Programs & Examples On #Cssedit

CCSEdit is a program for web design totally focused on editing CSS owned by MacRabbit.

Ruby 'require' error: cannot load such file

require loads a file from the $LOAD_PATH. If you want to require a file relative to the currently executing file instead of from the $LOAD_PATH, use require_relative.

Sort arrays of primitive types in descending order

If performance is important, and the list usually already is sorted quite well.

Bubble sort should be one of the slowest ways of sorting, but I have seen cases where the best performance was a simple bi-directional bubble sort.

So this may be one of the few cases where you can benefit from coding it yourself. But you really need to do it right (make sure at least somebody else confirms your code, make a proof that it works etc.)

As somebody else pointed out, it may be even better to start with a sorted array, and keep it sorted while you change the contents. That may perform even better.

How to set a Default Route (To an Area) in MVC

This one interested me, and I finally had a chance to look into it. Other folks apparently haven't understood that this is an issue with finding the view, not an issue with the routing itself - and that's probably because your question title indicates that it's about routing.

In any case, because this is a View-related issue, the only way to get what you want is to override the default view engine. Normally, when you do this, it's for the simple purpose of switching your view engine (i.e. to Spark, NHaml, etc.). In this case, it's not the View-creation logic we need to override, but the FindPartialView and FindView methods in the VirtualPathProviderViewEngine class.

You can thank your lucky stars that these methods are in fact virtual, because everything else in the VirtualPathProviderViewEngine is not even accessible - it's private, and that makes it very annoying to override the find logic because you have to basically rewrite half of the code that's already been written if you want it to play nice with the location cache and the location formats. After some digging in Reflector I finally managed to come up with a working solution.

What I've done here is to first create an abstract AreaAwareViewEngine that derives directly from VirtualPathProviderViewEngine instead of WebFormViewEngine. I did this so that if you want to create Spark views instead (or whatever), you can still use this class as the base type.

The code below is pretty long-winded, so to give you a quick summary of what it actually does: It lets you put a {2} into the location format, which corresponds to the area name, the same way {1} corresponds to the controller name. That's it! That's what we had to write all this code for:


public abstract class BaseAreaAwareViewEngine : VirtualPathProviderViewEngine
    private static readonly string[] EmptyLocations = { };

    public override ViewEngineResult FindView(
        ControllerContext controllerContext, string viewName,
        string masterName, bool useCache)
        if (controllerContext == null)
            throw new ArgumentNullException("controllerContext");
        if (string.IsNullOrEmpty(viewName))
            throw new ArgumentNullException(viewName,
                "Value cannot be null or empty.");

        string area = getArea(controllerContext);
        return FindAreaView(controllerContext, area, viewName,
            masterName, useCache);

    public override ViewEngineResult FindPartialView(
        ControllerContext controllerContext, string partialViewName,
        bool useCache)
        if (controllerContext == null)
            throw new ArgumentNullException("controllerContext");
        if (string.IsNullOrEmpty(partialViewName))
            throw new ArgumentNullException(partialViewName,
                "Value cannot be null or empty.");

        string area = getArea(controllerContext);
        return FindAreaPartialView(controllerContext, area,
            partialViewName, useCache);

    protected virtual ViewEngineResult FindAreaView(
        ControllerContext controllerContext, string areaName, string viewName,
        string masterName, bool useCache)
        string controllerName =
        string[] searchedViewPaths;
        string viewPath = GetPath(controllerContext, ViewLocationFormats,
            "ViewLocationFormats", viewName, controllerName, areaName, "View",
            useCache, out searchedViewPaths);
        string[] searchedMasterPaths;
        string masterPath = GetPath(controllerContext, MasterLocationFormats,
            "MasterLocationFormats", masterName, controllerName, areaName,
            "Master", useCache, out searchedMasterPaths);
        if (!string.IsNullOrEmpty(viewPath) &&
            (!string.IsNullOrEmpty(masterPath) || 
            return new ViewEngineResult(CreateView(controllerContext, viewPath,
                masterPath), this);
        return new ViewEngineResult(

    protected virtual ViewEngineResult FindAreaPartialView(
        ControllerContext controllerContext, string areaName,
        string viewName, bool useCache)
        string controllerName =
        string[] searchedViewPaths;
        string partialViewPath = GetPath(controllerContext,
            ViewLocationFormats, "PartialViewLocationFormats", viewName,
            controllerName, areaName, "Partial", useCache,
            out searchedViewPaths);
        if (!string.IsNullOrEmpty(partialViewPath))
            return new ViewEngineResult(CreatePartialView(controllerContext,
                partialViewPath), this);
        return new ViewEngineResult(searchedViewPaths);

    protected string CreateCacheKey(string prefix, string name,
        string controller, string area)
        return string.Format(CultureInfo.InvariantCulture,
            prefix, name, controller, area);

    protected string GetPath(ControllerContext controllerContext,
        string[] locations, string locationsPropertyName, string name,
        string controllerName, string areaName, string cacheKeyPrefix,
        bool useCache, out string[] searchedLocations)
        searchedLocations = EmptyLocations;
        if (string.IsNullOrEmpty(name))
            return string.Empty;
        if ((locations == null) || (locations.Length == 0))
            throw new InvalidOperationException(string.Format("The property " +
                "'{0}' cannot be null or empty.", locationsPropertyName));
        bool isSpecificPath = IsSpecificPath(name);
        string key = CreateCacheKey(cacheKeyPrefix, name,
            isSpecificPath ? string.Empty : controllerName,
            isSpecificPath ? string.Empty : areaName);
        if (useCache)
            string viewLocation = ViewLocationCache.GetViewLocation(
                controllerContext.HttpContext, key);
            if (viewLocation != null)
                return viewLocation;
        if (!isSpecificPath)
            return GetPathFromGeneralName(controllerContext, locations, name,
                controllerName, areaName, key, ref searchedLocations);
        return GetPathFromSpecificName(controllerContext, name, key,
            ref searchedLocations);

    protected string GetPathFromGeneralName(ControllerContext controllerContext,
        string[] locations, string name, string controllerName,
        string areaName, string cacheKey, ref string[] searchedLocations)
        string virtualPath = string.Empty;
        searchedLocations = new string[locations.Length];
        for (int i = 0; i < locations.Length; i++)
            if (string.IsNullOrEmpty(areaName) && locations[i].Contains("{2}"))
            string testPath = string.Format(CultureInfo.InvariantCulture,
                locations[i], name, controllerName, areaName);
            if (FileExists(controllerContext, testPath))
                searchedLocations = EmptyLocations;
                virtualPath = testPath;
                    controllerContext.HttpContext, cacheKey, virtualPath);
                return virtualPath;
            searchedLocations[i] = testPath;
        return virtualPath;

    protected string GetPathFromSpecificName(
        ControllerContext controllerContext, string name, string cacheKey,
        ref string[] searchedLocations)
        string virtualPath = name;
        if (!FileExists(controllerContext, name))
            virtualPath = string.Empty;
            searchedLocations = new string[] { name };
            cacheKey, virtualPath);
        return virtualPath;

    protected string getArea(ControllerContext controllerContext)
        // First try to get area from a RouteValue override, like one specified in the Defaults arg to a Route.
        object areaO;
        controllerContext.RouteData.Values.TryGetValue("area", out areaO);

        // If not specified, try to get it from the Controller's namespace
        if (areaO != null)
            return (string)areaO;

        string namespa = controllerContext.Controller.GetType().Namespace;
        int areaStart = namespa.IndexOf("Areas.");
        if (areaStart == -1)
            return null;

        areaStart += 6;
        int areaEnd = namespa.IndexOf('.', areaStart + 1);
        string area = namespa.Substring(areaStart, areaEnd - areaStart);
        return area;

    protected static bool IsSpecificPath(string name)
        char ch = name[0];
        if (ch != '~')
            return (ch == '/');
        return true;

Now as stated, this isn't a concrete engine, so you have to create that as well. This part, fortunately, is much easier, all we need to do is set the default formats and actually create the views:


public class AreaAwareViewEngine : BaseAreaAwareViewEngine
    public AreaAwareViewEngine()
        MasterLocationFormats = new string[]
        ViewLocationFormats = new string[]
        PartialViewLocationFormats = ViewLocationFormats;

    protected override IView CreatePartialView(
        ControllerContext controllerContext, string partialPath)
        if (partialPath.EndsWith(".cshtml"))
            return new System.Web.Mvc.RazorView(controllerContext, partialPath, null, false, null);
            return new WebFormView(controllerContext, partialPath);

    protected override IView CreateView(ControllerContext controllerContext,
        string viewPath, string masterPath)
        if (viewPath.EndsWith(".cshtml"))
            return new RazorView(controllerContext, viewPath, masterPath, false, null);
            return new WebFormView(controllerContext, viewPath, masterPath);

Note that we've added few entries to the standard ViewLocationFormats. These are the new {2} entries, where the {2} will be mapped to the area we put in the RouteData. I've left the MasterLocationFormats alone, but obviously you can change that if you want.

Now modify your global.asax to register this view engine:


protected void Application_Start()
    ViewEngines.Engines.Add(new AreaAwareViewEngine());

...and register the default route:

public static void RegisterRoutes(RouteCollection routes)
        new { area = "AreaZ", controller = "Default", action = "ActionY" }
        new { controller = "Home", action = "Index", id = "" }

Now Create the AreaController we just referenced:

DefaultController.cs (in ~/Controllers/)

public class DefaultController : Controller
    public ActionResult ActionY()
        return View("TestView");

Obviously we need the directory structure and view to go with it - we'll keep this super simple:

TestView.aspx (in ~/Areas/AreaZ/Views/Default/ or ~/Areas/AreaZ/Views/Shared/)

<%@ Page Title="" Language="C#" Inherits="System.Web.Mvc.ViewPage" %>
This is a test view in AreaZ.

And that's it. Finally, we're done.

For the most part, you should be able to just take the BaseAreaAwareViewEngine and AreaAwareViewEngine and drop it into any MVC project, so even though it took a lot of code to get this done, you only have to write it once. After that, it's just a matter of editing a few lines in global.asax.cs and creating your site structure.

Automatically accept all SDK licences

in Windows : Open Cmd:

go to install path

falow common: cd D: or C:

go to sdk directory

with cd common

tools/bin/sdkmanager --licenses

Can I extend a class using more than 1 class in PHP?

class A extends B {}

class B extends C {}

Then A has extended both B and C

Is returning out of a switch statement considered a better practice than using break?

It depends, if your function only consists of the switch statement, then I think that its fine. However, if you want to perform any other operations within that function, its probably not a great idea. You also may have to consider your requirements right now versus in the future. If you want to change your function from option one to option two, more refactoring will be needed.

However, given that within if/else statements it is best practice to do the following:

var foo = "bar";

if(foo == "bar") {
    return 0;
else {
    return 100;

Based on this, the argument could be made that option one is better practice.

In short, there's no clear answer, so as long as your code adheres to a consistent, readable, maintainable standard - that is to say don't mix and match options one and two throughout your application, that is the best practice you should be following.

What does CultureInfo.InvariantCulture mean?

JetBrains offer a reasonable explanation,

"Ad-hoc conversion of data structures to text is largely dependent on the current culture, and may lead to unintended results when the code is executed on a machine whose locale differs from that of the original developer. To prevent ambiguities, ReSharper warns you of any instances in code where such a problem may occur."

but if I am working on a site I know will be in English only, I just ignore the suggestion.

How to place div in top right hand corner of page

You can use css float

<div style='float: left;'><a href="login.php">Log in</a></div>

<div style='float: right;'><a href="home.php">Back to Home</a></div>

Have a look at this CSS Positioning

How to add image in a TextView text?

fun TextView.addImage(atText: String, @DrawableRes imgSrc: Int, imgWidth: Int, imgHeight: Int) {
    val ssb = SpannableStringBuilder(this.text)

    val drawable = ContextCompat.getDrawable(this.context, imgSrc) ?: return
    drawable.setBounds(0, 0,
    val start = text.indexOf(atText)
    ssb.setSpan(VerticalImageSpan(drawable), start, start + atText.length, Spannable.SPAN_INCLUSIVE_EXCLUSIVE)
    this.setText(ssb, TextView.BufferType.SPANNABLE)

VerticalImageSpan class from great answer


val textView = findViewById<TextView>(
textView.setText("Send an [email-icon] to [email protected].")
textView.addImage("[email-icon]", R.drawable.ic_email,


Why VerticalImageSpan class?
ImageSpan.ALIGN_CENTER attribute requires API 29.
Also, after the test, I see that ImageSpan.ALIGN_CENTER only work if the image smaller than the text, if the image bigger than the text then only image is in center, text not center, it align on bottom of image

How to write MySQL query where A contains ( "a" or "b" )

You can write your query like so:

SELECT * FROM MyTable WHERE (A LIKE '%text1%' OR A LIKE '%text2%')

The % is a wildcard, meaning that it searches for all rows where column A contains either text1 or text2

How can I split a text file using PowerShell?

I've made a little modification to split files based on size of each part.

# Breaks a text file into multiple text files in a destination, where each
# file contains a maximum number of lines.
# When working with files that have a header, it is often desirable to have
# the header information repeated in all of the split files. Split-File
# supports this functionality with the -rc (RepeatCount) parameter.
# Specifies the path to an item. Wildcards are permitted.
#.PARAMETER LiteralPath
# Specifies the path to an item. Unlike Path, the value of LiteralPath is
# used exactly as it is typed. No characters are interpreted as wildcards.
# If the path includes escape characters, enclose it in single quotation marks.
# Single quotation marks tell Windows PowerShell not to interpret any
# characters as escape sequences.
#.PARAMETER Destination
# (Or -d) The location in which to place the chunked output files.
# (Or -s) The maximum size of each file. Size must be expressed in MB.
#.PARAMETER RepeatCount
# (Or -rc) Specifies the number of "header" lines from the input file that will
# be repeated in each output file. Typically this is 0 or 1 but it can be any
# number of lines.
# Split-File bigfile.csv -s 20 -rc 1
# Out-TempFile
function Split-File {


        [Parameter(ParameterSetName='Path', Position=1, Mandatory=$true, ValueFromPipeline=$true, ValueFromPipelineByPropertyName=$true)]

        [Parameter(ParameterSetName='LiteralPath', Mandatory=$true, ValueFromPipelineByPropertyName=$true)]





    process {

  # yeah! the cmdlet supports wildcards
        if ($LiteralPath) { $ResolveArgs = @{LiteralPath=$LiteralPath} }
        elseif ($Path) { $ResolveArgs = @{Path=$Path} }

        Resolve-Path @ResolveArgs | %{

            $InputName = [IO.Path]::GetFileNameWithoutExtension($_)
            $InputExt  = [IO.Path]::GetExtension($_)

            if ($RepeatCount) { $Header = Get-Content $_ -TotalCount:$RepeatCount }

   Resolve-Path @ResolveArgs | %{

    $InputName = [IO.Path]::GetFileNameWithoutExtension($_)
    $InputExt  = [IO.Path]::GetExtension($_)

    if ($RepeatCount) { $Header = Get-Content $_ -TotalCount:$RepeatCount }

    # get the input file in manageable chunks

    $Part = 1
    $buffer = ""
    Get-Content $_ -ReadCount:1 | %{

     # make an output filename with a suffix
     $OutputFile = Join-Path $Destination ('{0}-{1:0000}{2}' -f ($InputName,$Part,$InputExt))

     # In the first iteration the header will be
     # copied to the output file as usual
     # on subsequent iterations we have to do it
     if ($RepeatCount -and $Part -gt 1) {
      Set-Content $OutputFile $Header

     # test buffer size and dump data only if buffer is greater than size
     if ($buffer.length -gt ($Size * 1MB)) {
      # write this chunk to the output file
      Write-Host "Writing $OutputFile"
      Add-Content $OutputFile $buffer
      $Part += 1
      $buffer = ""
     } else {
      $buffer += $_ + "`r"

design a stack such that getMinimum( ) should be O(1)

To getMin elements from Stack. We have to use Two stack .i.e Stack s1 and Stack s2.

  1. Initially, both stacks are empty, so add elements to both stacks

---------------------Recursively call Step 2 to 4-----------------------

  1. if New element added to stack s1.Then pop elements from stack s2

  2. compare new elments with s2. which one is smaller , push to s2.

  3. pop from stack s2(which contains min element)

Code looks like:

package Stack;
import java.util.Stack;
public class  getMin 

        Stack<Integer> s1= new Stack<Integer>();
        Stack<Integer> s2 = new Stack<Integer>();

        void push(int x)
            if(s1.isEmpty() || s2.isEmpty())


               s1. push(x);
                int y = (Integer) s2.pop();
                if(x < y)
        public Integer pop()
            int x;
            x=(Integer) s1.pop();
            return x;

    public  int getmin()
            int x1;
            x1= (Integer)s2.pop();
            return x1;

    public static void main(String[] args) {
        getMin s = new getMin();


Modulo operator with negative values

The sign in such cases (i.e when one or both operands are negative) is implementation-defined. The spec says in §5.6/4 (C++03),

The binary / operator yields the quotient, and the binary % operator yields the remainder from the division of the first expression by the second. If the second operand of / or % is zero the behavior is undefined; otherwise (a/b)*b + a%b is equal to a. If both operands are nonnegative then the remainder is nonnegative; if not, the sign of the remainder is implementation-defined.

That is all the language has to say, as far as C++03 is concerned.

Is there a Google Sheets formula to put the name of the sheet into a cell?

I have a sheet that is made to used by others and I have quite a few indirect() references around, so I need to formulaically handle a changed sheet tab name.

I used the formula from JohnP2 (below) but was having trouble because it didn't update automatically when a sheet name was changed. You need to go to the actual formula, make an arbitrary change and refresh to run it again.

=REGEXREPLACE(CELL("address",'SHEET NAME'!A1),"'?([^']+)'?!.*","$1")

I solved this by using info found in this solution on how to force a function to refresh. It may not be the most elegant solution, but it forced Sheets to pay attention to this cell and update it regularly, so that it catches an updated sheet title.

=IF(TODAY()=TODAY(), REGEXREPLACE(CELL("address",'SHEET NAME'!A1),"'?([^']+)'?!.*","$1"), "")

Using this, Sheets know to refresh this cell every time you make a change, which results in the address being updated whenever it gets renamed by a user.

Fixed digits after decimal with f-strings

Include the type specifier in your format expression:

>>> a = 10.1234
>>> f'{a:.2f}'

How to inject Javascript in WebBrowser control?

For some reason Richard's solution didn't work on my end (insertAdjacentText failed with an exception). This however seems to work:

HtmlElement head = webBrowser1.Document.GetElementsByTagName("head")[0];
HtmlElement scriptEl = webBrowser1.Document.CreateElement("script");
IHTMLScriptElement element = (IHTMLScriptElement)scriptEl.DomElement;
element.text = "function sayHello() { alert('hello') }";

This answer explains how to get the IHTMLScriptElement interface into your project.

How to split a large text file into smaller files with equal number of lines?

Yes, there is a split command. It will split a file by lines or bytes.

$ split --help
Usage: split [OPTION]... [INPUT [PREFIX]]
Output fixed-size pieces of INPUT to PREFIXaa, PREFIXab, ...; default
size is 1000 lines, and default PREFIX is `x'.  With no INPUT, or when INPUT
is -, read standard input.

Mandatory arguments to long options are mandatory for short options too.
  -a, --suffix-length=N   use suffixes of length N (default 2)
  -b, --bytes=SIZE        put SIZE bytes per output file
  -C, --line-bytes=SIZE   put at most SIZE bytes of lines per output file
  -d, --numeric-suffixes  use numeric suffixes instead of alphabetic
  -l, --lines=NUMBER      put NUMBER lines per output file
      --verbose           print a diagnostic just before each
                            output file is opened
      --help     display this help and exit
      --version  output version information and exit

SIZE may have a multiplier suffix:
b 512, kB 1000, K 1024, MB 1000*1000, M 1024*1024,
GB 1000*1000*1000, G 1024*1024*1024, and so on for T, P, E, Z, Y.

Why is my Git Submodule HEAD detached from master?

i got tired of it always detaching so i just use a shell script to build it out for all my modules. i assume all submodules are on master: here is the script:

echo "Good Day Friend, building all submodules while checking out from MASTER branch."

git submodule update 
git submodule foreach git checkout master 
git submodule foreach git pull origin master 

execute it from your parent module

Convert String to Float in Swift

You have two options which are quite similar (by the approach and result):

// option 1:
var string_1 : String = "100"
var double_1 : Double = (string_1 as NSString).doubleValue + 99.0

// option 2: 
var string_2 : NSString = "100"
// or:  var string_2 = "100" as NSString
var number_2 : Double = string_2.doubleValue;

Redirect stderr and stdout in Bash

# Close STDOUT file descriptor
exec 1<&-
exec 2<&-

# Open STDOUT as $LOG_FILE file for read and write.
exec 1<>$LOG_FILE

# Redirect STDERR to STDOUT
exec 2>&1

echo "This line will appear in $LOG_FILE, not 'on screen'"

Now, simple echo will write to $LOG_FILE. Useful for daemonizing.

To the author of the original post,

It depends what you need to achieve. If you just need to redirect in/out of a command you call from your script, the answers are already given. Mine is about redirecting within current script which affects all commands/built-ins(includes forks) after the mentioned code snippet.

Another cool solution is about redirecting to both std-err/out AND to logger or log file at once which involves splitting "a stream" into two. This functionality is provided by 'tee' command which can write/append to several file descriptors(files, sockets, pipes, etc) at once: tee FILE1 FILE2 ... >(cmd1) >(cmd2) ...

exec 3>&1 4>&2 1> >(tee >(logger -i -t 'my_script_tag') >&3) 2> >(tee >(logger -i -t 'my_script_tag') >&4)
trap 'cleanup' INT QUIT TERM EXIT

get_pids_of_ppid() {
    local ppid="$1"

    local pids=`ps x -o pid,ppid | awk "\\$2 == \\"$ppid\\" { print \\$1 }"`

# Needed to kill processes running in background
cleanup() {
    local current_pid element
    local pids=( "$$" )


    while :; do
        [ -z "$current_pid" ] && break

        get_pids_of_ppid $current_pid
        local new_pids="$RETVAL"
        [ -z "$new_pids" ] && continue

        for element in $new_pids; do
            pids=("$element" "${pids[@]}")

    kill ${pids[@]} 2>/dev/null

So, from the beginning. Let's assume we have terminal connected to /dev/stdout(FD #1) and /dev/stderr(FD #2). In practice, it could be a pipe, socket or whatever.

  • Create FDs #3 and #4 and point to the same "location" as #1 and #2 respectively. Changing FD #1 doesn't affect FD #3 from now on. Now, FDs #3 and #4 point to STDOUT and STDERR respectively. These will be used as real terminal STDOUT and STDERR.
  • 1> >(...) redirects STDOUT to command in parens
  • parens(sub-shell) executes 'tee' reading from exec's STDOUT(pipe) and redirects to 'logger' command via another pipe to sub-shell in parens. At the same time it copies the same input to FD #3(terminal)
  • the second part, very similar, is about doing the same trick for STDERR and FDs #2 and #4.

The result of running a script having the above line and additionally this one:

echo "Will end up in STDOUT(terminal) and /var/log/messages" as follows:

$ ./my_script
Will end up in STDOUT(terminal) and /var/log/messages

$ tail -n1 /var/log/messages
Sep 23 15:54:03 wks056 my_script_tag[11644]: Will end up in STDOUT(terminal) and /var/log/messages

If you want to see clearer picture, add these 2 lines to the script:

ls -l /proc/self/fd/
ps xf

SQLDataReader Row Count

This will get you the row count, but will leave the data reader at the end.


Django URLs TypeError: view must be a callable or a list/tuple in the case of include()

Your code is

urlpatterns = [
    url(r'^$', 'myapp.views.home'),
    url(r'^contact/$', ''),
    url(r'^login/$', 'django.contrib.auth.views.login'),

change it to following as you're importing include() function :

urlpatterns = [
    url(r'^$', views.home),
    url(r'^login/$', views.login),

How to convert an int value to string in Go?


If you know the specific type of value use the corresponding formatter for example %d for int

More info - fmt

Modifying local variable from inside lambda

If you only need to pass the value from the outside into the lambda, and not get it out, you can do it with a regular anonymous class instead of a lambda:

list.forEach(new Consumer<Example>() {
    int ordinal = 0;
    public void accept(Example s) {

const to Non-const Conversion in C++

Changing a constant type will lead to an Undefined Behavior.

However, if you have an originally non-const object which is pointed to by a pointer-to-const or referenced by a reference-to-const then you can use const_cast to get rid of that const-ness.

Casting away constness is considered evil and should not be avoided. You should consider changing the type of the pointers you use in vector to non-const if you want to modify the data through it.

UnicodeEncodeError: 'charmap' codec can't encode - character maps to <undefined>, print function

I see three solutions to this:

  1. Change the output encoding, so it will always output UTF-8. See e.g. Setting the correct encoding when piping stdout in Python, but I could not get these example to work.

  2. Following example code makes the output aware of your target charset.

    # -*- coding: utf-8 -*-
    import sys
    print sys.stdout.encoding
    print u"Stöcker".encode(sys.stdout.encoding, errors='replace')
    print u"????????".encode(sys.stdout.encoding, errors='replace')

    This example properly replaces any non-printable character in my name with a question mark.

    If you create a custom print function, e.g. called myprint, using that mechanisms to encode output properly you can simply replace print with myprint whereever necessary without making the whole code look ugly.

  3. Reset the output encoding globally at the begin of the software:

    The page has a good summary what to do to change output encoding. Especially the section "StreamWriter Wrapper around Stdout" is interesting. Essentially it says to change the I/O encoding function like this:

    In Python 2:

    if sys.stdout.encoding != 'cp850':
      sys.stdout = codecs.getwriter('cp850')(sys.stdout, 'strict')
    if sys.stderr.encoding != 'cp850':
      sys.stderr = codecs.getwriter('cp850')(sys.stderr, 'strict')

    In Python 3:

    if sys.stdout.encoding != 'cp850':
      sys.stdout = codecs.getwriter('cp850')(sys.stdout.buffer, 'strict')
    if sys.stderr.encoding != 'cp850':
      sys.stderr = codecs.getwriter('cp850')(sys.stderr.buffer, 'strict')

    If used in CGI outputting HTML you can replace 'strict' by 'xmlcharrefreplace' to get HTML encoded tags for non-printable characters.

    Feel free to modify the approaches, setting different encodings, .... Note that it still wont work to output non-specified data. So any data, input, texts must be correctly convertable into unicode:

    # -*- coding: utf-8 -*-
    import sys
    import codecs
    sys.stdout = codecs.getwriter("iso-8859-1")(sys.stdout, 'xmlcharrefreplace')
    print u"Stöcker"                # works
    print "Stöcker".decode("utf-8") # works
    print "Stöcker"                 # fails

data.table vs dplyr: can one do something well the other can't or does poorly?

Reading Hadley and Arun's answers one gets the impression that those who prefer dplyr's syntax would have in some cases to switch over to data.table or compromise for long running times.

But as some have already mentioned, dplyr can use data.table as a backend. This is accomplished using the dtplyr package which recently had it's version 1.0.0 release. Learning dtplyr incurs practically zero additional effort.

When using dtplyr one uses the function lazy_dt() to declare a lazy data.table, after which standard dplyr syntax is used to specify operations on it. This would look something like the following:

new_table <- mtcars2 %>% 
  lazy_dt() %>%
  filter(wt < 5) %>% 
  mutate(l100k = 235.21 / mpg) %>% # liters / 100 km
  group_by(cyl) %>% 
  summarise(l100k = mean(l100k))


#> Source: local data table [?? x 2]
#> Call:   `_DT1`[wt < 5][, `:=`(l100k = 235.21/mpg)][, .(l100k = mean(l100k)), 
#>     keyby = .(cyl)]
#>     cyl l100k
#>   <dbl> <dbl>
#> 1     4  9.05
#> 2     6 12.0 
#> 3     8 14.9 
#> # Use to access results

The new_table object is not evaluated until calling on it at which point the underlying data.table operation is executed.

I've recreated a benchmark analysis done by data.table author Matt Dowle back at December 2018 which covers the case of operations over large numbers of groups. I've found that dtplyr indeed enables for the most part those who prefer the dplyr syntax to keep using it while enjoying the speed offered by data.table.

CMD: How do I recursively remove the "Hidden"-Attribute of files and directories

To make a batch file for its current directory and sub directories:

cd %~dp0
attrib -h -r -s /s /d /l *.*

Check if enum exists in Java

Just use valueOf() method. If the value doesn't exist, it throws IllegalArgumentException and you can catch it like that:

      boolean isSettingCodeValid = true;

       try {
        } catch (IllegalArgumentException e) {
            // throw custom exception or change the isSettingCodeValid value
            isSettingCodeValid = false;

string encoding and decoding?

Aside from getting decode and encode backwards, I think part of the answer here is actually don't use the ascii encoding. It's probably not what you want.

To begin with, think of str like you would a plain text file. It's just a bunch of bytes with no encoding actually attached to it. How it's interpreted is up to whatever piece of code is reading it. If you don't know what this paragraph is talking about, go read Joel's The Absolute Minimum Every Software Developer Absolutely, Positively Must Know About Unicode and Character Sets right now before you go any further.

Naturally, we're all aware of the mess that created. The answer is to, at least within memory, have a standard encoding for all strings. That's where unicode comes in. I'm having trouble tracking down exactly what encoding Python uses internally for sure, but it doesn't really matter just for this. The point is that you know it's a sequence of bytes that are interpreted a certain way. So you only need to think about the characters themselves, and not the bytes.

The problem is that in practice, you run into both. Some libraries give you a str, and some expect a str. Certainly that makes sense whenever you're streaming a series of bytes (such as to or from disk or over a web request). So you need to be able to translate back and forth.

Enter codecs: it's the translation library between these two data types. You use encode to generate a sequence of bytes (str) from a text string (unicode), and you use decode to get a text string (unicode) from a sequence of bytes (str).

For example:

>>> s = "I look like a string, but I'm actually a sequence of bytes. \xe2\x9d\xa4"
>>> codecs.decode(s, 'utf-8')
u"I look like a string, but I'm actually a sequence of bytes. \u2764"

What happened here? I gave Python a sequence of bytes, and then I told it, "Give me the unicode version of this, given that this sequence of bytes is in 'utf-8'." It did as I asked, and those bytes (a heart character) are now treated as a whole, represented by their Unicode codepoint.

Let's go the other way around:

>>> u = u"I'm a string! Really! \u2764"
>>> codecs.encode(u, 'utf-8')
"I'm a string! Really! \xe2\x9d\xa4"

I gave Python a Unicode string, and I asked it to translate the string into a sequence of bytes using the 'utf-8' encoding. So it did, and now the heart is just a bunch of bytes it can't print as ASCII; so it shows me the hexadecimal instead.

We can work with other encodings, too, of course:

>>> s = "I have a section \xa7"
>>> codecs.decode(s, 'latin1')
u'I have a section \xa7'
>>> codecs.decode(s, 'latin1')[-1] == u'\u00A7'

>>> u = u"I have a section \u00a7"
>>> u
u'I have a section \xa7'
>>> codecs.encode(u, 'latin1')
'I have a section \xa7'

('\xa7' is the section character, in both Unicode and Latin-1.)

So for your question, you first need to figure out what encoding your str is in.

  • Did it come from a file? From a web request? From your database? Then the source determines the encoding. Find out the encoding of the source and use that to translate it into a unicode.

    s = [get from external source]
    u = codecs.decode(s, 'utf-8') # Replace utf-8 with the actual input encoding
  • Or maybe you're trying to write it out somewhere. What encoding does the destination expect? Use that to translate it into a str. UTF-8 is a good choice for plain text documents; most things can read it.

    u = u'My string'
    s = codecs.encode(u, 'utf-8') # Replace utf-8 with the actual output encoding
    [Write s out somewhere]
  • Are you just translating back and forth in memory for interoperability or something? Then just pick an encoding and stick with it; 'utf-8' is probably the best choice for that:

    u = u'My string'
    s = codecs.encode(u, 'utf-8')
    newu = codecs.decode(s, 'utf-8')

In modern programming, you probably never want to use the 'ascii' encoding for any of this. It's an extremely small subset of all possible characters, and no system I know of uses it by default or anything.

Python 3 does its best to make this immensely clearer simply by changing the names. In Python 3, str was replaced with bytes, and unicode was replaced with str.

What to do on TransactionTooLargeException

I faced with the same issue when I tried to send bitmap via Intent and at the same time when it happens I folded the application.

How it described in this article enter link description here it happens when an Activity is in the process of stopping, that means that the Activity was trying to send its saved state Bundles to the system OS for safe keeping for restoration later (after a config change or process death) but that one or more of the Bundles it sent were too large.

I solved it via hack by overriding onSaveInstanceState in my Activity:

protected void onSaveInstanceState(Bundle outState) {
    // super.onSaveInstanceState(outState);

and comment call super. It is a dirty hack but it is working perfectly. Bitmap was successfully sent without crashes. Hope this will help someone.

What is the best way to filter a Java Collection?

Are you sure you want to filter the Collection itself, rather than an iterator?

see org.apache.commons.collections.iterators.FilterIterator

or using version 4 of apache commons org.apache.commons.collections4.iterators.FilterIterator

How to use Spring Boot with MySQL database and JPA?

For Jpa based application: base package scan @EnableJpaRepositories(basePackages = "repository") You can try it once!!!
Project Structure

 +- stack
     +- app
     |   +-
     +- controller
     |   +-
     +- service
     |   +-
     +- repository
     |   +-
     +- model
     |   +-
    mysql, lombok, data-jpa

#Data source :

#Jpa/Hibernate : = org.hibernate.dialect.MySQL5Dialect
spring.jpa.hibernate.ddl-auto = update

@Table (name = "employee")
public class Employee {

    @GeneratedValue (strategy = GenerationType.IDENTITY)
    private Long id;

    @Column (name = "first_name")
    private String firstName;
    @Column (name = "last_name")
    private String lastName;
    @Column (name = "email")
    private String email;
    @Column (name = "phone_number")
    private String phoneNumber;
    @Column (name = "emp_desg")
    private String desgination;

public interface EmployeeRepository extends JpaRepository<Employee, Long> {

public class EmployeeController {

    private EmployeeService empService;

    @GetMapping (value = "/employees")
    public List<Employee> getAllEmployee(){
        return empService.getAllEmployees();

    @PostMapping (value = "/employee")
    public ResponseEntity<Employee> addEmp(@RequestBody Employee emp, HttpServletRequest 
                                         request) throws URISyntaxException {
        HttpHeaders headers = new HttpHeaders();
        headers.setLocation(new URI(request.getRequestURI() + "/" + emp.getId()));
        return new ResponseEntity<Employee>(emp, headers, HttpStatus.CREATED);

public interface EmployeeService {
    public List<Employee> getAllEmployees();
    public Employee saveEmployee(Employee emp);

public class EmployeeServiceImpl implements EmployeeService {

    private EmployeeRepository empRepository;

    public List<Employee> getAllEmployees() {
        return empRepository.findAll();

    public Employee saveEmployee(Employee emp) {

@EnableJpaRepositories(basePackages = "repository")
public class EmployeeApplication {
    public static void main(String[] args) {, args);

How to get the selected item of a combo box to a string variable in c#

You can use as below:

string selected = cmbbox.Text;

How to locate the Path of the current project directory in Java (IDE)?

This is the new way to do it:

Path root = FileSystems.getDefault().getPath("").toAbsolutePath();
Path filePath = Paths.get(root.toString(),"src", "main", "resources", fileName);

Or even better:

Path root = Paths.get(".").normalize().toAbsolutePath();

But I would take it one step further:

public String getUsersProjectRootDirectory() {
    String envRootDir = System.getProperty("user.dir");
    Path rootDIr = Paths.get(".").normalize().toAbsolutePath();
    if ( rootDir.startsWith(envRootDir) ) {
        return rootDir;
    } else {
        throw new RuntimeException("Root dir not found in user directory.");

Get the index of the object inside an array, matching a condition

Georg have already mentioned ES6 have Array.findIndex for this. And some other answers are workaround for ES5 using Array.some method.

One more elegant approach can be

var index;
for(index = yourArray.length; index-- > 0 && yourArray[index].prop2 !== "yutu";);

At the same time I will like to emphasize, Array.some may be implemented with binary or other efficient searching technique. So, it might perform better over for loop in some browser.

iPhone App Icons - Exact Radius?

If not considering stroke, the exact radius is actually 10px for 57x57 icon.

I get this info from iconreference.

How do I add images in laravel view?

You should store your images, css and JS files in a public directory. To create a link to any of them, use asset() helper:

{{ asset('img/myimage.png') }}

As alternative, you could use amazing Laravel Collective package for building forms and HTML elements, so your code will look like this:

{{ HTML::image('img/myimage.png', 'a picture') }}


Actually, it will takes 101 bytes.

MySQL Reference

checked = "checked" vs checked = true

document.getElementById('myRadio').checked is a boolean value. It should be true or false

document.getElementById('myRadio').checked = "checked"; casts the string to a boolean, which is true.

document.getElementById('myRadio').checked = true; just assigns true without casting.

Use true as it is marginally more efficient and is more intention revealing to maintainers.

Checking if a double (or float) is NaN in C++

You can use numeric_limits<float>::quiet_NaN( ) defined in the limits standard library to test with. There's a separate constant defined for double.

#include <iostream>
#include <math.h>
#include <limits>

using namespace std;

int main( )
   cout << "The quiet NaN for type float is:  "
        << numeric_limits<float>::quiet_NaN( )
        << endl;

   float f_nan = numeric_limits<float>::quiet_NaN();

   if( isnan(f_nan) )
       cout << "Float was Not a Number: " << f_nan << endl;

   return 0;

I don't know if this works on all platforms, as I only tested with g++ on Linux.

What's the best way to override a user agent CSS stylesheet rule that gives unordered-lists a 1em margin?

I don't understand why nobody points to the specific issue and some answers are totally misleading, especially the accepted answer. The issue is that the OP did not pick a rule that could possibly override the margin property that is set by the User Agent (UA) directly on the ul tag. Let's consider all the rules with a margin property used by the OP.

body {


The body element is way up in the DOM and the UA rule matches an element below, so the UA wins. It's the way inheritance works. Inheritance is the means by which, in the absence of any specific declarations from any source applied by the CSS cascade, a property value of an element is obtained from its parent element. Specificity on the parent element is useless, because the UA rule matches directly the element.

    margin:0 auto;

This is a better attempt, a more specific selector #mainNav, which matches the mainNav element lower in the DOM, but the same principle applies, because the ul element is still below this element in the DOM.

#mainNav ul li{

This went too far down in the DOM! Now, the selector matches the li element, which is below the ul element.

So, assuming that the UA rule used the selector ul and not !important, which is most likely the case, the solution would have been a simple ul { margin: 0; }, but it would be safer to make it more specific, say #mainNav ul { margin: 0 }.

Vue.js getting an element within a component

In Vue2 be aware that you can access this.$refs.uniqueName only after mounting the component.

What is the worst real-world macros/pre-processor abuse you've ever come across?

An 'architect', very humble guy, you know the type, had the following:

#define retrun return

because he liked to type fast. The brain-surgeon used to like to shout at people who were smarter than him (which was pretty much everyone), and threaten to use his black-belt on them.

How to check programmatically if an application is installed or not in Android?

This code checks to make sure the app is installed, but also checks to make sure it's enabled.

private boolean isAppInstalled(String packageName) {
    PackageManager pm = getPackageManager();
    try {
        pm.getPackageInfo(packageName, PackageManager.GET_ACTIVITIES);
        return pm.getApplicationInfo(packageName, 0).enabled;
    catch (PackageManager.NameNotFoundException e) {
        return false;

How does strcmp() work?

Here is my version, written for small microcontroller applications, MISRA-C compliant. The main aim with this code was to write readable code, instead of the one-line goo found in most compiler libs.

int8_t strcmp (const uint8_t* s1, const uint8_t* s2)
  while ( (*s1 != '\0') && (*s1 == *s2) )

  return (int8_t)( (int16_t)*s1 - (int16_t)*s2 );

Note: the code assumes 16 bit int type.

Iterating over each line of ls -l output

You can also try the find command. If you only want files in the current directory:

find . -d 1 -prune -ls

Run a command on each of them?

find . -d 1 -prune -exec echo {} \;

Count lines, but only in files?

find . -d 1 -prune -type f -exec wc -l {} \;

Safely override C++ virtual functions

I would suggest a slight change in your logic. It may or may not work, depending on what you need to accomplish.

handle_event() can still do the "boring default code" but instead of being virtual, at the point where you want it to do the "new exciting code" have the base class call an abstract method (i.e. must-be-overridden) method that will be supplied by your descendant class.

EDIT: And if you later decide that some of your descendant classes do not need to provide "new exciting code" then you can change the abstract to virtual and supply an empty base class implementation of that "inserted" functionality.

No ConcurrentList<T> in .Net 4.0?

I'm surprised no-one has mentioned using LinkedList as a base for writing a specialised class.

Often we don't need the full API's of the various collection classes, and if you write mostly functional side effect free code, using immutable classes as far as possible, then you'll actually NOT want to mutate the collection favouring various snapshot implementations.

LinkedList solves some difficult problems of creating snapshot copies/clones of large collections. I also use it to create "threadsafe" enumerators to enumerate over the collection. I can cheat, because I know that I'm not changing the collection in any way other than appending, I can keep track of the list size, and only lock on changes to list size. Then my enumerator code simply enumerates from 0 to n for any thread that wants a "snapshot" of the append only collection, that will be guaranteed to represent a "snapshot" of the collection at any moment in time, regardless of what other threads are appending to the head of the collection.

I'm pretty certain that most requirements are often extremely simple, and you need 2 or 3 methods only. Writing a truly generic library is awfully difficult, but solving your own codes needs can sometimes be easy with a trick or two.

Long live LinkedList and good functional programming.

Cheers, ... love ya all! Al

p.s. sample hack AppendOnly class here :

Check if string begins with something?

Have a look at JavaScript substring() method.

Iterating a JavaScript object's properties using jQuery

Late, but can be done by using Object.keys like,

var a={key1:'value1',key2:'value2',key3:'value3',key4:'value4'},_x000D_
var keys = Object.keys(a);_x000D_
   str+= '<li>'+keys[i]+' : '+a[keys[i]]+'</li>';_x000D_
<ul id="object-keys"></ul>

Difference between Iterator and Listiterator?

There are two differences:

  1. We can use Iterator to traverse Set and List and also Map type of Objects. While a ListIterator can be used to traverse for List-type Objects, but not for Set-type of Objects.

    That is, we can get a Iterator object by using Set and List, see here:

    By using Iterator we can retrieve the elements from Collection Object in forward direction only.

    Methods in Iterator:

    1. hasNext()
    2. next()
    3. remove()
    Iterator iterator = Set.iterator();
    Iterator iterator = List.iterator();
  2. But we get ListIterator object only from the List interface, see here:

    where as a ListIterator allows you to traverse in either directions (Both forward and backward). So it has two more methods like hasPrevious() and previous() other than those of Iterator. Also, we can get indexes of the next or previous elements (using nextIndex() and previousIndex() respectively )

    Methods in ListIterator:

    1. hasNext()
    2. next()
    3. previous()
    4. hasPrevious()
    5. remove()
    6. nextIndex()
    7. previousIndex()
    ListIterator listiterator = List.listIterator();

    i.e., we can't get ListIterator object from Set interface.

Reference : - What is the difference between Iterator and ListIterator ?

Is it possible to save HTML page as PDF using JavaScript or jquery?

This might be a late answer but this is the best around:

Pure javascript implementation. Allows you to specify just a single element by ID and convert it.

How to recover deleted rows from SQL server table?

It is possible using Apex Recovery Tool,i have successfully recovered my table rows which i accidentally deleted

if you download the trial version it will recover only 10th row

check here

Powershell: convert string to number

I demonstrate how to receive a string, for example "-484876800000" and tryparse the string to make sure it can be assigned to a long. I calculate the Date from universaltime and return a string. When you convert a string to a number, you must decide the numeric type and precision and test if the string data can be parse, otherwise, it will throw and error.

function universalToDate
 param (

    if ($paramValue)
        [long]$returnedLong = 0
        [bool]$result = [long]::TryParse($paramValue,[ref]$returnedLong)
        if ($result -eq 1)

Hide Text with CSS, Best Practice?

Another way

position: absolute;
top: 0px;
left: -5000px;

How to do a regular expression replace in MySQL?

The one below basically finds the first match from the left and then replaces all occurences of it (tested in ).


SELECT REGEX_REPLACE('dis ambiguity', 'dis[[:space:]]*ambiguity', 'disambiguity');


  var_original VARCHAR(1000),
  var_pattern VARCHAR(1000),
  var_replacement VARCHAR(1000)
  COMMENT 'Based on'
  DECLARE var_replaced VARCHAR(1000) DEFAULT var_original;
  DECLARE var_leftmost_match VARCHAR(1000) DEFAULT
    REGEX_CAPTURE_LEFTMOST(var_original, var_pattern);
    WHILE var_leftmost_match IS NOT NULL DO
      IF var_replacement <> var_leftmost_match THEN
        SET var_replaced = REPLACE(var_replaced, var_leftmost_match, var_replacement);
        SET var_leftmost_match = REGEX_CAPTURE_LEFTMOST(var_replaced, var_pattern);
          SET var_leftmost_match = NULL;
        END IF;
      END WHILE;
  RETURN var_replaced;
END $$

  var_original VARCHAR(1000),
  var_pattern VARCHAR(1000)
  Captures the leftmost substring that matches the [var_pattern]
  IN [var_original], OR NULL if no match.
  DECLARE var_temp_l VARCHAR(1000);
  DECLARE var_temp_r VARCHAR(1000);
  DECLARE var_left_trim_index INT;
  DECLARE var_right_trim_index INT;
  SET var_left_trim_index = 1;
  SET var_right_trim_index = 1;
  SET var_temp_l = '';
  SET var_temp_r = '';
  WHILE (CHAR_LENGTH(var_original) >= var_left_trim_index) DO
    SET var_temp_l = LEFT(var_original, var_left_trim_index);
    IF var_temp_l REGEXP var_pattern THEN
      WHILE (CHAR_LENGTH(var_temp_l) >= var_right_trim_index) DO
        SET var_temp_r = RIGHT(var_temp_l, var_right_trim_index);
        IF var_temp_r REGEXP var_pattern THEN
          RETURN var_temp_r;
          END IF;
        SET var_right_trim_index = var_right_trim_index + 1;
        END WHILE;
      END IF;
    SET var_left_trim_index = var_left_trim_index + 1;
END $$

How to implement a lock in JavaScript

Locks are a concept required in a multi-threaded system. Even with worker threads, messages are sent by value between workers so that locking is unnecessary.

I suspect you need to just set a semaphore (flagging system) between your buttons.

How to use group by with union in t-sql

You need to alias the subquery. Thus, your statement should be:

From    (
        Select id, time
        From dbo.tablea
        Union All
        Select id, time
        From dbo.tableb
        ) As Z
Group By

Java: Instanceof and Generics

The runtime type of the object is a relatively arbitrary condition to filter on. I suggest keeping such muckiness away from your collection. This is simply achieved by having your collection delegate to a filter passed in a construction.

public interface FilterObject {
     boolean isAllowed(Object obj);

public class FilterOptimizedList<E> implements List<E> {
     private final FilterObject filter;
     public FilterOptimizedList(FilterObject filter) {
         if (filter == null) {
             throw NullPointerException();
         this.filter = filter;
     public int indexOf(Object obj) {
         if (!filter.isAllows(obj)) {
              return -1;

     final List<String> longStrs = new FilterOptimizedList<String>(
         new FilterObject() { public boolean isAllowed(Object obj) {
             if (obj == null) {
                 return true;
             } else if (obj instanceof String) {
                 String str = (String)str;
                 return str.length() > = 4;
             } else {
                 return false;

C# event with custom arguments

Example with no parameters:

delegate void NewEventHandler();
public event NewEventHandler OnEventHappens;

And from another class, you can subscribe to

otherClass.OnEventHappens += ExecuteThisFunctionWhenEventHappens;

And declare that function with no parameters.

Add a UIView above all, even the navigation bar

I'd use a UIViewController subclass containing a "Container View" that embeds your others view controllers. You'll then be able to add the navigation controller inside the Container View (using the embed relationship segue for example).

See Implementing a Container View Controller

Download files in laravel using Response::download

File downloads are super simple in Laravel 5.

As @Ashwani mentioned Laravel 5 allows file downloads with response()->download() to return file for download. We no longer need to mess with any headers. To return a file we simply:

return response()->download(public_path('file_path/from_public_dir.pdf'));

from within the controller.

Reusable Download Route/Controller

Now let's make a reusable file download route and controller so we can server up any file in our public/files directory.

Create the controller:

php artisan make:controller --plain DownloadsController

Create the route in app/Http/routes.php:

Route::get('/download/{file}', 'DownloadsController@download');

Make download method in app/Http/Controllers/DownloadsController:

class DownloadsController extends Controller
  public function download($file_name) {
    $file_path = public_path('files/'.$file_name);
    return response()->download($file_path);

Now simply drops some files in the public/files directory and you can server them up by linking to /download/filename.ext:

<a href="/download/filename.ext">File Name</a> // update to your own "filename.ext"

If you pulled in Laravel Collective's Html package you can use the Html facade:

{!! Html::link('download/filename.ext', 'File Name') !!}

HttpClient.GetAsync(...) never returns when using await/async

I'm going to put this in here more for completeness than direct relevance to the OP. I spent nearly a day debugging an HttpClient request, wondering why I was never getting back a response.

Finally found that I had forgotten to await the async call further down the call stack.

Feels about as good as missing a semicolon.

Check if checkbox is NOT checked on click - jQuery

The Answer already posted .But We can use the jquery in this way also


    $('#check1').click(function() {

    $('#check2').click(function() {

Regex Explanation ^.*$

  • ^ matches position just before the first character of the string
  • $ matches position just after the last character of the string
  • . matches a single character. Does not matter what character it is, except newline
  • * matches preceding match zero or more times

So, ^.*$ means - match, from beginning to end, any character that appears zero or more times. Basically, that means - match everything from start to end of the string. This regex pattern is not very useful.

Let's take a regex pattern that may be a bit useful. Let's say I have two strings The bat of Matt Jones and Matthew's last name is Jones. The pattern ^Matt.*Jones$ will match Matthew's last name is Jones. Why? The pattern says - the string should start with Matt and end with Jones and there can be zero or more characters (any characters) in between them.

Feel free to use an online tool like to test out regex patterns and strings.

Getting file size in Python?

You may use os.stat() function, which is a wrapper of system call stat():

import os

def getSize(filename):
    st = os.stat(filename)
    return st.st_size

VB.NET: Clear DataGridView

I had the same problem on gridview content clearing. The datasource i used was a datatable having no columns, and i added columns and rows programmatically to datatable. Then bind to datagridview. I tried the code related with gridview like gridView.Rows.Clear(), gridView.DataSource = Nothing

but it didn't work for me. Then try the below code related with datatable before binding it to datagridview each time.

  gridView.DataSource = dtStore

And is working fine, no replication in DataGridView

How to get an object's property's value by property name?


write-host ($obj | Select -ExpandProperty "SomeProp")

Or for that matter:


Need to install urllib2 for Python 3.5.1

In Python 3, urllib2 was replaced by two in-built modules named urllib.request and urllib.error

Adapted from source

So replace this:

import urllib2

With this:

import urllib.request as urllib2

Better way to generate array of all letters in the alphabet

for (char letter = 'a'; letter <= 'z'; letter++)

python: How do I know what type of exception occurred?

The actual exception can be captured in the following way:

    i = 1/0
except Exception as e:
    print e

You can learn more about exceptions from The Python Tutorial.

org.gradle.api.tasks.TaskExecutionException: Execution failed for task ':app:transformClassesWithDexForDebug'

I had the same issue and I could solve it like this:

1) If your minSdkVersion is set to 21 or a higher value, the only thing you need to do is to set multiDexEnabled in your build.gradle file at the module level, as shown below:

android {
    defaultConfig {
        minSdkVersion 21 
        targetSdkVersion 28
        multiDexEnabled true

2) However, if your minSdkVersion is set to 20 or less, you should use the MultiDex compatibility library, as follows:

2.1) Modify the module-level build.gradle file to enable MultiDex and add the MultiDex library as dependency, as shown below

android {
    defaultConfig {
        minSdkVersion 15 
        targetSdkVersion 28
        multiDexEnabled true

dependencies {
  implementation ''

2.2) According to the Application class or not, do one of the following actions:

2.2.1) If you do not cancel the Application class, modify your manifest file to set android: name in the <application> tag as shown below:

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

2.2.2) If you cancel the Application class, you must change it to extend MultiDexApplication (if possible) as shown below:

public class MyApplication extends MultiDexApplication { ... }

2.2.3) Also, if you override the Application class and can not change the base class, alternatively you can override the attachBaseContext () method and invoke MultiDex.install (this) to enable MultiDex:

public class MyApplication extends SomeOtherApplication {
  protected void attachBaseContext(Context base) {

Please use this link, it was really useful for me!

How to add/update an attribute to an HTML element using JavaScript?

What do you want to do with the attribute? Is it an html attribute or something of your own?

Most of the time you can simply address it as a property: want to set a title on an element? element.title = "foo" will do it.

For your own custom JS attributes the DOM is naturally extensible (aka expando=true), the simple upshot of which is that you can do element.myCustomFlag = foo and subsequently read it without issue.

Make WPF Application Fullscreen (Cover startmenu)

You're probably missing the WindowState="Maximized", try the following:

<Window x:Class="HTA.MainWindow"
    Title="MainWindow" Height="350" Width="525"
    WindowStyle="None" ResizeMode="NoResize"  
    WindowStartupLocation="CenterScreen" WindowState="Maximized">

Javascript, viewing [object HTMLInputElement]

When you get a value from client make and that a value for example.

var current_text = document.getElementById('user_text').value;
        var http = new XMLHttpRequest();
        http.onreadystatechange = function () {

            if (http.readyState == 4 &&  http.status == 200 ){
                var response = http.responseText;
              document.getElementById('server_response').value = response;


Error 5 : Access Denied when starting windows service

Your code may be running in the security context of a user that is not allowed to start a service.

Since you are using WCF, I am guessing that you are in the context of NETWORK SERVICE.


How to change already compiled .class file without decompile?

You can change the code when you decompiled it, but it has to be recompiled to a class file, the decompiler outputs java code, this has to be recompiled with the same classpath as the original jar/class file

Output of git branch in tree like fashion

It's not quite what you asked for, but

git log --graph --simplify-by-decoration --pretty=format:'%d' --all

does a pretty good job. It shows tags and remote branches as well. This may not be desirable for everyone, but I find it useful. --simplifiy-by-decoration is the big trick here for limiting the refs shown.

I use a similar command to view my log. I've been able to completely replace my gitk usage with it:

git log --graph --oneline --decorate --all

I use it by including these aliases in my ~/.gitconfig file:

    l = log --graph --oneline --decorate
    ll = log --graph --oneline --decorate --branches --tags
    lll = log --graph --oneline --decorate --all

Edit: Updated suggested log command/aliases to use simpler option flags.

Escape regex special characters in a Python string

Use re.escape

>>> import re
>>> re.escape(r'\ a.*$')
'\\\\\\ a\\.\\*\\$'
>>> print(re.escape(r'\ a.*$'))
\\\ a\.\*\$
>>> re.escape('')
>>> print(re.escape(''))

Repeating it here:


Return string with all non-alphanumerics backslashed; this is useful if you want to match an arbitrary literal string that may have regular expression metacharacters in it.

As of Python 3.7 re.escape() was changed to escape only characters which are meaningful to regex operations.

connecting to mysql server on another PC in LAN

mysql -u user -h -p

This should be enough for connection to MySQL server. Please, check the firewall of if remote connection to MySQL server is enabled.


How to execute multiple commands in a single line

Googling gives me this:

Command A & Command B

Execute Command A, then execute Command B (no evaluation of anything)

Command A | Command B

Execute Command A, and redirect all its output into the input of Command B

Command A && Command B

Execute Command A, evaluate the errorlevel after running and if the exit code (errorlevel) is 0, only then execute Command B

Command A || Command B

Execute Command A, evaluate the exit code of this command and if it's anything but 0, only then execute Command B

How to change navigation bar color in iOS 7 or 6?

The background color property is ignored on a UINavigationBar, so if you want to adjust the look and feel you either have to use the tintColor or call some of the other methods listed under "Customizing the Bar Appearance" of the UINavigationBar class reference (like setBackgroundImage:forBarMetrics:).

Be aware that the tintColor property works differently in iOS 7, so if you want a consistent look between iOS 7 and prior version using a background image might be your best bet. It's also worth mentioning that you can't configure the background image in the Storyboard, you'll have to create an IBOutlet to your UINavigationBar and change it in viewDidLoad or some other appropriate place.

Facebook page automatic "like" URL (for QR Code)

For a hyperlink just use ID++/like


To make it work with here's what you do:

Open the Facebook page you're looking for then change the URL to the mobile URL ( which is ).

Now you should see a big version of the mobile Facebook page. Copy the target URL of the like button.

Pop that URL into the QR generator to make a "scan to like" barcode. This will open the m.Facebook page in the browser of most mobiles directly from the QR reader. If they are not logged into Facebook then they will be prompted to log in and then click 'like'. If logged in, it will auto like.

Hope this helps!

Also, definitely include something with a "click here/scan here to like us on Facebook"

Select where count of one field is greater than one

As OMG Ponies stated, the having clause is what you are after. However, if you were hoping that you would get discrete rows instead of a summary (the "having" creates a summary) - it cannot be done in a single statement. You must use two statements in that case.

Regex AND operator

Maybe you are looking for something like this. If you want to select the complete line when it contains both "foo" and "baz" at the same time, this RegEx will comply that:


How do I specify the exit code of a console application in .NET?

If you are going to use the method suggested by David, you should also take a look at the [Flags] Attribute.

This allows you to do bit wise operations on enums.

enum ExitCodes : int
  Success = 0,
  SignToolNotInPath = 1,
  AssemblyDirectoryBad = 2,
  PFXFilePathBad = 4,
  PasswordMissing = 8,
  SignFailed = 16,
  UnknownError = 32


(ExitCodes.SignFailed | ExitCodes.UnknownError)

would be 16 + 32. :)

Creating a system overlay window (always on top)

This is an old Question but recently Android has a support for Bubbles. Bubbles are soon going to be launched but currently developers can start using them.They are designed to be an alternative to using SYSTEM_ALERT_WINDOW. Apps like (Facebook Messenger and MusiXMatch use the same concept).


Bubbles are created via the Notification API, you send your notification as normal. If you want it to bubble you need to attach some extra data to it. For more information about Bubbles you can go to the official Android Developer Guide on Bubbles.

How do I measure execution time of a command on the Windows command line?

Depending on the version of Windows you're using, just running bash will put you into Bash mode. This will allow you to use a bunch of commands that are not available on PowerShell directly (like the time command). Timing your command is now as easy as executing:

# The clause <your-command> (without the angle brackets) denotes the command you want to run.
$ time <your-command>

Note: You can easily quit from Bash mode and return back into your mainstream shell by running exit while in Bash mode.

This worked for me perfectly (Windows 10) after trying out other methods (like Measure-Command) which sometimes produce undesired stats. Hope this works for you as well.

jQuery Set Cursor Position in Text Area

Based on this question, the answer will not work perfectly for ie and opera when there is new line in the textarea. The answer explain how to adjust the selectionStart, selectionEnd before calling setSelectionRange.

I have try the adjustOffset from the other question with the solution proposed by @AVProgrammer and it work.

function adjustOffset(el, offset) {
    /* From */
    var val = el.value, newOffset = offset;
    if (val.indexOf("\r\n") > -1) {
        var matches = val.replace(/\r\n/g, "\n").slice(0, offset).match(/\n/g);
        newOffset += matches ? matches.length : 0;
    return newOffset;

$.fn.setCursorPosition = function(position){
    /* From */
    if(this.lengh == 0) return this;
    return $(this).setSelection(position, position);

$.fn.setSelection = function(selectionStart, selectionEnd) {
    /* From 
       modified to fit */
    if(this.lengh == 0) return this;
    input = this[0];

    if (input.createTextRange) {
        var range = input.createTextRange();
        range.moveEnd('character', selectionEnd);
        range.moveStart('character', selectionStart);;
    } else if (input.setSelectionRange) {
        selectionStart = adjustOffset(input, selectionStart);
        selectionEnd = adjustOffset(input, selectionEnd);
        input.setSelectionRange(selectionStart, selectionEnd);

    return this;

$.fn.focusEnd = function(){
    /* From */

JDBC ODBC Driver Connection

Didn't work with ODBC-Bridge for me too. I got the way around to initialize ODBC connection using ODBC driver.

 import java.sql.*;  
 public class UserLogin
     public static void main(String[] args)

            // C:\\databaseFileName.accdb" - location of your database 
           String url = "jdbc:odbc:Driver={Microsoft Access Driver (*.mdb, *.accdb)};DBQ=" + "C:\\emp.accdb";

            // specify url, username, pasword - make sure these are valid 
            Connection conn = DriverManager.getConnection(url, "username", "password");

            System.out.println("Connection Succesfull");
         catch (Exception e) 
            System.err.println("Got an exception! ");


PHP: if !empty & empty

Here's a compact way to do something different in all four cases:

if(empty($youtube)) {
    if(empty($link)) {
        # both empty
    } else {
        # only $youtube not empty
} else {
    if(empty($link)) {
        # only $link empty
    } else {
        # both not empty

If you want to use an expression instead, you can use ?: instead:

echo empty($youtube) ? ( empty($link) ? 'both empty' : 'only $youtube not empty' )
                     : ( empty($link) ? 'only $link empty' : 'both not empty' );

Is there an alternative sleep function in C to milliseconds?

You can use this cross-platform function:

#ifdef WIN32
#include <windows.h>
#elif _POSIX_C_SOURCE >= 199309L
#include <time.h>   // for nanosleep
#include <unistd.h> // for usleep

void sleep_ms(int milliseconds){ // cross-platform sleep function
#ifdef WIN32
#elif _POSIX_C_SOURCE >= 199309L
    struct timespec ts;
    ts.tv_sec = milliseconds / 1000;
    ts.tv_nsec = (milliseconds % 1000) * 1000000;
    nanosleep(&ts, NULL);
    if (milliseconds >= 1000)
      sleep(milliseconds / 1000);
    usleep((milliseconds % 1000) * 1000);

Laravel 5 - How to access image uploaded in storage within View?

One option would be to create a symbolic link between a subfolder in your storage directory and public directory.

For example

ln -s /path/to/laravel/storage/avatars /path/to/laravel/public/avatars

This is also the method used by Envoyer, a deployment manager built by Taylor Otwell, the developer of Laravel.

Remove the last character in a string in T-SQL?

Get the last character

Right(@string, len(@String) - (len(@String) - 1))

How to change the port of Tomcat from 8080 to 80?

On Ubuntu and Debian systems, there are several steps needed:

  1. In server.xml, change the line <Connector connectionTimeout="20000" port="8080" protocol="HTTP/1.1" redirectPort="8443"/> to have port="80".

  2. Install the recommended (not required) authbind package, with a command like:

    sudo apt-get install authbind

  3. Enable authbind in the server.xml file (in either /etc/tomcat6 or /etc/tomcat7) by uncommenting and setting the line like:


All three steps are needed.

MySQL : transaction within a stored procedure

Here's an example of a transaction that will rollback on error and return the error code.

    IN P_server_id VARCHAR(100),
    IN P_db_user_pw_creds VARCHAR(32),
    IN p_premium_status_name VARCHAR(100),
    IN P_premium_status_limit INT,
    IN P_user_tag VARCHAR(255),
    IN P_first_name VARCHAR(50),
    IN P_last_name VARCHAR(50)

    DECLARE errno INT;


    INSERT INTO server_users(server_id, db_user_pw_creds, premium_status_name, premium_status_limit)
    VALUES(P_server_id, P_db_user_pw_creds, P_premium_status_name, P_premium_status_limit);

    INSERT INTO client_users(user_id, server_id, user_tag, first_name, last_name, lat, lng)
    VALUES(P_server_id, P_server_id, P_user_tag, P_first_name, P_last_name, 0, 0);



This is assuming that autocommit is set to 0. Hope this helps.

gradient descent using python and numpy

I think your code is a bit too complicated and it needs more structure, because otherwise you'll be lost in all equations and operations. In the end this regression boils down to four operations:

  1. Calculate the hypothesis h = X * theta
  2. Calculate the loss = h - y and maybe the squared cost (loss^2)/2m
  3. Calculate the gradient = X' * loss / m
  4. Update the parameters theta = theta - alpha * gradient

In your case, I guess you have confused m with n. Here m denotes the number of examples in your training set, not the number of features.

Let's have a look at my variation of your code:

import numpy as np
import random

# m denotes the number of examples here, not the number of features
def gradientDescent(x, y, theta, alpha, m, numIterations):
    xTrans = x.transpose()
    for i in range(0, numIterations):
        hypothesis =, theta)
        loss = hypothesis - y
        # avg cost per example (the 2 in 2*m doesn't really matter here.
        # But to be consistent with the gradient, I include it)
        cost = np.sum(loss ** 2) / (2 * m)
        print("Iteration %d | Cost: %f" % (i, cost))
        # avg gradient per example
        gradient =, loss) / m
        # update
        theta = theta - alpha * gradient
    return theta

def genData(numPoints, bias, variance):
    x = np.zeros(shape=(numPoints, 2))
    y = np.zeros(shape=numPoints)
    # basically a straight line
    for i in range(0, numPoints):
        # bias feature
        x[i][0] = 1
        x[i][1] = i
        # our target variable
        y[i] = (i + bias) + random.uniform(0, 1) * variance
    return x, y

# gen 100 points with a bias of 25 and 10 variance as a bit of noise
x, y = genData(100, 25, 10)
m, n = np.shape(x)
numIterations= 100000
alpha = 0.0005
theta = np.ones(n)
theta = gradientDescent(x, y, theta, alpha, m, numIterations)

At first I create a small random dataset which should look like this:

Linear Regression

As you can see I also added the generated regression line and formula that was calculated by excel.

You need to take care about the intuition of the regression using gradient descent. As you do a complete batch pass over your data X, you need to reduce the m-losses of every example to a single weight update. In this case, this is the average of the sum over the gradients, thus the division by m.

The next thing you need to take care about is to track the convergence and adjust the learning rate. For that matter you should always track your cost every iteration, maybe even plot it.

If you run my example, the theta returned will look like this:

Iteration 99997 | Cost: 47883.706462
Iteration 99998 | Cost: 47883.706462
Iteration 99999 | Cost: 47883.706462
[ 29.25567368   1.01108458]

Which is actually quite close to the equation that was calculated by excel (y = x + 30). Note that as we passed the bias into the first column, the first theta value denotes the bias weight.

How to remove a class from elements in pure JavaScript?

var elems = document.querySelectorAll(".widget.hover");

[], function(el) {

You can patch .classList into IE9. Otherwise, you'll need to modify the .className.

var elems = document.querySelectorAll(".widget.hover");

[], function(el) {
    el.className = el.className.replace(/\bhover\b/, "");

The .forEach() also needs a patch for IE8, but that's pretty common anyway.

How do I read an attribute on a class at runtime?

When you have Overridden Methods with same Name Use the helper below

public static TValue GetControllerMethodAttributeValue<T, TT, TAttribute, TValue>(this T type, Expression<Func<T, TT>> exp, Func<TAttribute, TValue> valueSelector) where TAttribute : Attribute
            var memberExpression = exp?.Body as MethodCallExpression;

            if (memberExpression.Method.GetCustomAttributes(typeof(TAttribute), false).FirstOrDefault() is TAttribute attr && valueSelector != null)
                return valueSelector(attr);

            return default(TValue);

Usage: var someController = new SomeController(Some params); var str = typeof(SomeController).GetControllerMethodAttributeValue(x => someController.SomeMethod(It.IsAny()), (RouteAttribute routeAttribute) => routeAttribute.Template);

Using putty to scp from windows to Linux

You can use PSCP to copy files from Windows to Linux.

  1. Download PSCP from
  2. Open cmd in the directory with pscp.exe file
  3. Type command pscp source_file user@host:destination_file


Align button at the bottom of div using CSS

You can use position:absolute; to absolutely position an element within a parent div. When using position:absolute; the element will be positioned absolutely from the first positioned parent div, if it can't find one it will position absolutely from the window so you will need to make sure the content div is positioned.

To make the content div positioned, all position values that aren't static will work, but relative is the easiest since it doesn't change the divs positioning by itself.

So add position:relative; to the content div, remove the float from the button and add the following css to the button:

position: absolute;
right:    0;
bottom:   0;

Understanding the Gemfile.lock file

in regards to the exclamation mark I just found out it's on gems fetched via :git, e.g.

gem "foo", :git => "[email protected]:company/foo.git"

Identify duplicates in a List

Just try this :

Example if List values are: [1, 2, 3, 4, 5, 6, 4, 3, 7, 8] duplicate item [3, 4].

        List<Integer> dup = new ArrayList<>();
        for (int i = 0; i < list.size() - 1; i++) {
            if (list.get(i) == list.get(i + 1)) {
                if (!dup.contains(list.get(i + 1))) {
                    dup.add(list.get(i + 1));
        System.out.println("duplicate item " + dup);

Determine what attributes were changed in Rails after_save callback?

In case you can do this on before_save instead of after_save, you'll be able to use this:


it returns an array of all changed columns in this record.

you can also use:


which returns a hash of columns that changed and before and after results as arrays

C - casting int to char and append char to char

Casting int to char involves losing data and the compiler will probably warn you.

Extracting a particular byte from an int sounds more reasonable and can be done like this:

number & 0x000000ff; /* first byte */
(number & 0x0000ff00) >> 8; /* second byte */
(number & 0x00ff0000) >> 16; /* third byte */
(number & 0xff000000) >> 24; /* fourth byte */

Load view from an external xib file in storyboard

My full example is here, but I will provide a summary below.


Add a .swift and .xib file each with the same name to your project. The .xib file contains your custom view layout (using auto layout constraints preferably).

Make the swift file the xib file's owner.

enter image description here Code

Add the following code to the .swift file and hook up the outlets and actions from the .xib file.

import UIKit
class ResuableCustomView: UIView {

    let nibName = "ReusableCustomView"
    var contentView: UIView?

    @IBOutlet weak var label: UILabel!
    @IBAction func buttonTap(_ sender: UIButton) {
        label.text = "Hi"

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)

        guard let view = loadViewFromNib() else { return }
        view.frame = self.bounds
        contentView = view

    func loadViewFromNib() -> UIView? {
        let bundle = Bundle(for: type(of: self))
        let nib = UINib(nibName: nibName, bundle: bundle)
        return nib.instantiate(withOwner: self, options: nil).first as? UIView

Use it

Use your custom view anywhere in your storyboard. Just add a UIView and set the class name to your custom class name.

enter image description here

For a while Christopher Swasey's approach was the best approach I had found. I asked a couple of the senior devs on my team about it and one of them had the perfect solution! It satisfies every one of the concerns that Christopher Swasey so eloquently addressed and it doesn't require boilerplate subclass code(my main concern with his approach). There is one gotcha, but other than that it is fairly intuitive and easy to implement.

  1. Create a custom UIView class in a .swift file to control your xib. i.e. MyCustomClass.swift
  2. Create a .xib file and style it as you want. i.e. MyCustomClass.xib
  3. Set the File's Owner of the .xib file to be your custom class (MyCustomClass)
  4. GOTCHA: leave the class value (under the identity Inspector) for your custom view in the .xib file blank. So your custom view will have no specified class, but it will have a specified File's Owner.
  5. Hook up your outlets as you normally would using the Assistant Editor.
    • NOTE: If you look at the Connections Inspector you will notice that your Referencing Outlets do not reference your custom class (i.e. MyCustomClass), but rather reference File's Owner. Since File's Owner is specified to be your custom class, the outlets will hook up and work propery.
  6. Make sure your custom class has @IBDesignable before the class statement.
  7. Make your custom class conform to the NibLoadable protocol referenced below.
    • NOTE: If your custom class .swift file name is different from your .xib file name, then set the nibName property to be the name of your .xib file.
  8. Implement required init?(coder aDecoder: NSCoder) and override init(frame: CGRect) to call setupFromNib() like the example below.
  9. Add a UIView to your desired storyboard and set the class to be your custom class name (i.e. MyCustomClass).
  10. Watch IBDesignable in action as it draws your .xib in the storyboard with all of it's awe and wonder.

Here is the protocol you will want to reference:

public protocol NibLoadable {
    static var nibName: String { get }

public extension NibLoadable where Self: UIView {

    public static var nibName: String {
        return String(describing: Self.self) // defaults to the name of the class implementing this protocol.

    public static var nib: UINib {
        let bundle = Bundle(for: Self.self)
        return UINib(nibName: Self.nibName, bundle: bundle)

    func setupFromNib() {
        guard let view = Self.nib.instantiate(withOwner: self, options: nil).first as? UIView else { fatalError("Error loading \(self) from nib") }
        view.translatesAutoresizingMaskIntoConstraints = false
        view.leadingAnchor.constraint(equalTo: self.safeAreaLayoutGuide.leadingAnchor, constant: 0).isActive = true
        view.topAnchor.constraint(equalTo: self.safeAreaLayoutGuide.topAnchor, constant: 0).isActive = true
        view.trailingAnchor.constraint(equalTo: self.safeAreaLayoutGuide.trailingAnchor, constant: 0).isActive = true
        view.bottomAnchor.constraint(equalTo: self.safeAreaLayoutGuide.bottomAnchor, constant: 0).isActive = true

And here is an example of MyCustomClass that implements the protocol (with the .xib file being named MyCustomClass.xib):

class MyCustomClass: UIView, NibLoadable {

    @IBOutlet weak var myLabel: UILabel!

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)

    override init(frame: CGRect) {
        super.init(frame: frame)


NOTE: If you miss the Gotcha and set the class value inside your .xib file to be your custom class, then it will not draw in the storyboard and you will get a EXC_BAD_ACCESS error when you run the app because it gets stuck in an infinite loop of trying to initialize the class from the nib using the init?(coder aDecoder: NSCoder) method which then calls Self.nib.instantiate and calls the init again.

How to correctly catch change/focusOut event on text input in React.js?

Its late, yet it's worth your time nothing that, there are some differences in browser level implementation of focusin and focusout events and react synthetic onFocus and onBlur. focusin and focusout actually bubble, while onFocus and onBlur dont. So there is no exact same implementation for focusin and focusout as of now for react. Anyway most cases will be covered in onFocus and onBlur.

simple vba code gives me run time error 91 object variable or with block not set

Check the version of the excel, if you are using older version then Value2 is not available for you and thus it is showing an error, while it will work with 2007+ version. Or the other way, the object is not getting created and thus the Value2 property is not available for the object.

Automatically get loop index in foreach loop in Perl

In Perl prior to 5.10, you can say


use strict;
use warnings;

my @a = qw/a b c d e/;

my $index;
for my $elem (@a) {
    print "At index ", $index++, ", I saw $elem\n";


for my $index (0 .. $#a) {
    print "At index $index I saw $a[$elem]\n";

In Perl 5.10, you use state to declare a variable that never gets reinitialized (unlike ones created with my). This lets you keep the $index variable in a smaller scope, but it can lead to bugs (if you enter the loop a second time it will still have the last value):


use 5.010;
use strict;
use warnings;

my @a = qw/a b c d e/;

for my $elem (@a) {
    state $index;
    say "At index ", $index++, ", I saw $elem";

In Perl 5.12 you can say


use 5.012; # This enables strict
use warnings;

my @a = qw/a b c d e/;

while (my ($index, $elem) = each @a) {
    say "At index $index I saw $elem";

But be warned: you there are restrictions to what you are allowed to do with @a while iterating over it with each.

It won't help you now, but in Perl 6 you will be able to say


my @a = <a b c d e>;
for @a Z 0 .. Inf -> $elem, $index {
    say "at index $index, I saw $elem"

The Z operator zips the two lists together (i.e. it takes one element from the first list, then one element from the second, then one element from the first, and so on). The second list is a lazy list that contains every integer from 0 to infinity (at least theoretically). The -> $elem, $index says that we are taking two values at a time from the result of the zip. The rest should look normal to you (unless you are not familiar with the say function from 5.10 yet).

What does the "assert" keyword do?

assert is a debugging tool that will cause the program to throw an AssertionFailed exception if the condition is not true. In this case, the program will throw an exception if either of the two conditions following it evaluate to false. Generally speaking, assert should not be used in production code

Trying to get property of non-object in

Your error

Notice: Trying to get property of non-object in C:\wamp\www\phone\pages\init.php on line 22

Your comment

@22 is <?php echo $sidemenu->mname."<br />";?>

$sidemenu is not an object, and you are trying to access one of its properties.

That is the reason for your error.

Java Array Sort descending?

You could use this to sort all kind of Objects

sort(T[] a, Comparator<? super T> c) 

Arrays.sort(a, Collections.reverseOrder());

Arrays.sort() cannot be used directly to sort primitive arrays in descending order. If you try to call the Arrays.sort() method by passing reverse Comparator defined by Collections.reverseOrder() , it will throw the error

no suitable method found for sort(int[],comparator)

That will work fine with 'Array of Objects' such as Integer array but will not work with a primitive array such as int array.

The only way to sort a primitive array in descending order is, first sort the array in ascending order and then reverse the array in place. This is also true for two-dimensional primitive arrays.

Matplotlib - global legend and title aside subplots

For legend labels can use something like below. Legendlabels are the plot lines saved. modFreq are where the name of the actual labels corresponding to the plot lines. Then the third parameter is the location of the legend. Lastly, you can pass in any arguments as I've down here but mainly need the first three. Also, you are supposed to if you set the labels correctly in the plot command. To just call legend with the location parameter and it finds the labels in each of the lines. I have had better luck making my own legend as below. Seems to work in all cases where have never seemed to get the other way going properly. If you don't understand let me know:

legendLabels = []
for i in range(modSize):
    legendLabels.append(ax.plot(x,hstack((array([0]),actSum[j,semi,i,semi])), color=plotColor[i%8], dashes=dashes[i%4])[0]) #linestyle=dashs[i%4]       
legArgs = dict(title='AM Templates (Hz)',bbox_to_anchor=[.4,1.05],borderpad=0.1,labelspacing=0,handlelength=1.8,handletextpad=0.05,frameon=False,ncol=4, columnspacing=0.02) #ncol,numpoints,columnspacing,title,bbox_transform,prop
leg = ax.legend(tuple(legendLabels),tuple(modFreq),'upper center',**legArgs)

You can also use the leg to change fontsizes or nearly any parameter of the legend.

Global title as stated in the above comment can be done with adding text per the link provided:

f.text(0.5,0.975,'The new formatter, default settings',horizontalalignment='center',

Mouseover or hover vue.js

Please take a look at the vue-mouseover package if you are not satisfied how does this code look:

    @mouseover="isMouseover = true"
    @mouseleave="isMouseover = false"

vue-mouseover provides a v-mouseover directive that automaticaly updates the specified data context property when the cursor enters or leaves an HTML element the directive is attached to.

By default in the next example isMouseover property will be true when the cursor is over an HTML element and false otherwise:

<div v-mouseover="isMouseover" />

Also by default isMouseover will be initially assigned when v-mouseover is attached to the div element, so it will not remain unassigned before the first mouseenter/mouseleave event.

You can specify custom values via v-mouseover-value directive:



        mouseenter: customMouseenterValue,
        mouseleave: customMouseleaveValue

Custom default values can be passed to the package via options object during setup.

Get current cursor position in a textbox

Here's one possible method.

function isMouseInBox(e) {
  var textbox = document.getElementById('textbox');

  // Box position & sizes
  var boxX = textbox.offsetLeft;
  var boxY = textbox.offsetTop;
  var boxWidth = textbox.offsetWidth;
  var boxHeight = textbox.offsetHeight;

  // Mouse position comes from the 'mousemove' event
  var mouseX = e.pageX;
  var mouseY = e.pageY;
  if(mouseX>=boxX && mouseX<=boxX+boxWidth) {
    if(mouseY>=boxY && mouseY<=boxY+boxHeight){
       // Mouse is in the box
       return true;

document.addEventListener('mousemove', function(e){

How can I determine the character encoding of an excel file?

For Excel 2010 it should be UTF-8. Instruction by MS :

"The basic document structure of a SpreadsheetML document consists of the Sheets and Sheet elements, which reference the worksheets in the Workbook. A separate XML file is created for each Worksheet. For example, the SpreadsheetML for a workbook that has two worksheets name MySheet1 and MySheet2 is located in the Workbook.xml file and is shown in the following code example.

<?xml version="1.0" encoding="UTF-8" standalone="yes" ?> 
<workbook xmlns= xmlns:r="">
        <sheet name="MySheet1" sheetId="1" r:id="rId1" /> 
        <sheet name="MySheet2" sheetId="2" r:id="rId2" /> 

The worksheet XML files contain one or more block level elements such as SheetData. sheetData represents the cell table and contains one or more Row elements. A row contains one or more Cell elements. Each cell contains a CellValue element that represents the value of the cell. For example, the SpreadsheetML for the first worksheet in a workbook, that only has the value 100 in cell A1, is located in the Sheet1.xml file and is shown in the following code example.

<?xml version="1.0" encoding="UTF-8" ?> 
<worksheet xmlns="">
        <row r="1">
            <c r="A1">


Detection of cell encodings:

Add Items to ListView - Android

public OnClickListener moreListener = new OnClickListener() {

      public void onClick(View v) {

How do I tokenize a string in C++?

Here's an approach that allows you control over whether empty tokens are included (like strsep) or excluded (like strtok).

#include <string.h> // for strchr and strlen

 * want_empty_tokens==true  : include empty tokens, like strsep()
 * want_empty_tokens==false : exclude empty tokens, like strtok()
std::vector<std::string> tokenize(const char* src,
                                  char delim,
                                  bool want_empty_tokens)
  std::vector<std::string> tokens;

  if (src and *src != '\0') // defensive
    while( true )  {
      const char* d = strchr(src, delim);
      size_t len = (d)? d-src : strlen(src);

      if (len or want_empty_tokens)
        tokens.push_back( std::string(src, len) ); // capture token

      if (d) src += len+1; else break;

  return tokens;

How to read html from a url in python 3

Note that Python3 does not read the html code as a string but as a bytearray, so you need to convert it to one with decode.

import urllib.request

fp = urllib.request.urlopen("")
mybytes =

mystr = mybytes.decode("utf8")

print(mystr) error adding symbols: DSO missing from command line

I found another case and therefore I thing you are all wrong.

This is what I had:

/usr/lib64/gcc/x86_64-suse-linux/4.8/../../../../x86_64-suse-linux/bin/ld: eggtrayicon.o: undefined reference to symbol 'XFlush'
/usr/lib64/ error adding symbols: DSO missing from command line

The problem is that the command line DID NOT contain -lX11 - although the should be added as a dependency because there were also GTK and GNOME libraries in the arguments.

So, the only explanation for me is that this message might have been intended to help you, but it didn't do it properly. This was probably simple: the library that provides the symbol was not added to the command line.

Please note three important rules concerning linkage in POSIX:

  • Dynamic libraries have defined dependencies, so only libraries from the top-dependency should be supplied in whatever order (although after the static libraries)
  • Static libraries have just undefined symbols - it's up to you to know their dependencies and supply all of them in the command line
  • The order in static libraries is always: requester first, provider follows. Otherwise you'll get undefined symbol message, just like when you forgot to add the library to the command line
  • When you specify the library with -l<name>, you never know whether it will take lib<name>.so or lib<name>.a. The dynamic library is preferred, if found, and static libraries only can be enforced by compiler option - that's all. And whether you have any problems as above, it depends on whether you had static or dynamic libraries
  • Well, sometimes the dependencies may be lacking in dynamic libraries :D

How to check if internet connection is present in Java?

This code should do the job reliably.

Note that when using the try-with-resources statement we don't need to close the resources.


public class InternetAvailabilityChecker
    public static boolean isInternetAvailable() throws IOException
        return isHostAvailable("") || isHostAvailable("")
                || isHostAvailable("")|| isHostAvailable("");

    private static boolean isHostAvailable(String hostName) throws IOException
        try(Socket socket = new Socket())
            int port = 80;
            InetSocketAddress socketAddress = new InetSocketAddress(hostName, port);
            socket.connect(socketAddress, 3000);

            return true;
        catch(UnknownHostException unknownHost)
            return false;

How do I iterate through table rows and cells in JavaScript?

Using a single for loop:

var table = document.getElementById('tableID');  
var count = table.rows.length;  
for(var i=0; i<count; i++) {    

Define preprocessor macro through CMake?

The other solution proposed on this page are useful some versions of Cmake < 3.3.2. Here the solution for the version I am using (i.e., 3.3.2). Check the version of your Cmake by using $ cmake --version and pick the solution that fits with your needs. The cmake documentation can be found on the official page.

With CMake version 3.3.2, in order to create

#define foo

I needed to use:

add_definitions(-Dfoo)   # <--------HERE THE NEW CMAKE LINE inside CMakeLists.txt
add_executable( ....)

and, in order to have a preprocessor macro definition like this other one:

#define foo=5

the line is so modified:

add_definitions(-Dfoo=5)   # <--------HERE THE NEW CMAKE LINE inside CMakeLists.txt
add_executable( ....)

Why won't bundler install JSON gem?

I ran into this error while trying to get a project to run on my local dev box (OSX 10.6), using Sinatra and Postgresql (through activerecord), running on an rvm'd ruby 2.1. I found my answer here:

My exact problem (after the first block of log entries):

I also get an error when trying to build native extensions for gems

The answer:

rvm reinstall 2.1.0 --disable-binary

The explanation:

OSX does not have a package manager so all libraries have to be installed manually by user, this makes it virtually impossible to link the binary dynamically, and as you can see there are problems with the (pseudo)statically linked binary.

For the sake of completeness, I had first forgotten to update rvm (rvm get head), which yielded some other errors, but still needed the --disable-binary flag once I had done so.

Scrollview can host only one direct child

Wrap all the children inside of another LinearLayout with wrap_content for both the width and the height as well as the vertical orientation.

How to replace existing value of ArrayList element in Java

You must use



Your elements will become like this. [zero, one, three]

then add this

list.add(indexYouWantedToReplace, newElement)

Your elements will become like this. [zero, one, new, three]

Get filename from file pointer

You can get the path via Example:

>>> f = open('foo/bar.txt')

You might need os.path.basename if you want only the file name:

>>> import os
>>> f = open('foo/bar.txt')
>>> os.path.basename(

File object docs (for Python 2) here.

Single TextView with multiple colored text

I have write down some code for other question which is similar to this one, but that question got duplicated so i can't answer there so i am just putting my code here if someone looking for same requirement.

It's not fully working code, you need to make some minor changes to get it worked.

Here is the code:

I've used @Graeme idea of using spannable text.

String colorfulText = "colorfulText";       
    Spannable span = new SpannableString(colorfulText);             

    for ( int i = 0, len = colorfulText.length(); i < len; i++ ){
        span.setSpan(new ForegroundColorSpan(getRandomColor()), i, i+1,Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);                     


Random Color Method:

  private int getRandomColor(){
        Random rnd = new Random();
        return Color.argb(255, rnd.nextInt(256), rnd.nextInt(256), rnd.nextInt(256));

how to convert date to a format `mm/dd/yyyy`

Use CONVERT with the Value specifier of 101, whilst casting your data to date:


Retrieve WordPress root directory path?

There are 2 answers for this question Url & directory. Either way, the elegant way would be to define two constants for later use.

define (ROOT_URL, get_site_url() );
define (ROOT_DIR, get_theme_root() );

Valid characters in a Java class name

Class names should be nouns in UpperCamelCase, with the first letter of every word capitalised. Use whole words — avoid acronyms and abbreviations (unless the abbreviation is much more widely used than the long form, such as URL or HTML). The naming conventions can be read over here:

How does numpy.histogram() work?

import numpy as np    
hist, bin_edges = np.histogram([1, 1, 2, 2, 2, 2, 3], bins = range(5))

Below, hist indicates that there are 0 items in bin #0, 2 in bin #1, 4 in bin #3, 1 in bin #4.

# array([0, 2, 4, 1])   

bin_edges indicates that bin #0 is the interval [0,1), bin #1 is [1,2), ..., bin #3 is [3,4).

print (bin_edges)
# array([0, 1, 2, 3, 4]))  

Play with the above code, change the input to np.histogram and see how it works.

But a picture is worth a thousand words:

import matplotlib.pyplot as plt[:-1], hist, width = 1)
plt.xlim(min(bin_edges), max(bin_edges))   

enter image description here

Finding Android SDK on Mac and adding to PATH

Find the Android SDK location

Android Studio 
  > Preferences
  > Appearance & Behaviour
  > System Settings 
  > Android SDK
  > Android SDK Location

Create a .bash_profile file for your environment variables

  • Open the Terminal app
  • Go to your home directory via cd ~
  • Create the file with touch .bash_profile

Add the PATH variable to your .bash_profile

  • Open the file via open .bash_profile
  • Add export PATH=$PATH: [your SDK location] /platform-tools to the file and hit ?s to save it. By default it's:

    export PATH=$PATH:/Users/yourUserName/Library/Android/sdk/platform-tools

  • Go back to your Terminal App and load the variable with source ~/.bash_profile

Reading an image file in C/C++

corona is nice. From the tutorial:

corona::Image* image = corona::OpenImage("img.jpg", corona::PF_R8G8B8A8);
if (!image) {
  // error!

int width  = image->getWidth();
int height = image->getHeight();
void* pixels = image->getPixels();

// we're guaranteed that the first eight bits of every pixel is red,
// the next eight bits is green, and so on...
typedef unsigned char byte;
byte* p = (byte*)pixels;
for (int i = 0; i < width * height; ++i) {
  byte red   = *p++;
  byte green = *p++;
  byte blue  = *p++;
  byte alpha = *p++;

pixels would be a one dimensional array, but you could easily convert a given x and y position to a position in a 1D array. Something like pos = (y * width) + x

How to create a oracle sql script spool file

This will spool the output from the anonymous block into a file called output_<YYYYMMDD>.txt located in the root of the local PC C: drive where <YYYYMMDD> is the current date:



column date_column new_value today_var
select to_char(sysdate, 'yyyymmdd') date_column
  from dual

SPOOL C:\output_&today_var..txt

   ab varchar2(10) := 'Raj';
   cd varchar2(10);
   a  number := 10;
   c  number;
   d  number; 
   c := a+10;
   SELECT ab, c 
     INTO cd, d 
     FROM dual;
   DBMS_OUTPUT.put_line('cd: '||cd);
   DBMS_OUTPUT.put_line('d: '||d);



PROMPT Done, please see file C:\output_&today_var..txt

Hope it helps...


After your comment to output a value for every iteration of a cursor (I realise each value will be the same in this example but you should get the gist of what i'm doing):

   c := a+10;
   FOR i IN 1 .. 10
      c := a+10;
      -- Output the value of C
      DBMS_OUTPUT.put_line('c: '||c);

Which is more efficient, a for-each loop, or an iterator?

Iterator is an interface in the Java Collections framework that provides methods to traverse or iterate over a collection.

Both iterator and for loop acts similar when your motive is to just traverse over a collection to read its elements.

for-each is just one way to iterate over the Collection.

For example:

List<String> messages= new ArrayList<>();

//using for-each loop
for(String msg: messages){

//using iterator 
Iterator<String> it = messages.iterator();
    String msg =;

And for-each loop can be used only on objects implementing the iterator interface.

Now back to the case of for loop and iterator.

The difference comes when you try to modify a collection. In this case, iterator is more efficient because of its fail-fast property. ie. it checks for any modification in the structure of underlying collection before iterating over the next element. If there are any modifications found, it will throw the ConcurrentModificationException.

(Note: This functionality of iterator is only applicable in case of collection classes in java.util package. It is not applicable for concurrent collections as they are fail-safe by nature)

How to show alert message in mvc 4 controller?

Response.Write(@"<script language='javascript'>alert('Message: 
\n" + "Hi!" + " .');</script>");

How to right align widget in horizontal linear layout Android?

setting the view's layout_weight="1" would do the trick.!

<LinearLayout xmlns:android=""

    android:layout_weight="1" />


How to make an array of arrays in Java

there is the class I mentioned in the comment we had with Sean Patrick Floyd : I did it with a peculiar use which needs WeakReference, but you can change it by any object with ease.

Hoping this can help someone someday :)

import java.lang.ref.WeakReference;
import java.util.LinkedList;
import java.util.NoSuchElementException;
import java.util.Queue;

 * @author leBenj
public class Array2DWeakRefsBuffered<T>
    private final WeakReference<T>[][] _array;
    private final Queue<T> _buffer;

    private final int _width;

    private final int _height;

    private final int _bufferSize;

    @SuppressWarnings( "unchecked" )
    public Array2DWeakRefsBuffered( int w , int h , int bufferSize )
        _width = w;
        _height = h;
        _bufferSize = bufferSize;
        _array = new WeakReference[_width][_height];
        _buffer = new LinkedList<T>();

     * Tests the existence of the encapsulated object
     * /!\ This DOES NOT ensure that the object will be available on next call !
     * @param x
     * @param y
     * @return
     * @throws IndexOutOfBoundsException
     */public boolean exists( int x , int y ) throws IndexOutOfBoundsException
        if( x >= _width || x < 0 )
            throw new IndexOutOfBoundsException( "Index out of bounds (get) : [ x = " + x + "]" );
        if( y >= _height || y < 0 )
            throw new IndexOutOfBoundsException( "Index out of bounds (get) : [ y = " + y + "]" );
        if( _array[x][y] != null )
            T elem = _array[x][y].get();
            if( elem != null )
            return true;
        return false;

     * Gets the encapsulated object
     * @param x
     * @param y
     * @return
     * @throws IndexOutOfBoundsException
     * @throws NoSuchElementException
    public T get( int x , int y ) throws IndexOutOfBoundsException , NoSuchElementException
        T retour = null;
        if( x >= _width || x < 0 )
            throw new IndexOutOfBoundsException( "Index out of bounds (get) : [ x = " + x + "]" );
        if( y >= _height || y < 0 )
            throw new IndexOutOfBoundsException( "Index out of bounds (get) : [ y = " + y + "]" );
        if( _array[x][y] != null )
            retour = _array[x][y].get();
            if( retour == null )
            throw new NoSuchElementException( "Dereferenced WeakReference element at [ " + x + " ; " + y + "]" );
            throw new NoSuchElementException( "No WeakReference element at [ " + x + " ; " + y + "]" );
        return retour;

     * Add/replace an object
     * @param o
     * @param x
     * @param y
     * @throws IndexOutOfBoundsException
    public void set( T o , int x , int y ) throws IndexOutOfBoundsException
        if( x >= _width || x < 0 )
            throw new IndexOutOfBoundsException( "Index out of bounds (set) : [ x = " + x + "]" );
        if( y >= _height || y < 0 )
            throw new IndexOutOfBoundsException( "Index out of bounds (set) : [ y = " + y + "]" );
        _array[x][y] = new WeakReference<T>( o );

        // store local "visible" references : avoids deletion, works in FIFO mode
        _buffer.add( o );
        if(_buffer.size() > _bufferSize)


Example of how to use it :

// a 5x5 array, with at most 10 elements "bufferized" -> the last 10 elements will not be taken by GC process
Array2DWeakRefsBuffered<Image> myArray = new Array2DWeakRefsBuffered<Image>(5,5,10);
Image img = myArray.set(anImage,0,0);
    System.out.println("Image at 3,3 is still in memory");

What does the [Flags] Enum Attribute mean in C#?

There's something overly verbose to me about the if ((x & y) == y)... construct, especially if x AND y are both compound sets of flags and you only want to know if there's any overlap.

In this case, all you really need to know is if there's a non-zero value[1] after you've bitmasked.

[1] See Jaime's comment. If we were authentically bitmasking, we'd only need to check that the result was positive. But since enums can be negative, even, strangely, when combined with the [Flags] attribute, it's defensive to code for != 0 rather than > 0.

Building off of @andnil's setup...

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace BitFlagPlay
    class Program
        public enum MyColor
            Yellow = 0x01,
            Green = 0x02,
            Red = 0x04,
            Blue = 0x08

        static void Main(string[] args)
            var myColor = MyColor.Yellow | MyColor.Blue;
            var acceptableColors = MyColor.Yellow | MyColor.Red;

            Console.WriteLine((myColor & MyColor.Blue) != 0);     // True
            Console.WriteLine((myColor & MyColor.Red) != 0);      // False                
            Console.WriteLine((myColor & acceptableColors) != 0); // True
            // ... though only Yellow is shared.

            Console.WriteLine((myColor & MyColor.Green) != 0);    // Wait a minute... ;^D


Adding List<t>.add() another list

List<T>.Add adds a single element. Instead, use List<T>.AddRange to add multiple values.

Additionally, List<T>.AddRange takes an IEnumerable<T>, so you don't need to convert tripDetails into a List<TripDetails>, you can pass it directly, e.g.:


No numeric types to aggregate - change in groupby() behaviour?

I got this error generating a data frame consisting of timestamps and data:

df = pd.DataFrame({'data':value}, index=pd.DatetimeIndex(timestamp))

Adding the suggested solution works for me:

df = pd.DataFrame({'data':value}, index=pd.DatetimeIndex(timestamp), dtype=float))

Thanks Chang She!


2005-01-01 00:10:00  7.53
2005-01-01 00:20:00  7.54
2005-01-01 00:30:00  7.62
2005-01-01 00:40:00  7.68
2005-01-01 00:50:00  7.81
2005-01-01 01:00:00  7.95
2005-01-01 01:10:00  7.96
2005-01-01 01:20:00  7.95
2005-01-01 01:30:00  7.98
2005-01-01 01:40:00  8.06
2005-01-01 01:50:00  8.04
2005-01-01 02:00:00  8.06
2005-01-01 02:10:00  8.12
2005-01-01 02:20:00  8.12
2005-01-01 02:30:00  8.25
2005-01-01 02:40:00  8.27
2005-01-01 02:50:00  8.17
2005-01-01 03:00:00  8.21
2005-01-01 03:10:00  8.29
2005-01-01 03:20:00  8.31
2005-01-01 03:30:00  8.25
2005-01-01 03:40:00  8.19
2005-01-01 03:50:00  8.17
2005-01-01 04:00:00  8.18
2005-01-01 00:00:00  7.636000
2005-01-01 01:00:00  7.990000
2005-01-01 02:00:00  8.165000
2005-01-01 03:00:00  8.236667
2005-01-01 04:00:00  8.180000

jquery $(window).height() is returning the document height

Here's a question and answer for this: Difference between screen.availHeight and window.height()

Has pics too, so you can actually see the differences. Hope this helps.

Basically, $(window).height() give you the maximum height inside of the browser window (viewport), and$(document).height() gives you the height of the document inside of the browser. Most of the time, they will be exactly the same, even with scrollbars.

How to add "active" class to Html.ActionLink in ASP.NET MVC

is possible with a lambda function

string controllerAction = ViewContext.RouteData.Values["Controller"].ToString() + ViewContext.RouteData.Values["Action"].ToString();
    Func<string, string> IsSelected= x => x==controllerAction ? "active" : "";

then usage

 @Html.ActionLink("Inicio", "Index", "Home", new { area = "" }, new { @class = IsSelected("HomeIndex")})

Implements vs extends: When to use? What's the difference?

As shown in the figure given below, a class extends another class, an interface extends another interface but a class implements an interface. enter image description here

For more details

Frequency table for a single variable

The answer provided by @DSM is simple and straightforward, but I thought I'd add my own input to this question. If you look at the code for pandas.value_counts, you'll see that there is a lot going on.

If you need to calculate the frequency of many series, this could take a while. A faster implementation would be to use numpy.unique with return_counts = True

Here is an example:

import pandas as pd
import numpy as np

my_series = pd.Series([1,2,2,3,3,3])

3    3
2    2
1    1
dtype: int64

Notice here that the item returned is a pandas.Series

In comparison, numpy.unique returns a tuple with two items, the unique values and the counts.

vals, counts = np.unique(my_series, return_counts=True)
print(vals, counts)
[1 2 3] [1 2 3]

You can then combine these into a dictionary:

results = dict(zip(vals, counts))
{1: 1, 2: 2, 3: 3}

And then into a pandas.Series

1    1
2    2
3    3
dtype: int64

Know relationships between all the tables of database in SQL Server

Microsoft Visio is probably the best I've came across, although as far as I know it won't automatically generate based on your relationships.

EDIT: try this in Visio, could give you what you need

How do I get a computer's name and IP address using VB.NET?

Thanks Shuwaiee

I made a slight change though as using it in a Private Sub already.

Dim GetIPAddress()

Dim strHostName As String

Dim strIPAddress As String

strHostName = System.Net.Dns.GetHostName()

strIPAddress = System.Net.Dns.GetHostByName(strHostName).AddressList(0).ToString()

MessageBox.Show("Host Name: " & strHostName & vbCrLf & "IP Address: " & strIPAddress)

But also made a change to the way the details are displayed so that they can show on seperate lines using & vbCrLf &

MessageBox.Show("Host Name: " & strHostName & vbCrLf & "IP Address: " & strIPAddress)

Hope this helps someone.

Show diff between commits

Simplest for checking the changes in the last 2 commits after pull:

git diff HEAD~2 

gcc error: wrong ELF class: ELFCLASS64

sudo apt-get install ia32-libs 

How do I convert a number to a numeric, comma-separated formatted string?

Quick & dirty for int to nnn,nnn...

declare @i int = 123456789
select replace(convert(varchar(128), cast(@i as money), 1), '.00', '')
>> 123,456,789

How to create a windows service from java app

If you use Gradle Build Tool you can try my windows-service-plugin, which facilitates using of Apache Commons Daemon Procrun.

To create a java windows service application with the plugin you need to go through several simple steps.

  1. Create a main service class with the appropriate method.

    public class MyService {
        public static void main(String[] args) {
            String command = "start";
            if (args.length > 0) {
                command = args[0];
            if ("start".equals(command)) {
                // process service start function
            } else {
                // process service stop function
  2. Include the plugin into your build.gradle file.

    buildscript {
      repositories {
        maven {
          url ""
      dependencies {
        classpath ""
    apply plugin: ""

    The same script snippet for new, incubating, plugin mechanism introduced in Gradle 2.1:

    plugins {
      id "" version "1.1.0"
  3. Configure the plugin.

    windowsService {
      architecture = 'amd64'
      displayName = 'TestService'
      description = 'Service generated with using gradle plugin'   
      startClass = 'MyService'
      startMethod = 'main'
      startParams = 'start'
      stopClass = 'MyService'
      stopMethod = 'main'
      stopParams = 'stop'
      startup = 'auto'
  4. Run createWindowsService gradle task to create a windows service distribution.

That's all you need to do to create a simple windows service. The plugin will automatically download Apache Commons Daemon Procrun binaries, extract this binaries to the service distribution directory and create batch files for installation/uninstallation of the service.

In ${project.buildDir}/windows-service directory you will find service executables, batch scripts for installation/uninstallation of the service and all runtime libraries. To install the service run <project-name>-install.bat and if you want to uninstall the service run <project-name>-uninstall.bat. To start and stop the service use <project-name>w.exe executable.

Note that the method handling service start should create and start a separate thread to carry out the processing, and then return. The main method is called from different threads when you start and stop the service.

For more information, please read about the plugin and Apache Commons Daemon Procrun.

Add click event on div tag using javascript

the document class selector:


also the document query selector


How can I combine multiple rows into a comma-delimited list in Oracle?

The WM_CONCAT function (if included in your database, pre Oracle 11.2) or LISTAGG (starting Oracle 11.2) should do the trick nicely. For example, this gets a comma-delimited list of the table names in your schema:

select listagg(table_name, ', ') within group (order by table_name) 
  from user_tables;


select wm_concat(table_name) 
  from user_tables;

More details/options

Link to documentation

Retrieve specific commit from a remote Git repository

You can simply fetch the remote repo with:

git fetch <repo>


  • <repo> can be a remote repo name (e.g. origin) or even a remote repo URL (e.g.

for example:

git fetch 

after you fetched the repos you may merge the commits that you want (since the question is about retrieve one commit, instead merge you may use cherry-pick to pick just one commit):

git merge <commit>
  • <commit> can be the SHA1 commit

for example:

git cherry-pick 0a071603d87e0b89738599c160583a19a6d95545


git merge 0a071603d87e0b89738599c160583a19a6d95545

if is the latest commit that you want to merge, you also may use FETCH_HEAD variable :

git cherry-pick (or merge) FETCH_HEAD

Get ALL User Friends Using Facebook Graph API - Android

In v2.0 of the Graph API, calling /me/friends returns the person's friends who also use the app.

In addition, in v2.0, you must request the user_friends permission from each user. user_friends is no longer included by default in every login. Each user must grant the user_friends permission in order to appear in the response to /me/friends. See the Facebook upgrade guide for more detailed information, or review the summary below.

The /me/friendlists endpoint and user_friendlists permission are not what you're after. This endpoint does not return the users friends - its lets you access the lists a person has made to organize their friends. It does not return the friends in each of these lists. This API and permission is useful to allow you to render a custom privacy selector when giving people the opportunity to publish back to Facebook.

If you want to access a list of non-app-using friends, there are two options:

  1. If you want to let your people tag their friends in stories that they publish to Facebook using your App, you can use the /me/taggable_friends API. Use of this endpoint requires review by Facebook and should only be used for the case where you're rendering a list of friends in order to let the user tag them in a post.

  2. If your App is a Game AND your Game supports Facebook Canvas, you can use the /me/invitable_friends endpoint in order to render a custom invite dialog, then pass the tokens returned by this API to the standard Requests Dialog.

In other cases, apps are no longer able to retrieve the full list of a user's friends (only those friends who have specifically authorized your app using the user_friends permission).

For apps wanting allow people to invite friends to use an app, you can still use the Send Dialog on Web or the new Message Dialog on iOS and Android.

How to launch jQuery Fancybox on page load?

Maybe this will help... this was used in the full size jQuery calendar click event ( but it can be used more generally to deal with fancybox being launched by jQuery.

  eventClick: function(calEvent, jsEvent, view) {
      jQuery("body").after('<a id="link_'+calEvent.url+'" style="display: hidden;" href="">Steve</a>');
    return false;

How to load specific image from assets with Swift

You cannot load images directly with @2x or @3x, system selects appropriate image automatically, just specify the name using UIImage:

UIImage(named: "green-square-Retina")

How to output JavaScript with PHP

You are using " instead of ' It is mixing up php syntax with javascript. PHP is going to print javascript with echo function, but it is taking the js codes as wrong php syntax. so try this,


echo "<script type='text/javascript'>";
echo "document.write('Hello World!')";
echo "</script>";


How to convert String to DOM Document object in java?

Either escape the double quotes with \

String xmlString = "<element attribname=\"value\" attribname1=\"value1\"> pcdata</element>"

or use single quotes instead

String xmlString = "<element attribname='value' attribname1='value1'> pcdata</element>"

Run jar file with command line arguments

For the question

How can i run a jar file in command prompt but with arguments


To pass arguments to the jar file at the time of execution

java -jar myjar.jar arg1 arg2

In the main() method of "Main-Class" [mentioned in the manifest.mft file]of your JAR file. you can retrieve them like this:

String arg1 = args[0];
String arg2 = args[1];

Adding 'serial' to existing column in Postgres

You can also use START WITH to start a sequence from a particular point, although setval accomplishes the same thing, as in Euler's answer, eg,

SELECT MAX(a) + 1 FROM foo;
CREATE SEQUENCE foo_a_seq START WITH 12345; -- replace 12345 with max above
ALTER TABLE foo ALTER COLUMN a SET DEFAULT nextval('foo_a_seq');

Expand Python Search Path to Other Source

There are a few possible ways to do this:

  • Set the environment variable PYTHONPATH to a colon-separated list of directories to search for imported modules.
  • In your program, use sys.path.append('/path/to/search') to add the names of directories you want Python to search for imported modules. sys.path is just the list of directories Python searches every time it gets asked to import a module, and you can alter it as needed (although I wouldn't recommend removing any of the standard directories!). Any directories you put in the environment variable PYTHONPATH will be inserted into sys.path when Python starts up.
  • Use site.addsitedir to add a directory to sys.path. The difference between this and just plain appending is that when you use addsitedir, it also looks for .pth files within that directory and uses them to possibly add additional directories to sys.path based on the contents of the files. See the documentation for more detail.

Which one of these you want to use depends on your situation. Remember that when you distribute your project to other users, they typically install it in such a manner that the Python code files will be automatically detected by Python's importer (i.e. packages are usually installed in the site-packages directory), so if you mess with sys.path in your code, that may be unnecessary and might even have adverse effects when that code runs on another computer. For development, I would venture a guess that setting PYTHONPATH is usually the best way to go.

However, when you're using something that just runs on your own computer (or when you have nonstandard setups, e.g. sometimes in web app frameworks), it's not entirely uncommon to do something like

import sys
from os.path import dirname

How do I upload a file with the JS fetch API?

This is a basic example with comments. The upload function is what you are looking for:

// Select your input type file and store it in a variable
const input = document.getElementById('fileinput');

// This will upload the file after having read it
const upload = (file) => {
  fetch('', { // Your POST endpoint
    method: 'POST',
    headers: {
      // Content-Type may need to be completely **omitted**
      // or you may need something
      "Content-Type": "You will perhaps need to define a content-type here"
    body: file // This is your file object
    response => response.json() // if the response is a JSON object
    success => console.log(success) // Handle the success response object
    error => console.log(error) // Handle the error response object

// Event handler executed when a file is selected
const onSelectFile = () => upload(input.files[0]);

// Add a listener on your input
// It will be triggered when a file will be selected
input.addEventListener('change', onSelectFile, false);

What is PECS (Producer Extends Consumer Super)?

public class Test {

    public class A {}

    public class B extends A {}

    public class C extends B {}

    public void testCoVariance(List<? extends B> myBlist) {
        B b = new B();
        C c = new C();
        myBlist.add(b); // does not compile
        myBlist.add(c); // does not compile
        A a = myBlist.get(0); 

    public void testContraVariance(List<? super B> myBlist) {
        B b = new B();
        C c = new C();
        A a = myBlist.get(0); // does not compile

ImageMagick security policy 'PDF' blocking conversion

On Ubuntu 19.10, I have done this in /etc/ImageMagick-6/policy.xml

uncomment this

<policy domain="module" rights="read | write" pattern="{PS,PDF,XPS}" />

and comment this

<!-- <policy domain="coder" rights="none" pattern="PDF" /> -->

After that, this command work without error

convert -thumbnail x300 -background white -alpha remove sample.pdf sample.png 

What is the difference between require_relative and require in Ruby?

The top answers are correct, but deeply technical. For those newer to Ruby:

  • require_relative will most likely be used to bring in code from another file that you wrote.

for example, what if you have data in ~/my-project/data.rb and you want to include that in ~/my-project/solution.rb? in solution.rb you would add require_relative 'data'.

it is important to note these files do not need to be in the same directory. require_relative '../../folder1/folder2/data' is also valid.

  • require will most likely be used to bring in code from a library someone else wrote.

for example, what if you want to use one of the helper functions provided in the active_support library? you'll need to install the gem with gem install activesupport and then in the file require 'active_support'.

require 'active_support/all'

Said differently--

  • require_relative requires a file specifically pointed to relative to the file that calls it.

  • require requires a file included in the $LOAD_PATH.

Synchronizing a local Git repository with a remote one

git fetch --prune

-p, --prune
After fetching, remove any remote-tracking branches which no longer exist on the remote. prune options

How do I get the current username in .NET using C#?

I went over most of the answers here and none of them gave me the right user name.

In my case I wanted to get the logged in user name, while running my app from a different user, like when shift+right click on a file and "Run as a different user".

The answers I tried gave me the 'other' username.

This blog post supplies a way to get the logged in user name, which works even in my scenario:

It uses Wtsapi

Merge 2 arrays of objects

For those who are experimenting with modern things:

var odd = [
    { name : "1", arr: "in odd" },
    { name : "3", arr: "in odd" }

var even = [
    { name : "1", arr: "in even" },
    { name : "2", arr: "in even" },
    { name : "4", arr: "in even" }

// ----
// ES5 using Array.filter and Array.find
function merge(a, b, prop){
  var reduced = a.filter(function(aitem){
      return ! b.find(function(bitem){
          return aitem[prop] === bitem[prop];
  return reduced.concat(b);
console.log( "ES5", merge(odd, even, "name") );

// ----
// ES6 arrow functions
function merge(a, b, prop){
    var reduced =  a.filter( aitem => ! b.find ( bitem => aitem[prop] === bitem[prop]) )
  return reduced.concat(b);
console.log( "ES6", merge(odd, even, "name") );

// ----
// ES6 one-liner
var merge = (a, b, p) => a.filter( aa => ! b.find ( bb => aa[p] === bb[p]) ).concat(b);

console.log( "ES6 one-liner", merge(odd, even, "name") );

// Results
// ( stuff in the "b" array replaces things in the "a" array )
// [
//    {
//         "name": "3",
//         "arr": "in odd"
//     },
//     {
//         "name": "1",
//         "arr": "in even"
//     },
//     {
//         "name": "2",
//         "arr": "in even"
//     },
//     {
//         "name": "4",
//         "arr": "in even"
//     }
// ]

How to set an HTTP proxy in Python 2.7?

It looks like has been updated to use the environment variables http_proxy and https_proxy.


set http_proxy=
set https_proxy=

Linux/OS X:

export http_proxy=
export https_proxy=
sudo -E python

However if this still doesn't work for you, you can always install pip through a proxy using setuptools' easy_install by setting the same environment variables.


set http_proxy=
set https_proxy=
easy_install pip

Linux/OS X:

export http_proxy=
export https_proxy=
sudo -E easy_install pip

Then once it's installed, use:

pip install --proxy="user:password@server:port" packagename

From the pip man page:

Have pip use a proxy server to access sites. This can be specified using "user:[email protected]:port" notation. If the password is left out, pip will ask for it.

Convert comma separated string to array in PL/SQL

We can never run out of alternatives of doing the same thing differently, right? I recently found this is pretty handy:

   BAR   VARCHAR2 (200) := '1,2,3';
                     FROM DUAL
                             IS NOT NULL)



Static methods in Python?

I think that Steven is actually right. To answer the original question, then, in order to set up a class method, simply assume that the first argument is not going to be a calling instance, and then make sure that you only call the method from the class.

(Note that this answer refers to Python 3.x. In Python 2.x you'll get a TypeError for calling the method on the class itself.)

For example:

class Dog:
    count = 0 # this is a class variable
    dogs = [] # this is a class variable

    def __init__(self, name): = name is an instance variable
        Dog.count += 1

    def bark(self, n): # this is an instance method
        print("{} says: {}".format(, "woof! " * n))

    def rollCall(n): #this is implicitly a class method (see comments below)
        print("There are {} dogs.".format(Dog.count))
        if n >= len(Dog.dogs) or n < 0:
            print("They are:")
            for dog in Dog.dogs:
                print("  {}".format(dog))
            print("The dog indexed at {} is {}.".format(n, Dog.dogs[n]))

fido = Dog("Fido")
rex = Dog("Rex")

In this code, the "rollCall" method assumes that the first argument is not an instance (as it would be if it were called by an instance instead of a class). As long as "rollCall" is called from the class rather than an instance, the code will work fine. If we try to call "rollCall" from an instance, e.g.:


however, it would cause an exception to be raised because it would send two arguments: itself and -1, and "rollCall" is only defined to accept one argument.

Incidentally, rex.rollCall() would send the correct number of arguments, but would also cause an exception to be raised because now n would be representing a Dog instance (i.e., rex) when the function expects n to be numerical.

This is where the decoration comes in: If we precede the "rollCall" method with


then, by explicitly stating that the method is static, we can even call it from an instance. Now,


would work. The insertion of @staticmethod before a method definition, then, stops an instance from sending itself as an argument.

You can verify this by trying the following code with and without the @staticmethod line commented out.

class Dog:
    count = 0 # this is a class variable
    dogs = [] # this is a class variable

    def __init__(self, name): = name is an instance variable
        Dog.count += 1

    def bark(self, n): # this is an instance method
        print("{} says: {}".format(, "woof! " * n))

    def rollCall(n):
        print("There are {} dogs.".format(Dog.count))
        if n >= len(Dog.dogs) or n < 0:
            print("They are:")
            for dog in Dog.dogs:
                print("  {}".format(dog))
            print("The dog indexed at {} is {}.".format(n, Dog.dogs[n]))

fido = Dog("Fido")
rex = Dog("Rex")

How to get today's Date?

If you want midnight (0:00am) for the current date, you can just use the default constructor and zero out the time portions:

Date today = new Date();
today.setHours(0); today.setMinutes(0); today.setSeconds(0);

edit: update with Calendar since those methods are deprecated

Calendar today = Calendar.getInstance();
today.clear(Calendar.HOUR); today.clear(Calendar.MINUTE); today.clear(Calendar.SECOND);
Date todayDate = today.getTime();

how to create inline style with :before and :after

If you really need it inline, for example because you are loading some user-defined colors dynamically, you can always add a <style> element right before your content.

<style>#project-slide-1:before { color: #ff0000; }</style>
<div id="project-slide-1" class="project-slide"> ... </div>

Example use case with PHP and some (wordpress inspired) dummy functions:

<style>#project-slide-<?php the_ID() ?>:before { color: <?php the_field('color') ?>; }</style>
<div id="project-slide-<?php the_ID() ?>" class="project-slide"> ... </div>

Since HTML 5.2 it is valid to place style elements inside the body, although it is still recommend to place style elements in the head.


Link vs compile vs controller

Compile :

This is the phase where Angular actually compiles your directive. This compile function is called just once for each references to the given directive. For example, say you are using the ng-repeat directive. ng-repeat will have to look up the element it is attached to, extract the html fragment that it is attached to and create a template function.

If you have used HandleBars, underscore templates or equivalent, its like compiling their templates to extract out a template function. To this template function you pass data and the return value of that function is the html with the data in the right places.

The compilation phase is that step in Angular which returns the template function. This template function in angular is called the linking function.

Linking phase :

The linking phase is where you attach the data ( $scope ) to the linking function and it should return you the linked html. Since the directive also specifies where this html goes or what it changes, it is already good to go. This is the function where you want to make changes to the linked html, i.e the html that already has the data attached to it. In angular if you write code in the linking function its generally the post-link function (by default). It is kind of a callback that gets called after the linking function has linked the data with the template.

Controller :

The controller is a place where you put in some directive specific logic. This logic can go into the linking function as well, but then you would have to put that logic on the scope to make it "shareable". The problem with that is that you would then be corrupting the scope with your directives stuff which is not really something that is expected. So what is the alternative if two Directives want to talk to each other / co-operate with each other? Ofcourse you could put all that logic into a service and then make both these directives depend on that service but that just brings in one more dependency. The alternative is to provide a Controller for this scope ( usually isolate scope ? ) and then this controller is injected into another directive when that directive "requires" the other one. See tabs and panes on the first page of for an example.

ng-model for `<input type="file"/>` (with directive DEMO)

This is a slightly modified version that lets you specify the name of the attribute in the scope, just as you would do with ng-model, usage:

    <myUpload key="file"></myUpload>


.directive('myUpload', function() {
    return {
        link: function postLink(scope, element, attrs) {
            element.find("input").bind("change", function(changeEvent) {                        
                var reader = new FileReader();
                reader.onload = function(loadEvent) {
                    scope.$apply(function() {
                        scope[attrs.key] =;                                
                if (typeof([0]) === 'object') {

        controller: 'FileUploadCtrl',
                '<span class="btn btn-success fileinput-button">' +
                '<i class="glyphicon glyphicon-plus"></i>' +
                '<span>Replace Image</span>' +
                '<input type="file" accept="image/*" name="files[]" multiple="">' +
        restrict: 'E'


PHP - Extracting a property from an array of objects

The solution depends on the PHP version you are using. At least there are 2 solutions:

First (Newer PHP versions)

As @JosepAlsina said before the best and also shortest solution is to use array_column as following:

$catIds = array_column($objects, 'id');

Notice: For iterating an array containing \stdClasses as used in the question it is only possible with PHP versions >= 7.0. But when using an array containing arrays you can do the same since PHP >= 5.5.

Second (Older PHP versions)

@Greg said in older PHP versions it is possible to do following:

$catIds = array_map(create_function('$o', 'return $o->id;'), $objects);

But beware: In newer PHP versions >= 5.3.0 it is better to use Closures, like followed:

$catIds = array_map(function($o) { return $o->id; }, $objects);

The difference

First solution creates a new function and puts it into your RAM. The garbage collector does not delete the already created and already called function instance out of memory for some reason. And that regardless of the fact, that the created function instance can never be called again, because we have no pointer for it. And the next time when this code is called, the same function will be created again. This behavior slowly fills your memory...

Both examples with memory output to compare them:


while (true)
    $objects = array_map(create_function('$o', 'return $o->id;'), $objects);

    echo memory_get_usage() . "\n";


// the output


while (true)
    $objects = array_map(function($o) { return $o->id; }, $objects);

    echo memory_get_usage() . "\n";


// the output

This may also be discussed here

Memory leak?! Is Garbage Collector doing right when using 'create_function' within 'array_map'?

Laravel: Get Object From Collection By Attribute

I know this question was originally asked before Laravel 5.0 was released, but as of Laravel 5.0, Collections support the where() method for this purpose.

For Laravel 5.0, 5.1, and 5.2, the where() method on the Collection will only do an equals comparison. Also, it does a strict equals comparison (===) by default. To do a loose comparison (==), you can either pass false as the third parameter or use the whereLoose() method.

As of Laravel 5.3, the where() method was expanded to work more like the where() method for the query builder, which accepts an operator as the second parameter. Also like the query builder, the operator will default to an equals comparison if none is supplied. The default comparison was also switched from strict by default to loose by default. So, if you'd like a strict comparison, you can use whereStrict(), or just use === as the operator for where().

Therefore, as of Laravel 5.0, the last code example in the question will work exactly as intended:

$foods = Food::all();
$green_foods = $foods->where('color', 'green'); // This will work.  :)

// This will only work in Laravel 5.3+
$cheap_foods = $foods->where('price', '<', 5);

// Assuming "quantity" is an integer...
// This will not match any records in 5.0, 5.1, 5.2 due to the default strict comparison.
// This will match records just fine in 5.3+ due to the default loose comparison.
$dozen_foods = $foods->where('quantity', '12');

How to make one Observable sequence wait for another to complete before emitting?

If you want to make sure that the order of execution is retained you can use flatMap as the following example

const first = Rx.Observable.of(1).delay(1000).do(i => console.log(i));
const second = Rx.Observable.of(11).delay(500).do(i => console.log(i));
const third = Rx.Observable.of(111).do(i => console.log(i));

  .flatMap(() => second)
  .flatMap(() => third)
  .subscribe(()=> console.log('finished'));

The outcome would be:


Check if string has space in between (or anywhere)

It's also possible to use a regular expression to achieve this when you want to test for any whitespace character and not just a space.

var text = "sossjj ssskkk";
var regex = new Regex(@"\s");
regex.IsMatch(text); // true

Re-enabling window.alert in Chrome

In Chrome Browser go to setting , clear browsing history and then reload the page

Convert a tensor to numpy array in Tensorflow?

To convert back from tensor to numpy array you can simply run .eval() on the transformed tensor.

Visual Studio Code - is there a Compare feature like that plugin for Notepad ++?

In your terminal type:

code --diff file1.txt file2.txt

A tab will open up in VS Code showing the differences in the two files.

Why isn't this code to plot a histogram on a continuous value Pandas column working?


After your comments this actually makes perfect sense why you don't get a histogram of each different value. There are 1.4 million rows, and ten discrete buckets. So apparently each bucket is exactly 10% (to within what you can see in the plot).

A quick rerun of your data:

In [25]: df.hist(column='Trip_distance')

enter image description here

Prints out absolutely fine.

The df.hist function comes with an optional keyword argument bins=10 which buckets the data into discrete bins. With only 10 discrete bins and a more or less homogeneous distribution of hundreds of thousands of rows, you might not be able to see the difference in the ten different bins in your low resolution plot:

In [34]: df.hist(column='Trip_distance', bins=50)

enter image description here

Angular 4 checkbox change value

I am guessing that this is what something you are trying to achieve.

<input type="checkbox" value="a" (click)="click($event)">A
<input type="checkbox" value="b" (click)="click($event)">B


Getting error "No such module" using Xcode, but the framework is there

I found that the Import Paths in the Build Settings was wrong for a custom (MySQL) module. After pointing that to the right direction the message was gone.

Adding Multiple Values in ArrayList at a single index

Use two dimensional array instead. For instance, int values[][] = new int[2][5]; Arrays are faster, when you are not manipulating much.

Loop Through Each HTML Table Column and Get the Data using jQuery

When you create your table, put your td with class = "suma"


   //funcion suma todo

   var sum = 0;
       sum += parseInt($(this).text());                                   

   // funcion suma por check                                           

    $( "input:checkbox").change(function(){

   function suma2Total(){
      var sum2 = 0;
        sum2 += parseInt($(this).text());       

Ejemplo completo

Code Sign error: The identity 'iPhone Developer' doesn't match any valid certificate/private key pair in the default keychain

This usually happens to me when I forget to change the company to match mine.

  1. Select the target under Groups & Files
  2. Click the Get Info button
  3. Choose the Properties tab
  4. Under Identifier, make sure it says com.YOURREALCOMPANYNAME.APPNAME

When you create a new app, it usually says, "com.yourcompany". Change it to whatever you registered with, in my case com.DavidKanarek

PHP convert date format dd/mm/yyyy => yyyy-mm-dd

Try Using DateTime::createFromFormat

$date = DateTime::createFromFormat('d/m/Y', "24/04/2012");
echo $date->format('Y-m-d');




If the date is 5/4/2010 (both D/M/YYYY or DD/MM/YYYY), this below method is used to convert 5/4/2010 to 2010-4-5 (both YYYY-MM-DD or YYYY-M-D) format.

$old_date = explode('/', '5/4/2010'); 
$new_data = $old_date[2].'-'.$old_date[1].'-'.$old_date[0];



Excel: replace part of cell's string value

what you're looking for is SUBSTITUTE:


Will substitute Author for Authoring without messing with everything else

Commit history on remote repository

This is what worked for me:

git fetch --all 
git log production/master

Note that this fetches from ALL remotes, i.e. potentially you "have to clone 2GB worth of objects just to look through the commit logs".