Programs & Examples On #Libssh

libssh is a mulitplatform C library implementing the SSHv2 and SSHv1 protocol on client and server side.

curl: (35) SSL connect error

If updating cURL doesn't fix it, updating NSS should do the trick.

ssh : Permission denied (publickey,gssapi-with-mic)

In Centos 7

Error : publickey,gssapi-keyex,gssapi-with-mic

Ans : Root access to vi /etc/ssh/sshd_config and change the PasswordAuthentication ( no ) to yes.

2 . Restart the sshd services

root> systemctl restart sshd.service

  1. Logon into local id via putty without key.

Github permission denied: ssh add agent has no identities

This worked for me:
chmod 700 .ssh chmod 600 .ssh/id_rsa chmod 644 .ssh/

Then, type this: ssh-add ~/.ssh/id_rsa

Curl: Fix CURL (51) SSL error: no alternative certificate subject name matches

Editor's note: this is a very dangerous approach, if you are using a version of PHP old enough to use it. It opens your code to man-in-the-middle attacks and removes one of the primary purposes of an encrypted connection. The ability to do this has been removed from modern versions of PHP because it is so dangerous. The only reason this has been upvoted 70 time is because people are lazy. DO NOT DO THIS.

I know it's a (very) old question and it's about command line, but when I searched Google for "SSL: no alternative certificate subject name matches target host name", this was the first hit.

It took me a good while to figure out the answer so hope this saves someone a lot of time! In PHP add this to your cUrl setopts:

curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, FALSE);
curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, FALSE);

p.s: this should be a temporary solution. Since this is a certificate error, best thing is to have the certificate fixed ofcourse!

cURL not working (Error #77) for SSL connections on CentOS for non-root users

Check that you have the correct rights set on CA certificates bundle. Usually, that means read access for everyone to CA files in the /etc/ssl/certs directory, for instance /etc/ssl/certs/ca-certificates.crt.

You can see what files have been configured for you curl version with the

curl-config --configure
command :

$ curl-config --configure
 'CFLAGS=-march=x86-64 -mtune=generic -O2 -pipe -fstack-protector --param=ssp-buffer-size=4' 'LDFLAGS=-Wl,-O1,--sort-common,--as-needed,-z,relro' 

Here you need read access to /etc/ssl/certs/ca-certificates.crt

$ curl-config --configure
 '--build' 'i486-linux-gnu' 
 'CFLAGS=-g -O2' 

And the same here.

How can I decrypt MySQL passwords

Hashing is a one-way process but using a password-list you can regenerate the hashes and compare to the stored hash to 'crack' the password.

This site attempts to do this for you - run through passwords lists and tell you the cleartext password based on your hash.

What are the differences between git branch, fork, fetch, merge, rebase and clone?


This answer includes GitHub as many folks have asked about that too.

Local repositories

Git (locally) has a directory (.git) which you commit your files to and this is your 'local repository'. This is different from systems like SVN where you add and commit to the remote repository immediately.

Git stores each version of a file that changes by saving the entire file. It is also different from SVN in this respect as you could go to any individual version without 'recreating' it through delta changes.

Git doesn't 'lock' files at all and thus avoids the 'exclusive lock' functionality for an edit (older systems like pvcs come to mind), so all files can always be edited, even when off-line. It actually does an amazing job of merging file changes (within the same file!) together during pulls or fetches/pushes to a remote repository such as GitHub. The only time you need to do manual changes (actually editing a file) is if two changes involve the same line(s) of code.


Branches allow you to preserve the main code (the 'master' branch), make a copy (a new branch) and then work within that new branch. If the work takes a while or master gets a lot of updates since the branch was made then merging or rebasing (often preferred for better history and easier to resolve conflicts) against the master branch should be done. When you've finished, you merge the changes made in the branch back in to the master repository. Many organizations use branches for each piece of work whether it is a feature, bug or chore item. Other organizations only use branches for major changes such as version upgrades.

Fork: With a branch you control and manage the branch, whereas with a fork someone else controls accepting the code back in.

Broadly speaking, there are two main approaches to doing branches. The first is to keep most changes on the master branch, only using branches for larger and longer-running things like version changes where you want to have two branches available for different needs. The second is whereby you basically make a branch for every feature request, bug fix or chore and then manually decide when to actually merge those branches into the main master branch. Though this sounds tedious, this is a common approach and is the one that I currently use and recommend because this keeps the master branch cleaner and it's the master that we promote to production, so we only want completed, tested code, via the rebasing and merging of branches.

The standard way to bring a branch 'in' to master is to do a merge. Branches can also be "rebased" to 'clean up' history. It doesn't affect the current state and is done to give a 'cleaner' history.

Basically, the idea is that you branched from a certain point (usually from master). Since you branched, 'master' itself has since moved forward from that branching point. It will be 'cleaner' (easier to resolve issues and the history will be easier to understand) if all the changes you have done in a branch are played against the current state of master with all of its latest changes. So, the process is: save the changes; get the 'new' master, and then reapply (this is the rebase part) the changes again against that. Be aware that rebase, just like merge, can result in conflicts that you have to manually resolve (i.e. edit and fix).

One guideline to note:
Only rebase if the branch is local and you haven't pushed it to remote yet!
This is mainly because rebasing can alter the history that other people see which may include their own commits.

Tracking branches

These are the branches that are named origin/branch_name (as opposed to just branch_name). When you are pushing and pulling the code to/from remote repositories this is actually the mechanism through which that happens. For example, when you git push a branch called building_groups, your branch goes first to origin/building_groups and then that goes to the remote repository. Similarly, if you do a git fetch building_groups, the file that is retrieved is placed in your origin/building_groups branch. You can then choose to merge this branch into your local copy. Our practice is to always do a git fetch and a manual merge rather than just a git pull (which does both of the above in one step).

Fetching new branches.

Getting new branches: At the initial point of a clone you will have all the branches. However, if other developers add branches and push them to the remote there needs to be a way to 'know' about those branches and their names in order to be able to pull them down locally. This is done via a git fetch which will get all new and changed branches into the locally repository using the tracking branches (e.g., origin/). Once fetched, one can git branch --remote to list the tracking branches and git checkout [branch] to actually switch to any given one.


Merging is the process of combining code changes from different branches, or from different versions of the same branch (for example when a local branch and remote are out of sync). If one has developed work in a branch and the work is complete, ready and tested, then it can be merged into the master branch. This is done by git checkout master to switch to the master branch, then git merge your_branch. The merge will bring all the different files and even different changes to the same files together. This means that it will actually change the code inside files to merge all the changes.

When doing the checkout of master it's also recommended to do a git pull origin master to get the very latest version of the remote master merged into your local master. If the remote master changed, i.e., moved forward, you will see information that reflects that during that git pull. If that is the case (master changed) you are advised to git checkout your_branch and then rebase it to master so that your changes actually get 'replayed' on top of the 'new' master. Then you would continue with getting master up-to-date as shown in the next paragraph.

If there are no conflicts, then master will have the new changes added in. If there are conflicts, this means that the same files have changes around similar lines of code that it cannot automatically merge. In this case git merge new_branch will report that there's conflict(s) to resolve. You 'resolve' them by editing the files (which will have both changes in them), selecting the changes you want, literally deleting the lines of the changes you don't want and then saving the file. The changes are marked with separators such as ======== and <<<<<<<<.

Once you have resolved any conflicts you will once again git add and git commit those changes to continue the merge (you'll get feedback from git during this process to guide you).

When the process doesn't work well you will find that git merge --abort is very handy to reset things.

Interactive rebasing and squashing / reordering / removing commits

If you have done work in a lot of small steps, e.g., you commit code as 'work-in-progress' every day, you may want to 'squash' those many small commits into a few larger commits. This can be particularly useful when you want to do code reviews with colleagues. You don't want to replay all the 'steps' you took (via commits), you want to just say here is the end effect (diff) of all of my changes for this work in one commit.

The key factor to evaluate when considering whether to do this is whether the multiple commits are against the same file or files more than once (better to squash commits in that case). This is done with the interactive rebasing tool. This tool lets you squash commits, delete commits, reword messages, etc. For example, git rebase -i HEAD~10 (note: that's a ~, not a -) brings up the following:

interactive rebasing in Git

Be careful though and use this tool 'gingerly'. Do one squash/delete/reorder at a time, exit and save that commit, then reenter the tool. If commits are not contiguous you can reorder them (and then squash as needed). You can actually delete commits here too, but you really need to be sure of what you are doing when you do that!


There are two main approaches to collaboration in Git repositories. The first, detailed above, is directly via branches that people pull and push from/to. These collaborators have their SSH keys registered with the remote repository. This will let them push directly to that repository. The downside is that you have to maintain the list of users. The other approach - forking - allows anybody to 'fork' the repository, basically making a local copy in their own Git repository account. They can then make changes and when finished send a 'pull request' (really it's more of a 'push' from them and a 'pull' request for the actual repository maintainer) to get the code accepted.

This second method, using forks, does not require someone to maintain a list of users for the repository.


GitHub (a remote repository) is a remote source that you normally push and pull those committed changes to if you have (or are added to) such a repository, so local and remote are actually quite distinct. Another way to think of a remote repository is that it is a .git directory structure that lives on a remote server.

When you 'fork' - in the GitHub web browser GUI you can click on this button Image of fork button - you create a copy ('clone') of the code in your GitHub account. It can be a little subtle first time you do it, so keep making sure you look at whose repository a code base is listed under - either the original owner or 'forked from' and you, e.g., like this:

Image of name of forked repository

Once you have the local copy, you can make changes as you wish (by pulling and pushing them to a local machine). When you are done then you submit a 'pull request' to the original repository owner/admin (sounds fancy but actually you just click on this: Image of pull request button) and they 'pull' it in.

More common for a team working on code together is to 'clone' the repository (click on the 'copy' icon on the repository's main screen). Then, locally type git clone and paste. This will set you up locally and you can also push and pull to the (shared) GitHub location.


As indicated in the section on GitHub, a clone is a copy of a repository. When you have a remote repository you issue the git clone command against its URL and you then end up with a local copy, or clone, of the repository. This clone has everything, the files, the master branch, the other branches, all the existing commits, the whole shebang. It is this clone that you do your adds and commits against and then the remote repository itself is what you push those commits to. It's this local/remote concept that makes Git (and systems similar to it such as Mercurial) a DVCS (Distributed Version Control System) as opposed to the more traditional CVSs (Code Versioning Systems) such as SVN, PVCS, CVS, etc. where you commit directly to the remote repository.


Visualization of the core concepts can be seen at and

If you want a visual display of how the changes are working, you can't beat the visual tool gitg (gitx for macOS) with a GUI that I call 'the subway map' (esp. London Underground), great for showing who did what, how things changes, diverged and merged, etc.

You can also use it to add, commit and manage your changes!

Image of gitg/gitx interface

Although gitg/gitx is fairly minimal, the number of GUI tools continues to expand. Many Mac users use brotherbard's fork of gitx and for Linux, a great option is smart-git with an intuitive yet powerful interface:

Image of smart-git GUI

Note that even with a GUI tool, you will probably do a lot of commands at the command line.

For this, I have the following aliases in my ~/.bash_aliases file (which is called from my ~/.bashrc file for each terminal session):

# git
alias g='git status'
alias gcob='git checkout -b '
alias gcom='git checkout master'
alias gd='git diff'
alias gf='git fetch'
alias gfrm='git fetch; git reset --hard origin/master'
alias gg='git grep '
alias gits='alias | grep "^alias g.*git.*$"'
alias gl='git log'
alias gl1='git log --oneline'
alias glf='git log --name-status'
alias glp='git log -p'
alias gpull='git pull '
alias gpush='git push '

AND I have the following "git aliases" in my ~/.gitconfig file - why have these ?
So that branch completion (with the TAB key) works !

So these are:

  co = checkout
  cob = checkout -b

Example usage: git co [branch] <- tab completion for branches will work.

GUI Learning Tool

You may find useful in learning some of the base concepts. Screen shot: enter image description here

Finally, 7 key lifesavers!

  1. You make changes, add and commit them (but don't push) and then oh! you realize you are in master!

    git reset [filename(s)]
    git checkout -b [name_for_a_new_branch]
    git add [file(s)]
    git commit -m "A useful message"
    Voila!  You've moved that 'master' commit to its own branch !
  2. You mess up some files while working in a local branch and simply want to go back to what you had the last time you did a git pull:

    git reset --hard origin/master  # You will need to be comfortable doing this!
  3. You start making changes locally, you edit half a dozen files and then, oh crap, you're still in the master (or another) branch:

    git checkout -b new_branch_name  # just create a new branch
    git add .                      # add the changes files
    git commit -m"your message"    # and commit them
  4. You mess up one particular file in your current branch and want to basically 'reset' that file (lose changes) to how it was the the last time you pulled it from the remote repository:

    git checkout your/directories/filename

    This actually resets the file (like many Git commands it is not well named for what it is doing here).

  5. You make some changes locally, you want to make sure you don't lose them while you do a git reset or rebase: I often make a manual copy of the entire project (cp -r ../my_project ~/) when I am not sure if I might mess up in Git or lose important changes.

  6. You are rebasing but things gets messed up:

    git rebase --abort # To abandon interactive rebase and merge issues
  7. Add your Git branch to your PS1 prompt (see, e.g.

    Image of prompt

    The branch is selenium_rspec_conversion.

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

update: The original answer bellow is good for 2011, but since 2012, one is likely better using Python's ipaddress stdlib module - besides checking IP validity for IPv4 and IPv6, it can do a lot of other things as well.</update>

It looks like you are trying to validate IP addresses. A regular expression is probably not the best tool for this.

If you want to accept all valid IP addresses (including some addresses that you probably didn't even know were valid) then you can use IPy (Source):

from IPy import IP

If the IP address is invalid it will throw an exception.

Or you could use socket (Source):

import socket
    # legal
except socket.error:
    # Not legal

If you really want to only match IPv4 with 4 decimal parts then you can split on dot and test that each part is an integer between 0 and 255.

def validate_ip(s):
    a = s.split('.')
    if len(a) != 4:
        return False
    for x in a:
        if not x.isdigit():
            return False
        i = int(x)
        if i < 0 or i > 255:
            return False
    return True

Note that your regular expression doesn't do this extra check. It would accept 999.999.999.999 as a valid address.


From the MySQL 5.5 manual page:

LOCAL works only if your server and your client both have been configured to permit it. For example, if mysqld was started with --local-infile=0, LOCAL does not work. See Section 6.1.6, “Security Issues with LOAD DATA LOCAL”.

You should set the option:


into your [mysql] entry of my.cnf file or call mysql client with the --local-infile option:

mysql --local-infile -uroot -pyourpwd yourdbname

You have to be sure that the same parameter is defined into your [mysqld] section too to enable the "local infile" feature server side.

It's a security restriction.

ERROR 1396 (HY000): Operation CREATE USER failed for 'jack'@'localhost'

The MySQL server is running with the --skip-grant-tables option so it cannot execute this statement

How to dynamically change the color of the selected menu item of a web page?

Set the styles for class active and hover:

Than you need to make the li active, on the server side. So when you are drawing the menu, you should know which page is loaded and set it to:

 <li class="active">Question</li>

But if you are changing the content without reloading, you cannot change set the active li element on the server, you need to use javascript:

<script type="text/javascript" src=""></script>
  .menu{width: 300px; height: 25; font-size: 18px;}
  .menu li{list-style: none; float: left; margin-right: 4px; padding: 5px;}
  .menu li:hover, .menu {
        background-color: #f90;

<ul class="menu">
<li>Item 1</li>
<li class="active">Item 2</li>
<li>Item 3</li>
<li>Item 4</li>
<li>Item 5</li>
<li>Item 6</li>

<script type="text/javascript">

var make_button_active = function()
  //Get item siblings
  var siblings =($(this).siblings());

  //Remove active class on all buttons
  siblings.each(function (index)

  //Add the clicked button class

//Attach events to menu
    $(".menu li").click(make_button_active);



Git: Remove committed file after push

update: added safer method

preferred method:

  1. check out the previous (unchanged) state of your file; notice the double dash

    git checkout HEAD^ -- /path/to/file
  2. commit it:

    git commit -am "revert changes on this file, not finished with it yet"
  3. push it, no force needed:

    git push
  4. get back to your unfinished work, again do (3 times arrow up):

    git checkout HEAD^ -- /path/to/file

effectively 'uncommitting':

To modify the last commit of the repository HEAD, obfuscating your accidentally pushed work, while potentially running into a conflict with your colleague who may have pulled it already, and who will grow grey hair and lose lots of time trying to reconcile his local branch head with the central one:

To remove file change from last commit:

  1. to revert the file to the state before the last commit, do:

    git checkout HEAD^ /path/to/file
  2. to update the last commit with the reverted file, do:

    git commit --amend
  3. to push the updated commit to the repo, do:

    git push -f

Really, consider using the preferred method mentioned before.

Maven: mvn command not found

I tried solutions from other threads. Adding M2 and M2_HOME at System variables, and even at User variables. Running cmd as admin. None of the methods worked.

But today I added entire path to maven bin to my System variables "PATH" (C:\Program Files (x86)\Apache Software Foundation\apache-maven-3.1.0\bin) besides other paths, and so far it's working good. Hopefully it'll stay that way.

PostgreSQL: ERROR: operator does not exist: integer = character varying

I think it is telling you exactly what is wrong. You cannot compare an integer with a varchar. PostgreSQL is strict and does not do any magic typecasting for you. I'm guessing SQLServer does typecasting automagically (which is a bad thing).

If you want to compare these two different beasts, you will have to cast one to the other using the casting syntax ::.

Something along these lines:

create view view1
select table1.col1,table2.col1,table3.col3
from table1 
inner join
inner join 
table1.col4::varchar = table2.col5
/* Here col4 of table1 is of "integer" type and col5 of table2 is of type "varchar" */
/* ERROR: operator does not exist: integer = character varying */

Notice the varchar typecasting on the table1.col4.

Also note that typecasting might possibly render your index on that column unusable and has a performance penalty, which is pretty bad. An even better solution would be to see if you can permanently change one of the two column types to match the other one. Literately change your database design.

Or you could create a index on the casted values by using a custom, immutable function which casts the values on the column. But this too may prove suboptimal (but better than live casting).

Get the size of a 2D array

Expanding on what Mark Elliot said earlier, the easiest way to get the size of a 2D array given that each array in the array of arrays is of the same size is:

array.length * array[0].length

Change output format for MySQL command line results to CSV

How about using sed? It comes standard with most (all?) Linux OS.

sed 's/\t/<your_field_delimiter>/g'.

This example uses GNU sed (Linux). For POSIX sed (AIX/Solaris)I believe you would type a literal TAB instead of \t

Example (for CSV output):

#mysql mysql -B -e "select * from user" | while read; do sed 's/\t/,/g'; done


How to declare a variable in a PostgreSQL query

In DBeaver you can use parameters in queries just like you can from code, so this will work:

FROM somewhere
WHERE something = :myvar

When you run the query DBeaver will ask you for the value for :myvar and run the query.

What is the advantage of using heredoc in PHP?

First of all, all the reasons are subjective. It's more like a matter of taste rather than a reason.

Personally, I find heredoc quite useless and use it occasionally, most of the time when I need to get some HTML into a variable and don't want to bother with output buffering, to form an HTML email message for example.

Formatting doesn't fit general indentation rules, but I don't think it's a big deal.

       //some code at it's proper level
       $this->body = <<<HERE
heredoc text sticks to the left border
but it seems OK to me.
       $this->title = "Feedback";
       //and so on

As for the examples in the accepted answer, it is merely cheating.
String examples, in fact, being more concise if one won't cheat on them

$sql = "SELECT * FROM $tablename
        WHERE id in [$order_ids_list]
        AND product_name = 'widgets'";

$x = 'The point of the "argument" was to illustrate the use of here documents';

versionCode vs versionName in Android Manifest

android:versionCode — An integer value that represents the version of the application code, relative to other versions.

The value is an integer so that other applications can programmatically evaluate it, for example to check an upgrade or downgrade relationship. You can set the value to any integer you want, however you should make sure that each successive release of your application uses a greater value. The system does not enforce this behavior, but increasing the value with successive releases is normative.

android:versionName — A string value that represents the release version of the application code, as it should be shown to users.

The value is a string so that you can describe the application version as a .. string, or as any other type of absolute or relative version identifier.

As with android:versionCode, the system does not use this value for any internal purpose, other than to enable applications to display it to users. Publishing services may also extract the android:versionName value for display to users.

Typically, you would release the first version of your application with versionCode set to 1, then monotonically increase the value with each release, regardless whether the release constitutes a major or minor release. This means that the android:versionCode value does not necessarily have a strong resemblance to the application release version that is visible to the user (see android:versionName, below). Applications and publishing services should not display this version value to users.

Insert current date/time using now() in a field using MySQL/PHP


worked for me . but my field type is date only and yours is datetime. i am not sure if this is the case

Get the decimal part from a double

Use a regex: Regex.Match("\.(?\d+)") Someone correct me if I'm wrong here

"Cannot verify access to path (C:\inetpub\wwwroot)", when adding a virtual directory

ACCESSING LOCAL WEBSITE WITH IIS without Physical Path Authentication

  1. Make sure you have installed URL Rewrite to your IIS Manager

enter image description here

  1. Open the URL Rewrite application then navigate to Inbound Rules>Import Rules

enter image description here

  1. To import the rule, click the browse button then locate your .htaccess file then click import button

enter image description here

  1. The text labeled with red are errors that are not accepted by IIS, so you have to remove them by clicking the errors in the converted rules and remove the text from the rewrite rules. Once you have get rid of the errors Click the APPLY button located at the top right corner. Then try to access your site without engaging users into the pool auth.

enter image description here

I hope it helps. That's what I did.

What programming languages can one use to develop iPhone, iPod Touch and iPad (iOS) applications?

Apple lifted the restrictions on non-Objective C/C/C++ apps -- you just can't load code that isn't in the app bundle.

MonoTouch lets you use .NET languages -- C# is directly supported, but if you have Windows, you can make assemblies in any .NET language and use it.

There are rumors that Apple is going to support other languages directly -- I keep hearing ruby, but they are just rumors.

I think Lua is being used for game logic on a lot of apps.

EDIT (in 2018): Generally you can use any language that you can get to compile for iOS or even install language interpreters. The main thing you cannot do is load code from the Internet that wasn't in the app bundle.

People do this all of the time anyway (see React Native apps loading JavaScript from servers), but, technically, it's not allowed. The main thing that will get you attention from Apple if you make some kind of App Store that loads whole App-like things.

EDIT (in 2020): from @Pylot in comments: I know this is a long time ago, but now at least technically you can load code that isn’t embedded in the app, as you can write with JavaScript using the webview. Not staying your answer is wrong or anything, I definitely agree with you. but I was looking for something and found this post on the way. Figured if anyone sees this it might help them out.

SQL Server Management Studio missing

In SQL Server 2016 it has its own link:

enter image description here

Just download it here:

How to generate a random number in C++?

If you are using boost libs you can obtain a random generator in this way:

#include <iostream>
#include <string>

// Used in randomization
#include <ctime>
#include <boost/random/mersenne_twister.hpp>
#include <boost/random/uniform_int_distribution.hpp>
#include <boost/random/variate_generator.hpp>

using namespace std;
using namespace boost;

int current_time_nanoseconds(){
    struct timespec tm;
    clock_gettime(CLOCK_REALTIME, &tm);
    return tm.tv_nsec;

int main (int argc, char* argv[]) {
    unsigned int dice_rolls = 12;
    random::mt19937 rng(current_time_nanoseconds());
    random::uniform_int_distribution<> six(1,6);

    for(unsigned int i=0; i<dice_rolls; i++){
        cout << six(rng) << endl;

Where the function current_time_nanoseconds() gives the current time in nanoseconds which is used as a seed.

Here is a more general class to get random integers and dates in a range:

#include <iostream>
#include <ctime>
#include <boost/random/mersenne_twister.hpp>
#include <boost/random/uniform_int_distribution.hpp>
#include <boost/random/variate_generator.hpp>
#include "boost/date_time/posix_time/posix_time.hpp"
#include "boost/date_time/gregorian/gregorian.hpp"

using namespace std;
using namespace boost;
using namespace boost::posix_time;
using namespace boost::gregorian;

class Randomizer {
    static const bool debug_mode = false;
    random::mt19937 rng_;

    // The private constructor so that the user can not directly instantiate
    Randomizer() {
            this->rng_ = random::mt19937();
            this->rng_ = random::mt19937(current_time_nanoseconds());

    int current_time_nanoseconds(){
        struct timespec tm;
        clock_gettime(CLOCK_REALTIME, &tm);
        return tm.tv_nsec;

    // C++ 03
    // ========
    // Dont forget to declare these two. You want to make sure they
    // are unacceptable otherwise you may accidentally get copies of
    // your singleton appearing.
    Randomizer(Randomizer const&);     // Don't Implement
    void operator=(Randomizer const&); // Don't implement

    static Randomizer& get_instance(){
        // The only instance of the class is created at the first call get_instance ()
        // and will be destroyed only when the program exits
        static Randomizer instance;
        return instance;
    bool method() { return true; };

    int rand(unsigned int floor, unsigned int ceil){
        random::uniform_int_distribution<> rand_ = random::uniform_int_distribution<> (floor,ceil);
        return (rand_(rng_));

    // Is not considering the millisecons
    time_duration rand_time_duration(){
        boost::posix_time::time_duration floor(0, 0, 0, 0);
        boost::posix_time::time_duration ceil(23, 59, 59, 0);
        unsigned int rand_seconds = rand(floor.total_seconds(), ceil.total_seconds());
        return seconds(rand_seconds);

    date rand_date_from_epoch_to_now(){
        date now = second_clock::local_time().date();
        return rand_date_from_epoch_to_ceil(now);

    date rand_date_from_epoch_to_ceil(date ceil_date){
        date epoch = ptime(date(1970,1,1)).date();
        return rand_date_in_interval(epoch, ceil_date);

    date rand_date_in_interval(date floor_date, date ceil_date){
        return rand_ptime_in_interval(ptime(floor_date), ptime(ceil_date)).date();

    ptime rand_ptime_from_epoch_to_now(){
        ptime now = second_clock::local_time();
        return rand_ptime_from_epoch_to_ceil(now);

    ptime rand_ptime_from_epoch_to_ceil(ptime ceil_date){
        ptime epoch = ptime(date(1970,1,1));
        return rand_ptime_in_interval(epoch, ceil_date);

    ptime rand_ptime_in_interval(ptime floor_date, ptime ceil_date){
        time_duration const diff = ceil_date - floor_date;
        long long gap_seconds = diff.total_seconds();
        long long step_seconds = Randomizer::get_instance().rand(0, gap_seconds);
        return floor_date + seconds(step_seconds);

What are bitwise shift (bit-shift) operators and how do they work?

Be aware of that only 32 bit version of PHP is available on the Windows platform.

Then if you for instance shift << or >> more than by 31 bits, results are unexpectable. Usually the original number instead of zeros will be returned, and it can be a really tricky bug.

Of course if you use 64 bit version of PHP (Unix), you should avoid shifting by more than 63 bits. However, for instance, MySQL uses the 64-bit BIGINT, so there should not be any compatibility problems.

UPDATE: From PHP 7 Windows, PHP builds are finally able to use full 64 bit integers: The size of an integer is platform-dependent, although a maximum value of about two billion is the usual value (that's 32 bits signed). 64-bit platforms usually have a maximum value of about 9E18, except on Windows prior to PHP 7, where it was always 32 bit.

how to add the missing RANDR extension

First off, Xvfb doesn't read configuration from xorg.conf. Xvfb is a variant of the KDrive X servers and like all members of that family gets its configuration from the command line.

It is true that XRandR and Xinerama are mutually exclusive, but in the case of Xvfb there's no Xinerama in the first place. You can enable the XRandR extension by starting Xvfb using at least the following command line options

Xvfb +extension RANDR [further options]

Truncate a string straight JavaScript

in case you want to truncate by word.

function limit(str, limit, end) {_x000D_
      limit = (limit)? limit : 100;_x000D_
      end = (end)? end : '...';_x000D_
      str = str.split(' ');_x000D_
      if (str.length > limit) {_x000D_
        var cutTolimit = str.slice(0, limit);_x000D_
        return cutTolimit.join(' ') + ' ' + end;_x000D_
      return str.join(' ');_x000D_
    var limit = limit('ILorem ipsum dolor sit amet, consectetur adipiscing elit. Vivamus metus magna, maximus a dictum et, hendrerit ac ligula. Vestibulum massa sapien, venenatis et massa vel, commodo elementum turpis. Nullam cursus, enim in semper luctus, odio turpis dictum lectus', 20);_x000D_

How to change the href for a hyperlink using jQuery

The simple way to do so is :

Attr function (since jQuery version 1.0)

$("a").attr("href", "") 


Prop function (since jQuery version 1.6)

$("a").prop("href", "")

Also, the advantage of above way is that if selector selects a single anchor, it will update that anchor only and if selector returns a group of anchor, it will update the specific group through one statement only.

Now, there are lot of ways to identify exact anchor or group of anchors:

Quite Simple Ones:

  1. Select anchor through tag name : $("a")
  2. Select anchor through index: $("a:eq(0)")
  3. Select anchor for specific classes (as in this class only anchors with class active) : $("")
  4. Selecting anchors with specific ID (here in example profileLink ID) : $("a#proileLink")
  5. Selecting first anchor href: $("a:first")

More useful ones:

  1. Selecting all elements with href attribute : $("[href]")
  2. Selecting all anchors with specific href: $("a[href='']")
  3. Selecting all anchors not having specific href: $("a[href!='']")
  4. Selecting all anchors with href containing specific URL: $("a[href*='']")
  5. Selecting all anchors with href starting with specific URL: $("a[href^='']")
  6. Selecting all anchors with href ending with specific URL: $("a[href$='']")

Now, if you want to amend specific URLs, you can do that as:

For instance if you want to add proxy website for all the URLs going to, you can implement it as follows:

      this.href = this.href.replace(/http:\/\/\//gi, function (x) {
        return ""+encodeURIComponent(x);

How can I temporarily disable a foreign key constraint in MySQL?

To turn off foreign key constraint globally, do the following:


and remember to set it back when you are done


WARNING: You should only do this when you are doing single user mode maintenance. As it might resulted in data inconsistency. For example, it will be very helpful when you are uploading large amount of data using a mysqldump output.

Under which circumstances textAlign property works in Flutter?

Specify crossAxisAlignment: CrossAxisAlignment.start in your column

How can I find all the subsets of a set, with exactly n elements?

Without using itertools:

In Python 3 you can use yield from to add a subset generator method to buit-in set class:

class SetWithSubset(set):
    def subsets(self):
        s1 = []
        s2 = list(self)

        def recfunc(i=0):            
            if i == len(s2):
                yield frozenset(s1)
                yield from recfunc(i + 1)
                s1.append(s2[ i ])
                yield from recfunc(i + 1)

        yield from recfunc()

For example below snippet works as expected:

x = SetWithSubset({1,2,3,5,6})
{2,3} in x.subsets()            # True
set() in x.subsets()            # True
x in x.subsets()                # True
x|{7} in x.subsets()            # False
set([5,3]) in x.subsets()       # True - better alternative: set([5,3]) < x
len(x.subsets())                # 32

comparing 2 strings alphabetically for sorting purposes

You do say that the comparison is for sorting purposes. Then I suggest instead:


It returns -1 since "a" < "b", 1 or 0 otherwise, like you need for Array.prototype.sort()

Keep in mind that sorting is locale dependent. E.g. in German, ä is a variant of a, so "ä".localeCompare("b", "de-DE") returns -1. In Swedish, ä is one of the last letters in the alphabet, so "ä".localeCompare("b", "se-SE") returns 1.

Without the second parameter to localeCompare, the browser's locale is used. Which in my experience is never what I want, because then it'll sort differently than the server, which has a fixed locale for all users.

What is HTML5 ARIA?

What is ARIA?

ARIA emerged as a way to address the accessibility problem of using a markup language intended for documents, HTML, to build user interfaces (UI). HTML includes a great many features to deal with documents (P, h3,UL,TABLE) but only basic UI elements such as A, INPUT and BUTTON. Windows and other operating systems support APIs that allow (Assistive Technology) AT to access the functionality of UI controls. Internet Explorer and other browsers map the native HTML elements to the accessibility API, but the html controls are not as rich as the controls common on desktop operating systems, and are not enough for modern web applications Custom controls can extend html elements to provide the rich UI needed for modern web applications. Before ARIA, the browser had no way to expose this extra richness to the accessibility API or AT. The classic example of this issue is adding a click handler to an image. It creates what appears to be a clickable button to a mouse user, but is still just an image to a keyboard or AT user.

The solution was to create a set of attributes that allow developers to extend HTML with UI semantics. The ARIA term for a group of HTML elements that have custom functionality and use ARIA attributes to map these functions to accessibility APIs is a “Widget. ARIA also provides a means for authors to document the role of content itself, which in turn, allows AT to construct alternate navigation mechanisms for the content that are much easier to use than reading the full text or only iterating over a list of the links.

It is important to remember that in simple cases, it is much preferred to use native HTML controls and style them rather than using ARIA. That is don’t reinvent wheels, or checkboxes, if you don’t have to.

Fortunately, ARIA markup can be added to existing sites without changing the behavior for mainstream users. This greatly reduces the cost of modifying and testing the website or application.

What exactly does the .join() method do?

join() is for concatenating all list elements. For concatenating just two strings "+" would make more sense:

strid = repr(595)
print array.array('c', random.sample(string.ascii_letters, 20 - len(strid)))
    .tostring() + strid

Create the perfect JPA entity

I'll try to answer several key points: this is from long Hibernate/ persistence experience including several major applications.

Entity Class: implement Serializable?

Keys needs to implement Serializable. Stuff that's going to go in the HttpSession, or be sent over the wire by RPC/Java EE, needs to implement Serializable. Other stuff: not so much. Spend your time on what's important.

Constructors: create a constructor with all required fields of the entity?

Constructor(s) for application logic, should have only a few critical "foreign key" or "type/kind" fields which will always be known when creating the entity. The rest should be set by calling the setter methods -- that's what they're for.

Avoid putting too many fields into constructors. Constructors should be convenient, and give basic sanity to the object. Name, Type and/or Parents are all typically useful.

OTOH if application rules (today) require a Customer to have an Address, leave that to a setter. That is an example of a "weak rule". Maybe next week, you want to create a Customer object before going to the Enter Details screen? Don't trip yourself up, leave possibility for unknown, incomplete or "partially entered" data.

Constructors: also, package private default constructor?

Yes, but use 'protected' rather than package private. Subclassing stuff is a real pain when the necessary internals are not visible.


Use 'property' field access for Hibernate, and from outside the instance. Within the instance, use the fields directly. Reason: allows standard reflection, the simplest & most basic method for Hibernate, to work.

As for fields 'immutable' to the application -- Hibernate still needs to be able to load these. You could try making these methods 'private', and/or put an annotation on them, to prevent application code making unwanted access.

Note: when writing an equals() function, use getters for values on the 'other' instance! Otherwise, you'll hit uninitialized/ empty fields on proxy instances.

Protected is better for (Hibernate) performance?



This is relevant to working with entities, before they've been saved -- which is a thorny issue. Hashing/comparing on immutable values? In most business applications, there aren't any.

A customer can change address, change the name of their business, etc etc -- not common, but it happens. Corrections also need to be possible to make, when the data was not entered correctly.

The few things that are normally kept immutable, are Parenting and perhaps Type/Kind -- normally the user recreates the record, rather than changing these. But these do not uniquely identify the entity!

So, long and short, the claimed "immutable" data isn't really. Primary Key/ ID fields are generated for the precise purpose, of providing such guaranteed stability & immutability.

You need to plan & consider your need for comparison & hashing & request-processing work phases when A) working with "changed/ bound data" from the UI if you compare/hash on "infrequently changed fields", or B) working with "unsaved data", if you compare/hash on ID.

Equals/HashCode -- if a unique Business Key is not available, use a non-transient UUID which is created when the entity is initialized

Yes, this is a good strategy when required. Be aware that UUIDs are not free, performance-wise though -- and clustering complicates things.

Equals/HashCode -- never refer to related entities

"If related entity (like a parent entity) needs to be part of the Business Key then add a non insertable, non updatable field to store the parent id (with the same name as the ManytoOne JoinColumn) and use this id in the equality check"

Sounds like good advice.

Hope this helps!

Android Studio - local path doesn't exist

I fixed this by adding "Gradle-aware make" before launch in my launch configuration.

enter image description here

Spring Boot Adding Http Request Interceptors

WebMvcConfigurerAdapter will be deprecated with Spring 5. From its Javadoc:

@deprecated as of 5.0 {@link WebMvcConfigurer} has default methods (made possible by a Java 8 baseline) and can be implemented directly without the need for this adapter

As stated above, what you should do is implementing WebMvcConfigurer and overriding addInterceptors method.

public class WebMvcConfig implements WebMvcConfigurer {

    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new MyCustomInterceptor());

Failed to resolve: android

I had this issue when creating a new project in Android Studio using Kotlin. The way that finally helped me:

allprojects {
    repositories {
        maven {
            url ""

com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: No operations allowed after connection closed

If you don't want use connection pool (you sure, that your app has only one connection), you can do this - if connection falls you must establish new one - call method .openSession() instead .getCurrentSession()

For example:

SessionFactory sf = null;
// get session factory
// ...
Session session = null;
try {
        session = sessionFactory.getCurrentSession();
} catch (HibernateException ex) {
        session = sessionFactory.openSession();

If you use Mysql, you can set autoReconnect property:

    <property name="hibernate.connection.url">jdbc:mysql://</property>

I hope this helps.

Show div on scrollDown after 800px

You can also, do this.

$(window).on("scroll", function () {
   if ($(this).scrollTop() > 800) {
      #code here
   } else {
      #code here

How to determine MIME type of file in android?

Sometimes Jeb's and Jens's answers don't work and return null. In this case I use follow solution. Head of file usually contains type signature. I read it and compare with known in list of signatures.

 * @param is InputStream on start of file. Otherwise signature can not be defined.
 * @return int id of signature or -1, if unknown signature was found. See SIGNATURE_ID_(type) constants to
 *      identify signature by its id.
 * @throws IOException in cases of read errors.
public static int getSignatureIdFromHeader(InputStream is) throws IOException {
    // read signature from head of source and compare with known signatures
    int signatureId = -1;
    int sigCount = SIGNATURES.length;
    int[] byteArray = new int[MAX_SIGNATURE_LENGTH];
    StringBuilder builder = new StringBuilder();
    for (int i = 0; i < MAX_SIGNATURE_LENGTH; i++) {
        byteArray[i] =;
    if (DEBUG) {
        Log.d(TAG, "head bytes=" + builder.toString());
    for (int i = 0; i < MAX_SIGNATURE_LENGTH; i++) {

        // check each bytes with known signatures
        int bytes = byteArray[i];
        int lastSigId = -1;
        int coincidences = 0;

        for (int j = 0; j < sigCount; j++) {
            int[] sig = SIGNATURES[j];

            if (DEBUG) {
                Log.d(TAG, "compare" + i + ": " + Integer.toHexString(bytes) + " with " + sig[i]);
            if (bytes == sig[i]) {
                lastSigId = j;

        // signature is unknown
        if (coincidences == 0) {
        // if first bytes of signature is known we check signature for full coincidence
        if (coincidences == 1) {
            int[] sig = SIGNATURES[lastSigId];
            int sigLength = sig.length;
            boolean isSigKnown = true;
            for (; i < MAX_SIGNATURE_LENGTH && i < sigLength; i++) {
                bytes = byteArray[i];
                if (bytes != sig[i]) {
                    isSigKnown = false;
            if (isSigKnown) {
                signatureId = lastSigId;
    return signatureId;

signatureId is an index of signature in array of signatures. For example,

private static final int[] SIGNATURE_PNG = hexStringToIntArray("89504E470D0A1A0A");
private static final int[] SIGNATURE_JPEG = hexStringToIntArray("FFD8FF");
private static final int[] SIGNATURE_GIF = hexStringToIntArray("474946");

public static final int SIGNATURE_ID_JPEG = 0;
public static final int SIGNATURE_ID_PNG = 1;
public static final int SIGNATURE_ID_GIF = 2;
private static final int[][] SIGNATURES = new int[3][];

static {

Now I have file type even if URI of file haven't. Next I get mime type by file type. If you don't know which mime type to get, you can find proper in this table.

It works for a lot of file types. But for video it doesn't work, because you need to known video codec to get a mime type. To get video's mime type I use MediaMetadataRetriever.

jQuery: How to capture the TAB keypress within a Textbox

Above shown methods did not work for me, may be i am using bit old jquery, then finally the below shown code snippet works for - posting just in case somebody in my same position

$('#textBox').live('keydown', function(e) {
    if (e.keyCode == 9) {

Calling a Variable from another Class

I would suggest to use a variable instead of a public field:

public class Variables
   private static string name = "";

   public static string Name
        get { return name; }
        set { name = value; }


From another class, you call your variable like this:

public class Main
    public void DoSomething()
         string var = Variables.Name;

Jquery select change not firing

Try this

$('body').on('change', '#multiid', function() {
    // your stuff

please check .on() selector

How to map an array of objects in React

@FurkanO has provided the right approach. Though to go for a more cleaner approach (es6 way) you can do something like this

    name: 'Sam',
    email: '[email protected]'
    name: 'Ash',
    email: '[email protected]'
].map( ( {name, email} ) => {
    return <p key={email}>{name} - {email}</p>


How to set selected item of Spinner by value, not by position?

here is my solution

List<Country> list = CountryBO.GetCountries(0);
CountriesAdapter dataAdapter = new CountriesAdapter(this,list);

and getItemIndexById below

public int getItemIndexById(String id) {
    for (Country item : this.items) {
            return this.items.indexOf(item);
    return 0;

Hope this help!

Proper way to empty a C-String

If you are trying to clear out a receive buffer for something that receives strings I have found the best way is to use memset as described above. The reason is that no matter how big the next received string is (limited to sizeof buffer of course), it will automatically be an asciiz string if written into a buffer that has been pre-zeroed.

How to get a single value from FormGroup

for Angular 6+ and >=RC.6


<form [formGroup]="formGroup">
  <input type="text" formControlName="myName">


public formGroup: FormGroup;

should also work.

Could not load file or assembly 'System, Version=, Culture=neutral, PublicKeyToken=b77a5c561934e089' or one of its dependencies

i just changed my target .net framework and it worked .in my case i changed from .net 4.7 to .net 4. Right click your solution and select properties selct properties

Click Application >> Target Framework

The FastCGI process exited unexpectedly

As the answer of 'sepehr' this issues are because of VC++ Redistributable suitable version for PHP are not installed or need to be reinstalled again.

I faced it before so i'll explain my steps to fix it.

1- Each PHP version is built by a specific Visual C++ Redistributable version like (10, 11,12,14,..) what ever. ((How you know!! look.. ))

  • Check back enter link description here The PHP Site then at the left side of this page, look at "Which version do I choose?" then see what version of VC++ is fits your PHP version installed.

  • Now YOU HAVE TO Download both of VC++ 32 and 64. and if your PC has it already then Unistall them first. and then install what you downloaded recently bu (first 32 then 64).

- VC download links are exists on the mentioned PHP Site on the left side also.

I hope it helps you.

Git: Find the most recent common ancestor of two branches

As noted in a prior answer, although git merge-base works,

$ git merge-base myfeature develop

If myfeature is the current branch, as is common, you can use --fork-point:

$ git merge-base --fork-point develop

This argument works only in sufficiently recent versions of git. Unfortunately it doesn't always work, however, and it is not clear why. Please refer to the limitations noted toward the end of this answer.

For full commit info, consider:

$ git log -1 $(git merge-base --fork-point develop) 

Oracle 12c Installation failed to access the temporary location

Install it from CMD using the command

setup.exe -ignorePrereq -J"-Doracle.install.client.validate.clientSupportedOSCheck=false"


shell script to remove a file if it already exist

if [ $( ls <file> ) ]; then rm <file>; fi

Also, if you redirect your output with > instead of >> it will overwrite the previous file

Escape double quotes in parameter

The 2nd document quoted by Peter Mortensen in his comment on the answer of Codesmith made things much clearer for me. That document was written by The link repeated: A Better Way To Understand Quoting and Escaping of Windows Command Line Arguments.

Some further trial and error leads to the following guideline:

Escape every double quote " with a caret ^. If you want other characters with special meaning to the Windows command shell (e.g., <, >, |, &) to be interpreted as regular characters instead, then escape them with a caret, too.

If you want your program foo to receive the command line text "a\"b c" > d and redirect its output to file out.txt, then start your program as follows from the Windows command shell:

foo ^"a\^"b c^" ^> d > out.txt

If foo interprets \" as a literal double quote and expects unescaped double quotes to delimit arguments that include whitespace, then foo interprets the command as specifying one argument a"b c, one argument >, and one argument d.

If instead foo interprets a doubled double quote "" as a literal double quote, then start your program as

foo ^"a^"^"b c^" ^> d > out.txt

The key insight from the quoted document is that, to the Windows command shell, an unescaped double quote triggers switching between two possible states.

Some further trial and error implies that in the initial state, redirection (to a file or pipe) is recognized and a caret ^ escapes a double quote and the caret is removed from the input. In the other state, redirection is not recognized and a caret does not escape a double quote and isn't removed. Let's refer to these states as 'outside' and 'inside', respectively.

If you want to redirect the output of your command, then the command shell must be in the outside state when it reaches the redirection, so there must be an even number of unescaped (by caret) double quotes preceding the redirection. foo "a\"b " > out.txt won't work -- the command shell passes the entire "a\"b " > out.txt to foo as its combined command line arguments, instead of passing only "a\"b " and redirecting the output to out.txt.

foo "a\^"b " > out.txt won't work, either, because the caret ^ is encountered in the inside state where it is an ordinary character and not an escape character, so "a\^"b " > out.txt gets passed to foo.

The only way that (hopefully) always works is to keep the command shell always in the outside state, because then redirection works.

If you don't need redirection (or other characters with special meaning to the command shell), then you can do without the carets. If foo interprets \" as a literal double quote, then you can call it as

foo "a\"b c"

Then foo receives "a\"b c" as its combined arguments text and can interpret it as a single argument equal to a"b c.

Now -- finally -- to the original question. myscript '"test"' called from the Windows command shell passes '"test"' to myscript. Apparently myscript interprets the single and double quotes as argument delimiters and removes them. You need to figure out what myscript accepts as a literal double quote and then specify that in your command, using ^ to escape any characters that have special meaning to the Windows command shell. Given that myscript is also available on Unix, perhaps \" does the trick. Try

myscript \^"test\^"

or, if you don't need redirection,

myscript \"test\"

How to compile and run C files from within Notepad++ using NppExec plugin?

I've made a single powerfull script that will:

-Compile and run multi language code like C, C++, Java, Python and C#.
-Delete the old executable before compiling code.
-Only run the code if it's compiled successfully.

I've also made a very noob friendly tutorial Transform Notepad++ to Powerful Multi Languages IDE which contains some additional scripts like to only run or Compile the code, run code inside CMD etc.

npp_console 1               //open console
NPP_CONSOLE -               //disable output of commands
npe_console m-              //disable unnecessary output
con_colour bg= 191919 fg= F5F5F5    //set console colors
npp_save                //save the file
cd $(CURRENT_DIRECTORY)         //follow current directory
NPP_CONSOLE +               //enable output
IF $(EXT_PART)==.c GOTO C       //if .c file goto C label
IF $(EXT_PART)==.cpp GOTO CPP       //if .cpp file goto CPP label
IF $(EXT_PART) GOTO JAVA     //if .java file goto JAVA label
IF $(EXT_PART)==.cs GOTO C#     //if .cs file goto C# label
IF $(EXT_PART) GOTO PYTHON     //if .py file goto PYTHON label
GOTO EXITSCRIPT             // else treat it as a text file and goto EXITSCRIPT
//C label
cmd /C if exist "$(NAME_PART).exe" cmd /c del "$(NAME_PART).exe"//delete existing executable file if exists
gcc "$(FILE_NAME)" -o $(NAME_PART)              //compile file
IF $(EXITCODE) != 0 GOTO EXITSCRIPT             //if any compilation error then abort
echo C CODE COMPILED SUCCESSFULLY:              //print message on console
$(NAME_PART)                                            //run file in cmd, set color to green and pause cmd after output
GOTO EXITSCRIPT                         //finally exits

cmd /C if exist "$(NAME_PART).exe" cmd /c del "$(NAME_PART).exe"
g++ "$(FILE_NAME)" -o $(NAME_PART)

cmd /C if exist "$(NAME_PART).class" cmd /c del "$(NAME_PART).class"
javac $(FILE_NAME) -Xlint
java $(NAME_PART)

cmd /C if exist "$(NAME_PART).exe" cmd /c del "$(NAME_PART).exe"
csc $(FILE_NAME)

echo RUNNING PYTHON SCRIPT IN CMD:              //python is a script so no need to compile
python $(NAME_PART).py

// that's all, folks!

Create code first, many to many, with additional fields in association table

One way to solve this error is to put the ForeignKey attribute on top of the property you want as a foreign key and add the navigation property.

Note: In the ForeignKey attribute, between parentheses and double quotes, place the name of the class referred to in this way.

enter image description here

The maximum recursion 100 has been exhausted before statement completion

it is just a sample to avoid max recursion error. we have to use option (maxrecursion 365); or option (maxrecursion 0);

DECLARE @EntDt datetime; 
set @STARTDATE = '01/01/2009';  
set @EntDt = '12/31/2009'; 
declare @dcnt int; 
;with DateList as   
    select @STARTDATE DateValue   
    union all   
    select DateValue + 1 from    DateList      
    where   DateValue + 1 < convert(VARCHAR(15),@EntDt,101)   
  select count(*) as DayCnt from (   
  select DateValue,DATENAME(WEEKDAY, DateValue ) as WEEKDAY from DateList
  where DATENAME(WEEKDAY, DateValue ) not IN ( 'Saturday','Sunday' )     
option (maxrecursion 365);

Using <style> tags in the <body> with other HTML

Because this is HTML is not valid does not have any affect on the outcome ... it just means that the HTML does adhere to the standard (merely for organizational purposes). For the sake of being valid it could have been written this way:

<style type="text/css">
  p.first {color:blue}
  p.second {color:green}
<p class="first" style="color:green;">Hello World</p>
<p class="second" style="color:blue;">Hello World</p>

My guess is that the browser applies the last style it comes across.

Make a VStack fill the width of the screen in SwiftUI

You can do it by using GeometryReader



struct ContentView : View {
    var body: some View {
        GeometryReader { geometry in
            VStack {
               Text("Turtle Rock").frame(width: geometry.size.width, height: geometry.size.height, alignment: .topLeading).background(

Your output like:

enter image description here

How to properly set the 100% DIV height to match document/window height?

The easiest way is to add the:

$('#ID').css("height", $(document).height());

after the correct page height is determined by the browser. If the document height is changed once more re-run the above code.

Hide/encrypt password in bash file to stop accidentally seeing it

Although this is not a built in Unix solution, I've implemented a solution for this using a shell script that can be included in whatever shell script you are using. This is usable on POSIX compliant setups. (sh, bash, ksh, zsh) The full description is available in the github repo -> This solution will auto-generate a key for your script and store the key and your password (or other secrets) in a hidden directory under your user (i.e. ~/.encpass).

In your script you just need to source and then call the get_secret method. For example:


Pasted below is lite version of the code for can get the full version over on github) for easier visibility:

 # Copyright (c) 2020 Plyint, LLC <[email protected]>. All Rights Reserved.
 # This file is licensed under the MIT License (MIT). 
 # Please see LICENSE.txt for more information.
 # This script allows a user to encrypt a password (or any other secret) at 
 # runtime and then use it, decrypted, within a script.  This prevents shoulder 
 # surfing passwords and avoids storing the password in plain text, which could 
 # inadvertently be sent to or discovered by an individual at a later date.
 # This script generates an AES 256 bit symmetric key for each script (or user-
 # defined bucket) that stores secrets.  This key will then be used to encrypt 
 # all secrets for that script or bucket. sets up a directory 
 # (.encpass) under the user's home directory where keys and secrets will be 
 # stored.
 # For further details, see or run "./encpass ?" from the command line.

 encpass_checks() {
    [ -n "$ENCPASS_CHECKS" ] && return

    if [ -z "$ENCPASS_HOME_DIR" ]; then
    [ ! -d "$ENCPASS_HOME_DIR" ] && mkdir -m 700 "$ENCPASS_HOME_DIR"

    if [ -f "$ENCPASS_HOME_DIR/.extension" ]; then
        # Extension enabled, load it...
        ENCPASS_EXTENSION="$(cat "$ENCPASS_HOME_DIR/.extension")"
        if [ -f "./extensions/$ENCPASS_EXTENSION/$ENCPASS_EXT_FILE" ]; then
            # shellcheck source=/dev/null
          . "./extensions/$ENCPASS_EXTENSION/$ENCPASS_EXT_FILE"
        elif [ ! -z "$(command -v encpass-"$ENCPASS_EXTENSION".sh)" ]; then 
            # shellcheck source=/dev/null
            . "$(command -v encpass-$"
            encpass_die "Error: Extension $ENCPASS_EXTENSION could not be found."

        # Extension specific checks, mandatory function for extensions
        # Use default OpenSSL implementation
        if [ ! -x "$(command -v openssl)" ]; then
            echo "Error: OpenSSL is not installed or not accessible in the current path." \
                "Please install it and try again." >&2
            exit 1

        [ ! -d "$ENCPASS_HOME_DIR/keys" ] && mkdir -m 700 "$ENCPASS_HOME_DIR/keys"
        [ ! -d "$ENCPASS_HOME_DIR/secrets" ] && mkdir -m 700 "$ENCPASS_HOME_DIR/secrets"
        [ ! -d "$ENCPASS_HOME_DIR/exports" ] && mkdir -m 700 "$ENCPASS_HOME_DIR/exports"



 # Checks if the enabled extension has implented the passed function and if so calls it
 encpass_ext_func() {
   [ ! -z "$ENCPASS_EXTENSION" ] && ENCPASS_EXT_FUNC="$(command -v "encpass_${ENCPASS_EXTENSION}_$1")" || return
    [ ! -z "$ENCPASS_EXT_FUNC" ] && shift && $ENCPASS_EXT_FUNC "$@" 

 # Initializations performed when the script is included by another script
 encpass_include_init() {
    encpass_ext_func "include_init" "$@"
    [ ! -z "$ENCPASS_EXT_FUNC" ] && return

    if [ -n "$1" ] && [ -n "$2" ]; then
    elif [ -n "$1" ]; then
        if [ -z "$ENCPASS_BUCKET" ]; then
          ENCPASS_BUCKET=$(basename "$0")
        ENCPASS_BUCKET=$(basename "$0")

 encpass_generate_private_key() {

    [ ! -d "$ENCPASS_KEY_DIR" ] && mkdir -m 700 "$ENCPASS_KEY_DIR"

    if [ ! -f "$ENCPASS_KEY_DIR/private.key" ]; then
        (umask 0377 && printf "%s" "$(openssl rand -hex 32)" >"$ENCPASS_KEY_DIR/private.key")

 encpass_set_private_key_abs_name() {
    [ ! -n "$1" ] && [ ! -f "$ENCPASS_PRIVATE_KEY_ABS_NAME" ] && encpass_generate_private_key

 encpass_set_secret_abs_name() {
    [ ! -n "$1" ] && [ ! -f "$ENCPASS_SECRET_ABS_NAME" ] && set_secret

 encpass_rmfifo() {
    trap - EXIT
    kill "$1" 2>/dev/null
    rm -f "$2"

 encpass_mkfifo() {
    mkfifo -m 600 "$fifo" || encpass_die "Error: unable to create named pipe"
    printf '%s\n' "$fifo"

 get_secret() {
    encpass_ext_func "get_secret" "$@"; [ ! -z "$ENCPASS_EXT_FUNC" ] && return

    [ "$(basename "$0")" != "" ] && encpass_include_init "$1" "$2"

    encpass_decrypt_secret "$@"

 set_secret() {

    encpass_ext_func "set_secret" "$@"; [ ! -z "$ENCPASS_EXT_FUNC" ] && return

    if [ "$1" != "reuse" ] || { [ -z "$ENCPASS_SECRET_INPUT" ] && [ -z "$ENCPASS_CSECRET_INPUT" ]; }; then
        echo "Enter $ENCPASS_SECRET_NAME:" >&2
        stty -echo
        read -r ENCPASS_SECRET_INPUT
        stty echo
        echo "Confirm $ENCPASS_SECRET_NAME:" >&2
        stty -echo
        stty echo

        # Use named pipe to securely pass secret to openssl
        fifo="$(encpass_mkfifo set_secret_fifo)"


        [ ! -d "$ENCPASS_SECRET_DIR" ] && mkdir -m 700 "$ENCPASS_SECRET_DIR"

        # Generate IV and create secret file
        printf "%s" "$(openssl rand -hex 16)" > "$ENCPASS_SECRET_DIR/$ENCPASS_SECRET_NAME.enc"

        echo "$ENCPASS_SECRET_INPUT" > "$fifo" &
        # Allow expansion now so PID is set
        # shellcheck disable=SC2064
        trap "encpass_rmfifo $! $fifo" EXIT HUP TERM INT TSTP

        # Append encrypted secret to IV in the secret file
        openssl enc -aes-256-cbc -e -a -iv "$ENCPASS_OPENSSL_IV" \
            -K "$(cat "$ENCPASS_HOME_DIR/keys/$ENCPASS_BUCKET/private.key")" \
            -in "$fifo" 1>> "$ENCPASS_SECRET_DIR/$ENCPASS_SECRET_NAME.enc"
        encpass_die "Error: secrets do not match.  Please try again."

 encpass_decrypt_secret() {
    encpass_ext_func "decrypt_secret" "$@"; [ ! -z "$ENCPASS_EXT_FUNC" ] && return

    if [ -f "$ENCPASS_PRIVATE_KEY_ABS_NAME" ]; then
        ENCPASS_DECRYPT_RESULT="$(dd if="$ENCPASS_SECRET_ABS_NAME" ibs=1 skip=32 2> /dev/null | openssl enc -aes-256-cbc \
            -d -a -iv "$(head -c 32 "$ENCPASS_SECRET_ABS_NAME")" -K "$(cat "$ENCPASS_PRIVATE_KEY_ABS_NAME")" 2> /dev/null)"
        if [ ! -z "$ENCPASS_DECRYPT_RESULT" ]; then
            echo "$ENCPASS_DECRYPT_RESULT"
            # If a failed unlock command occurred and the user tries to show the secret
            # Present either a locked or failed decrypt error.
            if [ -f "$ENCPASS_HOME_DIR/keys/$ENCPASS_BUCKET/private.lock" ]; then 
            echo "**Locked**"
                # The locked file wasn't present as expected.  Let's display a failure
            echo "Error: Failed to decrypt"
    elif [ -f "$ENCPASS_HOME_DIR/keys/$ENCPASS_BUCKET/private.lock" ]; then
        echo "**Locked**"
        echo "Error: Unable to decrypt. The key file \"$ENCPASS_PRIVATE_KEY_ABS_NAME\" is not present."

 encpass_die() {
   echo "$@" >&2
   exit 1

How do I redirect to the previous action in ASP.NET MVC?

If you want to redirect from a button in the View you could use:

@Html.ActionLink("Back to previous page", null, null, null, new { href = Request.UrlReferrer})

How to make inline functions in C#

Not only Inside methods, it can be used inside classes also.

class Calculator
        public static int Sum(int x,int y) => x + y;
        public static Func<int, int, int>  Add = (x, y) => x + y;
        public static Action<int,int> DisplaySum = (x, y) => Console.WriteLine(x + y);

How to download a folder from github?

There is a button Download ZIP. If you want to do a sparse checkout there are many solutions on the site. For example here.

How to detect pressing Enter on keyboard using jQuery?

I spent sometime coming up with this solution i hope it helps someone.


  $('#loginforms').keypress(function(e) {
    if (e.which == 13) {
    alert('login pressed');

 $('#signupforms').keypress(function(e) {
    if (e.which == 13) {


Java: how do I get a class literal from a generic type?

To expound on cletus' answer, at runtime all record of the generic types is removed. Generics are processed only in the compiler and are used to provide additional type safety. They are really just shorthand that allows the compiler to insert typecasts at the appropriate places. For example, previously you'd have to do the following:

List x = new ArrayList();
x.add(new SomeClass());
Iterator i = x.iterator();
SomeClass z = (SomeClass);


List<SomeClass> x = new ArrayList<SomeClass>();
x.add(new SomeClass());
Iterator<SomeClass> i = x.iterator();
SomeClass z =;

This allows the compiler to check your code at compile-time, but at runtime it still looks like the first example.

Git and nasty "error: cannot lock existing info/refs fatal"

In case of, the solution is more poetic - the only problem may be in rights assigned to the project members. Simple members don't have write rights! Please make sure that you have the Moderator or Administrator rights. This needs to be set at at the project settings by an Administrator, of course.

Convert ASCII TO UTF-8 Encoding

Using iconv looks like best solution but i my case I have Notice form this function: "Detected an illegal character in input string in" (without igonore). I use 2 functions to manipulate ASCII strings convert it to array of ASCII code and then serialize:

public static function ToAscii($string) {
    $strlen = strlen($string);
    $charCode = array();
    for ($i = 0; $i < $strlen; $i++) {
        $charCode[] = ord(substr($string, $i, 1));
    $result = json_encode($charCode);
    return $result;

public static function fromAscii($string) {
    $charCode = json_decode($string);
    $result = '';
    foreach ($charCode as $code) {
        $result .= chr($code);
    return $result;

Cloning a private Github repo

When cloning from private repos with 2FA enable, there is a simple steps which you need to follow

  1. Go to your Git account
  2. Go to Settings-> Developer Settings->Personal Access Token
  3. Click on Generate new token
  4. Create a token with title you want and with the functionalities
  5. When you are cloning the private repo, by using git clone repoName, after entering your user name, give personal access token as the password.

Follow same steps when you get Authentication failed error message for Private repo

How to include !important in jquery

var tabsHeight = 650;

$("tabs").attr('style', 'height: '+ tabsHeight +'px !important');


.myclass{height:650px !important;}



Repository Pattern Step by Step Explanation

This is a nice example: The Repository Pattern Example in C#

Basically, repository hides the details of how exactly the data is being fetched/persisted from/to the database. Under the covers:

  • for reading, it creates the query satisfying the supplied criteria and returns the result set
  • for writing, it issues the commands necessary to make the underlying persistence engine (e.g. an SQL database) save the data

Best way to convert IList or IEnumerable to Array

In case you don't have Linq, I solved it the following way:

    private T[] GetArray<T>(IList<T> iList) where T: new()
        var result = new T[iList.Count];

        iList.CopyTo(result, 0);

        return result;

Hope it helps

Beautiful way to remove GET-variables with PHP?

basename($_SERVER['REQUEST_URI']) returns everything after and including the '?',

In my code sometimes I need only sections, so separate it out so I can get the value of what I need on the fly. Not sure on the performance speed compared to other methods, but it's really useful for me.

$urlprotocol = 'http'; if ($_SERVER["HTTPS"] == "on") {$urlprotocol .= "s";} $urlprotocol .= "://";
$urldomain = $_SERVER["SERVER_NAME"];
$urluri = $_SERVER['REQUEST_URI'];
$urlvars = basename($urluri);
$urlpath = str_replace($urlvars,"",$urluri);

$urlfull = $urlprotocol . $urldomain . $urlpath . $urlvars;

How do you round a number to two decimal places in C#?

One thing you may want to check is the Rounding Mechanism of Math.Round:

Other than that, I recommend the Math.Round(inputNumer, numberOfPlaces) approach over the *100/100 one because it's cleaner.

Use Fieldset Legend with bootstrap

Just wanted to summarize all the correct answers above in short. Because I had to spend lot of time to figure out which answer resolves the issue and what's going on behind the scenes.

There seems to be two problems of fieldset with bootstrap:

  1. The bootstrap sets the width to the legend as 100%. That is why it overlays the top border of the fieldset.
  2. There's a bottom border for the legend.

So, all we need to fix this is set the legend width to auto as follows:

legend.scheduler-border {
   width: auto; // fixes the problem 1
   border-bottom: none; // fixes the problem 2

How to split string using delimiter char using T-SQL?

You need a split function:

Create Function [dbo].[udf_Split]
    @DelimitedList nvarchar(max)
    , @Delimiter nvarchar(2) = ','
    With CorrectedList As
        Select Case When Left(@DelimitedList, Len(@Delimiter)) <> @Delimiter Then @Delimiter Else '' End
            + @DelimitedList
            + Case When Right(@DelimitedList, Len(@Delimiter)) <> @Delimiter Then @Delimiter Else '' End
            As List
            , Len(@Delimiter) As DelimiterLen
        , Numbers As 
        Select TOP( Coalesce(DataLength(@DelimitedList)/2,0) ) Row_Number() Over ( Order By c1.object_id ) As Value
        From sys.columns As c1
            Cross Join sys.columns As c2
    Select CharIndex(@Delimiter, CL.list, N.Value) + CL.DelimiterLen As Position
        , Substring (
                    , CharIndex(@Delimiter, CL.list, N.Value) + CL.DelimiterLen     
                    , CharIndex(@Delimiter, CL.list, N.Value + 1)                           
                        - ( CharIndex(@Delimiter, CL.list, N.Value) + CL.DelimiterLen ) 
                    ) As Value
    From CorrectedList As CL
        Cross Join Numbers As N
    Where N.Value <= DataLength(CL.List) / 2
        And Substring(CL.List, N.Value, CL.DelimiterLen) = @Delimiter

With your split function, you would then use Cross Apply to get the data:

Select T.Col1, T.Col2
    , Substring( Z.Value, 1, Charindex(' = ', Z.Value) - 1 ) As AttributeName
    , Substring( Z.Value, Charindex(' = ', Z.Value) + 1, Len(Z.Value) ) As Value
From Table01 As T
    Cross Apply dbo.udf_Split( T.Col3, '|' ) As Z

Android turn On/Off WiFi HotSpot programmatically

**For Oreo & PIE ** I found below way through this

private WifiManager.LocalOnlyHotspotReservation mReservation;
private boolean isHotspotEnabled = false;

private boolean isLocationPermissionEnable() {
    if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
        ActivityCompat.requestPermissions(this, new String[] {Manifest.permission.ACCESS_COARSE_LOCATION}, 2);
        return false;
    return true;

@RequiresApi(api = Build.VERSION_CODES.O)
private void turnOnHotspot() {
    if (!isLocationPermissionEnable()) {
    WifiManager manager = (WifiManager) getApplicationContext().getSystemService(Context.WIFI_SERVICE);

    if (manager != null) {
        // Don't start when it started (existed)
        manager.startLocalOnlyHotspot(new WifiManager.LocalOnlyHotspotCallback() {

            public void onStarted(WifiManager.LocalOnlyHotspotReservation reservation) {
                //Log.d(TAG, "Wifi Hotspot is on now");
                mReservation = reservation;
                isHotspotEnabled = true;

            public void onStopped() {
                //Log.d(TAG, "onStopped: ");
                isHotspotEnabled = false;

            public void onFailed(int reason) {
                //Log.d(TAG, "onFailed: ");
                isHotspotEnabled = false;
        }, new Handler());

@RequiresApi(api = Build.VERSION_CODES.O)
private void turnOffHotspot() {
    if (!isLocationPermissionEnable()) {
    if (mReservation != null) {
        isHotspotEnabled = false;

@RequiresApi(api = Build.VERSION_CODES.O)
private void toggleHotspot() {
    if (!isHotspotEnabled) {
    } else {

@RequiresApi(api = Build.VERSION_CODES.O)
private void enableLocationSettings() {
    LocationRequest mLocationRequest = new LocationRequest();
    LocationSettingsRequest.Builder builder = new LocationSettingsRequest.Builder();
            .setAlwaysShow(false); // Show dialog

    Task<LocationSettingsResponse> task= LocationServices.getSettingsClient(this).checkLocationSettings(;

    task.addOnCompleteListener(task1 -> {
        try {
            LocationSettingsResponse response = task1.getResult(ApiException.class);
            // All location settings are satisfied. The client can initialize location
            // requests here.

        } catch (ApiException exception) {
            switch (exception.getStatusCode()) {
                case LocationSettingsStatusCodes.RESOLUTION_REQUIRED:
                    // Location settings are not satisfied. But could be fixed by showing the
                    // user a dialog.
                    try {
                        // Cast to a resolvable exception.
                        ResolvableApiException resolvable = (ResolvableApiException) exception;
                        // Show the dialog by calling startResolutionForResult(),
                        // and check the result in onActivityResult().
                        resolvable.startResolutionForResult(HotspotActivity.this, REQUEST_ENABLE_LOCATION_SYSTEM_SETTINGS);
                    } catch (IntentSender.SendIntentException e) {
                        // Ignore the error.
                    } catch (ClassCastException e) {
                        // Ignore, should be an impossible error.
                case LocationSettingsStatusCodes.SETTINGS_CHANGE_UNAVAILABLE:
                    // Location settings are not satisfied. However, we have no way to fix the
                    // settings so we won't show the dialog.

@RequiresApi(api = Build.VERSION_CODES.O)
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    final LocationSettingsStates states = LocationSettingsStates.fromIntent(data);
    switch (requestCode) {
            switch (resultCode) {
                case Activity.RESULT_OK:
                    // All required changes were successfully made
                case Activity.RESULT_CANCELED:
                    // The user was asked to change settings, but chose not to


btnHotspot.setOnClickListenr(view -> {
   if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
        // Step 1: Enable the location settings use Google Location Service
        // Step 2:
        // Step 3: If OK then check the location permission and enable hotspot
        // Step 4:

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

implementation ''

Uncaught TypeError: Cannot read property 'value' of undefined

Seems like one of your values, with a property key of 'value' is undefined. Test that i1, i2and __i are defined before executing the if statements:

var i1 = document.getElementById('i1');
var i2 = document.getElementById('i2');
var __i = {'user' : document.getElementsByName("username")[0], 'pass' : document.getElementsByName("password")[0] };
if(i1 && i2 && __i.user && __i.pass)
    if(  __i.user.value.length >= 1 ) { i1.value = ''; } else { i1.value = 'Acc'; }

    if(  __i.pass.value.length >= 1 ) { i2.value = ''; } else { i2.value = 'Pwd'; }

How do I collapse a table row in Bootstrap?

You are using collapse on the div inside of your table row (tr). So when you collapse the div, the row is still there. You need to change it to where your id and class are on the tr instead of the div.

Change this:

<tr><td><div class="collapse out" id="collapseme">Should be collapsed</div></td></tr>

to this:

<tr class="collapse out" id="collapseme"><td><div>Should be collapsed</div></td></tr>


EDIT: If you are unable to upgrade to 3.0.0, I found a JQuery workaround in 2.3.2:

Remove your data-toggle and data-target and add this JQuery to your button.

$(".btn").click(function() {
    if($("#collapseme").hasClass("out")) {
    } else {


Delete all files in directory (but not directory) - one liner solution



There is this method available in the same file. This will also recursively deletes all sub-folders and files under them.


Angular 2: How to access an HTTP response body?

Unfortunately, many of the answers simply indicate how to access the Response’s body as text. By default, the body of the response object is text, not an object as it is passed through a stream.

What you are looking for is the json() function of the Body object property on the Response object. MDN explains it much better than I:

The json() method of the Body mixin takes a Response stream and reads it to completion. It returns a promise that resolves with the result of parsing the body text as JSON.

response.json().then(function(data) { console.log(data);});

or using ES6:

response.json().then((data) => { console.log(data) });


This function returns a Promise by default, but note that this can be easily converted to an Observable for downstream consumption (stream pun not intended but works great).

Without invoking the json() function, the data, especially when attempting to access the _body property of the Response object, will be returned as text, which is obviously not what you want if you are looking for a deep object (as in an object with properties, or than can’t be simply converted into another objected).

Example of response objects

what is the difference between const_iterator and iterator?

Performance wise there is no difference. The only purpose of having const_iterator over iterator is to manage the accessesibility of the container on which the respective iterator runs. You can understand it more clearly with an example:

std::vector<int> integers{ 3, 4, 56, 6, 778 };

If we were to read & write the members of a container we will use iterator:

for( std::vector<int>::iterator it = integers.begin() ; it != integers.end() ; ++it )
       {*it = 4;  std::cout << *it << std::endl; }

If we were to only read the members of the container integers you might wanna use const_iterator which doesn't allow to write or modify members of container.

for( std::vector<int>::const_iterator it = integers.begin() ; it != integers.end() ; ++it )
       { cout << *it << endl; }

NOTE: if you try to modify the content using *it in second case you will get an error because its read-only.

How to programmatically close a JFrame

This answer was given by Alex and I would like to recommend it. It worked for me and another thing it's straightforward and so simple.

setVisible(false); //you can't see me!
dispose(); //Destroy the JFrame object

How do I install Maven with Yum?

For future reference and for simplicity sake for the lazy people out there that don't want much explanations but just run things and make it work asap:

1) sudo wget -O /etc/yum.repos.d/epel-apache-maven.repo

2) sudo sed -i s/\$releasever/6/g /etc/yum.repos.d/epel-apache-maven.repo

3) sudo yum install -y apache-maven

4) mvn --version

Hope you enjoyed this copy & paste session.

Resizing an image in an HTML5 canvas

The problem with some of this solutions is that they access directly the pixel data and loop through it to perform the downsampling. Depending on the size of the image this can be very resource intensive, and it would be better to use the browser's internal algorithms.

The drawImage() function is using a linear-interpolation, nearest-neighbor resampling method. That works well when you are not resizing down more than half the original size.

If you loop to only resize max one half at a time, the results would be quite good, and much faster than accessing pixel data.

This function downsample to half at a time until reaching the desired size:

  function resize_image( src, dst, type, quality ) {
     var tmp = new Image(),
         canvas, context, cW, cH;

     type = type || 'image/jpeg';
     quality = quality || 0.92;

     cW = src.naturalWidth;
     cH = src.naturalHeight;

     tmp.src = src.src;
     tmp.onload = function() {

        canvas = document.createElement( 'canvas' );

        cW /= 2;
        cH /= 2;

        if ( cW < src.width ) cW = src.width;
        if ( cH < src.height ) cH = src.height;

        canvas.width = cW;
        canvas.height = cH;
        context = canvas.getContext( '2d' );
        context.drawImage( tmp, 0, 0, cW, cH );

        dst.src = canvas.toDataURL( type, quality );

        if ( cW <= src.width || cH <= src.height )

        tmp.src = dst.src;

  // The images sent as parameters can be in the DOM or be image objects
  resize_image( $( '#original' )[0], $( '#smaller' )[0] );

Credits to this post

Using python's eval() vs. ast.literal_eval()?

eval: This is very powerful, but is also very dangerous if you accept strings to evaluate from untrusted input. Suppose the string being evaluated is "os.system('rm -rf /')" ? It will really start deleting all the files on your computer.

ast.literal_eval: Safely evaluate an expression node or a string containing a Python literal or container display. The string or node provided may only consist of the following Python literal structures: strings, bytes, numbers, tuples, lists, dicts, sets, booleans, None, bytes and sets.


eval(expression, globals=None, locals=None)
import ast


# python 2.x - doesn't accept operators in string format
import ast
ast.literal_eval('[1, 2, 3]')  # output: [1, 2, 3]
ast.literal_eval('1+1') # output: ValueError: malformed string

# python 3.0 -3.6
import ast
ast.literal_eval("1+1") # output : 2
ast.literal_eval("{'a': 2, 'b': 3, 3:'xyz'}") # output : {'a': 2, 'b': 3, 3:'xyz'}
# type dictionary
ast.literal_eval("",{}) # output : Syntax Error required only one parameter
ast.literal_eval("__import__('os').system('rm -rf /')") # output : error

eval("__import__('os').system('rm -rf /')") 
# output : start deleting all the files on your computer.
# restricting using global and local variables
eval("__import__('os').system('rm -rf /')",{'__builtins__':{}},{})
# output : Error due to blocked imports by passing  '__builtins__':{} in global

# But still eval is not safe. we can access and break the code as given below
s = """
(lambda fc=(
lambda n: [
    c for c in 
        if c.__name__ == n
eval(s, {'__builtins__':{}})

In the above code ().__class__.__bases__[0] nothing but object itself. Now we instantiated all the subclasses, here our main enter code hereobjective is to find one class named n from it.

We need to code object and function object from instantiated subclasses. This is an alternative way from CPython to access subclasses of object and attach the system.

From python 3.7 ast.literal_eval() is now stricter. Addition and subtraction of arbitrary numbers are no longer allowed. link

reading HttpwebResponse json response, C#

First you need an object

public class MyObject {
  public string Id {get;set;}
  public string Text {get;set;}

Then in here

    using (var twitpicResponse = (HttpWebResponse)request.GetResponse()) {

        using (var reader = new StreamReader(twitpicResponse.GetResponseStream())) {
            JavaScriptSerializer js = new JavaScriptSerializer();
            var objText = reader.ReadToEnd();
            MyObject myojb = (MyObject)js.Deserialize(objText,typeof(MyObject));


I haven't tested with the hierarchical object you have, but this should give you access to the properties you want.

JavaScriptSerializer System.Web.Script.Serialization

What charset does Microsoft Excel use when saving files?

While it is true that exporting an excel file that contains special characters to csv can be a pain in the ass, there is however a simple work around: simply copy/paste the cells into a google docs and then save from there.

How do I revert an SVN commit?

svn merge -r 1944:1943 . should revert the changes of r1944 in your working copy. You can then review the changes in your working copy (with diff), but you'd need to commit in order to apply the revert into the repository.

How to place two divs next to each other?

Try to use below code changes to place two divs in front of each other

#wrapper {
  width: 500px;
  border: 1px solid black;

JSFiddle link

Unable to create/open lock file: /data/mongod.lock errno:13 Permission denied

I was having the same problem on a Ubuntu ec2 instance. I was following this amazon article on page 7:

Mongodb path in /etc/mongodb.conf was set to /var/lib/mongodb (primary install location and working). When I changed to /data/db (EBS volume) I was getting 'errno:13 Permission denied'.

  1. First I ran sudo service mongodb stop.
  2. Then I used ls -la to see what group & owner mongodb assigned to /var/lib/mongodb (existing path) and I changed the /data/db (new path) with chown and chgrp to match. (example: sudo chown -R mongodb:mongodb /data/db)
  3. Then I updated the path in etc/mongodb.conf to /data/db and deleted the old mongo files in /var/lib/mongodb directory.
  4. Then I ran sudo service mongodb start and waited about a minute. If you try to connect to 27017 immediately you won't be able to.
  5. After a minute check /data/db (EBS volume) and mongo should have placed a journal, mongod.lock, local.ns, local.0, etc. If not try sudo service mongodb restart and check a minute later.

I just spent over a hour with this. Changing the group and deleting the old files is probably not necessary, but that's what worked for me.

This is a great video about mounting a ebs volume to ec2 instance:

<button> background image

Replace button #rock With #rock

No need for additional selector scope. You're using an id which is as specific as you can be.

JsBin example:

How do I create the small icon next to the website tab for my site?

This is for the icon in the browser (most of the sites omit the type):

<link rel="icon" type="image/"
     href="" />


<link rel="icon" type="image/png"
     href="" />


<link rel="apple-touch-icon"

for the shortcut icon:

<link rel="shortcut icon"
     href="" />

Place them in the <head></head> section.

Edit may 2019 some additional examples from MDN

Access to the path 'c:\inetpub\wwwroot\myapp\App_Data' is denied

I created copy of my inet folder, to make a duplicate of the site. It showed 'access denied .../App_Data/viewstate/1/6/6/0 ... '. On checking it showed that app_data folder is having IIS_IUSER addes but does not have modify or write acess checked. Just check those boxes and the instance begin to run.

How can I count the number of matches for a regex?

From Java 9, you can use the stream provided by Matcher.results()

long matches = matcher.results().count();

Docker compose port mapping

If you want to access redis from the host (, you have to use the ports command.

    context: .
    dockerfile: Dockerfile-redis
    - "6379:6379"

How can I troubleshoot Python "Could not find platform independent libraries <prefix>"

Try export PYTHONHOME=/usr/local. Python should be installed in /usr/local on OS X.

This answer has received a little more attention than I anticipated, I'll add a little bit more context.

Normally, Python looks for its libraries in the paths prefix/lib and exec_prefix/lib, where prefix and exec_prefix are configuration options. If the PYTHONHOME environment variable is set, then the value of prefix and exec_prefix are inherited from it. If the PYTHONHOME environment variable is not set, then prefix and exec_prefix default to /usr/local (and I believe there are other ways to set prefix/exec_prefix as well, but I'm not totally familiar with them).

Normally, when you receive the error message Could not find platform independent libraries <prefix>, the string <prefix> would be replaced with the actual value of prefix. However, if prefix has an empty value, then you get the rather cryptic messages posted in the question. One way to get an empty prefix would be to set PYTHONHOME to an empty string. More info about PYTHONHOME, prefix, and exec_prefix is available in the official docs.

How to convert time milliseconds to hours, min, sec format in JavaScript?

To Convert time in millisecond to human readable format.

 function timeConversion(millisec) {

        var seconds = (millisec / 1000).toFixed(1);

        var minutes = (millisec / (1000 * 60)).toFixed(1);

        var hours = (millisec / (1000 * 60 * 60)).toFixed(1);

        var days = (millisec / (1000 * 60 * 60 * 24)).toFixed(1);

        if (seconds < 60) {
            return seconds + " Sec";
        } else if (minutes < 60) {
            return minutes + " Min";
        } else if (hours < 24) {
            return hours + " Hrs";
        } else {
            return days + " Days"

"Out Put Sample"

Entity Framework: "Store update, insert, or delete statement affected an unexpected number of rows (0)."

Recently, I'm trying upgrade EF5 to EF6 sample project . The table of sample project has decimal(5,2) type columns. Database migration successfully completed. But, initial data seed generated exception.

Model :

    public partial class Weather
    public decimal TMax {get;set;}
    public decimal TMin {get;set;}

Wrong Configuration :

public partial class WeatherMap : EntityTypeConfiguration<Weather>

    public WeatherMap()
        this.Property(t => t.TMax).HasColumnName("TMax");
        this.Property(t => t.TMin).HasColumnName("TMin");

Data :

    internal static Weather[] data = new Weather[365]
      new Weather() {...,TMax = 3.30M,TMin = -12.00M,...},
      new Weather() {...,TMax = 5.20M,TMin = -10.00M,...},
      new Weather() {...,TMax = 3.20M,TMin = -8.00M,...},
      new Weather() {...,TMax = 11.00M,TMin = -7.00M,...},
      new Weather() {...,TMax = 9.00M,TMin = 0.00M,...},

I found the problem, Seeding data has precision values, but configuration does not have precision and scale parameters. TMax and TMin fields defined with decimal(10,0) in sample table.

Correct Configuration :

public partial class WeatherMap : EntityTypeConfiguration<Weather>

    public WeatherMap()
        this.Property(t => t.TMax).HasPrecision(5,2).HasColumnName("TMax");
        this.Property(t => t.TMin).HasPrecision(5,2).HasColumnName("TMin");

My sample project run with: MySql 5.6.14, Devart.Data.MySql, MVC4, .Net 4.5.1, EF6.01

Best regards.

Automating running command on Linux from Windows using PuTTY

Try MtPutty, you can automate the ssh login in it. Its a great tool especially if you need to login to multiple servers many times. Try it here

Another tool worth trying is TeraTerm. Its really easy to use for the ssh automation stuff. You can get it here. But my favorite one is always MtPutty.

How to get maximum value from the Collection (for example ArrayList)?

There is no particularly efficient way to find the maximum value in an unsorted list -- you just need to check them all and return the highest value.

HTML form action and onsubmit issues



No input file specified

It worked for me..add on top of .htaccess file. It would disable FastCGI on godaddy shared hosting account.

Options +ExecCGI

addhandler x-httpd-php5-cgi .php

Sorting arrays in NumPy by column

Simply using sort, use coloumn number based on which you want to sort.

a = np.array([1,1], [1,-1], [-1,1], [-1,-1]])
print (a)
a = np.array(sorted(a, key=lambda a_entry: a_entry[0]))
print (a)

Using LIKE in an Oracle IN clause

Yes, you can use this query (Instead of 'Specialist' and 'Developer', type any strings you want separated by comma and change employees table with your table)

SELECT * FROM employees em
    WHERE EXISTS (select 1 from table(sys.dbms_debug_vc2coll('Specialist', 'Developer')) mt where em.job like ('%' || mt.column_value || '%'));

Why my query is better than the accepted answer: You don't need a CREATE TABLE permission to run it. This can be executed with just SELECT permissions.

How to convert QString to int?

You can use:

QString str = "10";
int n = str.toInt();


n = 10

cut or awk command to print first field of first row

awk, sed, pipe, that's heavy

set `cat /etc/*release`; echo $1

What does yield mean in PHP?

An interesting aspect, which worth to be discussed here, is yielding by reference. Every time we need to change a parameter such that it is reflected outside of the function, we have to pass this parameter by reference. To apply this to generators, we simply prepend an ampersand & to the name of the generator and to the variable used in the iteration:

 * Yields by reference.
 * @param int $from
function &counter($from) {
    while ($from > 0) {
        yield $from;

foreach (counter(100) as &$value) {
    echo $value . '...';

// Output: 99...98...97...96...95...

The above example shows how changing the iterated values within the foreach loop changes the $from variable within the generator. This is because $from is yielded by reference due to the ampersand before the generator name. Because of that, the $value variable within the foreach loop is a reference to the $from variable within the generator function.

Java AES encryption and decryption

If for a block cipher you're not going to use a Cipher transformation that includes a padding scheme, you need to have the number of bytes in the plaintext be an integral multiple of the block size of the cipher.

So either pad out your plaintext to a multiple of 16 bytes (which is the AES block size), or specify a padding scheme when you create your Cipher objects. For example, you could use:

Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");

Unless you have a good reason not to, use a padding scheme that's already part of the JCE implementation. They've thought out a number of subtleties and corner cases you'll have to realize and deal with on your own otherwise.

Ok, your second problem is that you are using String to hold the ciphertext.

In general,

String s = new String(someBytes);
byte[] retrievedBytes = s.getBytes();

will not have someBytes and retrievedBytes being identical.

If you want/have to hold the ciphertext in a String, base64-encode the ciphertext bytes first and construct the String from the base64-encoded bytes. Then when you decrypt you'll getBytes() to get the base64-encoded bytes out of the String, then base64-decode them to get the real ciphertext, then decrypt that.

The reason for this problem is that most (all?) character encodings are not capable of mapping arbitrary bytes to valid characters. So when you create your String from the ciphertext, the String constructor (which applies a character encoding to turn the bytes into characters) essentially has to throw away some of the bytes because it can make no sense of them. Thus, when you get bytes out of the string, they are not the same bytes you put into the string.

In Java (and in modern programming in general), you cannot assume that one character = one byte, unless you know absolutely you're dealing with ASCII. This is why you need to use base64 (or something like it) if you want to build strings from arbitrary bytes.

Check if table exists without using "select from"

After reading all of the above, I prefer the following statement:

       SELECT * FROM information_schema.tables 
       WHERE table_schema = 'db' 
       AND table_name = 'table'

It indicates exactly what you want to do and it actually returns a 'boolean'.

How to set different colors in HTML in one statement?

You could use CSS for this and create classes for the elements. So you'd have something like this

p.detail { color:#4C4C4C;font-weight:bold;font-family:Calibri;font-size:20 } { color:#FF0000;font-weight:bold;font-family:Tahoma;font-size:20 }

Then your HTML would read:

<p class="detail">My Name is: <span class="name">Tintinecute</span> </p>

It's a lot neater then inline stylesheets, is easier to maintain and provides greater reuse.

Here's the complete HTML to demonstrate what I mean:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "">
<html xmlns="">
    <style type="text/css">
    p.detail { color:#4C4C4C;font-weight:bold;font-family:Calibri;font-size:20 } { color:#FF0000;font-weight:bold;font-family:Tahoma;font-size:20 }
    <p class="detail">My Name is: <span class="name">Tintinecute</span> </p>

You'll see that I have the stylesheet classes in a style tag in the header, and then I only apply those classes in the code such as <p class="detail"> ... </p>. Go through the w3schools tutorial, it will only take a couple of hours and will really turn you around when it comes to styling your HTML elements. If you cut and paste that into an HTML document you can edit the styles and see what effect they have when you open the file in a browser. Experimenting like this is a great way to learn.

How to convert array into comma separated string in javascript

The method array.toString() actually calls array.join() which result in a string concatenated by commas. ref

var array = ['a','b','c','d','e','f'];_x000D_
document.write(array.toString()); // "a,b,c,d,e,f"

Also, you can implicitly call Array.toString() by making javascript coerce the Array to an string, like:

//will implicitly call array.toString()
str = ""+array;
str = `${array}`;


The join() method joins all elements of an array into a string.


It accepts a separator as argument, but the default is already a comma ,

str = arr.join([separator = ','])


var array = ['A', 'B', 'C'];
var myVar1 = array.join();      // 'A,B,C'
var myVar2 = array.join(', ');  // 'A, B, C'
var myVar3 = array.join(' + '); // 'A + B + C'
var myVar4 = array.join('');    // 'ABC'


If any element of the array is undefined or null , it is treated as an empty string.

Browser support:

It is available pretty much everywhere today, since IE 5.5 (1999~2000).


What does ^M character mean in Vim?

try :%s/\^M// At least this worked for me.

Check if an array is empty or exists

This is what I use. The first condition covers truthy, which has both null and undefined. Second condition checks for an empty array.

if(arrayName && arrayName.length > 0){
    //do something.

or thanks to tsemer's comment I added a second version

if(arrayName && arrayName.length)

Then I made a test for the second condition, using Scratchpad in Firefox:

var array1;_x000D_
var array2 = [];_x000D_
var array3 = ["one", "two", "three"];_x000D_
var array4 = null;_x000D_
if (array1 && array1.length) {_x000D_
  console.log("array1! has a value!");_x000D_
if (array2 && array2.length) {_x000D_
  console.log("array2! has a value!");_x000D_
if (array3 && array3.length) {_x000D_
  console.log("array3! has a value!");_x000D_
if (array4 && array4.length) {_x000D_
  console.log("array4! has a value!");_x000D_

which also proves that if(array2 && array2.length) and if(array2 && array2.length > 0) are exactly doing the same

How can one use multi threading in PHP applications

How about pcntl_fork?

check our the manual page for examples: PHP pcntl_fork


    $pid = pcntl_fork();
    if ($pid == -1) {
        die('could not fork');
    } else if ($pid) {
        // we are the parent
        pcntl_wait($status); //Protect against Zombie children
    } else {
        // we are the child


What is the best way to get the first letter from a string in Java, returned as a string of length 1?

import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.BenchmarkMode;
import org.openjdk.jmh.annotations.Fork;
import org.openjdk.jmh.annotations.Measurement;
import org.openjdk.jmh.annotations.Mode;
import org.openjdk.jmh.annotations.OutputTimeUnit;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.Setup;
import org.openjdk.jmh.annotations.State;
import org.openjdk.jmh.annotations.Warmup;

import java.util.concurrent.TimeUnit;

@Warmup(iterations = 5, time = 1)
@Fork(value = 1)
@Measurement(iterations = 5, time = 1)
public class StringFirstCharBenchmark {

    private String source;

    public void init() {
        source = "MALE";

    public String substring() {
        return source.substring(0, 1);

    public String indexOf() {
        return String.valueOf(source.indexOf(0));


| Benchmark                           Mode  Cnt   Score   Error  Units |
| StringFirstCharBenchmark.indexOf    avgt    5  23.777 ? 5.788  ns/op |
| StringFirstCharBenchmark.substring  avgt    5  11.305 ? 1.411  ns/op |

How do I position one image on top of another in HTML?

It may be a little late but for this you can do:

enter image description here


<!-- html -->
<div class="images-wrapper">
  <img src="images/1" alt="image 1" />
  <img src="images/2" alt="image 2" />
  <img src="images/3" alt="image 3" />
  <img src="images/4" alt="image 4" />


// In _extra.scss
$maxImagesNumber: 5;

.images-wrapper {
  img {
    position: absolute;
    padding: 5px;
    border: solid black 1px;

  @for $i from $maxImagesNumber through 1 {
    :nth-child(#{ $i }) {
      z-index: #{ $maxImagesNumber - ($i - 1) };
      left: #{ ($i - 1) * 30 }px;

Adobe Reader Command Line Reference

To open a PDF at page 100 the follow works

<path to Adobe Reader> /A "page=100" "<Path To PDF file>"

If you require more than one argument separate them with &

I use the following in a batch file to open the book I'm reading to the page I was up to.

C:\Program Files\Adobe\Reader 10.0\Reader\AcroRd32.exe /A "page=149&pagemode=none" "D:\books\MCTS(70-562) ASP.Net 3.5 Development.pdf"

The best list of command line args for Adobe Reader I have found is here.

It's for version 7 but all the arguments I tried worked.

As for closing the file, I think you will need to use the SDK, or if you are opening the file from code you could close the file from code once you have finished with it.

Converting an object to a string

I would recommend using JSON.stringify, which converts the set of the variables in the object to a JSON string. Most modern browsers support this method natively, but for those that don't, you can include a JS version:

var obj = {
  name: 'myObj'


Simple GUI Java calculator

This is the working code...

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.*;

public class JavaCalculator extends JFrame {

    private JButton jbtNum1;
    private JButton jbtNum2;
    private JButton jbtNum3;
    private JButton jbtNum4;
    private JButton jbtNum5;
    private JButton jbtNum6;
    private JButton jbtNum7;
    private JButton jbtNum8;
    private JButton jbtNum9;
    private JButton jbtNum0;
    private JButton jbtEqual;
    private JButton jbtAdd;
    private JButton jbtSubtract;
    private JButton jbtMultiply;
    private JButton jbtDivide;
    private JButton jbtSolve;
    private JButton jbtClear;
    private double TEMP;
    private double SolveTEMP;
    private JTextField jtfResult;

    Boolean addBool = false;
    Boolean subBool = false;
    Boolean divBool = false;
    Boolean mulBool = false;

    String display = "";

    public JavaCalculator() {

        JPanel p1 = new JPanel();
        p1.setLayout(new GridLayout(4, 3));
        p1.add(jbtNum1 = new JButton("1"));
        p1.add(jbtNum2 = new JButton("2"));
        p1.add(jbtNum3 = new JButton("3"));
        p1.add(jbtNum4 = new JButton("4"));
        p1.add(jbtNum5 = new JButton("5"));
        p1.add(jbtNum6 = new JButton("6"));
        p1.add(jbtNum7 = new JButton("7"));
        p1.add(jbtNum8 = new JButton("8"));
        p1.add(jbtNum9 = new JButton("9"));
        p1.add(jbtNum0 = new JButton("0"));
        p1.add(jbtClear = new JButton("C"));

        JPanel p2 = new JPanel();
        p2.setLayout(new FlowLayout());
        p2.add(jtfResult = new JTextField(20));

        JPanel p3 = new JPanel();
        p3.setLayout(new GridLayout(5, 1));
        p3.add(jbtAdd = new JButton("+"));
        p3.add(jbtSubtract = new JButton("-"));
        p3.add(jbtMultiply = new JButton("*"));
        p3.add(jbtDivide = new JButton("/"));
        p3.add(jbtSolve = new JButton("="));

        JPanel p = new JPanel();
        p.setLayout(new GridLayout());
        p.add(p2, BorderLayout.NORTH);
        p.add(p1, BorderLayout.SOUTH);
        p.add(p3, BorderLayout.EAST);


        jbtNum1.addActionListener(new ListenToOne());
        jbtNum2.addActionListener(new ListenToTwo());
        jbtNum3.addActionListener(new ListenToThree());
        jbtNum4.addActionListener(new ListenToFour());
        jbtNum5.addActionListener(new ListenToFive());
        jbtNum6.addActionListener(new ListenToSix());
        jbtNum7.addActionListener(new ListenToSeven());
        jbtNum8.addActionListener(new ListenToEight());
        jbtNum9.addActionListener(new ListenToNine());
        jbtNum0.addActionListener(new ListenToZero());

        jbtAdd.addActionListener(new ListenToAdd());
        jbtSubtract.addActionListener(new ListenToSubtract());
        jbtMultiply.addActionListener(new ListenToMultiply());
        jbtDivide.addActionListener(new ListenToDivide());
        jbtSolve.addActionListener(new ListenToSolve());
        jbtClear.addActionListener(new ListenToClear());
    } //JavaCaluclator()

    class ListenToClear implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            //display = jtfResult.getText();
            addBool = false;
            subBool = false;
            mulBool = false;
            divBool = false;

            TEMP = 0;
            SolveTEMP = 0;

    class ListenToOne implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            display = jtfResult.getText();
            jtfResult.setText(display + "1");

    class ListenToTwo implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            display = jtfResult.getText();
            jtfResult.setText(display + "2");

    class ListenToThree implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            display = jtfResult.getText();
            jtfResult.setText(display + "3");

    class ListenToFour implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            display = jtfResult.getText();
            jtfResult.setText(display + "4");

    class ListenToFive implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            display = jtfResult.getText();
            jtfResult.setText(display + "5");

    class ListenToSix implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            display = jtfResult.getText();
            jtfResult.setText(display + "6");

    class ListenToSeven implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            display = jtfResult.getText();
            jtfResult.setText(display + "7");

    class ListenToEight implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            display = jtfResult.getText();
            jtfResult.setText(display + "8");

    class ListenToNine implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            display = jtfResult.getText();
            jtfResult.setText(display + "9");

    class ListenToZero implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            display = jtfResult.getText();
            jtfResult.setText(display + "0");

    class ListenToAdd implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            TEMP = Double.parseDouble(jtfResult.getText());
            addBool = true;

    class ListenToSubtract implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            TEMP = Double.parseDouble(jtfResult.getText());
            subBool = true;

    class ListenToMultiply implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            TEMP = Double.parseDouble(jtfResult.getText());
            mulBool = true;

    class ListenToDivide implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            TEMP = Double.parseDouble(jtfResult.getText());
            divBool = true;

    class ListenToSolve implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            SolveTEMP = Double.parseDouble(jtfResult.getText());
            if (addBool == true)
                SolveTEMP = SolveTEMP + TEMP;
            else if ( subBool == true)
                SolveTEMP = SolveTEMP - TEMP;
            else if ( mulBool == true)
                SolveTEMP = SolveTEMP * TEMP;
            else if ( divBool == true)
                            SolveTEMP = SolveTEMP / TEMP;
            jtfResult.setText(  Double.toString(SolveTEMP));

            addBool = false;
            subBool = false;
            mulBool = false;
            divBool = false;

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        JavaCalculator calc = new JavaCalculator();

} //JavaCalculator

Regex to match only letters

You can try this regular expression : [^\W\d_] or [a-zA-Z].

Very Long If Statement in Python

According to PEP8, long lines should be placed in parentheses. When using parentheses, the lines can be broken up without using backslashes. You should also try to put the line break after boolean operators.

Further to this, if you're using a code style check such as pycodestyle, the next logical line needs to have different indentation to your code block.

For example:

if (abcdefghijklmnopqrstuvwxyz > some_other_long_identifier and
        here_is_another_long_identifier != and_finally_another_long_name):
    # ... your code here ...

NameError: name 'datetime' is not defined

You need to import the module datetime first:

>>> import datetime

After that it works:

>>> import datetime
>>> date =
>>> date, 11, 12)

Get url without querystring

You can use System.Uri

Uri url = new Uri("");
string path = String.Format("{0}{1}{2}{3}", url.Scheme, 
    Uri.SchemeDelimiter, url.Authority, url.AbsolutePath);

Or you can use substring

string url = "";
string path = url.Substring(0, url.IndexOf("?"));

EDIT: Modifying the first solution to reflect brillyfresh's suggestion in the comments.

Android: Clear the back stack

Kotlin example:

      val intent = Intent(this@LoginActivity,
      intent.flags = Intent.FLAG_ACTIVITY_CLEAR_TOP or Intent.FLAG_ACTIVITY_NEW_TASK

Why do I get a "Null value was assigned to a property of primitive type setter of" error message when using HibernateCriteriaBuilder in Grails

Change the parameter type from primitive to Object and put a null check in the setter. See example below

public void setPhoneNumber(Long phoneNumber) {
    if (phoneNumber != null)
        this.phoneNumber = phoneNumber;
        this.extension = 0l;

How to make an ImageView with rounded corners?

The following creates a rounded rectangle layout object that draws a rounded rectangle around any child objects that are placed in it. It also demonstrates how to create views and layouts programmatically without using the layout xml files.

package android.example;

import android.os.Bundle;
import android.util.DisplayMetrics;
import android.util.TypedValue;
import android.view.ViewGroup.LayoutParams;
import android.widget.LinearLayout;
import android.widget.TextView;

public class MessageScreen extends Activity {
 /** Called when the activity is first created. */
 public void onCreate(Bundle savedInstanceState) {
  int mainBackgroundColor = Color.parseColor("#2E8B57");
  int labelTextColor = Color.parseColor("#FF4500");
  int messageBackgroundColor = Color.parseColor("#3300FF");
  int messageTextColor = Color.parseColor("#FFFF00");

  DisplayMetrics metrics = new DisplayMetrics();
  float density = metrics.density;
  int minMarginSize = Math.round(density * 8);
  int paddingSize = minMarginSize * 2;
  int maxMarginSize = minMarginSize * 4;

  TextView label = new TextView(this);
   * The LayoutParams are instructions to the Layout that will contain the
   * View for laying out the View, so you need to use the LayoutParams of
   * the Layout that will contain the View.
  LinearLayout.LayoutParams labelLayoutParams = new LinearLayout.LayoutParams(
    LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
  label.setTextSize(TypedValue.COMPLEX_UNIT_SP, 18);
  label.setPadding(paddingSize, paddingSize, paddingSize, paddingSize);

  TextView message = new TextView(this);
  RoundedRectangle.LayoutParams messageLayoutParams = new RoundedRectangle.LayoutParams(
 LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT);
   * This is one of the calls must made to force a ViewGroup to call its
   * draw method instead of just calling the draw method of its children.
   * This tells the RoundedRectangle to put some extra space around the
   * View.
  messageLayoutParams.setMargins(minMarginSize, paddingSize,
    minMarginSize, maxMarginSize);
  message.setTextSize(TypedValue.COMPLEX_UNIT_SP, paddingSize);

  RoundedRectangle messageContainer = new RoundedRectangle(this);
  LinearLayout.LayoutParams messageContainerLayoutParams = new LinearLayout.LayoutParams(
    LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT);
  messageContainerLayoutParams.setMargins(paddingSize, 0, paddingSize, 0);
   * This is one of the calls must made to force a ViewGroup to call its
   * draw method instead of just calling the draw method of its children.
   * This tells the RoundedRectangle to color the the exta space that was
   * put around the View as well as the View. This is exterior color of
   * the RoundedRectangle.
   * This is one of the calls must made to force a ViewGroup to call its
   * draw method instead of just calling the draw method of its children.
   * This is the interior color of the RoundedRectangle. It must be
   * different than the exterior color of the RoundedRectangle or the
   * RoundedRectangle will not call its draw method.
  // Add the message to the RoundedRectangle.

  LinearLayout main = new LinearLayout(this);
  LinearLayout.LayoutParams mainLayoutParams = new LinearLayout.LayoutParams(
    LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT);


The class for RoundedRectangle layout object is as defined here:

 *  A LinearLayout that draws a rounded rectangle around the child View that was added to it.
package android.example;

import android.content.Context;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.widget.LinearLayout;

 * A LinearLayout that has rounded corners instead of square corners.
 * @author Danny Remington
 * @see LinearLayout
public class RoundedRectangle extends LinearLayout {
 private int mInteriorColor;

 public RoundedRectangle(Context p_context) {

 public RoundedRectangle(Context p_context, AttributeSet attributeSet) {
  super(p_context, attributeSet);

 // Listener for the onDraw event that occurs when the Layout is drawn.
 protected void onDraw(Canvas canvas) {
  Rect rect = new Rect(0, 0, getWidth(), getHeight());
  RectF rectF = new RectF(rect);
  DisplayMetrics metrics = new DisplayMetrics();
  Activity activity = (Activity) getContext();
  float density = metrics.density;
  int arcSize = Math.round(density * 10);

  Paint paint = new Paint();

  canvas.drawRoundRect(rectF, arcSize, arcSize, paint);

  * Set the background color to use inside the RoundedRectangle.
  * @param Primitive int - The color inside the rounded rectangle.
 public void setInteriorColor(int interiorColor) {
  mInteriorColor = interiorColor;

  * Get the background color used inside the RoundedRectangle.
  * @return Primitive int - The color inside the rounded rectangle.
 public int getInteriorColor() {
  return mInteriorColor;


Only one expression can be specified in the select list when the subquery is not introduced with EXISTS

It's complaining about


inside the subquery. Only one column can be returned from the subquery unless you are performing an exists query. I'm not sure why you want to do a count on the same column twice, superficially it looks redundant to what you are doing. The subquery here is only a filter it is not the same as a join. i.e. you use it to restrict data, not to specify what columns to get back.

How to get javax.comm API?

you can find Java Communications API 2.0 in below link

Count if two criteria match - EXCEL formula

Add the sheet name infront of the cell, e.g.:


Assumes the sheet name is "stock"

How can I force browsers to print background images in CSS?

Browsers, by default, have their option to print background-colors and images turned off. You can add some lines in CSS to bypass this. Just add:

* {
    -webkit-print-color-adjust: exact !important;   /* Chrome, Safari */
    color-adjust: exact !important;                 /*Firefox*/

Note: It's not working on the entire body but you could speciy it for a inner element or a container div element.

Count number of times value appears in particular column in MySQL

SELECT column_name, COUNT(column_name)
FROM table_name
GROUP BY column_name

Difference between application/x-javascript and text/javascript content types

Use type="application/javascript"

In case of HTML5, the type attribute is obsolete, you may remove it. Note: that it defaults to "text/javascript" according to, so I would suggest to add the "application/javascript" instead of removing it.
The type attribute gives the language of the script or format of the data. If the attribute is present, its value must be a valid MIME type. The charset parameter must not be specified. The default, which is used if the attribute is absent, is "text/javascript".

Use "application/javascript", because "text/javascript" is obsolete:

RFC 4329:

  1. Deployed Scripting Media Types and Compatibility

    Various unregistered media types have been used in an ad-hoc fashion to label and exchange programs written in ECMAScript and JavaScript. These include:

    +-----------------------------------------------------+ | text/javascript | text/ecmascript | | text/javascript1.0 | text/javascript1.1 | | text/javascript1.2 | text/javascript1.3 | | text/javascript1.4 | text/javascript1.5 | | text/jscript | text/livescript | | text/x-javascript | text/x-ecmascript | | application/x-javascript | application/x-ecmascript | | application/javascript | application/ecmascript | +-----------------------------------------------------+

Use of the "text" top-level type for this kind of content is known to be problematic. This document thus defines text/javascript and text/
ecmascript but marks them as "obsolete". Use of experimental and
unregistered media types, as listed in part above, is discouraged.
The media types,

  * application/javascript
  * application/ecmascript

which are also defined in this document, are intended for common use and should be used instead.

This document defines equivalent processing requirements for the
types text/javascript, text/ecmascript, and application/javascript.
Use of and support for the media type application/ecmascript is
considerably less widespread than for other media types defined in
this document. Using that to its advantage, this document defines
stricter processing rules for this type to foster more interoperable

x-javascript is experimental, don't use it.

How to specify the actual x axis values to plot as x axis ticks in R

You'll find the answer to your question in the help page for ?axis.

Here is one of the help page examples, modified with your data:

Option 1: use xaxp to define the axis labels

plot(x,y, xaxt="n")
axis(1, xaxp=c(10, 200, 19), las=2)

Option 2: Use at and seq() to define the labels:

plot(x,y, xaxt="n")
axis(1, at = seq(10, 200, by = 10), las=2)

Both these options yield the same graphic:

enter image description here

PS. Since you have a large number of labels, you'll have to use additional arguments to get the text to fit in the plot. I use las to rotate the labels.

What is the opposite of evt.preventDefault();

This is not a direct answer for the question but it may help someone. My point is you only call preventDefault() based on some conditions as there is no point of having an event if you call preventDefault() for all the cases. So having if conditions and calling preventDefault() only when the condition/s satisfied will work the function in usual way for the other cases.

$('.btnEdit').click(function(e) {

   var status = $(this).closest('tr').find('td').eq(3).html().trim();
   var tripId = $(this).attr('tripId');

  if (status == 'Completed') {

     alert("You can't edit completed reservations");

 } else if (tripId != '') {

    alert("You can't edit a reservation which is already attached to a trip");
 //else it will continue as usual


How to create and add users to a group in Jenkins for authentication?

According to this posting by the lead Jenkins developer, Kohsuke Kawaguchi, in 2009, there is no group support for the built-in Jenkins user database. Group support is only usable when integrating Jenkins with LDAP or Active Directory. This appears to be the same in 2012.

However, as Vadim wrote in his answer, you don't need group support for the built-in Jenkins user database, thanks to the Role strategy plug-in.

file_get_contents("php://input") or $HTTP_RAW_POST_DATA, which one is better to get the body of JSON request?

php://input is a read-only stream that allows you to read raw data from the request body. In the case of POST requests, it is preferable to use php://input instead of $HTTP_RAW_POST_DATA as it does not depend on special php.ini directives. Moreover, for those cases where $HTTP_RAW_POST_DATA is not populated by default, it is a potentially less memory intensive alternative to activating always_populate_raw_post_data.


How to get a right click mouse event? Changing EventArgs to MouseEventArgs causes an error in Form1Designer?

For me neither the MouseClick or Click event worked, because the events, simply, are not called when you right click. The quick way to do it is:

 private void button1_MouseUp(object sender, MouseEventArgs e)
        if (e.Button == MouseButtons.Right)
            //do something here
        else//left or middle click
            //do something here

You can modify that to do exactly what you want depended on the arguments' values.

WARNING: There is one catch with only using the mouse up event. if you mousedown on the control and then you move the cursor out of the control to release it, you still get the event fired. In order to avoid that, you should also make sure that the mouse up occurs within the control in the event handler. Checking whether the mouse cursor coordinates are within the control's rectangle before you check the buttons will do it properly.

Implementing Singleton with an Enum (in Java)

Like all enum instances, Java instantiates each object when the class is loaded, with some guarantee that it's instantiated exactly once per JVM. Think of the INSTANCE declaration as a public static final field: Java will instantiate the object the first time the class is referred to.

The instances are created during static initialization, which is defined in the Java Language Specification, section 12.4.

For what it's worth, Joshua Bloch describes this pattern in detail as item 3 of Effective Java Second Edition.

Several ports (8005, 8080, 8009) required by Tomcat Server at localhost are already in use

Your Tomcat is probably running already. That's why you have got an error. I've had the same problem before. I solved it very simply:

  1. Restart your computer
  2. Open Eclipse
  3. Run your Tomcat

That's all.

How can I list all foreign keys referencing a given table in SQL Server?

You can find through below query :

 SELECT OBJECT_NAME (FK.referenced_object_id) 'Referenced Table', 
      OBJECT_NAME(FK.parent_object_id) 'Referring Table', 'Foreign Key', 
      COL_NAME(FK.referenced_object_id, FKC.referenced_column_id) 'Referenced Column',
      COL_NAME(FK.parent_object_id,FKC.parent_column_id) 'Referring Column'
     FROM sys.foreign_keys AS FK
             INNER JOIN sys.foreign_key_columns AS FKC 
                 ON FKC.constraint_object_id = FK.OBJECT_ID
     WHERE OBJECT_NAME (FK.referenced_object_id) = 'YourTableName'
     AND COL_NAME(FK.referenced_object_id, FKC.referenced_column_id) = 'YourColumnName'
     order by  OBJECT_NAME(FK.parent_object_id)

Caused by: Cannot recover key

I had the same error when we imported a key into a keystore that was build using a 64bit OpenSSL Version. When we followed the same procedure to import the key into a keystore that was build using a 32 bit OpenSSL version everything went fine.

How to update two tables in one statement in SQL Server 2005?

Sorry, afaik, you cannot do that. To update attributes in two different tables, you will need to execute two separate statements. But they can be in a batch ( a set of SQL sent to the server in one round trip)

IE7 Z-Index Layering Issues

I encountered this issue, but on a large project where HTML changes had to be requested and became a whole issue, so I was looking for a pure css solution.

By placing position:relative; z-index:-1 on my main body content my header drop down content suddenly displayed above the body content in ie7 (it was already displaying without issue in all other browsers and in ie8+)

The problem with that was then this disabled all hover and click actions on all content in the element with the z-index:-1 so i went to the parent element of the whole page and gave it a position:relative; z-index:1

Which fixed the issue and retained the correct layering functionality.

Feels a bit hacky, but worked as required.

Convert a number range to another range, maintaining ratio

Here is a Javascript version that returns a function that does the rescaling for predetermined source and destination ranges, minimizing the amount of computation that has to be done each time.

// This function returns a function bound to the 
// min/max source & target ranges given.
// oMin, oMax = source
// nMin, nMax = dest.
function makeRangeMapper(oMin, oMax, nMin, nMax ){
    //range check
    if (oMin == oMax){
        console.log("Warning: Zero input range");
        return undefined;

    if (nMin == nMax){
        console.log("Warning: Zero output range");
        return undefined

    //check reversed input range
    var reverseInput = false;
    let oldMin = Math.min( oMin, oMax );
    let oldMax = Math.max( oMin, oMax );
    if (oldMin != oMin){
        reverseInput = true;

    //check reversed output range
    var reverseOutput = false;  
    let newMin = Math.min( nMin, nMax )
    let newMax = Math.max( nMin, nMax )
    if (newMin != nMin){
        reverseOutput = true;

    // Hot-rod the most common case.
    if (!reverseInput && !reverseOutput) {
        let dNew = newMax-newMin;
        let dOld = oldMax-oldMin;
        return (x)=>{
            return ((x-oldMin)* dNew / dOld) + newMin;

    return (x)=>{
        let portion;
        if (reverseInput){
            portion = (oldMax-x)*(newMax-newMin)/(oldMax-oldMin);
        } else {
            portion = (x-oldMin)*(newMax-newMin)/(oldMax-oldMin)
        let result;
        if (reverseOutput){
            result = newMax - portion;
        } else {
            result = portion + newMin;

        return result;

Here is an example of using this function to scale 0-1 into -0x80000000, 0x7FFFFFFF

let normTo32Fn = makeRangeMapper(0, 1, -0x80000000, 0x7FFFFFFF);
let fs = normTo32Fn(0.5);
let fs2 = normTo32Fn(0);

How to validate a file upload field using Javascript/jquery

Check it's value property:

In jQuery (since your tag mentions it):


Or in vanilla JavaScript:


DropDownList's SelectedIndexChanged event not firing

For me answer was aspx page attribute, i added Async="true" to page attributes and this solved my problem.

<%@ Page Language="C#" MasterPageFile="~/MasterPage/Reports.Master"..... 
    AutoEventWireup="true" Async="true" %>

This is the structure of my update panel

  <asp:UpdatePanel ID="updt" runat="server">

      <asp:DropDownList ID="id" runat="server" AutoPostBack="true"        onselectedindexchanged="your server side function" />


Image is not showing in browser?

I also had a similar problem and tried all of the above but nothing worked. And then I noticed that the image was loading fine for one file and not for another. The reason was: My image was named image.jpg and a page named about.html could not load it while login.html could. This was because image.jpg was below about and above login. So I guess login.html could refer to the image and about.html couldn't find it. I renamed about.html to zabout.html and re-renamed it back. Worked. Same may be the case for images enclosed in folders.

Android button font size

I tried to put the font size in the styles.xml but when i went to use it it was only allowing resources from the dimen folder so put it in there instead, dont know it this is right


Can't choose class as main class in IntelliJ

Select the folder containing the package tree of these classes, right-click and choose "Mark Directory as -> Source Root"

How to show another window from mainwindow in QT

  1. Implement a slot in your QMainWindow where you will open your new Window,
  2. Place a widget on your QMainWindow,
  3. Connect a signal from this widget to a slot from the QMainWindow (for example: if the widget is a QPushButton connect the signal click() to the QMainWindow custom slot you have created).

Code example:


// ...
include "newwindow.h"
// ...
public slots:
   void openNewWindow();
// ...
   NewWindow *mMyNewWindow;
// ...


// ...
      // ...
      connect(mMyButton, SIGNAL(click()), this, SLOT(openNewWindow()));
      // ...
// ...
void MainWindow::openNewWindow()
   mMyNewWindow = new NewWindow(); // Be sure to destroy your window somewhere
   // ...

This is an example on how display a custom new window. There are a lot of ways to do this.


It's the identifier for your current session in PHP. If you delete it, you won't be able to access/make use of session variables. I'd suggest you keep it.

Convert string to symbol-able in ruby

This is not answering the question itself, but I found this question searching for the solution to convert a string to symbol and use it on a hash.

hsh =
str_to_symbol = "Book Author Title".downcase.gsub(/\s+/, "_").to_sym
hsh[str_to_symbol] = 10
p hsh
# => {book_author_title: 10}

Hope it helps someone like me!

How do I upload a file with metadata using a REST web service?

Just because you're not wrapping the entire request body in JSON, doesn't meant it's not RESTful to use multipart/form-data to post both the JSON and the file(s) in a single request:

curl -F "metadata=<metadata.json" -F "[email protected]"

on the server side:

class AddFileResource(Resource):
    def render_POST(self, request):
        metadata = json.loads(request.args['metadata'][0])
        file_body = request.args['file'][0]

to upload multiple files, it's possible to either use separate "form fields" for each:

curl -F "metadata=<metadata.json" -F "[email protected]" -F "[email protected]" which case the server code will have request.args['file1'][0] and request.args['file2'][0]

or reuse the same one for many:

curl -F "metadata=<metadata.json" -F "[email protected]" -F "[email protected]" which case request.args['files'] will simply be a list of length 2.

or pass multiple files through a single field:

curl -F "metadata=<metadata.json" -F "[email protected],some-other-file.tar.gz" which case request.args['files'] will be a string containing all the files, which you'll have to parse yourself — not sure how to do it, but I'm sure it's not difficult, or better just use the previous approaches.

The difference between @ and < is that @ causes the file to get attached as a file upload, whereas < attaches the contents of the file as a text field.

P.S. Just because I'm using curl as a way to generate the POST requests doesn't mean the exact same HTTP requests couldn't be sent from a programming language such as Python or using any sufficiently capable tool.

Filtering a spark dataframe based on date

I find the most readable way to express this is using a sql expression:

df.filter("my_date < date'2015-01-01'")

we can verify this works correctly by looking at the physical plan from .explain()

+- *(1) Filter (isnotnull(my_date#22) && (my_date#22 < 16436))

nginx upload client_max_body_size issue

Does your upload die at the very end? 99% before crashing? Client body and buffers are key because nginx must buffer incoming data. The body configs (data of the request body) specify how nginx handles the bulk flow of binary data from multi-part-form clients into your app's logic.

The clean setting frees up memory and consumption limits by instructing nginx to store incoming buffer in a file and then clean this file later from disk by deleting it.

Set body_in_file_only to clean and adjust buffers for the client_max_body_size. The original question's config already had sendfile on, increase timeouts too. I use the settings below to fix this, appropriate across your local config, server, & http contexts.

client_body_in_file_only clean;
client_body_buffer_size 32K;

client_max_body_size 300M;

sendfile on;
send_timeout 300s;

Rails 4: List of available datatypes

Here are all the Rails 4 (ActiveRecord migration) datatypes:

  • :binary
  • :boolean
  • :date
  • :datetime
  • :decimal
  • :float
  • :integer
  • :bigint
  • :primary_key
  • :references
  • :string
  • :text
  • :time
  • :timestamp

These are the same as with Rails 3.

If you use PostgreSQL, you can also take advantage of these:

  • :hstore
  • :json
  • :jsonb
  • :array
  • :cidr_address
  • :ip_address
  • :mac_address

They are stored as strings if you run your app with a not-PostgreSQL database.

Edit, 2016-Sep-19:

There's a lot more postgres specific datatypes in Rails 4 and even more in Rails 5.

How do you set a JavaScript onclick event to a class with css

Many 3rd party JavaScript libraries allow you to select all elements that have a CSS class of a particular name applied to them. Then you can iterate those elements and dynamically attach the handler.

There is no CSS-specific manner to do this.

In JQuery, you can do:

$(".myCssClass").click(function() { alert("hohoho"); });

How to convert a std::string to const char* or char*?

I am working with an API with a lot of functions get as an input a char*.

I have created a small class to face this kind of problem, I have implemented the RAII idiom.

class DeepString
        DeepString(const DeepString& other);
        DeepString& operator=(const DeepString& other);
        char* internal_; 

        explicit DeepString( const string& toCopy): 
            internal_(new char[toCopy.size()+1]) 
        ~DeepString() { delete[] internal_; }
        char* str() const { return internal_; }
        const char* c_str()  const { return internal_; }

And you can use it as:

void aFunctionAPI(char* input);

//  other stuff

aFunctionAPI("Foo"); //this call is not safe. if the function modified the 
                     //literal string the program will crash
std::string myFoo("Foo");
aFunctionAPI(myFoo.c_str()); //this is not compiling
aFunctionAPI(const_cast<char*>(myFoo.c_str())); //this is not safe std::string 
                                                //implement reference counting and 
                                                //it may change the value of other
                                                //strings as well.
DeepString myDeepFoo(myFoo);
aFunctionAPI(myFoo.str()); //this is fine

I have called the class DeepString because it is creating a deep and unique copy (the DeepString is not copyable) of an existing string.

How to calculate age in T-SQL with years, months, and days

Here is SQL code that gives you the number of years, months, and days since the sysdate. Enter value for input_birth_date this format(dd_mon_yy). note: input same value(birth date) for years, months & days such as 01-mar-85

select trunc((sysdate -to_date('&input_birth_date_dd_mon_yy'))/365) years,
trunc(mod(( sysdate -to_date('&input_birth_date_dd_mon_yy'))/365,1)*12) months,
trunc((mod((mod((sysdate -to_date('&input_birth_date_dd_mon_yy'))/365,1)*12),1)*30)+1) days 
 from dual

SQL Server 2008: TOP 10 and distinct together

  FROM MyDatabase
  Where EXISTS 
     Select Distinct[A] FROM MyDatabase

Create URL from a String

URL url = new URL(yourUrl, "/api/v1/status.xml");

According to the javadocs this constructor just appends whatever resource to the end of your domain, so you would want to create 2 urls:

URL domain = new URL("");
URL url = new URL(domain + "/files/resource.xml");


How to clear exisiting dropdownlist items when its content changes?

Just 2 simple steps to solve your issue

First of all check AppendDataBoundItems property and make it assign false

Secondly clear all the items using property .clear()

ddl1.datasource = sql1;

jQuery: find element by text

Best way in my opinion.

$.fn.findByContentText = function (text) {
    return $(this).contents().filter(function () {
        return $(this).text().trim() == text.trim();

Facebook Like-Button - hide count?

Adding the following to your css should hide the text element for users and keep FB Happy

    display:none !important; /*in your stylesheets to hide the counter!*/

-- Update

Try using a different approach.

How to get IP address of the device from code?

This is my helper util to read IP and MAC addresses. Implementation is pure-java, but I have a comment block in getMACAddress() which could read the value from the special Linux(Android) file. I've run this code only on few devices and Emulator but let me know here if you find weird results.

// AndroidManifest.xml permissions
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

// test functions
Utils.getIPAddress(true); // IPv4
Utils.getIPAddress(false); // IPv6

import java.util.*;   
//import org.apache.http.conn.util.InetAddressUtils;

public class Utils {

     * Convert byte array to hex string
     * @param bytes toConvert
     * @return hexValue
    public static String bytesToHex(byte[] bytes) {
        StringBuilder sbuf = new StringBuilder();
        for(int idx=0; idx < bytes.length; idx++) {
            int intVal = bytes[idx] & 0xff;
            if (intVal < 0x10) sbuf.append("0");
        return sbuf.toString();

     * Get utf8 byte array.
     * @param str which to be converted
     * @return  array of NULL if error was found
    public static byte[] getUTF8Bytes(String str) {
        try { return str.getBytes("UTF-8"); } catch (Exception ex) { return null; }

     * Load UTF8withBOM or any ansi text file.
     * @param filename which to be converted to string
     * @return String value of File
     * @throws if error occurs
    public static String loadFileAsString(String filename) throws {
        final int BUFLEN=1024;
        BufferedInputStream is = new BufferedInputStream(new FileInputStream(filename), BUFLEN);
        try {
            ByteArrayOutputStream baos = new ByteArrayOutputStream(BUFLEN);
            byte[] bytes = new byte[BUFLEN];
            boolean isUTF8=false;
            int read,count=0;           
            while(( != -1) {
                if (count==0 && bytes[0]==(byte)0xEF && bytes[1]==(byte)0xBB && bytes[2]==(byte)0xBF ) {
                    baos.write(bytes, 3, read-3); // drop UTF8 bom marker
                } else {
                    baos.write(bytes, 0, read);
            return isUTF8 ? new String(baos.toByteArray(), "UTF-8") : new String(baos.toByteArray());
        } finally {
            try{ is.close(); } catch(Exception ignored){} 

     * Returns MAC address of the given interface name.
     * @param interfaceName eth0, wlan0 or NULL=use first interface 
     * @return  mac address or empty string
    public static String getMACAddress(String interfaceName) {
        try {
            List<NetworkInterface> interfaces = Collections.list(NetworkInterface.getNetworkInterfaces());
            for (NetworkInterface intf : interfaces) {
                if (interfaceName != null) {
                    if (!intf.getName().equalsIgnoreCase(interfaceName)) continue;
                byte[] mac = intf.getHardwareAddress();
                if (mac==null) return "";
                StringBuilder buf = new StringBuilder();
                for (byte aMac : mac) buf.append(String.format("%02X:",aMac));  
                if (buf.length()>0) buf.deleteCharAt(buf.length()-1);
                return buf.toString();
        } catch (Exception ignored) { } // for now eat exceptions
        return "";
        /*try {
            // this is so Linux hack
            return loadFileAsString("/sys/class/net/" +interfaceName + "/address").toUpperCase().trim();
        } catch (IOException ex) {
            return null;

     * Get IP address from first non-localhost interface
     * @param useIPv4   true=return ipv4, false=return ipv6
     * @return  address or empty string
    public static String getIPAddress(boolean useIPv4) {
        try {
            List<NetworkInterface> interfaces = Collections.list(NetworkInterface.getNetworkInterfaces());
            for (NetworkInterface intf : interfaces) {
                List<InetAddress> addrs = Collections.list(intf.getInetAddresses());
                for (InetAddress addr : addrs) {
                    if (!addr.isLoopbackAddress()) {
                        String sAddr = addr.getHostAddress();
                        //boolean isIPv4 = InetAddressUtils.isIPv4Address(sAddr);
                        boolean isIPv4 = sAddr.indexOf(':')<0;

                        if (useIPv4) {
                            if (isIPv4) 
                                return sAddr;
                        } else {
                            if (!isIPv4) {
                                int delim = sAddr.indexOf('%'); // drop ip6 zone suffix
                                return delim<0 ? sAddr.toUpperCase() : sAddr.substring(0, delim).toUpperCase();
        } catch (Exception ignored) { } // for now eat exceptions
        return "";


Disclaimer: Ideas and example code to this Utils class came from several SO posts and Google. I have cleaned and merged all examples.

What is the error "Every derived table must have its own alias" in MySQL?

I think it's asking you to do this:

      FROM (SELECT * FROM TT2) as myalias
     ) as anotheralias;

But why would you write this query in the first place?

How do I use $rootScope in Angular to store variables?

Sharing data between controllers is what Factories/Services are very good for. In short, it works something like this.

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

app.factory('items', function() {
    var items = [];
    var itemsService = {};

    itemsService.add = function(item) {
    itemsService.list = function() {
        return items;

    return itemsService;

function Ctrl1($scope,items) {
    $scope.list = items.list; 

function Ctrl2($scope, items) {
    $scope.add = items.add;

You can see a working example in this fiddle:

Using Laravel Homestead: 'no input file specified'

If you renamed the folder containing your Homestead project, you'll get this error. Visit your Homestead.yaml file and update any references to point to the renamed folder, then do vagrant up (etc.) again

Pandas count(distinct) equivalent

Here an approach to have count distinct over multiple columns. Let's have some data:

data = {'CLIENT_CODE':[1,1,2,1,2,2,3],
        'PRODUCT_CODE': [100,150,220,400,50,80,100]
table = pd.DataFrame(data)

0   1       201301      100
1   1       201301      150
2   2       201301      220
3   1       201302      400
4   2       201302      50
5   2       201302      80
6   3       201302      100

Now, list the columns of interest and use groupby in a slightly modified syntax:

columns = ['YEAR_MONTH', 'PRODUCT_CODE']

We obtain:

1           2            3
2           2            3
3           1            1

Print out the values of a (Mat) matrix in OpenCV C++

#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/highgui/highgui.hpp>

#include <iostream>
#include <iomanip>

using namespace cv;
using namespace std;

int main(int argc, char** argv)
    double data[4] = {-0.0000000077898273846583732, -0.03749374753019832, -0.0374787251930463, -0.000000000077893623846343843};
    Mat src = Mat(1, 4, CV_64F, &data);
    for(int i=0; i<4; i++)
        cout << setprecision(3) <<<double>(0,i) << endl;

    return 0;

How to run a makefile in Windows?

So if you're using Vscode and Mingw then you should first make sure that the bin folder of the mingw is included in the environment path and it is preferred to change the mingw32-make.exe to make to ease the task and then create a makefile and include this code in it .

    gcc -o filename filename.c

Then save the makefile and open Vscode Code terminal and write make. Then makefile will get executed.

how to convert an RGB image to numpy array?

OpenCV image format supports the numpy array interface. A helper function can be made to support either grayscale or color images. This means the BGR -> RGB conversion can be conveniently done with a numpy slice, not a full copy of image data.

Note: this is a stride trick, so modifying the output array will also change the OpenCV image data. If you want a copy, use .copy() method on the array!

import numpy as np

def img_as_array(im):
    """OpenCV's native format to a numpy array view"""
    w, h, n = im.width, im.height, im.channels
    modes = {1: "L", 3: "RGB", 4: "RGBA"}
    if n not in modes:
        raise Exception('unsupported number of channels: {0}'.format(n))
    out = np.asarray(im)
    if n != 1:
        out = out[:, :, ::-1]  # BGR -> RGB conversion
    return out

Phone: numeric keyboard for text input

As of mid-2015, I believe this is the best solution:

<input type="number" pattern="[0-9]*" inputmode="numeric">

This will give you the numeric keypad on both Android and iOS:

enter image description here

It also gives you the expected desktop behavior with the up/down arrow buttons and keyboard friendly up/down arrow key incrementing:

enter image description here

Try it in this code snippet:

  <input type="number" pattern="[0-9]*" inputmode="numeric">_x000D_
  <button type="submit">Submit</button>_x000D_

By combining both type="number" and pattern="[0-9]*, we get a solution that works everywhere. And, its forward compatible with the future HTML 5.1 proposed inputmode attribute.

Note: Using a pattern will trigger the browser's native form validation. You can disable this using the novalidate attribute, or you can customize the error message for a failed validation using the title attribute.

If you need to be able to enter leading zeros, commas, or letters - for example, international postal codes - check out this slight variant.

Credits and further reading:

How to sleep for five seconds in a batch file/cmd

An improvement of the code proposed by the user Aacini, It has resolution of hundredths of a second and does not fail when the time reaches 23:59:59,99:

for /f "tokens=1,2,3,4 delims=:," %%A in ("%TIME%") do set /a HH=%%A, MM=1%%B-100, SS=1%%C-100, CC=1%%D-100, TBASE=((HH*60+MM)*60+SS)*100+CC

:: Example delay 1 seg.
set /a TFIN=%TBASE%+100

for /f "tokens=1,2,3,4 delims=:," %%A in ("%TIME%") do set /a HH=%%A, MM=1%%B-100, SS=1%%C-100, CC=1%%D-100, TACTUAL=((HH*60+MM)*60+SS)*100+CC

if %TACTUAL% lss %TFIN% goto ESPERAR

How to save the contents of a div as a image?

There are several of this same question (1, 2). One way of doing it is using canvas. Here's a working solution. Here you can see some working examples of using this library.

What's the difference between interface and @interface in java?

interface: defines the contract for a class which implements it

@interface: defines the contract for an annotation

Can I use multiple "with"?

Yes - just do it this way:

WITH DependencedIncidents AS
lalala AS

You don't need to repeat the WITH keyword

When do I need to use AtomicBoolean in Java?

There are two main reasons why you can use an atomic boolean. First its mutable, you can pass it in as a reference and change the value that is a associated to the boolean itself, for example.

public final class MyThreadSafeClass{

    private AtomicBoolean myBoolean = new AtomicBoolean(false);
    private SomeThreadSafeObject someObject = new SomeThreadSafeObject();

    public boolean doSomething(){
         return myBoolean.get(); //will return true

and in the someObject class

public final class SomeThreadSafeObject{
    public void doSomeWork(AtomicBoolean b){

More importantly though, its thread safe and can indicate to developers maintaining the class, that this variable is expected to be modified and read from multiple threads. If you do not use an AtomicBoolean you must synchronize the boolean variable you are using by declaring it volatile or synchronizing around the read and write of the field.

Why is ZoneOffset.UTC != ZoneId.of("UTC")?

The answer comes from the javadoc of ZoneId (emphasis mine) ...

A ZoneId is used to identify the rules used to convert between an Instant and a LocalDateTime. There are two distinct types of ID:

  • Fixed offsets - a fully resolved offset from UTC/Greenwich, that uses the same offset for all local date-times
  • Geographical regions - an area where a specific set of rules for finding the offset from UTC/Greenwich apply

Most fixed offsets are represented by ZoneOffset. Calling normalized() on any ZoneId will ensure that a fixed offset ID will be represented as a ZoneOffset.

... and from the javadoc of ZoneId#of (emphasis mine):

This method parses the ID producing a ZoneId or ZoneOffset. A ZoneOffset is returned if the ID is 'Z', or starts with '+' or '-'.

The argument id is specified as "UTC", therefore it will return a ZoneId with an offset, which also presented in the string form:




As you use the equals method for comparison, you check for object equivalence. Because of the described difference, the result of the evaluation is false.

When the normalized() method is used as proposed in the documentation, the comparison using equals will return true, as normalized() will return the corresponding ZoneOffset:

Normalizes the time-zone ID, returning a ZoneOffset where possible.

    .equals(now.withZoneSameInstant(ZoneId.of("UTC").normalized())); // true

As the documentation states, if you use "Z" or "+0" as input id, of will return the ZoneOffset directly and there is no need to call normalized():

now.withZoneSameInstant(ZoneOffset.UTC).equals(now.withZoneSameInstant(ZoneId.of("Z"))); //true
now.withZoneSameInstant(ZoneOffset.UTC).equals(now.withZoneSameInstant(ZoneId.of("+0"))); //true

To check if they store the same date time, you can use the isEqual method instead:

    .isEqual(now.withZoneSameInstant(ZoneId.of("UTC"))); // true


System.out.println("equals - ZoneId.of(\"UTC\"): " + nowZoneOffset
System.out.println("equals - ZoneId.of(\"UTC\").normalized(): " + nowZoneOffset
System.out.println("equals - ZoneId.of(\"Z\"): " + nowZoneOffset
System.out.println("equals - ZoneId.of(\"+0\"): " + nowZoneOffset
System.out.println("isEqual - ZoneId.of(\"UTC\"): "+ nowZoneOffset


equals - ZoneId.of("UTC"): false
equals - ZoneId.of("UTC").normalized(): true
equals - ZoneId.of("Z"): true
equals - ZoneId.of("+0"): true
isEqual - ZoneId.of("UTC"): true

angular 4: *ngIf with multiple conditions

You got a ninja ')'.

Try :

<div *ngIf="currentStatus !== 'open' || currentStatus !== 'reopen'">

How do I create a MessageBox in C#?

I got the same error 'System.Windows.Forms.MessageBox' is a 'type' but is used like a 'variable', even if using:

MessageBox.Show("Hello, World!");

I guess my initial attempts with invalid syntax caused some kind of bug and I ended up fixing it by adding a space between "MessageBox.Show" and the brackets ():

MessageBox.Show ("Hello, World!");

Now using the original syntax without the extra space works again:

MessageBox.Show("Hello, World!");

Operation is not valid due to the current state of the object, when I select a dropdown list

I know an answer has already been accepted for this problem but someone asked in the comments if there was a solution that could be done outside the web.config. I had a ListView producing the exact same error and setting EnableViewState to false resolved this problem for me.

Angular.js vs Knockout.js vs Backbone.js

It depends on the nature of your application. And, since you did not describe it in great detail, it is an impossible question to answer. I find Backbone to be the easiest, but I work in Angular all day. Performance is more up to the coder than the framework, in my opinion.

Are you doing heavy DOM manipulation? I would use jQuery and Backbone.

Very data driven app? Angular with its nice data binding.

Game programming? None - direct to canvas; maybe a game engine.

Change values on matplotlib imshow() graph axis

I would try to avoid changing the xticklabels if possible, otherwise it can get very confusing if you for example overplot your histogram with additional data.

Defining the range of your grid is probably the best and with imshow it can be done by adding the extent keyword. This way the axes gets adjusted automatically. If you want to change the labels i would use set_xticks with perhaps some formatter. Altering the labels directly should be the last resort.

fig, ax = plt.subplots(figsize=(6,6))

ax.imshow(hist,, interpolation='none', extent=[80,120,32,0])
ax.set_aspect(2) # you may also use am.imshow(..., aspect="auto") to restore the aspect ratio

enter image description here

Flask Error: "Method Not Allowed The method is not allowed for the requested URL"

I had a similar problem when I deployed my Flask app in the IIS. Apparently, IIS does not accept route that include an underline ("_"). When I removed the underline, problem was resolved.

Converting Milliseconds to Minutes and Seconds?


Duration d = Duration.ofMillis( … ) ;
int minutes = d.toMinutesPart() ;
int seconds = d.toSecondsPart() ;

Java 9 and later

In Java 9 and later, create a Duration and call the to…Part methods. In this case: toMinutesPart and toSecondsPart.

Capture the start & stop of your stopwatch.

Instant start =; 
Instant stop =;

Represent elapsed time in a Duration object.

Duration d = Duration.between( start , stop );

Interrogate for each part, the minutes and the seconds.

int minutes = d.toMinutesPart();
int seconds = d.toSecondsPart();

You might also want to see if your stopwatch ran expectedly long.

Boolean ranTooLong = ( d.toDaysPart() > 0 ) || ( d.toHoursPart() > 0 ) ;

Java 8

In Java 8, the Duration class lacks to…Part methods. You will need to do math as shown in the other Answers.

long entireDurationAsSeconds = d.getSeconds();

Or let Duration do the math.

long minutesPart = d.toMinutes(); 
long secondsPart = d.minusMinutes( minutesPart ).getSeconds() ;

See live code in

Interval: 2016-12-18T08:39:34.099Z/2016-12-18T08:41:49.099Z

d.toString(): PT2M15S

d.getSeconds(): 135

Elapsed: 2M 15S


FYI, the resolution of now methods changed between Java 8 and Java 9. See this Question.

  • Java 9 captures the moment with a resolution as fine as nanoseconds. Resolution depends on capability of your computer’s hardware. I see microseconds (six digits of decimal fraction) on MacBook Pro Retina with macOS Sierra.
  • Java 8 captures the moment only up to milliseconds. The implementation of Clock is limited to a resolution of milliseconds. So you can store values in nanoseconds but only capture them in milliseconds.

About java.time

The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.

To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.

The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.

You may exchange java.time objects directly with your database. Use a JDBC driver compliant with JDBC 4.2 or later. No need for strings, no need for java.sql.* classes.

Where to obtain the java.time classes?

Table of which java.time library to use with which version of Java or Android

How to get all values from python enum class?

Based on the answer by @Jeff, refactored to use a classmethod so that you can reuse the same code for any of your enums:

from enum import Enum

class ExtendedEnum(Enum):

    def list(cls):
        return list(map(lambda c: c.value, cls))

class OperationType(ExtendedEnum):




Convert XmlDocument to String

If you are using Windows.Data.Xml.Dom.XmlDocument version of XmlDocument (used in UWP apps for example), you can use yourXmlDocument.GetXml() to get the XML as a string.

What are the best PHP input sanitizing functions?

My 5 cents.

Nobody here understands the way mysql_real_escape_string works. This function do not filter or "sanitize" anything.
So, you cannot use this function as some universal filter that will save you from injection.
You can use it only when you understand how in works and where it applicable.

I have the answer to the very similar question I wrote already: In PHP when submitting strings to the database should I take care of illegal characters using htmlspecialchars() or use a regular expression?
Please click for the full explanation for the database side safety.

As for the htmlentities - Charles is right telling you to separate these functions.
Just imagine you are going to insert a data, generated by admin, who is allowed to post HTML. your function will spoil it.

Though I'd advise against htmlentities. This function become obsoleted long time ago. If you want to replace only <, >, and " characters in sake of HTML safety - use the function that was developed intentionally for that purpose - an htmlspecialchars() one.

Use of Finalize/Dispose method in C#

nobody answered the question about whether you should implement IDisposable even though you dont need it.

Short answer : No

Long answer:

This would allow a consumer of your class to use 'using'. The question I would ask is - why would they do it? Most devs will not use 'using' unless they know that they must - and how do they know. Either

  • its obviuos the them from experience (a socket class for example)
  • its documented
  • they are cautious and can see that the class implements IDisposable

So by implementing IDisposable you are telling devs (at least some) that this class wraps up something that must be released. They will use 'using' - but there are other cases where using is not possible (the scope of object is not local); and they will have to start worrying about the lifetime of the objects in those other cases - I would worry for sure. But this is not necessary

You implement Idisposable to enable them to use using, but they wont use using unless you tell them to.

So dont do it

Python - 'ascii' codec can't decode byte

If you are starting the python interpreter from a shell on Linux or similar systems (BSD, not sure about Mac), you should also check the default encoding for the shell.

Call locale charmap from the shell (not the python interpreter) and you should see

[user@host dir] $ locale charmap
[user@host dir] $ 

If this is not the case, and you see something else, e.g.

[user@host dir] $ locale charmap
[user@host dir] $ 

Python will (at least in some cases such as in mine) inherit the shell's encoding and will not be able to print (some? all?) unicode characters. Python's own default encoding that you see and control via sys.getdefaultencoding() and sys.setdefaultencoding() is in this case ignored.

If you find that you have this problem, you can fix that by

[user@host dir] $ export LC_CTYPE="en_EN.UTF-8"
[user@host dir] $ locale charmap
[user@host dir] $ 

(Or alternatively choose whichever keymap you want instead of en_EN.) You can also edit /etc/locale.conf (or whichever file governs the locale definition in your system) to correct this.

Eclipse : Failed to connect to remote VM. Connection refused.

As suat said, most of the time the connection refused is due to the fact that the port you set up is in use or there is a difference between the port number in your remote application debugging configuration in Eclipse and the port number used in the address attribute in


Check those things. Thanks!

Ifelse statement in R with multiple conditions

There is a simpler solution to this. What you describe is the natural behavior of the & operator and can thus be done primatively:

> c(1,1,NA) & c(1,0,NA) & c(1,NA,NA)

If all are 1, then 1 is returned. If any are 0, then 0. If all are NA, then NA.

In your case, the code would be:

DF$Den<-DF$Denial1 & DF$Denial2 & DF$Denial3

In order for this to work, you will need to stop working in character and use numeric or logical types.

MATLAB, Filling in the area between two sets of data, lines in one figure

Building off of @gnovice's answer, you can actually create filled plots with shading only in the area between the two curves. Just use fill in conjunction with fliplr.


x=0:0.01:2*pi;                  %#initialize x array
y1=sin(x);                      %#create first curve
y2=sin(x)+.5;                   %#create second curve
X=[x,fliplr(x)];                %#create continuous x value array for plotting
Y=[y1,fliplr(y2)];              %#create y values for out and then back
fill(X,Y,'b');                  %#plot filled area

enter image description here

By flipping the x array and concatenating it with the original, you're going out, down, back, and then up to close both arrays in a complete, many-many-many-sided polygon.

How to get a value of an element by name instead of ID

What element is used for the part with a green background? Just type the name of the element without "<" and ">" characters. For example type P, not <P> if the answer is the <P> element.

pod install -bash: pod: command not found

If you used homebrew to install ruby, this answer worked for me.

brew unlink ruby && brew link ruby

OSX 10.9.4

Using the value in a cell as a cell reference in a formula?


=SUM(INDIRECT(<start cell here> & ":" & <end cell here>))

7-zip commandline

Instead of the option a use option x, this will create the directories but only for extraction, not compression.

How to import module when module name has a '-' dash or hyphen in it?

If you can't rename the module to match Python naming conventions, create a new module to act as an intermediary:

 ---- ----
 tmp = __import__('foo-bar')

 ---- ----
 from foo_proxy import * 

How do I convert a long to a string in C++?

int main()
    long mylong = 123456789;
    string mystring;
    stringstream mystream;
    mystream << mylong;
    mystring = mystream.str();
    cout << mystring << "\n";
    return 0;

How to re-create database for Entity Framework?

My solution is best suited for :
- deleted your mdf file
- want to re-create your db.

In order to recreate your database you need add the connection using Visual Studio.

Step 1 : Go to Server Explorer add new connection( or look for a add db icon).

Step 2 : Change Datasource to Microsoft SQL Server Database File.

Step 3 : add any database name you desire in the Database file name field.(preferably the same name you have in the web.config AttachDbFilename attribute)

Step 4 : click browse and navigate to where you will like it to be located.

Step 5 : in the package manager console run command update-database