?

If your script always requires an Administrator's privileges then:

runas /user:Administrator "python"

Reset all changes after last commit in git

How can I undo every change made to my directory after the last commit, including deleting added files, resetting modified files, and adding back deleted files?

  1. You can undo changes to tracked files with:

    git reset HEAD --hard
  2. You can remove untracked files with:

    git clean -f
  3. You can remove untracked files and directories with:

    git clean -fd

    but you can't undo change to untracked files.

  4. You can remove ignored and untracked files and directories

    git clean -fdx

    but you can't undo change to ignored files.

You can also set clean.requireForce to false:

git config --global --add clean.requireForce false

to avoid using -f (--force) when you use git clean.

How do I use disk caching in Picasso?

For caching, I would use OkHttp interceptors to gain control over caching policy. Check out this sample that's included in the OkHttp library.

Here's how I'd use it with Picasso -

OkHttpClient okHttpClient = new OkHttpClient();
    okHttpClient.networkInterceptors().add(new Interceptor() {
        public Response intercept(Chain chain) throws IOException {
            Response originalResponse = chain.proceed(chain.request());
            return originalResponse.newBuilder().header("Cache-Control", "max-age=" + (60 * 60 * 24 * 365)).build();

    okHttpClient.setCache(new Cache(mainActivity.getCacheDir(), Integer.MAX_VALUE));
    OkHttpDownloader okHttpDownloader = new OkHttpDownloader(okHttpClient);
    Picasso picasso = new Picasso.Builder(mainActivity).downloader(okHttpDownloader).build();

CSS last-child selector: select last-element of specific class, not last child inside of parent?

I guess that the most correct answer is: Use :nth-child (or, in this specific case, its counterpart :nth-last-child). Most only know this selector by its first argument to grab a range of items based on a calculation with n, but it can also take a second argument "of [any CSS selector]".

Your scenario could be solved with this selector: .commentList .comment:nth-last-child(1 of .comment)

But being technically correct doesn't mean you can use it, though, because this selector is as of now only implemented in Safari.

For further reading:

Connection string with relative path to the database file

After several strange errors with relative paths in connectionstring I felt the need to post this here.

When using "|DataDirectory|" or "~" you are not allowed to step up and out using "../" !

Example is using several projects accessing the same localdb file placed in one of the projects.

" ~/../other" and " |DataDirectory|/../other" will fail

Even if it is clearly written at MSDN here the errors it gave where a bit unclear so hard to find and could not find it here at SO.

How to import cv2 in python3?

well, there was 2 issues: 1.instead of pip, pip3 should be used. 2.its better to use virtual env. because i have had multiple python version installed

how to toggle attr() in jquery

This answer is counting that the second parameter is useless when calling removeAttr! (as it was when this answer was posted) Do not use this otherwise!

Can't beat RienNeVaPlus's clean answer, but it does the job as well, it's basically a more compressed way to do the ternary operation:

$('.list-sort')[$('.list-sort').hasAttr('colspan') ? 
    'removeAttr' : 'attr']('colspan', 6);

an extra variable can be used in these cases, when you need to use the reference more than once:

var $listSort = $('.list-sort'); 
$listSort[$listSort.hasAttr('colspan') ? 'removeAttr' : 'attr']('colspan', 6);

Call static method with reflection

I prefer simplicity...

private void _InvokeNamespaceClassesStaticMethod(string namespaceName, string methodName, params object[] parameters) {
    foreach(var _a in AppDomain.CurrentDomain.GetAssemblies()) {
        foreach(var _t in _a.GetTypes()) {
            try {
                if((_t.Namespace == namespaceName) && _t.IsClass) _t.GetMethod(methodName, (BindingFlags.Static | BindingFlags.Public))?.Invoke(null, parameters);
            } catch { }


    _InvokeNamespaceClassesStaticMethod("mySolution.Macros", "Run");

But in case you're looking for something a little more robust, including the handling of exceptions...

private InvokeNamespaceClassStaticMethodResult[] _InvokeNamespaceClassStaticMethod(string namespaceName, string methodName, bool throwExceptions, params object[] parameters) {
    var results = new List<InvokeNamespaceClassStaticMethodResult>();
    foreach(var _a in AppDomain.CurrentDomain.GetAssemblies()) {
        foreach(var _t in _a.GetTypes()) {
            if((_t.Namespace == namespaceName) && _t.IsClass) {
                var method_t = _t.GetMethod(methodName, parameters.Select(_ => _.GetType()).ToArray());
                if((method_t != null) && method_t.IsPublic && method_t.IsStatic) {
                    var details_t = new InvokeNamespaceClassStaticMethodResult();
                    details_t.Namespace = _t.Namespace;
                    details_t.Class = _t.Name;
                    details_t.Method = method_t.Name;
                    try {
                        if(method_t.ReturnType == typeof(void)) {
                            method_t.Invoke(null, parameters);
                            details_t.Void = true;
                        } else {
                            details_t.Return = method_t.Invoke(null, parameters);
                    } catch(Exception ex) {
                        if(throwExceptions) {
                        } else {
                            details_t.Exception = ex;
    return results.ToArray();

private class InvokeNamespaceClassStaticMethodResult {
    public string Namespace;
    public string Class;
    public string Method;
    public object Return;
    public bool Void;
    public Exception Exception;

Usage is pretty much the same...

_InvokeNamespaceClassesStaticMethod("mySolution.Macros", "Run", false);

How can I wrap or break long text/word in a fixed width span?

In my case, display: block was breaking the design as intended.

The max-width property just saved me.

and for styling, you can use text-overflow: ellipsis as well.

my code was

max-width: 255px

how to check if a form is valid programmatically using jQuery Validation Plugin

2015 answer: we have this out of the box on modern browsers, just use the HTML5 CheckValidity API from jQuery. I've also made a jquery-html5-validity module to do this:

npm install jquery-html5-validity


var $ = require('jquery')

then you can run:



JavaScript load a page on button click

Don't abuse form elements where <a> elements will suffice.

    /* or put this in your stylesheet */

    .button {
        display: inline-block;
        padding: 3px 5px;
        border: 1px solid #000;
        background: #eee;


<!-- instead of abusing a button or input element -->
<a href="url" class="button">text</a>

Understanding `scale` in R

I thought I would contribute by providing a concrete example of the practical use of the scale function. Say you have 3 test scores (Math, Science, and English) that you want to compare. Maybe you may even want to generate a composite score based on each of the 3 tests for each observation. Your data could look as as thus:

student_id <- seq(1,10)
math <- c(502,600,412,358,495,512,410,625,573,522)
science <- c(95,99,80,82,75,85,80,95,89,86)
english <- c(25,22,18,15,20,28,15,30,27,18)
df <- data.frame(student_id,math,science,english)

Obviously it would not make sense to compare the means of these 3 scores as the scale of the scores are vastly different. By scaling them however, you have more comparable scoring units:

z <- scale(df[,2:4],center=TRUE,scale=TRUE)

You could then use these scaled results to create a composite score. For instance, average the values and assign a grade based on the percentiles of this average. Hope this helped!

Note: I borrowed this example from the book "R In Action". It's a great book! Would definitely recommend.

How to read a file in Groovy into a string?

String fileContents = new File('/path/to/file').text

If you need to specify the character encoding, use the following instead:

String fileContents = new File('/path/to/file').getText('UTF-8')

What is the difference between List and ArrayList?

There's no difference between list implementations in both of your examples. There's however a difference in a way you can further use variable myList in your code.

When you define your list as:

List myList = new ArrayList();

you can only call methods and reference members that are defined in the List interface. If you define it as:

ArrayList myList = new ArrayList();

you'll be able to invoke ArrayList-specific methods and use ArrayList-specific members in addition to those whose definitions are inherited from List.

Nevertheless, when you call a method of a List interface in the first example, which was implemented in ArrayList, the method from ArrayList will be called (because the List interface doesn't implement any methods).

That's called polymorphism. You can read up on it.

Installing Java on OS X 10.9 (Mavericks)

There isn't any need to install the JDK, which is the developer kit, just the JRE which is the runtime environment.

How to execute a java .class from the command line

You have no valid main method... The signature should be: public static void main(String[] args);

Hence, in your case the code should look like this:

public class Echo {
    public static void main (String[] arg) {


Edit: Please note that Oscar is also right in that you are missing . in your classpath, you would run into the problem I solve after you have dealt with that error.

Java - Check Not Null/Empty else assign default value

This is the best solution IMHO. It covers BOTH null and empty scenario, as is easy to understand when reading the code. All you need to know is that .getProperty returns a null when system prop is not set:

String DEFAULT_XYZ = System.getProperty("user.home") + "/xyz";
String PROP = Optional.ofNullable(System.getProperty("XYZ"))
        .filter(s -> !s.isEmpty())

Does static constexpr variable inside a function make sense?

In addition to given answer, it's worth noting that compiler is not required to initialize constexpr variable at compile time, knowing that the difference between constexpr and static constexpr is that to use static constexpr you ensure the variable is initialized only once.

Following code demonstrates how constexpr variable is initialized multiple times (with same value though), while static constexpr is surely initialized only once.

In addition the code compares the advantage of constexpr against const in combination with static.

#include <iostream>
#include <string>
#include <cassert>
#include <sstream>

const short const_short = 0;
constexpr short constexpr_short = 0;

// print only last 3 address value numbers
const short addr_offset = 3;

// This function will print name, value and address for given parameter
void print_properties(std::string ref_name, const short* param, short offset)
    // determine initial size of strings
    std::string title = "value \\ address of ";
    const size_t ref_size = ref_name.size();
    const size_t title_size = title.size();
    assert(title_size > ref_size);

    // create title (resize)
    title.append(" is ");
    title.append(title_size - ref_size, ' ');

    // extract last 'offset' values from address
    std::stringstream addr;
    addr << param;
    const std::string addr_str = addr.str();
    const size_t addr_size = addr_str.size();
    assert(addr_size - offset > 0);

    // print title / ref value / address at offset
    std::cout << title << *param << " " << addr_str.substr(addr_size - offset) << std::endl;

// here we test initialization of const variable (runtime)
void const_value(const short counter)
    static short temp = const_short;
    const short const_var = ++temp;
    print_properties("const", &const_var, addr_offset);

    if (counter)
        const_value(counter - 1);

// here we test initialization of static variable (runtime)
void static_value(const short counter)
    static short temp = const_short;
    static short static_var = ++temp;
    print_properties("static", &static_var, addr_offset);

    if (counter)
        static_value(counter - 1);

// here we test initialization of static const variable (runtime)
void static_const_value(const short counter)
    static short temp = const_short;
    static const short static_var = ++temp;
    print_properties("static const", &static_var, addr_offset);

    if (counter)
        static_const_value(counter - 1);

// here we test initialization of constexpr variable (compile time)
void constexpr_value(const short counter)
    constexpr short constexpr_var = constexpr_short;
    print_properties("constexpr", &constexpr_var, addr_offset);

    if (counter)
        constexpr_value(counter - 1);

// here we test initialization of static constexpr variable (compile time)
void static_constexpr_value(const short counter)
    static constexpr short static_constexpr_var = constexpr_short;
    print_properties("static constexpr", &static_constexpr_var, addr_offset);

    if (counter)
        static_constexpr_value(counter - 1);

// final test call this method from main()
void test_static_const()
    constexpr short counter = 2;

    std::cout << std::endl;

    std::cout << std::endl;

    std::cout << std::endl;

    std::cout << std::endl;

    std::cout << std::endl;

Possible program output:

value \ address of const is               1 564
value \ address of const is               2 3D4
value \ address of const is               3 244

value \ address of static is              1 C58
value \ address of static is              1 C58
value \ address of static is              1 C58

value \ address of static const is        1 C64
value \ address of static const is        1 C64
value \ address of static const is        1 C64

value \ address of constexpr is           0 564
value \ address of constexpr is           0 3D4
value \ address of constexpr is           0 244

value \ address of static constexpr is    0 EA0
value \ address of static constexpr is    0 EA0
value \ address of static constexpr is    0 EA0

As you can see yourself constexpr is initilized multiple times (address is not the same) while static keyword ensures that initialization is performed only once.

How to get a list of all valid IP addresses in a local network?

If you want to see which IP addresses are in use on a specific subnet then there are several different IP Address managers.

Try Angry IP Scanner or Solarwinds or Advanced IP Scanner

Java: is there a map function?

There is no notion of a function in the JDK as of java 6.

Guava has a Function interface though and the
Collections2.transform(Collection<E>, Function<E,E2>)
method provides the functionality you require.


// example, converts a collection of integers to their
// hexadecimal string representations
final Collection<Integer> input = Arrays.asList(10, 20, 30, 40, 50);
final Collection<String> output =
    Collections2.transform(input, new Function<Integer, String>(){

        public String apply(final Integer input){
            return Integer.toHexString(input.intValue());


[a, 14, 1e, 28, 32]

These days, with Java 8, there is actually a map function, so I'd probably write the code in a more concise way:

Collection<String> hex =

Travel/Hotel API's?

HotelsCombined has an easy-to-access and useful service to download the data feed files with hotels. Not exactly API, but something you can get, parse and use. Here is how you do it:

  1. Go to
  2. Register there (no company or bank data is needed)
  3. Open “Data feeds” page
  4. Choose “Standard data feed” -> “Single file” -> “CSV format” (you may get XML as well)

If you are interested in details, you may find the sample Python code to filter CSV file to get hotels for a specific city here:


Unfortunately, has introduced the new regulations: they've restricted the access to data feeds by default. To get the access, a partner must submit some information on why one needs the data. The HC team will review it and then (maybe) will grant access.

How to insert multiple rows from array using CodeIgniter framework?

Multiple insert/ batch insert is now supported by CodeIgniter.

$data = array(
      'title' => 'My title' ,
      'name' => 'My Name' ,
      'date' => 'My date'
      'title' => 'Another title' ,
      'name' => 'Another Name' ,
      'date' => 'Another date'

$this->db->insert_batch('mytable', $data);

// Produces: INSERT INTO mytable (title, name, date) VALUES ('My title', 'My name', 'My date'), ('Another title', 'Another name', 'Another date')

Why an abstract class implementing an interface can miss the declaration/implementation of one of the interface's methods?

When an Abstract Class Implements an Interface

In the section on Interfaces, it was noted that a class that implements an interface must implement all of the interface's methods. It is possible, however, to define a class that does not implement all of the interface's methods, provided that the class is declared to be abstract. For example,

abstract class X implements Y {   
    // implements all but one method of Y

class XX extends X {   
    // implements the remaining method in Y 

In this case, class X must be abstract because it does not fully implement Y, but class XX does, in fact, implement Y.


Get custom product attributes in Woocommerce

Update for 2018. You can use:

global $product;
echo wc_display_product_attributes( $product );

To customise the output, copy plugins/woocommerce/templates/single-product/product-attributes.php to themes/theme-child/woocommerce/single-product/product-attributes.php and modify that.

Can we have multiple <tbody> in same <table>?

Yes. I use them for dynamically hiding/revealing the relevant part of a table, e.g. a course. Viz.

  <tbody id="day1" style="display:none">
  <tbody id="day2">
  <tbody id="day3" style="display:none">

A button can be provided to toggle between everything or just the current day by manipulating tbodies without processing many rows individually.

getElementById returns null?

Also be careful how you execute the js on the page. For example if you do something like this:

(function(window, document, undefined){

  var foo = document.getElementById("foo");


})(window, document, undefined); 

This will return null because you'd be calling the document before it was loaded.

Better option..

(function(window, document, undefined){

// code that should be taken care of right away

window.onload = init;

  function init(){
    // the code to be called when the dom has loaded
    // #document has its nodes

})(window, document, undefined);

force client disconnect from server with and nodejs

I am using on the client side socket.disconnect();

client.emit('disconnect') didnt work for me

Regex for password must contain at least eight characters, at least one number and both lower and uppercase letters and special characters

In Java/Android, to test a password with at least one number, one letter, one special character in following pattern:


What is com.sun.proxy.$Proxy

What are they?

Nothing special. Just as same as common Java Class Instance.

But those class are Synthetic proxy classes created by java.lang.reflect.Proxy#newProxyInstance

What is there relationship to the JVM? Are they JVM implementation specific?

Introduced in 1.3

It is a part of Java. so each JVM should support it.

How are they created (Openjdk7 source)?

In short : they are created using JVM ASM tech ( defining javabyte code at runtime )

something using same tech:

What happens after calling java.lang.reflect.Proxy#newProxyInstance

  1. reading the source you can see newProxyInstance call getProxyClass0 to obtain a `Class


  2. after lots of cache or sth it calls the magic ProxyGenerator.generateProxyClass which return a byte[]
  3. call ClassLoader define class to load the generated $Proxy Class (the classname you have seen)
  4. just instance it and ready for use

What happens in magic sun.misc.ProxyGenerator

  1. draw a class(bytecode) combining all methods in the interfaces into one
  2. each method is build with same bytecode like

    1. get calling Method meth info (stored while generating)
    2. pass info into invocation handler's invoke()
    3. get return value from invocation handler's invoke()
    4. just return it
  3. the class(bytecode) represent in form of byte[]

How to draw a class

Thinking your java codes are compiled into bytecodes, just do this at runtime

Talk is cheap show you the code

core method in sun/misc/


 * Generate a class file for the proxy class.  This method drives the
 * class file generation process.
private byte[] generateClassFile() {

    /* ============================================================
     * Step 1: Assemble ProxyMethod objects for all methods to
     * generate proxy dispatching code for.

     * Record that proxy methods are needed for the hashCode, equals,
     * and toString methods of java.lang.Object.  This is done before
     * the methods from the proxy interfaces so that the methods from
     * java.lang.Object take precedence over duplicate methods in the
     * proxy interfaces.
    addProxyMethod(hashCodeMethod, Object.class);
    addProxyMethod(equalsMethod, Object.class);
    addProxyMethod(toStringMethod, Object.class);

     * Now record all of the methods from the proxy interfaces, giving
     * earlier interfaces precedence over later ones with duplicate
     * methods.
    for (int i = 0; i < interfaces.length; i++) {
        Method[] methods = interfaces[i].getMethods();
        for (int j = 0; j < methods.length; j++) {
            addProxyMethod(methods[j], interfaces[i]);

     * For each set of proxy methods with the same signature,
     * verify that the methods' return types are compatible.
    for (List<ProxyMethod> sigmethods : proxyMethods.values()) {

    /* ============================================================
     * Step 2: Assemble FieldInfo and MethodInfo structs for all of
     * fields and methods in the class we are generating.
    try {

        for (List<ProxyMethod> sigmethods : proxyMethods.values()) {
            for (ProxyMethod pm : sigmethods) {

                // add static field for method's Method object
                fields.add(new FieldInfo(pm.methodFieldName,
                     ACC_PRIVATE | ACC_STATIC));

                // generate code for proxy method and add it


    } catch (IOException e) {
        throw new InternalError("unexpected I/O Exception");

    if (methods.size() > 65535) {
        throw new IllegalArgumentException("method limit exceeded");
    if (fields.size() > 65535) {
        throw new IllegalArgumentException("field limit exceeded");

    /* ============================================================
     * Step 3: Write the final class file.

     * Make sure that constant pool indexes are reserved for the
     * following items before starting to write the final class file.
    for (int i = 0; i < interfaces.length; i++) {

     * Disallow new constant pool additions beyond this point, since
     * we are about to write the final constant pool table.

    ByteArrayOutputStream bout = new ByteArrayOutputStream();
    DataOutputStream dout = new DataOutputStream(bout);

    try {
         * Write all the items of the "ClassFile" structure.
         * See JVMS section 4.1.
                                    // u4 magic;
                                    // u2 minor_version;
                                    // u2 major_version;

        cp.write(dout);             // (write constant pool)

                                    // u2 access_flags;
        dout.writeShort(ACC_PUBLIC | ACC_FINAL | ACC_SUPER);
                                    // u2 this_class;
                                    // u2 super_class;

                                    // u2 interfaces_count;
                                    // u2 interfaces[interfaces_count];
        for (int i = 0; i < interfaces.length; i++) {

                                    // u2 fields_count;
                                    // field_info fields[fields_count];
        for (FieldInfo f : fields) {

                                    // u2 methods_count;
                                    // method_info methods[methods_count];
        for (MethodInfo m : methods) {

                                     // u2 attributes_count;
        dout.writeShort(0); // (no ClassFile attributes for proxy classes)

    } catch (IOException e) {
        throw new InternalError("unexpected I/O Exception");

    return bout.toByteArray();


 * Add another method to be proxied, either by creating a new
 * ProxyMethod object or augmenting an old one for a duplicate
 * method.
 * "fromClass" indicates the proxy interface that the method was
 * found through, which may be different from (a subinterface of)
 * the method's "declaring class".  Note that the first Method
 * object passed for a given name and descriptor identifies the
 * Method object (and thus the declaring class) that will be
 * passed to the invocation handler's "invoke" method for a given
 * set of duplicate methods.
private void addProxyMethod(Method m, Class fromClass) {
    String name = m.getName();
    Class[] parameterTypes = m.getParameterTypes();
    Class returnType = m.getReturnType();
    Class[] exceptionTypes = m.getExceptionTypes();

    String sig = name + getParameterDescriptors(parameterTypes);
    List<ProxyMethod> sigmethods = proxyMethods.get(sig);
    if (sigmethods != null) {
        for (ProxyMethod pm : sigmethods) {
            if (returnType == pm.returnType) {
                 * Found a match: reduce exception types to the
                 * greatest set of exceptions that can thrown
                 * compatibly with the throws clauses of both
                 * overridden methods.
                List<Class<?>> legalExceptions = new ArrayList<Class<?>>();
                    exceptionTypes, pm.exceptionTypes, legalExceptions);
                    pm.exceptionTypes, exceptionTypes, legalExceptions);
                pm.exceptionTypes = new Class[legalExceptions.size()];
                pm.exceptionTypes =
    } else {
        sigmethods = new ArrayList<ProxyMethod>(3);
        proxyMethods.put(sig, sigmethods);
    sigmethods.add(new ProxyMethod(name, parameterTypes, returnType,
                                   exceptionTypes, fromClass));

Full code about gen the proxy method

    private MethodInfo generateMethod() throws IOException {
        String desc = getMethodDescriptor(parameterTypes, returnType);
        MethodInfo minfo = new MethodInfo(methodName, desc,
            ACC_PUBLIC | ACC_FINAL);

        int[] parameterSlot = new int[parameterTypes.length];
        int nextSlot = 1;
        for (int i = 0; i < parameterSlot.length; i++) {
            parameterSlot[i] = nextSlot;
            nextSlot += getWordsPerType(parameterTypes[i]);
        int localSlot0 = nextSlot;
        short pc, tryBegin = 0, tryEnd;

        DataOutputStream out = new DataOutputStream(minfo.code);

        code_aload(0, out);

            handlerFieldName, "Ljava/lang/reflect/InvocationHandler;"));

        code_aload(0, out);

            methodFieldName, "Ljava/lang/reflect/Method;"));

        if (parameterTypes.length > 0) {

            code_ipush(parameterTypes.length, out);


            for (int i = 0; i < parameterTypes.length; i++) {


                code_ipush(i, out);

                codeWrapArgument(parameterTypes[i], parameterSlot[i], out);

        } else {


            "(Ljava/lang/Object;Ljava/lang/reflect/Method;" +

        if (returnType == void.class) {



        } else {

            codeUnwrapReturnValue(returnType, out);

        tryEnd = pc = (short) minfo.code.size();

        List<Class<?>> catchList = computeUniqueCatchList(exceptionTypes);
        if (catchList.size() > 0) {

            for (Class<?> ex : catchList) {
                minfo.exceptionTable.add(new ExceptionTableEntry(
                    tryBegin, tryEnd, pc,


            pc = (short) minfo.code.size();

            minfo.exceptionTable.add(new ExceptionTableEntry(
                tryBegin, tryEnd, pc, cp.getClass("java/lang/Throwable")));

            code_astore(localSlot0, out);



            code_aload(localSlot0, out);


                "<init>", "(Ljava/lang/Throwable;)V"));


setAttribute('display','none') not working

Try this:

setAttribute("hidden", true);

PHP code to convert a MySQL query to CSV

Look at the documentation regarding the SELECT ... INTO OUTFILE syntax.

SELECT a,b,a+b INTO OUTFILE '/tmp/result.txt'
  FROM test_table;

Print page numbers on pages when printing html

Can you try this, you can use content: counter(page);

     @page {
       @bottom-left {
            content: counter(page) "/" counter(pages);


running php script (php function) in linux bash

php test.php

should do it, or

php -f test.php

to be explicit.

Angular2 multiple router-outlet in the same template

There seems to be another (rather hacky) way to reuse the router-outlet in one template. This answer is intendend for informational purposes only and the techniques used here should probably not be used in production.

The router-outlet is wrapped by an ng-template. The template is updated by listening to events of the router. On every event the template is swapped and re-swapped with an empty placeholder. Without this "swapping" the template would not be updated.

This most definetly is not a recommended approach though, since the whole swapping of two templates seems a bit hacky.

in the controller:

  ngOnInit() { Event) => {
      this.myTemplateRef = this.trigger;
      setTimeout(() => {
        this.myTemplateRef = this.template;
      }, 0);

in the template:

<div class="would-be-visible-on-mobile-only">
  This would be the mobile-layout with a router-outlet (inside a template): 
  <ng-container *ngTemplateOutlet="myTemplateRef"></ng-container>


<div class="would-be-visible-on-desktop-only">
  This would be the desktop-layout with a router-outlet (inside a template): 
  <ng-container *ngTemplateOutlet="myTemplateRef"></ng-container>

<ng-template #template>
    This is my counter: {{counter}}
    inside the template, the router-outlet should follow

<ng-template #trigger>
  template to trigger changes...

Convert a row of a data frame to vector

When you extract a single row from a data frame you get a one-row data frame. Convert it to a numeric vector:


As @Roland suggests, unlist(df[1,]) will convert the one-row data frame to a numeric vector without dropping the names. Therefore unname(unlist(df[1,])) is another, slightly more explicit way to get to the same result.

As @Josh comments below, if you have a not-completely-numeric (alphabetic, factor, mixed ...) data frame, you need as.character(df[1,]) instead.

What is the C# version of's InputDialog?

Dynamic creation of a dialog box. You can customize to your taste.

Note there is no external dependency here except winform

private static DialogResult ShowInputDialog(ref string input)
        System.Drawing.Size size = new System.Drawing.Size(200, 70);
        Form inputBox = new Form();

        inputBox.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedDialog;
        inputBox.ClientSize = size;
        inputBox.Text = "Name";

        System.Windows.Forms.TextBox textBox = new TextBox();
        textBox.Size = new System.Drawing.Size(size.Width - 10, 23);
        textBox.Location = new System.Drawing.Point(5, 5);
        textBox.Text = input;

        Button okButton = new Button();
        okButton.DialogResult = System.Windows.Forms.DialogResult.OK;
        okButton.Name = "okButton";
        okButton.Size = new System.Drawing.Size(75, 23);
        okButton.Text = "&OK";
        okButton.Location = new System.Drawing.Point(size.Width - 80 - 80, 39);

        Button cancelButton = new Button();
        cancelButton.DialogResult = System.Windows.Forms.DialogResult.Cancel;
        cancelButton.Name = "cancelButton";
        cancelButton.Size = new System.Drawing.Size(75, 23);
        cancelButton.Text = "&Cancel";
        cancelButton.Location = new System.Drawing.Point(size.Width - 80, 39);

        inputBox.AcceptButton = okButton;
        inputBox.CancelButton = cancelButton; 

        DialogResult result = inputBox.ShowDialog();
        input = textBox.Text;
        return result;


string input="hede";
ShowInputDialog(ref input);

curl.h no such file or directory

sudo apt-get install curl-devel

sudo apt-get install libcurl-dev

(will install the default alternative)


sudo apt-get install libcurl4-openssl-dev

(the OpenSSL variant)


sudo apt-get install libcurl4-gnutls-dev

(the gnutls variant)

How do I remove objects from a JavaScript associative array?

For "Arrays":

If you know the index:

array.splice(index, 1);

If you know the value:

function removeItem(array, value) {
    var index = array.indexOf(value);
    if (index > -1) {
        array.splice(index, 1);
    return array;

The most upvoted answer for delete works well in case of objects but not for the real arrays. If I use delete it removes elements from loops but keeps the element as empty and length of array wont change. This may be a problem in some scenarios.

For example, if I do myArray.toString() on myArray after removal via delete, it creates an empty entry, i.e. ,,.

How to change font size in html?

You can do this by setting a style in your paragraph tag. For example if you wanted to change the font size to 28px.

<p style="font-size: 28px;"> Hello, World! </p>

You can also set the color by setting:

<p style="color: blue;"> Hello, World! </p>

However, if you want to preview font sizes and colors (which I recommend doing) before you add them to your website and use them. I recommend testing them out beforehand so you pick a good font size and color that contrasts well with the background. I recommend using this site if you wish to do so, couldn't find anything else:

Is it possible to force row level locking in SQL Server?


ALTER INDEX indexname ON tablename SET (ALLOW_PAGE_LOCKS = OFF);

load Js file in HTML

If this is your detail.html I don't see where do you load detail.js? Maybe this

<script src="js/index.js"></script>

should be this

<script src="js/detail.js"></script>


How to compile a c++ program in Linux?

For simple test project, g++ or make standalone are good options as already answered:

g++ -o hi hi.cpp


make hi

For real projects, however, the usage of a project manager is required. At the time I write this answer, the most used and open-source is cmake (an alternative could be QT qmake ).

Following is a simple CMake example:

Make sure you installed cmake on your linux distribution apt-get install cmake or yum install cmake.

Create a file CMakeLists.txt (the name is important) together with your source hi.cpp


add_executable( hi hi.cpp )

Then compile and run as:

cmake .

This allows the project to scale easily with libraries, sources, and much more. It also makes most IDEs to understand the project properly (Most IDEs accept CMake natively, like kdevelop, qtCreator, etc..)

Example of CMake integration with Qt-Creator

You could also generate Visual-Studio or XCode projects from CMake, in case you decide to port the software to other platforms in the future.

cmake -G Xcode . #will generate `hi.xcodeproj` you can load on macOS

reading from stdin in c++

You have not defined the variable input_line.

Add this:

string input_line;

And add this include.

#include <string>

Here is the full example. I also removed the semi-colon after the while loop, and you should have getline inside the while to properly detect the end of the stream.

#include <iostream>
#include <string>

int main() {
    for (std::string line; std::getline(std::cin, line);) {
        std::cout << line << std::endl;
    return 0;

In Java, how do you determine if a thread is running?

You can use this method:

boolean isAlive()

It returns true if the thread is still alive and false if the Thread is dead. This is not static. You need a reference to the object of the Thread class.

One more tip: If you're checking it's status to make the main thread wait while the new thread is still running, you may use join() method. It is more handy.

MAC addresses in JavaScript

The quick and simple answer is No.

Javascript is quite a high level language and does not have access to this sort of information.

Determine function name from within that function (without using traceback)

I guess inspect is the best way to do this. For example:

import inspect
def bar():
    print("My name is", inspect.stack()[0][3])

Performing a query on a result from another query?

Note that your initial query is probably not returning what you want:

SELECT availables.bookdate AS Date, DATEDIFF(now(),availables.updated_at) as Age 
FROM availables INNER JOIN rooms ON 
WHERE availables.bookdate BETWEEN  '2009-06-25' AND date_add('2009-06-25', INTERVAL 4 DAY) AND rooms.hostel_id = 5094 GROUP BY availables.bookdate

You are grouping by book date, but you are not using any grouping function on the second column of your query.

The query you are probably looking for is:

SELECT availables.bookdate AS Date, count(*) as subtotal, sum(DATEDIFF(now(),availables.updated_at) as Age)
FROM availables INNER JOIN rooms ON
WHERE availables.bookdate BETWEEN '2009-06-25' AND date_add('2009-06-25', INTERVAL 4 DAY) AND rooms.hostel_id = 5094
GROUP BY availables.bookdate

How is Perl's @INC constructed? (aka What are all the ways of affecting where Perl modules are searched for?)

As it was said already @INC is an array and you're free to add anything you want.

My CGI REST script looks like:

use strict;
use warnings;
    push @INC, '';
use Modules::Rest;

Subroutine gone is exported by

Why is semicolon allowed in this python snippet?

It's allowed because authors decided to allow it:

If move to question why authors decided todo so, I guess it's so because semi-column is allowed as simple statement termination at least in the following langages: C++, C, C#, R, Matlab,Perl,...

So it's faster to move into usage of Python for people with background in other language. And there are no lose of generality in such deicison.

Hello World in Python

Unfortunately the xkcd comic isn't completely up to date anymore.

Since Python 3.0 you have to write:

print("Hello world!")

And someone still has to write that antigravity library :(

How to loop through all enum values in C#?

Yes you can use the ?GetValue???s method:

var values = Enum.GetValues(typeof(Foos));

Or the typed version:

var values = Enum.GetValues(typeof(Foos)).Cast<Foos>();

I long ago added a helper function to my private library for just such an occasion:

public static class EnumUtil {
    public static IEnumerable<T> GetValues<T>() {
        return Enum.GetValues(typeof(T)).Cast<T>();


var values = EnumUtil.GetValues<Foos>();

"make clean" results in "No rule to make target `clean'"

You have fallen victim to the most common of errors in Makefiles. You always need to put a Tab at the beginning of each command. You've put spaces before the $(CC) $(CFLAGS) -o $@ $^ $(LDFLAGS) and @rm -f $(PROGRAMS) *.o core lines. If you replace them with a Tab, you'll be fine.

However, this error doesn't lead to a "No rule to make target ..." error. That probably means your issue lies beyond your Makefile. Have you checked this is the correct Makefile, as in the one you want to be specifying your commands? Try explicitly passing it as a parameter to make, make -f Makefile and let us know what happens.

Are PHP short tags acceptable to use?

I thought it worth mentioning that as of PHP 7:

  • Short ASP PHP tags <% … %> are gone
  • Short PHP tabs <? … ?> are still available if short_open_tag is set to true. This is the default.
  • Since PHP 5.4, Short Print tags <?=… ?> are always enabled, regardless of the short_open_tag setting.

Good riddance to the first one, as it interfered with other languages.

There is now no reason not to use the short print tags, apart from personal preference.

Of course, if you’re writing code to be compatible with legacy versions of PHP 5, you will need to stick to the old rules, but remember that anything before PHP 5.6 is now unsupported.


How to return first 5 objects of Array in Swift?

Update for swift 4:

[0,1,2,3,4,5].enumerated().compactMap{ $0 < 10000 ? $1 : nil }

For swift 3:

[0,1,2,3,4,5].enumerated().flatMap{ $0 < 10000 ? $1 : nil }

How can I make SMTP authenticated in C#

To send a message through TLS/SSL, you need to set Ssl of the SmtpClient class to true.

string to = "[email protected]";
string from = "[email protected]";
MailMessage message = new MailMessage(from, to);
message.Subject = "Using the new SMTP client.";
message.Body = @"Using this new feature, you can send an e-mail message from an application very easily.";
SmtpClient client = new SmtpClient(server);
// Credentials are necessary if the server requires the client 
// to authenticate before it will send e-mail on the client's behalf.
client.UseDefaultCredentials = true;
client.EnableSsl = true;

Else clause on Python while statement

In reply to Is there a specific reason?, here is one interesting application: breaking out of multiple levels of looping.

Here is how it works: the outer loop has a break at the end, so it would only be executed once. However, if the inner loop completes (finds no divisor), then it reaches the else statement and the outer break is never reached. This way, a break in the inner loop will break out of both loops, rather than just one.

for k in [2, 3, 5, 7, 11, 13, 17, 25]:
    for m in range(2, 10):
        if k == m:
        print 'trying %s %% %s' % (k, m)
        if k % m == 0:
            print 'found a divisor: %d %% %d; breaking out of loop' % (k, m)
    print 'breaking another level of loop'
    print 'no divisor could be found!'

For both while and for loops, the else statement is executed at the end, unless break was used.

In most cases there are better ways to do this (wrapping it into a function or raising an exception), but this works!

How do I use NSTimer?

there are a couple of ways of using a timer:

1) scheduled timer & using selector

NSTimer *t = [NSTimer scheduledTimerWithTimeInterval: 2.0
                      target: self
                      userInfo: nil repeats:NO];
  • if you set repeats to NO, the timer will wait 2 seconds before running the selector and after that it will stop;
  • if repeat: YES, the timer will start immediatelly and will repeat calling the selector every 2 seconds;
  • to stop the timer you call the timer's -invalidate method: [t invalidate];

As a side note, instead of using a timer that doesn't repeat and calls the selector after a specified interval, you could use a simple statement like this:

[self performSelector:@selector(onTick:) withObject:nil afterDelay:2.0];

this will have the same effect as the sample code above; but if you want to call the selector every nth time, you use the timer with repeats:YES;

2) self-scheduled timer

NSDate *d = [NSDate dateWithTimeIntervalSinceNow: 60.0];
NSTimer *t = [[NSTimer alloc] initWithFireDate: d
                              interval: 1
                              target: self
                              userInfo:nil repeats:YES];

NSRunLoop *runner = [NSRunLoop currentRunLoop];
[runner addTimer:t forMode: NSDefaultRunLoopMode];
[t release];
  • this will create a timer that will start itself on a custom date specified by you (in this case, after a minute), and repeats itself every one second

3) unscheduled timer & using invocation

NSMethodSignature *sgn = [self methodSignatureForSelector:@selector(onTick:)];
NSInvocation *inv = [NSInvocation invocationWithMethodSignature: sgn];
[inv setTarget: self];
[inv setSelector:@selector(onTick:)];

NSTimer *t = [NSTimer timerWithTimeInterval: 1.0

and after that, you start the timer manually whenever you need like this:

NSRunLoop *runner = [NSRunLoop currentRunLoop];
[runner addTimer: t forMode: NSDefaultRunLoopMode];

And as a note, onTick: method looks like this:

-(void)onTick:(NSTimer *)timer {
   //do smth

How do I tell a Python script to use a particular version

You can add a shebang line the to the top of the script:

#!/usr/bin/env python2.7

But that will only work when executing as ./

If you execute as python, then the whatever Python version that which python returns will be used.

In re: to virtualenv use: virtualenv -p /usr/bin/python3.2 or whatever to set it up to use that Python executable.

PHP session lost after redirect

If you are using Laravel and you experience this issue, what you need is to save your session data before redirecting.

// Redirect the user to the authorization URL.
header('Location: ' . $authorizationUrl);

Setting user agent of a java URLConnection

its work for me set the User-Agent in the addRequestProperty.

URL url = new URL(<URL>);
HttpURLConnection httpConn = (HttpURLConnection) url.openConnection();
httpConn.addRequestProperty("User-Agent","Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:56.0) Gecko/20100101 Firefox/56.0");

Enabling WiFi on Android Emulator

Apparently it does not and I didn't quite expect it would. HOWEVER Ivan brings up a good possibility that has escaped Android people.

What is the purpose of an emulator? to EMULATE, right? I don't see why for testing purposes -provided the tester understands the limitations- the emulator might not add a Wifi emulator.

It could for example emulate WiFi access by using the underlying internet connection of the host. Obviously testing WPA/WEP differencess would not make sense but at least it could toggle access via WiFi.

Or some sort of emulator plugin where there would be a base WiFi emulator that would emulate WiFi access via the underlying connection but then via configuration it could emulate WPA/WEP by providing a list of fake WiFi networks and their corresponding fake passwords that would be matched against a configurable list of credentials.

After all the idea is to do initial testing on the emulator and then move on to the actual device.

Spring Boot application can't resolve the org.springframework.boot package

Try this, It might work for you too.

  1. Open command prompt and go to the project folder.
  2. Build project (For Maven, Run mvn clean install)
  3. After successful build,
    • Open your project on any IDE (intellij / eclipse).
    • Restart your IDE incase it is already opened.

This worked for me on both v1.5 and v2.1

Using setDate in PreparedStatement

❐ Using java.sql.Date

If your table has a column of type DATE:

  • java.lang.String

    The method java.sql.Date.valueOf(java.lang.String) received a string representing a date in the format yyyy-[m]m-[d]d. e.g.:

    ps.setDate(2, java.sql.Date.valueOf("2013-09-04"));
  • java.util.Date

    Suppose you have a variable endDate of type java.util.Date, you make the conversion thus:

    ps.setDate(2, new java.sql.Date(endDate.getTime());
  • Current

    If you want to insert the current date:

    ps.setDate(2, new java.sql.Date(System.currentTimeMillis()));
    // Since Java 8
    ps.setDate(2, java.sql.Date.valueOf(;

❐ Using java.sql.Timestamp

If your table has a column of type TIMESTAMP or DATETIME:

  • java.lang.String

    The method java.sql.Timestamp.valueOf(java.lang.String) received a string representing a date in the format yyyy-[m]m-[d]d hh:mm:ss[.f...]. e.g.:

    ps.setTimestamp(2, java.sql.Timestamp.valueOf("2013-09-04 13:30:00");
  • java.util.Date

    Suppose you have a variable endDate of type java.util.Date, you make the conversion thus:

    ps.setTimestamp(2, new java.sql.Timestamp(endDate.getTime()));
  • Current

    If you require the current timestamp:

    ps.setTimestamp(2, new java.sql.Timestamp(System.currentTimeMillis()));
    // Since Java 8
    ps.setTimestamp(2, java.sql.Timestamp.from(;
    ps.setTimestamp(2, java.sql.Timestamp.valueOf(;

How to print a list in Python "nicely"

You mean something like...:

>>> print L
['this', 'is', 'a', ['and', 'a', 'sublist', 'too'], 'list', 'including', 'many', 'words', 'in', 'it']
>>> import pprint
>>> pprint.pprint(L)
 ['and', 'a', 'sublist', 'too'],

...? From your cursory description, standard library module pprint is the first thing that comes to mind; however, if you can describe example inputs and outputs (so that one doesn't have to learn PHP in order to help you;-), it may be possible for us to offer more specific help!

MongoDB distinct aggregation

Distinct and the aggregation framework are not inter-operable.

Instead you just want:

    {$group:{_id:{city:'$city', state:'$state'}, numberOfzipcodes:{$sum:1}}}, 
    {$group:{_id:'$_id.state', city:{$first:'$'}, 

How to dockerize maven project? and how many ways to accomplish it?

As a rule of thumb, you should build a fat JAR using Maven (a JAR that contains both your code and all dependencies).

Then you can write a Dockerfile that matches your requirements (if you can build a fat JAR you would only need a base os, like CentOS, and the JVM).

This is what I use for a Scala app (which is Java-based).

FROM centos:centos7

# Prerequisites.

RUN yum -y update
RUN yum -y install wget tar

# Oracle Java 7


RUN wget --no-cookies --no-check-certificate --header "Cookie:; oraclelicense=accept-securebackup-cookie"
RUN tar xzf server-jre-7u71-linux-x64.tar.gz
RUN rm -rf server-jre-7u71-linux-x64.tar.gz
RUN alternatives --install /usr/bin/java java /opt/jdk1.7.0_71/bin/java 1

# App

USER daemon

# This copies to local fat jar inside the image
ADD /local/path/to/packaged/app/appname.jar /app/appname.jar

# What to run when the container starts
ENTRYPOINT [ "java", "-jar", "/app/appname.jar" ]

# Ports used by the app

This creates a CentOS-based image with Java7. When started, it will execute your app jar.

The best way to deploy it is via the Docker Registry, it's like a Github for Docker images.

You can build an image like this:

# current dir must contain the Dockerfile
docker build -t username/projectname:tagname .

You can then push an image in this way:

docker push username/projectname # this pushes all tags

Once the image is on the Docker Registry, you can pull it from anywhere in the world and run it.

See Docker User Guide for more informations.

Something to keep in mind:

You could also pull your repository inside an image and build the jar as part of the container execution, but it's not a good approach, as the code could change and you might end up using a different version of the app without notice.

Building a fat jar removes this issue.

What are CN, OU, DC in an LDAP search?

I want to add somethings different from definitions of words. Most of them will be visual.

Technically, LDAP is just a protocol that defines the method by which directory data is accessed.Necessarily, it also defines and describes how data is represented in the directory service

Data is represented in an LDAP system as a hierarchy of objects, each of which is called an entry. The resulting tree structure is called a Directory Information Tree (DIT). The top of the tree is commonly called the root (a.k.a base or the suffix).the Data (Information) Model

To navigate the DIT we can define a path (a DN) to the place where our data is (cn=DEV-India,ou=Distrubition Groups,dc=gp,dc=gl,dc=google,dc=com will take us to a unique entry) or we can define a path (a DN) to where we think our data is (say, ou=Distrubition Groups,dc=gp,dc=gl,dc=google,dc=com) then search for the attribute=value or multiple attribute=value pairs to find our target entry (or entries).

enter image description here

If you want to get more depth information, you visit here

How to set lifetime of session

As long as the User does not delete their cookies or close their browser, the session should stay in existence.

Eclipse jump to closing brace

With Ctrl + Shift + L you can open the "key assist", where you can find all the shortcuts.

Switch case with fallthrough?

  • Do not use () behind function names in bash unless you like to define them.
  • use [23] in case to match 2 or 3
  • static string cases should be enclosed by '' instead of ""

If enclosed in "", the interpreter (needlessly) tries to expand possible variables in the value before matching.

case "$C" in

For case insensitive matching, you can use character classes (like [23]):

case "$C" in

# will match C='Abra' and C='abra'

# will match all letter cases at any char like `abra`, `ABRA` or `AbRa`


But abra didn't hit anytime because it will be matched by the first case.

If needed, you can omit ;; in the first case to continue testing for matches in following cases too. (;; jumps to esac)

Remove HTML Tags from an NSString on the iPhone

Another one way:


-(NSString *) stringByStrippingHTML:(NSString*)inputString;


(NSString *) stringByStrippingHTML:(NSString*)inputString
NSAttributedString *attrString = [[NSAttributedString alloc] initWithData:[inputString dataUsingEncoding:NSUTF8StringEncoding] options:@{NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType,NSCharacterEncodingDocumentAttribute: @(NSUTF8StringEncoding)} documentAttributes:nil error:nil];
NSString *str= [attrString string]; 

//you can add here replacements as your needs:
    [str stringByReplacingOccurrencesOfString:@"[" withString:@""];
    [str stringByReplacingOccurrencesOfString:@"]" withString:@""];
    [str stringByReplacingOccurrencesOfString:@"\n" withString:@""];

    return str;


cell.exampleClass.text = [self stringByStrippingHTML:[exampleJSONParsingArray valueForKey: @"key"]];

or simple

NSString *myClearStr = [self stringByStrippingHTML:rudeStr];

Python subprocess/Popen with a modified environment

The env parameter accepts a dictionary. You can simply take os.environ, add a key (your desired variable) (to a copy of the dict if you must) to that and use it as a parameter to Popen.

Converting any string into camel case

EDIT: Now working in IE8 without changes.

EDIT: I was in the minority about what camelCase actually is (Leading character lowercase vs. uppercase.). The community at large believes a leading lowercase is camel case and a leading capital is pascal case. I have created two functions that use regex patterns only. :) So we use a unified vocabulary I have changed my stance to match the majority.

All I believe you need is a single regex in either case:

var camel = " THIS is camel case "
camel = $.trim(camel)
    .replace(/[^A-Za-z]/g,' ') /* clean up non-letter characters */
    .replace(/(.)/g, function(a, l) { return l.toLowerCase(); })
    .replace(/(\s.)/g, function(a, l) { return l.toUpperCase(); })
// Returns "thisIsCamelCase"


var pascal = " this IS pascal case "
pascal = $.trim(pascal)
  .replace(/[^A-Za-z]/g,' ') /* clean up non-letter characters */
  .replace(/(.)/g, function(a, l) { return l.toLowerCase(); })
  .replace(/(^.|\s.)/g, function(a, l) { return l.toUpperCase(); })
// Returns "ThisIsPascalCase"

In functions: You will notice that in these functions the replace is swapping any non a-z with a space vs an empty string. This is to create word boundaries for capitalization. "hello-MY#world" -> "HelloMyWorld"

// remove \u00C0-\u00ff] if you do not want the extended letters like é
function toCamelCase(str) {
    var retVal = '';

    retVal = $.trim(str)
      .replace(/[^A-Za-z]/g, ' ') /* clean up non-letter characters */
      .replace(/(.)/g, function (a, l) { return l.toLowerCase(); })
      .replace(/(\s.)/g, function (a, l) { return l.toUpperCase(); })
      .replace(/[^A-Za-z\u00C0-\u00ff]/g, '');

    return retVal

function toPascalCase(str) {
    var retVal = '';

    retVal = $.trim(str)
      .replace(/[^A-Za-z]/g, ' ') /* clean up non-letter characters */
      .replace(/(.)/g, function (a, l) { return l.toLowerCase(); })
      .replace(/(^.|\s.)/g, function (a, l) { return l.toUpperCase(); })
      .replace(/[^A-Za-z\u00C0-\u00ff]/g, '');

    return retVal


  • I left A-Za-z vs adding the case insensitivity flag (i) to the pattern (/[^A-Z]/ig) for readability.
  • This works in IE8 (srsly, who uses IE8 anymore.) Using the (F12) dev tools I have tested in IE11, IE10, IE9, IE8, IE7 and IE5. Works in all document modes.
  • This will correctly case the first letter of strings starting with or without whitespace.


How to iterate over a std::map full of strings in C++

Another worthy optimization is the c_str ( ) member of the STL string classes, which returns an immutable null terminated string that can be passed around as a LPCTSTR, e. g., to a custom function that expects a LPCTSTR. Although I haven't traced through the destructor to confirm it, I suspect that the string class looks after the memory in which it creates the copy.

How does autowiring work in Spring?

There are 3 ways you can create an instance using @Autowired.

1. @Autowired on Properties

The annotation can be used directly on properties, therefore eliminating the need for getters and setters:

    public class UserService {

        public String getName() {
            return "service name";

    public class UserController {

        UserService userService


In the above example, Spring looks for and injects userService when UserController is created.

2. @Autowired on Setters

The @Autowired annotation can be used on setter methods. In the below example, when the annotation is used on the setter method, the setter method is called with the instance of userService when UserController is created:

public class UserController {

    private UserService userService;

    public void setUserService(UserService userService) {
            this.userService = userService;

3. @Autowired on Constructors

The @Autowired annotation can also be used on constructors. In the below example, when the annotation is used on a constructor, an instance of userService is injected as an argument to the constructor when UserController is created:

public class UserController {

    private UserService userService;

    public UserController(UserService userService) {
        this.userService= userService;

How to delete from select in MySQL?

  FROM posts AS p1 
) AS p2
USING (id)

convert strtotime to date time format in php

$unixtime = 1307595105;
echo $time = date("m/d/Y h:i:s A T",$unixtime);


How to embed a SWF file in an HTML page?

This one will work, I am sure!

<embed src="application.swf" quality="high" pluginspage="" type="application/x-shockwave-flash" width="690" height="430">

Adding sheets to end of workbook in Excel (normal method not working?)

Be sure to fully qualify your sheets with which workbook they are referencing!

 mainWB.Sheets.Add(After:=mainWB.Sheets(mainWB.Sheets.Count)).Name = new_sheet_name

Databound drop down list - initial value

I know this already has a chosen answer - but I wanted to toss in my two cents. I have a databound dropdown list:

  ConnectionString="<%$ ConnectionStrings:DBConnectionString %>"
  SelectCommand="SELECT CountryCode_PK, CountryCode_PK + ' - ' + Name AS N'Name' FROM TBL_Country ORDER BY CountryCode_PK"

In the codebehind, I have this - (which selects United States by default):

if (this.IsPostBack)
  //handle posted data
  country.SelectedValue = "US";

The page initially loads based on the 'US' value rather than trying to worry about a selectedIndex (what if another item is added into the data table - I don't want to have to re-code)

How to execute IN() SQL queries with Spring's JDBCTemplate effectively?

I do the "in clause" query with spring jdbc like this:

String sql = "SELECT bg.goodsid FROM beiker_goods bg WHERE bg.goodsid IN (:goodsid)";

List ids = Arrays.asList(new Integer[]{12496,12497,12498,12499});
Map<String, List> paramMap = Collections.singletonMap("goodsid", ids);
NamedParameterJdbcTemplate template = 
    new NamedParameterJdbcTemplate(getJdbcTemplate().getDataSource());

List<Long> list = template.queryForList(sql, paramMap, Long.class);

How to enable CORS in apache tomcat

Just to add a bit of extra info over the right solution. Be aware that you'll need this class org.apache.catalina.filters.CorsFilter. So in order to have it, if your tomcat is not 7.0.41 or higher, download 'tomcat-catalina.7.0.41.jar' or higher ( you can do it from ) and put it in the 'lib' folder inside Tomcat installation folders. I actually used 7.0.42 Hope it helps!

If list index exists, do X

A lot of answers, not the simple one.

To check if a index 'id' exists at dictionary dict:

dic = {}
dic['name'] = "joao"
dic['age']  = "39"

if 'age' in dic

returns true if 'age' exists.

Android Facebook integration with invalid key hash

According Facebook Login for Android, you must provide the key hash value. In order to obtain it, you will need the key used to sign your application.

keytool \
    -exportcert \
    -alias YourKeyAlias \
    -storepass YourStoreKeyPassword \
    -keystore PathToYourKeyStoreFile | openssl sha1 -binary | openssl base64

How to export settings?

For posterity, this post mentions,

in the latest release of Visual Studio Code (May 2016) it is now possible to list the installed extension in the command line

code --list-extensions

On Mac, execute something like:

"/Applications/Visual Studio" --list-extensions

To install, use:

--install-extension <ext> //see 'code --help'

Header div stays at top, vertical scrolling div below with scrollbar only attached to that div

Found the flex magic.

Here's an example of how to do a fixed header and a scrollable content. Code:

<!DOCTYPE html>
<html style="height: 100%">
    <meta charset=utf-8 />
    <title>Holy Grail</title>
    <!-- Reset browser defaults -->
    <link rel="stylesheet" href="reset.css">
  <body style="display: flex; height: 100%; flex-direction: column">
    <div style="flex: 1; overflow: auto">
        CONTENT - START<br/>
        for (var i=0 ; i<1000 ; ++i) {
          document.write(" Very long content!");
        <br/>CONTENT - END

* The advantage of the flex solution is that the content is independent of other parts of the layout. For example, the content doesn't need to know height of the header.

For a full Holy Grail implementation (header, footer, nav, side, and content), using flex display, go to here.

How to load data to hive from HDFS without removing the source file?

I found that, when you use EXTERNAL TABLE and LOCATION together, Hive creates table and initially no data will present (assuming your data location is different from the Hive 'LOCATION').

When you use 'LOAD DATA INPATH' command, the data get MOVED (instead of copy) from data location to location that you specified while creating Hive table.

If location is not given when you create Hive table, it uses internal Hive warehouse location and data will get moved from your source data location to internal Hive data warehouse location (i.e. /user/hive/warehouse/).

How to uninstall Golang?

  1. Go to the directory

    cd /usr/local
  2. Remove it with super user privileges

    sudo rm -rf go

Jquery insert new row into table at a certain index


$('#my_table > tbody:last').append(newRow); // this will add new row inside tbody

$("table#myTable tr").last().after(newRow);  // this will add new row outside tbody 
                                             //i.e. between thead and tbody
                                             //.before() will also work similar

How to get a random number in Ruby

Well, I figured it out. Apparently there is a builtin (?) function called rand:

rand(n + 1)

If someone answers with a more detailed answer, I'll mark that as the correct answer.

how to set windows service username and password through commandline

This works:

sc.exe config "[servicename]" obj= "[.\username]" password= "[password]"

Where each of the [bracketed] items are replaced with the true arguments. (Keep the quotes, but don't keep the brackets.)

Just keep in mind that:

  • The spacing in the above example matters. obj= "foo" is correct; obj="foo" is not.
  • '.' is an alias to the local machine, you can specify a domain there (or your local computer name) if you wish.
  • Passwords aren't validated until the service is started
  • Quote your parameters, as above. You can sometimes get by without quotes, but good luck.

How to change the text on the action bar

Update: Latest ActionBar (Title) pattern:

FYI, ActionBar was introduced in API Level 11. ActionBar is a window feature at the top of the Activity that may display the activity title, navigation modes, and other interactive items like search.

I exactly remember about customizing title bar and making it consistent through the application. So I can make a comparison with the earlier days and can list some of the advantages of using ActionBar:

  1. It offers your users a familiar interface across applications that the system gracefully adapts for different screen configurations.
  2. Developers don't need to write much code for displaying the Activity Title, icons and navigation modes because ActionBar is already ready with top level abstraction.

For example:

enter image description here

enter image description here

=> Normal way,

getActionBar().setTitle("Hello world App");   
getSupportActionBar().setTitle("Hello world App");  // provide compatibility to all the versions

=> Customizing Action Bar,

For example:

public void setActionBar(String heading) {
    // TODO Auto-generated method stub actionBar = getSupportActionBar();
    actionBar.setBackgroundDrawable(new ColorDrawable(getResources().getColor(R.color.title_bar_gray)));


Styling the Action Bar:

The ActionBar provides you with basic and familiar looks, navigation modes and other quick actions to perform. But that doesn't mean it looks the same in every app. You can customize it as per your UI and design requirements. You just have to define and write styles and themes.

Read more at: Styling the Action Bar

And if you want to generate styles for ActionBar then this Style Generator tool can help you out.


Old: Earlier days:

=> Normal way,

you can Change the Title of each screen (i.e. Activity) by setting their Android:label

   <activity android:name=".Hello_World"
                  android:label="This is the Hello World Application">

=> Custom - Title - bar

But if you want to Customize title-bar in your own way, i.e. Want to put Image icon and custom-text, then the following code works for me:


<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android=""


<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android=""

<ImageView android:id="@+id/ImageView01" 


  android:text="This is my new title" 

public class TitleBar extends Activity {

    public void onCreate(Bundle savedInstanceState) {
        final boolean customTitleSupported = 
        if (customTitleSupported) {
        final TextView myTitleText = (TextView) findViewById(;
        if (myTitleText != null) {
            myTitleText.setText("NEW TITLE");
            // user can also set color using "Color" and then
            // "Color value constant"
            // myTitleText.setBackgroundColor(Color.GREEN);


The strings.xml file is defined under the values folder.

<?xml version="1.0" encoding="utf-8"?>
    <string name="hello">Hello World, Set_Text_TitleBar!</string>
    <string name="app_name">Set_Text_TitleBar</string>
    <color name="titlebackgroundcolor">#3232CD</color>
    <color name="titletextcolor">#FFFF00</color>

CSS show div background image on top of other contained elements

How about making the <div id="mainWrapperDivWithBGImage"> as three divs, where the two outside divs hold the rounded corners images, and the middle div simply has a background-color to match the rounded corner images. Then you could simply place the other elements inside the middle div, or:

#outside_left{width:10px; float:left;}
#outside_right{width:10px; float:right;}
#middle{background-color:#color of rnd_crnrs_foo.gif; float:left;}



<div id="mainWrapperDivWithBGImage">
  <div id="outside_left><img src="rnd_crnrs_left.gif" /></div>
  <div id="middle">
    <div id="another_div"><img src="foo.gif" /></div>
  <div id="outside_right><img src="rnd_crnrs_right.gif" /></div>

You may have to do position:relative; and such.

Authentication failed for

Control Panel --> Credential Manager --> Manage Windows Credentials --> Choose the entry of the git repository, and Edit the user and password. Delete '. git/config' and try again. Attention this will may reset some git settings too!

Specify a Root Path of your HTML directory for script links?

As Alexander Jank mentioned <base href=""> is great. When using sub-domains e.g. base works great, because the JS and CSS loads from the said sub-domain and is accessible to both and

When using the root path, and your JS and CSS files are located in, or, then the subdomain has no access and the root of the subdomain is not accessible, except using the base.

jquery - Click event not working for dynamically created button

the simple and easy way to do that is use on event:


but we can say this is not the best way to do this. I suggest a another way to do this is use clone() method instead of using dynamic html. Write some html in you file for example:

<div id='div1'></div>

Now in the script tag make a clone of this div then all the properties of this div would follow with new element too. For Example:

var dynamicDiv = jQuery('#div1').clone(true);

Now use the element dynamicDiv wherever you want to add it or change its properties as you like. Now all jQuery functions will work with this element

c# datagridview doubleclick on row with FullRowSelect

This will work, make sure your control Event is assigned to this code, it has probably been lost, I also noticed that Double click will only work if the cell is not empty. Try double clicking on a cell with content, don't mess with the designer

 private void dgvReport_CellContentDoubleClick(object sender, DataGridViewCellEventArgs e)

   //do something


wkhtmltopdf: cannot connect to X server

sudo -i
apt-get install wkhtmltopdf xvfb libicu48
mv /usr/bin/wkhtmltopdf /usr/bin/wkhtmltopdf-origin
touch /usr/bin/wkhtmltopdf && chmod +x /usr/bin/wkhtmltopdf && cat > /usr/bin/wkhtmltopdf << END

/usr/bin/xvfb-run -a -s "-screen 0 1024x768x24" /usr/bin/wkhtmltopdf-origin  "\$@"

How to markdown nested list items in Bitbucket?


  • It is possible to nest a bulleted-unnumbered list into a higher numbered list.
  • But in the bulleted-unnumbered list the automatically numbered list will not start: Its is not supported.
    • To start a new numbered list after a bulleted-unnumbered one, put a piece of text between them, or a subtitle: A new numbered list cannot start just behind the bulleted: The interpreter will not start the numbering.

in practice

  1. Dog

    1. German Shepherd - with only a single space ahead.
    2. Belgian Shepherd - max 4 spaces ahead.
      • Number in front of a line interpreted as a "numbering bullet", so making the indentation.
        • ..and ignores the written digit: Places/generates its own, in compliance with the structure.
        • So it is OK to use only just "1" ones, to get your numbered list.
          • Or whatever integer number, even of more digits: The list numbering will continue by increment ++1.
        • However, the first item in the numbered list will be kept, so the first leading will usually be the number "1".
    3. Malinois - 5 spaces makes 3rd level already.
      1. MalinoisB - 5 spaces makes 3rd level already.
      2. Groenendael - 8 spaces makes 3rd level yet too.
        1. Tervuren - 9 spaces for 4th level - Intentionaly started by "55".
        2. TervurenB - numbered by "88", in the source code.
  2. Cat

    1. Siberian; a. SiberianA - problem reproduced: letters (i.e. "a" here) not recognized by the interpreter as "numbering".
      • No matter, it is indented to its separated line, in the source code.
    2. Siamese
      • a. so written manually as a workaround misusing bullets, unnumbered list.

Make hibernate ignore class variables that are not mapped

Placing @Transient on getter with private field worked for me.

private String name;

    public String getName() {
        return name;

    public void setName(String name) { = name;

Best way to move files between S3 buckets?


As pointed out by alberge (+1), nowadays the excellent AWS Command Line Interface provides the most versatile approach for interacting with (almost) all things AWS - it meanwhile covers most services' APIs and also features higher level S3 commands for dealing with your use case specifically, see the AWS CLI reference for S3:

  • sync - Syncs directories and S3 prefixes. Your use case is covered by Example 2 (more fine grained usage with --exclude, --include and prefix handling etc. is also available):

    The following sync command syncs objects under a specified prefix and bucket to objects under another specified prefix and bucket by copying s3 objects. [...]

    aws s3 sync s3://from_my_bucket s3://to_my_other_bucket

For completeness, I'll mention that the lower level S3 commands are also still available via the s3api sub command, which would allow to directly translate any SDK based solution to the AWS CLI before adopting its higher level functionality eventually.

Initial Answer

Moving files between S3 buckets can be achieved by means of the PUT Object - Copy API (followed by DELETE Object):

This implementation of the PUT operation creates a copy of an object that is already stored in Amazon S3. A PUT copy operation is the same as performing a GET and then a PUT. Adding the request header, x-amz-copy-source, makes the PUT operation copy the source object into the destination bucket. Source

There are respective samples for all existing AWS SDKs available, see Copying Objects in a Single Operation. Naturally, a scripting based solution would be the obvious first choice here, so Copy an Object Using the AWS SDK for Ruby might be a good starting point; if you prefer Python instead, the same can be achieved via boto as well of course, see method copy_key() within boto's S3 API documentation.

PUT Object only copies files, so you'll need to explicitly delete a file via DELETE Object still after a successful copy operation, but that will be just another few lines once the overall script handling the bucket and file names is in place (there are respective examples as well, see e.g. Deleting One Object Per Request).

When to use <span> instead <p>?

Span is completely non-semantic. It has no meaning, and serves merely as an element for cosmetic effects.

Paragraphs have semantic meaning - they tell a machine (like a browser or a screen reader) that the content they encapsulate is a block of text, and has the same meaning as a paragraph of text in a book.

Make the first character Uppercase in CSS

Make it lowercase first:

.m_title {text-transform: lowercase}

Then make it the first letter uppercase:

.m_title:first-letter {text-transform: uppercase}

"text-transform: capitalize" works for a word; but if you want to use for sentences this solution is perfect.

Minimal web server using netcat

The problem you are facing is that nc does not know when the web client is done with its request so it can respond to the request.
A web session should go something like this.

TCP session is established.
Browser Request Header: GET / HTTP/1.1
Browser Request Header: Host:
Browser Request Header: \n #Note: Browser is telling Webserver that the request header is complete.
Server Response Header: HTTP/1.1 200 OK
Server Response Header: Content-Type: text/html
Server Response Header: Content-Length: 24
Server Response Header: \n #Note: Webserver is telling browser that response header is complete 
Server Message Body: <html>sample html</html>
Server Message Body: \n #Note: Webserver is telling the browser that the requested resource is finished. 
The server closes the TCP session.

Lines that begin with "\n" are simply empty lines without even a space and contain nothing more than a new line character.

I have my bash httpd launched by xinetd, xinetd tutorial. It also logs date, time, browser IP address, and the entire browser request to a log file, and calculates Content-Length for the Server header response.

user@machine:/usr/local/bin# cat ./bash_httpd
Log=$( echo -n "["$(date "+%F %T %Z")"] $REMOTE_HOST ")$(
        while read I[$x] && [ ${#I[$x]} -gt 1 ];do
              echo -n '"'${I[$x]} | sed -e's,.$,",'; let "x = $x + 1";
        done ;
); echo $Log >> /var/log/bash_httpd

Message_Body=$(echo -en '<html>Sample html</html>')
echo -en "HTTP/1.0 200 OK\nContent-Type: text/html\nContent-Length: ${#Message_Body}\n\n$Message_Body"

To add more functionality, you could incorporate.

            METHOD=$(echo ${I[0]} |cut -d" " -f1)
            REQUEST=$(echo ${I[0]} |cut -d" " -f2)
            HTTP_VERSION=$(echo ${I[0]} |cut -d" " -f3)
            If METHOD = "GET" ]; then 
                case "$REQUEST" in

                    "/") Message_Body="HTML formatted home page stuff"
                    /who) Message_Body="HTML formatted results of who"
                    /ps) Message_Body="HTML formatted results of ps"
                    *) Message_Body= "Error Page not found header and content"


Happy bashing!

Javascript array sort and unique

function sort() only is only good if your number has same digit, example:

var myData = ["3","11","1","2"]

will return;

var myData = ["1","11","2","3"]

and here improvement for function from mrmonkington

myData.sort().sort(function(a,b){return a - b;}).filter(function(el,i,a){if(i==a.indexOf(el) & el.length>0)return 1;return 0;})

the above function will also delete empty array and you can checkout the demo below

Compare two dates with JavaScript

Compare < and > just as usual, but anything involving = should use a + prefix. Like so:

var x = new Date('2013-05-23');
var y = new Date('2013-05-23');

// less than, greater than is fine:
x < y; => false
x > y; => false
x === y; => false, oops!

// anything involving '=' should use the '+' prefix
// it will then compare the dates' millisecond values
+x <= +y;  => true
+x >= +y;  => true
+x === +y; => true

pandas groupby sort descending order

Other instance of preserving the order or sort by descending:

In [97]: import pandas as pd                                                                                                    

In [98]: df = pd.DataFrame({'name':['A','B','C','A','B','C','A','B','C'],'Year':[2003,2002,2001,2003,2002,2001,2003,2002,2001]})

#### Default groupby operation:
In [99]: for each in df.groupby(["Year"]): print each                                                                           
(2001,    Year name
2  2001    C
5  2001    C
8  2001    C)
(2002,    Year name
1  2002    B
4  2002    B
7  2002    B)
(2003,    Year name
0  2003    A
3  2003    A
6  2003    A)

### order preserved:
In [100]: for each in df.groupby(["Year"], sort=False): print each                                                               
(2003,    Year name
0  2003    A
3  2003    A
6  2003    A)
(2002,    Year name
1  2002    B
4  2002    B
7  2002    B)
(2001,    Year name
2  2001    C
5  2001    C
8  2001    C)

In [106]: df.groupby(["Year"], sort=False).apply(lambda x: x.sort_values(["Year"]))                        
        Year name
2003 0  2003    A
     3  2003    A
     6  2003    A
2002 1  2002    B
     4  2002    B
     7  2002    B
2001 2  2001    C
     5  2001    C
     8  2001    C

In [107]: df.groupby(["Year"], sort=False).apply(lambda x: x.sort_values(["Year"])).reset_index(drop=True)
   Year name
0  2003    A
1  2003    A
2  2003    A
3  2002    B
4  2002    B
5  2002    B
6  2001    C
7  2001    C
8  2001    C

How can I show dots ("...") in a span with hidden overflow?

Well, the "text-overflow: ellipsis" worked for me, but just if my limit was based on 'width', I has needed a solution that can be applied on lines ( on the'height' instead the 'width' ) so I did this script:

function listLimit (elm, line){
    var maxHeight = parseInt(elm.css('line-Height'))*line;

    while(elm.height() > maxHeight){
        var text = elm.text();

And when I must, for example, that my h3 has only 2 lines I do :

   listLimit ($(this), 2)

I dunno if that was the best practice for performance needs, but worked for me.

How to get the current directory of the cmdlet being executed

You can also use:

(Resolve-Path .\).Path

The part in brackets returns a PathInfo object.

(Available since PowerShell 2.0.)

CSS Resize/Zoom-In effect on Image while keeping Dimensions

You could achieve that simply by wrapping the image by a <div> and adding overflow: hidden to that element:

<div class="img-wrapper">
    <img src="..." />
.img-wrapper {
    display: inline-block; /* change the default display type to inline-block */
    overflow: hidden;      /* hide the overflow */


Also it's worth noting that <img> element (like the other inline elements) sits on its baseline by default. And there would be a 4~5px gap at the bottom of the image.

That vertical gap belongs to the reserved space of descenders like: g j p q y. You could fix the alignment issue by adding vertical-align property to the image with a value other than baseline.

Additionally for a better user experience, you could add transition to the images.

Thus we'll end up with the following:

.img-wrapper img {
    transition: all .2s ease;
    vertical-align: middle;


How to convert a string or integer to binary in Ruby?

I asked a similar question. Based on @sawa's answer, the most succinct way to represent an integer in a string in binary format is to use the string formatter:

"%b" % 245
=> "11110101"

You can also choose how long the string representation to be, which might be useful if you want to compare fixed-width binary numbers:

1.upto(10).each { |n| puts "%04b" % n }

How to add ID property to Html.BeginForm() in mvc?

This should get the id added.

ASP.NET MVC 5 and lower:

<% using (Html.BeginForm(null, null, FormMethod.Post, new { id = "signupform" }))
   { } %>

ASP.NET Core: You can use tag helpers in forms to avoid the odd syntax for setting the id.

<form asp-controller="Account" asp-action="Register" method="post" id="signupform" role="form"></form>

Displaying one div on top of another

Here is the jsFiddle

    border: 2px solid red;
    width: 400px;
    height: 200px;
    position: absolute;

#curtain {
    border: 1px solid blue;
    width: 400px;
    height: 200px;
    position: absolute;

Use Z-index to move the one you want on top.

sendmail: how to configure sendmail on ubuntu?

Combine two answers above, I finally make it work. Just be careful that the first single quote for each string is a backtick (`) in file

#Change to your mail config directory:
cd /etc/mail

#Make a auth subdirectory
mkdir auth
chmod 700 auth  #maybe not, because I cannot apply cmd "cd auth" if I do so.

#Create a file with your auth information to the smtp server
cd auth
touch client-info

#In the file, put the following, matching up to your smtp server: "U:root" "I:user" "P:password"

#Generate the Authentication database, make both files readable only by root
makemap hash client-info < client-info
chmod 600 client-info
cd ..

#Add the following lines to Make sure you update your smtp server
#The first single quote for each string should be changed to a backtick (`) like this:
FEATURE(`authinfo',`hash /etc/mail/auth/client-info')dnl

sudo sendmailconfig

How to print exact sql query in zend framework ?

Select objects have a __toString() method in Zend Framework.

From the Zend Framework manual:

$select = $db->select()

$sql = $select->__toString();
echo "$sql\n";

// The output is the string:
//   SELECT * FROM "products"

An alternative solution would be to use the Zend_Db_Profiler. i.e.


// your code
$this->update($up_value,'customer_id ='.$userid.' and address_id <> '.$data['address_Id']); 


how to exit a python script in an if statement

This works fine for me:

while True:
   answer = input('Do you want to continue?:')
   if answer.lower().startswith("y"):
      print("ok, carry on then")
   elif answer.lower().startswith("n"):
      print("sayonara, Robocop")

edit: use input in python 3.2 instead of raw_input

Terminating a script in PowerShell

I realize this is an old post but I find myself coming back to this thread a lot as it is one of the top search results when searching for this topic. However, I always leave more confused then when I came due to the conflicting information. Ultimately I always have to perform my own tests to figure it out. So this time I will post my findings.

TL;DR Most people will want to use Exit to terminate a running scripts. However, if your script is merely declaring functions to later be used in a shell, then you will want to use Return in the definitions of said functions.

Exit vs Return vs Break

  • Exit: This will "exit" the currently running context. If you call this command from a script it will exit the script. If you call this command from the shell it will exit the shell.

    If a function calls the Exit command it will exit what ever context it is running in. So if that function is only called from within a running script it will exit that script. However, if your script merely declares the function so that it can be used from the current shell and you run that function from the shell, it will exit the shell because the shell is the context in which the function contianing the Exit command is running.

    Note: By default if you right click on a script to run it in PowerShell, once the script is done running, PowerShell will close automatically. This has nothing to do with the Exit command or anything else in your script. It is just a default PowerShell behavior for scripts being ran using this specific method of running a script. The same is true for batch files and the Command Line window.

  • Return: This will return to the previous call point. If you call this command from a script (outside any functions) it will return to the shell. If you call this command from the shell it will return to the shell (which is the previous call point for a single command ran from the shell). If you call this command from a function it will return to where ever the function was called from.

    Execution of any commands after the call point that it is returned to will continue from that point. If a script is called from the shell and it contains the Return command outside any functions then when it returns to the shell there are no more commands to run thus making a Return used in this way essentially the same as Exit.

  • Break: This will break out of loops and switch cases. If you call this command while not in a loop or switch case it will break out of the script. If you call Break inside a loop that is nested inside a loop it will only break out of the loop it was called in.

    There is also an interesting feature of Break where you can prefix a loop with a label and then you can break out of that labeled loop even if the Break command is called within several nested groups within that labeled loop.

    While ($true) {
        # Code here will run
        :myLabel While ($true) {
            # Code here will run
            While ($true) {
                # Code here will run
                While ($true) {
                    # Code here will run
                    Break myLabel
                    # Code here will not run
                # Code here will not run
            # Code here will not run
        # Code here will run

Can I convert a C# string value to an escaped string literal

Hallgrim's answer is excellent, but the "+", newline and indent additions were breaking functionality for me. An easy way around it is:

private static string ToLiteral(string input)
    using (var writer = new StringWriter())
        using (var provider = CodeDomProvider.CreateProvider("CSharp"))
            provider.GenerateCodeFromExpression(new CodePrimitiveExpression(input), writer, new CodeGeneratorOptions {IndentString = "\t"});
            var literal = writer.ToString();
            literal = literal.Replace(string.Format("\" +{0}\t\"", Environment.NewLine), "");
            return literal;

Android Eclipse - Could not find *.apk

Run Eclipse as "Administrator" and then import the project.

fatal: does not appear to be a git repository

I was facing same issue with my one of my feature branch. I tried above mentioned solution nothing worked. I resolved this issue by doing following things.

  • git pull origin feature-branch-name
  • git push

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

It entirely depends upon the Certificate Authority who issuing a certificate.

As far as Let's Encrypt CA, they wont issue TLS certificate on public IP address.

To know your Certificate authority , you can execute following command and look for an entry marked below.

curl -v -u <username>:<password> "https://IPaddress/.."

enter image description here

Difference between <input type='submit' /> and <button type='submit'>text</button>

Not sure where you get your legends from but:

Submit button with <button>

As with:

<button type="submit">(html content)</button>

IE6 will submit all text for this button between the tags, other browsers will only submit the value. Using <button> gives you more layout freedom over the design of the button. In all its intents and purposes, it seemed excellent at first, but various browser quirks make it hard to use at times.

In your example, IE6 will send text to the server, while most other browsers will send nothing. To make it cross-browser compatible, use <button type="submit" value="text">text</button>. Better yet: don't use the value, because if you add HTML it becomes rather tricky what is received on server side. Instead, if you must send an extra value, use a hidden field.

Button with <input>

As with:

<input type="button" />

By default, this does next to nothing. It will not even submit your form. You can only place text on the button and give it a size and a border by means of CSS. Its original (and current) intent was to execute a script without the need to submit the form to the server.

Normal submit button with <input>

As with:

<input type="submit" />

Like the former, but actually submits the surrounding form.

Image submit button with <input>

As with:

<input type="image" />

Like the former (submit), it will also submit a form, but you can use any image. This used to be the preferred way to use images as buttons when a form needed submitting. For more control, <button> is now used. This can also be used for server side image maps but that's a rarity these days. When you use the usemap-attribute and (with or without that attribute), the browser will send the mouse-pointer X/Y coordinates to the server (more precisely, the mouse-pointer location inside the button of the moment you click it). If you just ignore these extras, it is nothing more than a submit button disguised as an image.

There are some subtle differences between browsers, but all will submit the value-attribute, except for the <button> tag as explained above.

How to change port for jenkins window service when 8080 is being used

In linux,

sudo vi /etc/sysconfig/jenkins

set following configuration with any available port


How can I add a background thread to flask?

Your additional threads must be initiated from the same app that is called by the WSGI server.

The example below creates a background thread that executes every 5 seconds and manipulates data structures that are also available to Flask routed functions.

import threading
import atexit
from flask import Flask

POOL_TIME = 5 #Seconds

# variables that are accessible from anywhere
commonDataStruct = {}
# lock to control access to variable
dataLock = threading.Lock()
# thread handler
yourThread = threading.Thread()

def create_app():
    app = Flask(__name__)

    def interrupt():
        global yourThread

    def doStuff():
        global commonDataStruct
        global yourThread
        with dataLock:
        # Do your stuff with commonDataStruct Here

        # Set the next thread to happen
        yourThread = threading.Timer(POOL_TIME, doStuff, ())

    def doStuffStart():
        # Do initialisation stuff here
        global yourThread
        # Create your thread
        yourThread = threading.Timer(POOL_TIME, doStuff, ())

    # Initiate
    # When you kill Flask (SIGTERM), clear the trigger for the next thread
    return app

app = create_app()          

Call it from Gunicorn with something like this:

gunicorn -b --log-config log.conf myfile:app

What do .c and .h file extensions mean to C?

Of course, there is nothing that says the extension of a header file must be .h and the extension of a C source file must be .c. These are useful conventions.

E:\Temp> type my.interface

E:\Temp> type my.source
#include <stdio.h>

#include "my.interface"

int main(void) {
    char x[MYBUFFERSIZE] = {0};
    x[0] = 'a';
    return 0;

E:\Temp> gcc -x c my.source -o my.exe

E:\Temp> my

SQL Server : fetching records between two dates?

Try this:

select * 
from xxx 
where dates >= '2012-10-26 00:00:00.000' and dates <= '2012-10-27 23:59:59.997'

How to configure WAMP (localhost) to send email using Gmail?

If you open the php.ini file in wamp, you will find these two lines:


Add the server and port number for your host (you may need to contact them for details)

The following two lines don't exist:


So you will need to add them to be able to send mail from a server that requires authentication. So an example may be:

smtp_server =
smtp_port = 26
auth_username = [email protected]
auth_password = example_password

How can I use inverse or negative wildcards when pattern matching in a unix/linux shell?

A trick I haven't seen on here yet that doesn't use extglob, find, or grep is to treat two file lists as sets and "diff" them using comm:

comm -23 <(ls) <(ls *Music*)

comm is preferable over diff because it doesn't have extra cruft.

This returns all elements of set 1, ls, that are not also in set 2, ls *Music*. This requires both sets to be in sorted order to work properly. No problem for ls and glob expansion, but if you're using something like find, be sure to invoke sort.

comm -23 <(find . | sort) <(find . | grep -i '.jpg' | sort)

Potentially useful.

How to access parent scope from within a custom directive *with own scope* in AngularJS?

Accessing controller method means accessing a method on parent scope from directive controller/link/scope.

If the directive is sharing/inheriting the parent scope then it is quite straight forward to just invoke a parent scope method.

Little more work is required when you want to access parent scope method from Isolated directive scope.

There are few options (may be more than listed below) to invoke a parent scope method from isolated directives scope or watch parent scope variables (option#6 specially).

Note that I used link function in these examples but you can use a directive controller as well based on requirement.

Option#1. Through Object literal and from directive html template


<!DOCTYPE html>
<html ng-app="plunker">

    <meta charset="utf-8" />
    <title>AngularJS Plunker</title>
    <script>document.write('<base href="' + document.location + '" />');</script>
    <link rel="stylesheet" href="style.css" />
    <script data-require="[email protected]" src="" data-semver="1.3.9"></script>
    <script src="app.js"></script>

  <body ng-controller="MainCtrl">
    <p>Hello {{name}}!</p>

    <p> Directive Content</p>
    <sd-items-filter selected-items="selectedItems" selected-items-changed="selectedItemsChanged(selectedItems)" items="items"> </sd-items-filter>

    <P style="color:red">Selected Items (in parent controller) set to: {{selectedItemsReturnedFromDirective}} </p>




<select ng-model="selectedItems" multiple="multiple" style="height: 200px; width: 250px;" ng-change="selectedItemsChanged({selectedItems:selectedItems})" ng-options=" as group by item.model for item in items | orderBy:'name'">


var app = angular.module('plunker', []);

app.directive('sdItemsFilter', function() {
  return {
    restrict: 'E',
    scope: {
      items: '=',
      selectedItems: '=',
      selectedItemsChanged: '&'
    templateUrl: "itemfilterTemplate.html"

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

  $scope.selectedItems = ["allItems"];

  $scope.selectedItemsChanged = function(selectedItems1) {
    $scope.selectedItemsReturnedFromDirective = selectedItems1;

  $scope.items = [{
    "id": "allItems",
    "name": "All Items",
    "order": 0
  }, {
    "id": "CaseItem",
    "name": "Case Item",
    "model": "PredefinedModel"
  }, {
    "id": "Application",
    "name": "Application",
    "model": "Bank"


working plnkr:

Option#2. Through Object literal and from directive link/scope


<!DOCTYPE html>
<html ng-app="plunker">

    <meta charset="utf-8" />
    <title>AngularJS Plunker</title>
    <script>document.write('<base href="' + document.location + '" />');</script>
    <link rel="stylesheet" href="style.css" />
    <script data-require="[email protected]" src="" data-semver="1.3.9"></script>
    <script src="app.js"></script>

  <body ng-controller="MainCtrl">
    <p>Hello {{name}}!</p>

    <p> Directive Content</p>
    <sd-items-filter selected-items="selectedItems" selected-items-changed="selectedItemsChanged(selectedItems)" items="items"> </sd-items-filter>

    <P style="color:red">Selected Items (in parent controller) set to: {{selectedItemsReturnedFromDirective}} </p>




<select ng-model="selectedItems" multiple="multiple" style="height: 200px; width: 250px;" 
 ng-change="selectedItemsChangedDir()" ng-options=" as group by item.model for item in items | orderBy:'name'">


var app = angular.module('plunker', []);

app.directive('sdItemsFilter', function() {
  return {
    restrict: 'E',
    scope: {
      items: '=',
      selectedItems: '=',
      selectedItemsChanged: '&'
    templateUrl: "itemfilterTemplate.html",
    link: function (scope, element, attrs){
      scope.selectedItemsChangedDir = function(){

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

  $scope.selectedItems = ["allItems"];

  $scope.selectedItemsChanged = function(selectedItems1) {
    $scope.selectedItemsReturnedFromDirective = selectedItems1;

  $scope.items = [{
    "id": "allItems",
    "name": "All Items",
    "order": 0
  }, {
    "id": "CaseItem",
    "name": "Case Item",
    "model": "PredefinedModel"
  }, {
    "id": "Application",
    "name": "Application",
    "model": "Bank"

working plnkr:

Option#3. Through Function reference and from directive html template


<!DOCTYPE html>
<html ng-app="plunker">

    <meta charset="utf-8" />
    <title>AngularJS Plunker</title>
    <script>document.write('<base href="' + document.location + '" />');</script>
    <link rel="stylesheet" href="style.css" />
    <script data-require="[email protected]" src="" data-semver="1.3.9"></script>
    <script src="app.js"></script>

  <body ng-controller="MainCtrl">
    <p>Hello {{name}}!</p>

    <p> Directive Content</p>
    <sd-items-filter selected-items="selectedItems" selected-items-changed="selectedItemsChanged" items="items"> </sd-items-filter>

    <P style="color:red">Selected Items (in parent controller) set to: {{selectedItemsReturnFromDirective}} </p>




<select ng-model="selectedItems" multiple="multiple" style="height: 200px; width: 250px;" 
 ng-change="selectedItemsChanged()(selectedItems)" ng-options=" as group by item.model for item in items | orderBy:'name'">


var app = angular.module('plunker', []);

app.directive('sdItemsFilter', function() {
  return {
    restrict: 'E',
    scope: {
      items: '=',
      selectedItemsChanged: '&'
    templateUrl: "itemfilterTemplate.html"

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

  $scope.selectedItems = ["allItems"];

  $scope.selectedItemsChanged = function(selectedItems1) {
    $scope.selectedItemsReturnFromDirective = selectedItems1;

  $scope.items = [{
    "id": "allItems",
    "name": "All Items",
    "order": 0
  }, {
    "id": "CaseItem",
    "name": "Case Item",
    "model": "PredefinedModel"
  }, {
    "id": "Application",
    "name": "Application",
    "model": "Bank"

working plnkr:

Option#4. Through Function reference and from directive link/scope


<!DOCTYPE html>
<html ng-app="plunker">

    <meta charset="utf-8" />
    <title>AngularJS Plunker</title>
    <script>document.write('<base href="' + document.location + '" />');</script>
    <link rel="stylesheet" href="style.css" />
    <script data-require="[email protected]" src="" data-semver="1.3.9"></script>
    <script src="app.js"></script>

  <body ng-controller="MainCtrl">
    <p>Hello {{name}}!</p>

    <p> Directive Content</p>
    <sd-items-filter selected-items="selectedItems" selected-items-changed="selectedItemsChanged" items="items"> </sd-items-filter>

    <P style="color:red">Selected Items (in parent controller) set to: {{selectedItemsReturnedFromDirective}} </p>




<select ng-model="selectedItems" multiple="multiple" style="height: 200px; width: 250px;" ng-change="selectedItemsChangedDir()" ng-options=" as group by item.model for item in items | orderBy:'name'">


var app = angular.module('plunker', []);

app.directive('sdItemsFilter', function() {
  return {
    restrict: 'E',
    scope: {
      items: '=',
      selectedItems: '=',
      selectedItemsChanged: '&'
    templateUrl: "itemfilterTemplate.html",
    link: function (scope, element, attrs){
      scope.selectedItemsChangedDir = function(){

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

  $scope.selectedItems = ["allItems"];

  $scope.selectedItemsChanged = function(selectedItems1) {
    $scope.selectedItemsReturnedFromDirective = selectedItems1;

  $scope.items = [{
    "id": "allItems",
    "name": "All Items",
    "order": 0
  }, {
    "id": "CaseItem",
    "name": "Case Item",
    "model": "PredefinedModel"
  }, {
    "id": "Application",
    "name": "Application",
    "model": "Bank"


working plnkr:

Option#5: Through ng-model and two way binding, you can update parent scope variables.. So, you may not require to invoke parent scope functions in some cases.


<!DOCTYPE html>
<html ng-app="plunker">

    <meta charset="utf-8" />
    <title>AngularJS Plunker</title>
    <script>document.write('<base href="' + document.location + '" />');</script>
    <link rel="stylesheet" href="style.css" />
    <script data-require="[email protected]" src="" data-semver="1.3.9"></script>
    <script src="app.js"></script>

  <body ng-controller="MainCtrl">
    <p>Hello {{name}}!</p>

    <p> Directive Content</p>
    <sd-items-filter ng-model="selectedItems" selected-items-changed="selectedItemsChanged" items="items"> </sd-items-filter>

    <P style="color:red">Selected Items (in parent controller) set to: {{selectedItems}} </p>




<select ng-model="selectedItems" multiple="multiple" style="height: 200px; width: 250px;" 
 ng-options=" as group by item.model for item in items | orderBy:'name'">


var app = angular.module('plunker', []);

app.directive('sdItemsFilter', function() {
  return {
    restrict: 'E',
    scope: {
      items: '=',
      selectedItems: '=ngModel'
    templateUrl: "itemfilterTemplate.html"

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

  $scope.selectedItems = ["allItems"];

  $scope.items = [{
    "id": "allItems",
    "name": "All Items",
    "order": 0
  }, {
    "id": "CaseItem",
    "name": "Case Item",
    "model": "PredefinedModel"
  }, {
    "id": "Application",
    "name": "Application",
    "model": "Bank"

working plnkr:

Option#6: Through $watch and $watchCollection It is two way binding for items in all above examples, if items are modified in parent scope, items in directive would also reflect the changes.

If you want to watch other attributes or objects from parent scope, you can do that using $watch and $watchCollection as given below


<!DOCTYPE html>
<html ng-app="plunker">

  <meta charset="utf-8" />
  <title>AngularJS Plunker</title>
    document.write('<base href="' + document.location + '" />');
  <link rel="stylesheet" href="style.css" />
  <script data-require="[email protected]" src="" data-semver="1.3.9"></script>
  <script src="app.js"></script>

<body ng-controller="MainCtrl">
  <p>Hello {{user}}!</p>
  <p>directive is watching name and current item</p>
        <input type="text" ng-model="id" />
        <input type="text" ng-model="name" />
        <input type="text" ng-model="model" />

  <button style="margin-left:50px" type="buttun" ng-click="addItem()">Add Item</button>

  <p>Directive Contents</p>
  <sd-items-filter ng-model="selectedItems" current-item="currentItem" name="{{name}}" selected-items-changed="selectedItemsChanged" items="items"></sd-items-filter>

  <P style="color:red">Selected Items (in parent controller) set to: {{selectedItems}}</p>


script app.js

var app = angular.module('plunker', []);

app.directive('sdItemsFilter', function() {
  return {
    restrict: 'E',
    scope: {
      name: '@',
      currentItem: '=',
      items: '=',
      selectedItems: '=ngModel'
    template: '<select ng-model="selectedItems" multiple="multiple" style="height: 140px; width: 250px;"' +
      'ng-options=" as group by item.model for item in items | orderBy:\'name\'">' +
      '<option>--</option> </select>',
    link: function(scope, element, attrs) {
      scope.$watchCollection('currentItem', function() {
      scope.$watch('name', function() {

 app.controller('MainCtrl', function($scope) {
  $scope.user = 'World';

  $scope.addItem = function() {
      id: $,
      name: $,
      model: $scope.model
    $scope.currentItem = {};
    $ = $;
    $ = $;
    $scope.currentItem.model = $scope.model;

  $scope.selectedItems = ["allItems"];

  $scope.items = [{
    "id": "allItems",
    "name": "All Items",
    "order": 0
  }, {
    "id": "CaseItem",
    "name": "Case Item",
    "model": "PredefinedModel"
  }, {
    "id": "Application",
    "name": "Application",
    "model": "Bank"

You can always refer AngularJs documentation for detailed explanations about directives.

Visual Studio Error: (407: Proxy Authentication Required)

My case is when using two factor auth, outlook account and VS12.

I found out I have to

  • open IE (my corporate default browser)
  • log in to visual studio online account (including two factor auth)
  • connect again in VS12 (do the auth again for some reason)

How to set bootstrap navbar active class with Angular JS?

I use ng-class directive with $location to achieve it.

<ul class="nav">
<li data-ng-class="{active: ($location.path() == '/') }">
    <a href="#/">Carpeta Amarilla</a>
<li class="dropdown" data-ng-class="{active: ($location.path() == '/auditoria' || $location.path() == '/auditoria/todos') }">
    <a class="dropdown-toggle" data-toggle="dropdown" href="#">
        <b class="caret"></b>
    <ul class="dropdown-menu pull-right">
        <li data-ng-class="{active: ($location.path() == '/auditoria') }">
            <a href="#/auditoria">Por Legajo</a>
        <li data-ng-class="{active: ($location.path() == '/auditoria/todos') }">
            <a href="#/auditoria/todos">General</a>

It requires the navbar to be inside a main Controller with access to $location service like this:

bajasApp.controller('MenuCntl', ['$scope','$route', '$routeParams', '$location', 
   function MenuCntl($scope, $route, $routeParams, $location) {
   $scope.$route = $route;
   $scope.$location = $location;
   $scope.$routeParams = $routeParams;

How to compile C++ under Ubuntu Linux?

To compile source.cpp, run

g++ source.cpp

This command will compile source.cpp to file a.out in the same directory. To run the compiled file, run


If you compile another source file, with g++ source2.cpp, the new compiled file a.out will overwrite the a.out generated with source.cpp

If you want to compile source.cpp to a specific file, say compiledfile, run

g++ source.cpp -o compiledfile


g++ -o compiledfile source.cpp

This will create the compiledfile which is the compiled binary file. to run the compiledfile, run


If g++ is not in your $PATH, replace g++ with /usr/bin/g++.

Setting PATH environment variable in OSX permanently

I've found that there are some files that may affect the $PATH variable in macOS (works for me, 10.11 El Capitan), listed below:

  1. As the top voted answer said, vi /etc/paths, which is recommended from my point of view.

  2. Also don't forget the /etc/paths.d directory, which contains files may affect the $PATH variable, set the git and mono-command path in my case. You can ls -l /etc/paths.d to list items and rm /etc/paths.d/path_you_dislike to remove items.

  3. If you're using a "bash" environment (the default, for example), you should check out ~/.bash_profile or ~/.bashrc. There may be not that file yet, but these two files have effects on the $PATH.

  4. If you're using a "zsh" environment (Oh-My-Zsh, for example), you should check out ~./zshrc instead of ~/.bash* thing.

And don't forget to restart all the terminal windows, then echo $PATH. The $PATH string will be PATH_SET_IN_3&4:PATH_SET_IN_1:PATH_SET_IN_2.

Noticed that the first two ways (/etc/paths and /etc/path.d) is in / directory which will affect all the accounts in your computer while the last two ways (~/.bash* or ~/.zsh*) is in ~/ directory (aka, /Users/yourusername/) which will only affect your account settings.

Read more: Mac OS X: Set / Change $PATH Variable - nixCraft

Read whole ASCII file into C++ std::string

There are a couple of possibilities. One I like uses a stringstream as a go-between:

std::ifstream t("file.txt");
std::stringstream buffer;
buffer << t.rdbuf();

Now the contents of "file.txt" are available in a string as buffer.str().

Another possibility (though I certainly don't like it as well) is much more like your original:

std::ifstream t("file.txt");
t.seekg(0, std::ios::end);
size_t size = t.tellg();
std::string buffer(size, ' ');
t.seekg(0);[0], size); 

Officially, this isn't required to work under the C++98 or 03 standard (string isn't required to store data contiguously) but in fact it works with all known implementations, and C++11 and later do require contiguous storage, so it's guaranteed to work with them.

As to why I don't like the latter as well: first, because it's longer and harder to read. Second, because it requires that you initialize the contents of the string with data you don't care about, then immediately write over that data (yes, the time to initialize is usually trivial compared to the reading, so it probably doesn't matter, but to me it still feels kind of wrong). Third, in a text file, position X in the file doesn't necessarily mean you'll have read X characters to reach that point -- it's not required to take into account things like line-end translations. On real systems that do such translations (e.g., Windows) the translated form is shorter than what's in the file (i.e., "\r\n" in the file becomes "\n" in the translated string) so all you've done is reserved a little extra space you never use. Again, doesn't really cause a major problem but feels a little wrong anyway.

How to concatenate columns in a Postgres SELECT?

For example if there is employee table which consists of columns as:


if we want to concatenate f_name + l_name as name.

SELECT employee_number,f_name ::TEXT ||','|| l_name::TEXT  AS "NAME",email_id,phone_number,designation FROM EMPLOYEE;

What is the http-header "X-XSS-Protection"?

This header is getting somehow deprecated. You can read more about it here - X-XSS-Protection

  • Chrome has removed their XSS Auditor
  • Firefox has not, and will not implement X-XSS-Protection
  • Edge has retired their XSS filter

This means that if you do not need to support legacy browsers, it is recommended that you use Content-Security-Policy without allowing unsafe-inline scripts instead.

Java Class that implements Map and keeps insertion order?

Whenever i need to maintain the natural order of things that are known ahead of time, i use a EnumMap

the keys will be enums and you can insert in any order you want but when you iterate it will iterate in the enum order (the natural order).

Also when using EnumMap there should be no collisions which can be more efficient.

I really find that using enumMap makes for clean readable code. Here is an example

Zooming MKMapView to fit annotation pins?

Based on answers above you can use universal method to zoom map to fit all annotations and overlays at the same time.

-(MKMapRect)getZoomingRectOnMap:(MKMapView*)map toFitAllOverlays:(BOOL)overlays andAnnotations:(BOOL)annotations includeUserLocation:(BOOL)userLocation {
    if (!map) {
        return MKMapRectNull;

    NSMutableArray* overlaysAndAnnotationsCoordinateArray = [[NSMutableArray alloc]init];        
    if (overlays) {
        for (id <MKOverlay> overlay in map.overlays) {
            MKMapPoint overlayPoint = MKMapPointForCoordinate(overlay.coordinate);
            NSArray* coordinate = @[[NSNumber numberWithDouble:overlayPoint.x], [NSNumber numberWithDouble:overlayPoint.y]];
            [overlaysAndAnnotationsCoordinateArray addObject:coordinate];

    if (annotations) {
        for (id <MKAnnotation> annotation in map.annotations) {
            MKMapPoint annotationPoint = MKMapPointForCoordinate(annotation.coordinate);
            NSArray* coordinate = @[[NSNumber numberWithDouble:annotationPoint.x], [NSNumber numberWithDouble:annotationPoint.y]];
            [overlaysAndAnnotationsCoordinateArray addObject:coordinate];

    MKMapRect zoomRect = MKMapRectNull;
    if (userLocation) {
        MKMapPoint annotationPoint = MKMapPointForCoordinate(map.userLocation.coordinate);
        zoomRect = MKMapRectMake(annotationPoint.x, annotationPoint.y, 0.1, 0.1);

    for (NSArray* coordinate in overlaysAndAnnotationsCoordinateArray) {
        MKMapRect pointRect = MKMapRectMake([coordinate[0] doubleValue], [coordinate[1] doubleValue], 0.1, 0.1);
        zoomRect = MKMapRectUnion(zoomRect, pointRect);

    return zoomRect;

And then:

MKMapRect mapRect = [self getZoomingRectOnMap:mapView toFitAllOverlays:YES andAnnotations:YES includeUserLocation:NO];
[mapView setVisibleMapRect:mapRect edgePadding:UIEdgeInsetsMake(10.0, 10.0, 10.0, 10.0) animated:YES];

How to iterate through two lists in parallel?

Here's how to do it with list comprehension:

a = (1, 2, 3)
b = (4, 5, 6)
[print('f:', i, '; b', j) for i, j in zip(a, b)]


f: 1 ; b 4
f: 2 ; b 5
f: 3 ; b 6

How to filter wireshark to see only dns queries that are sent/received from/by my computer?

I would go through the packet capture and see if there are any records that I know I should be seeing to validate that the filter is working properly and to assuage any doubts.

That said, please try the following filter and see if you're getting the entries that you think you should be getting:

dns and ip.dst== or dns and ip.src==

What does the return keyword do in a void method in Java?

The Java language specification says you can have return with no expression if your method returns void.

converting multiple columns from character to numeric format in r

You could use convert from the hablar package:


# Sample df (stolen from the solution by Luca Braglia)
df <- tibble("a" = as.character(0:5),
                 "b" = paste(0:5, ".1", sep = ""),
                 "c" = letters[1:6])

# insert variable names in num()
df %>% convert(num(a, b))

Which gives you:

# A tibble: 6 x 3
      a     b c    
  <dbl> <dbl> <chr>
1    0. 0.100 a    
2    1. 1.10  b    
3    2. 2.10  c    
4    3. 3.10  d    
5    4. 4.10  e    
6    5. 5.10  f   

Or if you are lazy, let retype() from hablar guess the right data type:

df %>% retype()

which gives you:

# A tibble: 6 x 3
      a     b c    
  <int> <dbl> <chr>
1     0 0.100 a    
2     1 1.10  b    
3     2 2.10  c    
4     3 3.10  d    
5     4 4.10  e    
6     5 5.10  f   

How do I get the current location of an iframe?

Ok, so in this application, there is an iframe in which the user is supplied with links or some capacity that allows that iframe to browse to some external site. You are then looking to capture the URL to which the user has browsed.

Something to keep in mind. Since the URL is to an external source, you will be limited in how much you can interact with this iframe via javascript (or an client side access for that matter), this is known as browser cross-domain security, as apparently you have discovered. There are clever work arounds, as presented here Cross-domain, cross-frame Javascript, although I do not think this work around applies in this case.

About all you can access is the location, as you need.

I would suggest making the code presented more resilitant and less error prone. Try browsing the web sometime with IE or FF configured to show javascript errors. You will be surprised just how many javascript errors are thrown, largely because there is a lot of error prone javascript out there, which just continues to proliferate.

This solution assumes that the iframe in question is the same "window" context where you are running the javascript. (Meaning, it is not embedded within another frame or iframe, in which case, the javascript code gets more involved, and you likely need to recursively search through the window hierarchy.)

<iframe name='frmExternal' id='frmExternal' src=''></frame>
<input type='text' id='txtUrl' />
<input type='button' id='btnGetUrl' value='Get URL' onclick='GetIFrameUrl();' />

<script language='javascript' type='text/javascript'>
function GetIFrameUrl()
    if (!document.getElementById)

    var frm = document.getElementById("frmExternal");
    var txt = document.getElementById("txtUrl");

    if (frm == null || txt == null)
        // not great user feedback but slightly better than obnoxious script errors
       alert("There was a problem with this page, please refresh.");

    txt.value = frm.src;

Hope this helps.

How to write DataFrame to postgres table?

Pandas 0.24.0+ solution

In Pandas 0.24.0 a new feature was introduced specifically designed for fast writes to Postgres. You can learn more about it here:

import csv
from io import StringIO

from sqlalchemy import create_engine

def psql_insert_copy(table, conn, keys, data_iter):
    # gets a DBAPI connection that can provide a cursor
    dbapi_conn = conn.connection
    with dbapi_conn.cursor() as cur:
        s_buf = StringIO()
        writer = csv.writer(s_buf)

        columns = ', '.join('"{}"'.format(k) for k in keys)
        if table.schema:
            table_name = '{}.{}'.format(table.schema,
            table_name =

        sql = 'COPY {} ({}) FROM STDIN WITH CSV'.format(
            table_name, columns)
        cur.copy_expert(sql=sql, file=s_buf)

engine = create_engine('postgresql://myusername:mypassword@myhost:5432/mydatabase')
df.to_sql('table_name', engine, method=psql_insert_copy)

How to use XPath preceding-sibling correctly

You don't need to go level up and use .. since all buttons are on the same level:

//button[contains(.,'Arcade Reader')]/preceding-sibling::button[@name='settings']

How to pass parameters in $ajax POST?

      type: 'post',
      url: 'superman',
      data: { 
        "field1": "hello",
        "field2": "hello1"
      success: function (response) {
        alert("Success !!");
      error: function () {
        alert("Error !!");

type: 'POST', will append **parameters to the body of the request** which is not seen in the URL while type: 'GET', appends parameters to the URL which is visible.

Most of the popular web browsers contain network panels which displays the complete request.

In network panel select XHR to see requests.

This can also be done via this.

        'field1': 'hello', 
        'field2': 'hello1'
      function (response) {
        alert("Success !");

What is the "proper" way to cast Hibernate Query.list() to List<Type>?

You use a ResultTransformer like that:

public List<Foo> activeObjects() {
    Session s = acquireSession();
    Query   q = s.createQuery("from foo where active");
    return (List<Foo>) q.list();

How to place a JButton at a desired location in a JFrame using Java

First, remember your JPanel size height and size width, then observe: JButton coordinates is (xo, yo, x length , y length). If your window is 800x600, you just need to write:

JButton.setBounds(0, 500, 100, 100);

You just need to use a coordinate gap to represent the button, and know where the window ends and where the window begins.

Concatenating multiple text files into a single file in Bash

This appends the output to all.txt

cat *.txt >> all.txt

This overwrites all.txt

cat *.txt > all.txt

What is the use of verbose in Keras while validating the model?

verbose: Integer. 0, 1, or 2. Verbosity mode.

Verbose=0 (silent)

Verbose=1 (progress bar)

Train on 186219 samples, validate on 20691 samples
Epoch 1/2
186219/186219 [==============================] - 85s 455us/step - loss: 0.5815 - acc: 
0.7728 - val_loss: 0.4917 - val_acc: 0.8029
Train on 186219 samples, validate on 20691 samples
Epoch 2/2
186219/186219 [==============================] - 84s 451us/step - loss: 0.4921 - acc: 
0.8071 - val_loss: 0.4617 - val_acc: 0.8168

Verbose=2 (one line per epoch)

Train on 186219 samples, validate on 20691 samples
Epoch 1/1
 - 88s - loss: 0.5746 - acc: 0.7753 - val_loss: 0.4816 - val_acc: 0.8075
Train on 186219 samples, validate on 20691 samples
Epoch 1/1
 - 88s - loss: 0.4880 - acc: 0.8076 - val_loss: 0.5199 - val_acc: 0.8046

mysql: see all open connections to a given database?

In query browser right click on database and select processlist

File 'app/hero.ts' is not a module error in the console, where to store interfaces files in directory structure with angular2?

Sometimes this error occurs when the .ts file is not saved. So make sure all files in the project are saved otherwise try to restart the editor.

Android Stop Emulator from Command Line

adb kill-server will kill all emulators and restart the server clean.

Search for string and get count in vi editor

I suggest doing:

  1. Search either with * to do a "bounded search" for what's under the cursor, or do a standard /pattern search.
  2. Use :%s///gn to get the number of occurrences. Or you can use :%s///n to get the number of lines with occurrences.

** I really with I could find a plug-in that would giving messaging of "match N of N1 on N2 lines" with every search, but alas.

Note: Don't be confused by the tricky wording of the output. The former command might give you something like 4 matches on 3 lines where the latter might give you 3 matches on 3 lines. While technically accurate, the latter is misleading and should say '3 lines match'. So, as you can see, there really is never any need to use the latter ('n' only) form. You get the same info, more clearly, and more by using the 'gn' form.

grep --ignore-case --only

This is a known bug on the initial 2.5.1, and has been fixed in early 2007 (Redhat 2.5.1-5) according to the bug reports. Unfortunately Apple is still using 2.5.1 even on Mac OS X 10.7.2.

You could get a newer version via Homebrew (3.0) or MacPorts (2.26) or fink (3.0-1).

Edit: Apparently it has been fixed on OS X 10.11 (or maybe earlier), even though the grep version reported is still 2.5.1.

Case Statement Equivalent in R

You can use recode from the car package:

library(ggplot2) #get data
daimons$new_var <- recode(diamonds$clarity , "'I1' = 'low';'SI2' = 'low';else = 'high';")[1:10]

How to convert string date to Timestamp in java?

All you need to do is change the string within the java.text.SimpleDateFormat constructor to: "MM-dd-yyyy HH:mm:ss".

Just use the appropriate letters to build the above string to match your input date.

How to underline a UILabel in swift?

You can do this using NSAttributedString


let underlineAttribute = [NSAttributedString.Key.underlineStyle: NSUnderlineStyle.thick.rawValue]
let underlineAttributedString = NSAttributedString(string: "StringWithUnderLine", attributes: underlineAttribute)
myLabel.attributedText = underlineAttributedString


To have the same attributes for all texts of one UILabel, I suggest you to subclass UILabel and overriding text, like that:

Swift 5

Same as Swift 4.2 but: You should prefer the Swift initializer NSRange over the old NSMakeRange, you can shorten to .underlineStyle and linebreaks improve readibility for long method calls.

class UnderlinedLabel: UILabel {

override var text: String? {
    didSet {
        guard let text = text else { return }
        let textRange = NSRange(location: 0, length: text.count)
        let attributedText = NSMutableAttributedString(string: text)
                                    value: NSUnderlineStyle.single.rawValue,
                                    range: textRange)
        // Add other attributes if needed
        self.attributedText = attributedText

Swift 4.2

class UnderlinedLabel: UILabel {

override var text: String? {
    didSet {
        guard let text = text else { return }
        let textRange = NSMakeRange(0, text.count)
        let attributedText = NSMutableAttributedString(string: text)
        attributedText.addAttribute(NSAttributedString.Key.underlineStyle , value: NSUnderlineStyle.single.rawValue, range: textRange)
        // Add other attributes if needed
        self.attributedText = attributedText

Swift 3.0

class UnderlinedLabel: UILabel {
    override var text: String? {
        didSet {
            guard let text = text else { return }
            let textRange = NSMakeRange(0, text.characters.count)
            let attributedText = NSMutableAttributedString(string: text)
            attributedText.addAttribute(NSUnderlineStyleAttributeName , value: NSUnderlineStyle.styleSingle.rawValue, range: textRange)
            // Add other attributes if needed
            self.attributedText = attributedText

And you put your text like this :

@IBOutlet weak var label: UnderlinedLabel!
    override func viewDidLoad() {
        label.text = "StringWithUnderLine"


Swift (2.0 to 2.3):

class UnderlinedLabel: UILabel {
    override var text: String? {
        didSet {
            guard let text = text else { return }
            let textRange = NSMakeRange(0, text.characters.count)
            let attributedText = NSMutableAttributedString(string: text)
            attributedText.addAttribute(NSUnderlineStyleAttributeName, value:NSUnderlineStyle.StyleSingle.rawValue, range: textRange)
            // Add other attributes if needed
            self.attributedText = attributedText

Swift 1.2:

class UnderlinedLabel: UILabel {
    override var text: String! {
        didSet {
            let textRange = NSMakeRange(0, count(text))
            let attributedText = NSMutableAttributedString(string: text)
            attributedText.addAttribute(NSUnderlineStyleAttributeName, value:NSUnderlineStyle.StyleSingle.rawValue, range: textRange)
            // Add other attributes if needed
            self.attributedText = attributedText

Excel date to Unix timestamp

Here is a mapping for reference, assuming UTC for spreadsheet systems like Microsoft Excel:

                         Unix  Excel Mac    Excel    Human Date  Human Time
Excel Epoch       -2209075200      -1462        0    1900/01/00* 00:00:00 (local)
Excel = 2011 Mac† -2082758400          0     1462    1904/12/31  00:00:00 (local)
Unix Epoch                  0      24107    25569    1970/01/01  00:00:00 UTC
Example Below      1234567890      38395.6  39857.6  2009/02/13  23:31:30 UTC
Signed Int Max     2147483648      51886    50424    2038/01/19  03:14:08 UTC

One Second                  1       0.0000115740…             —  00:00:01
One Hour                 3600       0.0416666666…             -  01:00:00
One Day                 86400          1        1             -  24:00:00

*  “Jan Zero, 1900” is 1899/12/31; see the Bug section below. Excel 2011 for Mac (and older) use the 1904 date system.


As I often use awk to process CSV and space-delimited content, I developed a way to convert UNIX epoch to timezone/DST-appropriate Excel date format:

echo 1234567890 |awk '{ 
  # tries GNU date, tries BSD date on failure
  cmd = sprintf("date -d@%d +%%z 2>/dev/null || date -jf %%s %d +%%z", $1, $1)
  cmd |getline tz                                # read in time-specific offset
  hours = substr(tz, 2, 2) + substr(tz, 4) / 60  # hours + minutes (hi, India)
  if (tz ~ /^-/) hours *= -1                     # offset direction (east/west)
  excel = $1/86400 + hours/24 + 25569            # as days, plus offset
  printf "%.9f\n", excel

I used echo for this example, but you can pipe a file where the first column (for the first cell in .csv format, call it as awk -F,) is a UNIX epoch. Alter $1 to represent your desired column/cell number or use a variable instead.

This makes a system call to date. If you will reliably have the GNU version, you can remove the 2>/dev/null || date … +%%z and the second , $1. Given how common GNU is, I wouldn't recommend assuming BSD's version.

The getline reads the time zone offset outputted by date +%z into tz, which is then translated into hours. The format will be like -0700 (PDT) or +0530 (IST), so the first substring extracted is 07 or 05, the second is 00 or 30 (then divided by 60 to be expressed in hours), and the third use of tz sees whether our offset is negative and alters hours if needed.

The formula given in all of the other answers on this page is used to set excel, with the addition of the daylight-savings-aware time zone adjustment as hours/24.

If you're on an older version of Excel for Mac, you'll need to use 24107 in place of 25569 (see the mapping above).

To convert any arbitrary non-epoch time to Excel-friendly times with GNU date:

echo "last thursday" |awk '{ 
  cmd = sprintf("date -d \"%s\" +\"%%s %%z\"", $0)
  cmd |getline
  hours = substr($2, 2, 2) + substr($2, 4) / 60
  if ($2 ~ /^-/) hours *= -1
  excel = $1/86400 + hours/24 + 25569
  printf "%.9f\n", excel

This is basically the same code, but the date -d no longer has an @ to represent unix epoch (given how capable the string parser is, I'm actually surprised the @ is mandatory; what other date format has 9-10 digits?) and it's now asked for two outputs: the epoch and the time zone offset. You could therefore use e.g. @1234567890 as an input.


Lotus 1-2-3 (the original spreadsheet software) intentionally treated 1900 as a leap year despite the fact that it was not (this reduced the codebase at a time when every byte counted). Microsoft Excel retained this bug for compatibility, skipping day 60 (the fictitious 1900/02/29), retaining Lotus 1-2-3's mapping of day 59 to 1900/02/28. LibreOffice instead assigned day 60 to 1900/02/28 and pushed all previous days back one.

Any date before 1900/03/01 could be as much as a day off:

Day        Excel   LibreOffice
-1            -1    1899/12/29
 0    1900/01/00*   1899/12/30
 1    1900/01/01    1899/12/31
 2    1900/01/02    1900/01/01
59    1900/02/28    1900/02/27
60    1900/02/29(!) 1900/02/28
61    1900/03/01    1900/03/01

Excel doesn't acknowledge negative dates and has a special definition of the Zeroth of January (1899/12/31) for day zero. Internally, Excel does indeed handle negative dates (they're just numbers after all), but it displays them as numbers since it doesn't know how to display them as dates (nor can it convert older dates into negative numbers). Feb 29 1900, a day that never happened, is recognized by Excel but not LibreOffice.

warning: incompatible implicit declaration of built-in function ‘xyz’

Here is some C code that produces the above mentioned error:

int main(int argc, char **argv) {

Compiled like this on Fedora 17 Linux 64 bit with gcc:

el@defiant ~/foo2 $ gcc -o n n2.c                                                               
n2.c: In function ‘main’:
n2.c:2:3: warning: incompatible implicit declaration of built-in 
function ‘exit’ [enabled by default]
el@defiant ~/foo2 $ ./n 
el@defiant ~/foo2 $ 

To make the warning go away, add this declaration to the top of the file:

#include <stdlib.h>


I've been a big fan of REST in the past and it has many advantages over RPC on paper. You can present the client with different Content-Types, Caching, reuse of HTTP status codes, you can guide the client through the API and you can embed documentation in the API if it isn't mostly self-explaining anyway.

But my experience has been that in practice this doesn't hold up and instead you do a lot of unnecessary work to get everything right. Also the HTTP status codes often don't map to your domain logic exactly and using them in your context often feels a bit forced. But the worst thing about REST in my opinion is that you spend a lot of time to design your resources and the interactions they allow. And whenever you do some major additions to your API you hope you find a good solution to add the new functionality and you didn't design yourself into a corner already.

This often feels like a waste of time to me because most of the time I already have a perfectly fine and obvious idea about how to model an API as a set of remote procedure calls. And if I have gone through all this effort to model my problem inside the constraints of REST the next problem is how to call it from the client? Our programs are based on calling procedures so building a good RPC client library is easy, building a good REST client library not so much and in most cases you will just map back from your REST API on the server to a set of procedures in your client library.

Because of this, RPC feels a lot simpler and more natural to me today. What I really miss though is a consistent framework that makes it easy to write RPC services that are self-describing and interoperable. Therefore I created my own project to experiment with new ways to make RPC easier for myself and maybe somebody else finds it useful, too:

How can I undo a `git commit` locally and on a remote after `git push`

git reset HEAD~1 if you don't want your changes to be gone(unstaged changes). Change, commit and push again git push -f [origin] [branch]

How to unpublish an app in Google Play Developer Console

  1. Go to your "" dashboard
  2. Select your app
  3. In left menu item select "Store presence"
  4. Then, select "Pricing & distribution"
  5. Click "Unpublish" in "App Availability" section