Programs & Examples On #Image segmentation

Segmentation is a basic operation in image processing: its purpose is to group similar pixels into coherent regions = segments.

Golang read request body

Inspecting and mocking request body

When you first read the body, you have to store it so once you're done with it, you can set a new io.ReadCloser as the request body constructed from the original data. So when you advance in the chain, the next handler can read the same body.

One option is to read the whole body using ioutil.ReadAll(), which gives you the body as a byte slice.

You may use bytes.NewBuffer() to obtain an io.Reader from a byte slice.

The last missing piece is to make the io.Reader an io.ReadCloser, because bytes.Buffer does not have a Close() method. For this you may use ioutil.NopCloser() which wraps an io.Reader, and returns an io.ReadCloser, whose added Close() method will be a no-op (does nothing).

Note that you may even modify the contents of the byte slice you use to create the "new" body. You have full control over it.

Care must be taken though, as there might be other HTTP fields like content-length and checksums which may become invalid if you modify only the data. If subsequent handlers check those, you would also need to modify those too!

Inspecting / modifying response body

If you also want to read the response body, then you have to wrap the http.ResponseWriter you get, and pass the wrapper on the chain. This wrapper may cache the data sent out, which you can inspect either after, on on-the-fly (as the subsequent handlers write to it).

Here's a simple ResponseWriter wrapper, which just caches the data, so it'll be available after the subsequent handler returns:

type MyResponseWriter struct {
    buf *bytes.Buffer

func (mrw *MyResponseWriter) Write(p []byte) (int, error) {
    return mrw.buf.Write(p)

Note that MyResponseWriter.Write() just writes the data to a buffer. You may also choose to inspect it on-the-fly (in the Write() method) and write the data immediately to the wrapped / embedded ResponseWriter. You may even modify the data. You have full control.

Care must be taken again though, as the subsequent handlers may also send HTTP response headers related to the response data –such as length or checksums– which may also become invalid if you alter the response data.

Full example

Putting the pieces together, here's a full working example:

func loginmw(handler http.Handler) http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        body, err := ioutil.ReadAll(r.Body)
        if err != nil {
            log.Printf("Error reading body: %v", err)
            http.Error(w, "can't read body", http.StatusBadRequest)

        // Work / inspect body. You may even modify it!

        // And now set a new body, which will simulate the same data we read:
        r.Body = ioutil.NopCloser(bytes.NewBuffer(body))

        // Create a response wrapper:
        mrw := &MyResponseWriter{
            ResponseWriter: w,
            buf:            &bytes.Buffer{},

        // Call next handler, passing the response wrapper:
        handler.ServeHTTP(mrw, r)

        // Now inspect response, and finally send it out:
        // (You can also modify it before sending it out!)
        if _, err := io.Copy(w, mrw.buf); err != nil {
            log.Printf("Failed to send out response: %v", err)

Filter element based on .data() key/value

Two things I noticed (they may be mistakes from when you wrote it down though).

  1. You missed a dot in the first example ( $('.navlink').click )
  2. For filter to work, you have to return a value ( return $(this).data("selected")==true )

YYYY-MM-DD format date in shell script

You're looking for ISO 8601 standard date format, so if you have GNU date (or any date command more modern than 1988) just do: $(date -I)

How can I open a .db file generated by eclipse(android) form DDMS-->File explorer-->data--->data-->packagename-->database?

Depending on your platform you can use: sqlite3 file_name.db from the terminal. .tables will list the tables, .schema is full layout. SQLite commands like: select * from table_name; and such will print out the full contents. Type: ".exit" to exit. No need to download a GUI application.Use a semi-colon if you want it to execute a single command. Decent SQLite usage tutorial

How to get absolute value from double - c-language

I have found that using cabs(double), cabsf(float), cabsl(long double), __cabsf(float), __cabs(double), __cabsf(long double) is the solution

how to load url into div tag

Try the load() function.


Please not that for this to work, the URL to be loaded must either be on the same domain as the page that's calling it, or enable cross-origin HTTP requests ("Cross-Origin Resource Sharing", short CORS) on the server. This involves sending an additional HTTP header, in its most basic form:


to allow requests from everywhere.

C# Base64 String to JPEG Image

So with the code you have provided.

var bytes = Convert.FromBase64String(resizeImage.Content);
using (var imageFile = new FileStream(filePath, FileMode.Create))
    imageFile.Write(bytes ,0, bytes.Length);

Date constructor returns NaN in IE, but works in Firefox and Chrome

You can use the following code to parse ISO8601 date string:

function parseISO8601(d) {
    var timestamp = d;
    if (typeof (d) !== 'number') {
        timestamp = Date.parse(d);
    return new Date(timestamp);

What does it mean by command cd /d %~dp0 in Windows

Let's dissect it. There are three parts:

  1. cd -- This is change directory command.
  2. /d -- This switch makes cd change both drive and directory at once. Without it you would have to do cd %~d0 & cd %~p0. (%~d0 Changs active drive, cd %~p0 change the directory).
  3. %~dp0 -- This can be dissected further into three parts:
    1. %0 -- This represents zeroth parameter of your batch script. It expands into the name of the batch file itself.
    2. %~0 -- The ~ there strips double quotes (") around the expanded argument.
    3. %dp0 -- The d and p there are modifiers of the expansion. The d forces addition of a drive letter and the p adds full path.

Check whether a path is valid in Python without creating a file at the path's target

open(filename,'r')   #2nd argument is r and not w

will open the file or give an error if it doesn't exist. If there's an error, then you can try to write to the path, if you can't then you get a second error

    return True
except IOError:
        open(filename, 'w')
        return True
    except IOError:
        return False

Also have a look here about permissions on windows

Expand div to max width when float:left is set

Solution without fixing size on your margin

.content .right{
    overflow: auto; 
    background-color: red;

+1 for Merkuro, but if the size of the float changes your fixed margin will fail. If u use above CSS on the right div it will nicely change size with changing size on the left float. It is a bit more flexible like that. Check the fiddle here:

Why does corrcoef return a matrix?

corrcoef returns the normalised covariance matrix.

The covariance matrix is the matrix

Cov( X, X )    Cov( X, Y )

Cov( Y, X )    Cov( Y, Y )

Normalised, this will yield the matrix:

Corr( X, X )    Corr( X, Y )

Corr( Y, X )    Corr( Y, Y )

correlation1[0, 0 ] is the correlation between Strategy1Returns and itself, which must be 1. You just want correlation1[ 0, 1 ].

How to add a touch event to a UIView?

In iOS 3.2 and higher, you can use gesture recognizers. For example, this is how you would handle a tap event:

//The setup code (in viewDidLoad in your view controller)
UITapGestureRecognizer *singleFingerTap = 
  [[UITapGestureRecognizer alloc] initWithTarget:self 
[self.view addGestureRecognizer:singleFingerTap];

//The event handling method
- (void)handleSingleTap:(UITapGestureRecognizer *)recognizer
  CGPoint location = [recognizer locationInView:[recognizer.view superview]];

  //Do stuff here...

There are a bunch of built in gestures as well. Check out the docs for iOS event handling and UIGestureRecognizer. I also have a bunch of sample code up on github that might help.

How to forcefully set IE's Compatibility Mode off from the server-side?

Update: More useful information What does <meta http-equiv="X-UA-Compatible" content="IE=edge"> do?

Maybe this url can help you: Activating Browser Modes with Doctype

Edit: Today we were able to override the compatibility view with: <meta http-equiv="X-UA-Compatible" content="IE=EmulateIE8" />

PHP page redirect

Yes, you would use the header function.

/* Redirect browser */

It is a good practice to call exit() right after it so that code below it does not get executed.

Also, from the documentation:

Remember that header() must be called before any actual output is sent, either by normal HTML tags, blank lines in a file, or from PHP. It is a very common error to read code with include(), or require(), functions, or another file access function, and have spaces or empty lines that are output before header() is called. The same problem exists when using a single PHP/HTML file.

This means you should not echo anything right before the header() function, as doing so will more than likely throw an error. Also, you will need to verify that this code gets run before any other output as well.

Printf long long int in C with GCC?

If you are on windows and using mingw, gcc uses the win32 runtime, where printf needs %I64d for a 64 bit integer. (and %I64u for an unsinged 64 bit integer)

For most other platforms you'd use %lld for printing a long long. (and %llu if it's unsigned). This is standarized in C99.

gcc doesn't come with a full C runtime, it defers to the platform it's running on - so the general case is that you need to consult the documentation for your particular platform - independent of gcc.

How to make php display \t \n as tab and new line instead of characters

Put it in double quotes:

echo "\t";

Single quotes do not expand escaped characters.

Use the documentation when in doubt.

PHP validation/regex for URL

Use the filter_var() function to validate whether a string is URL or not:

var_dump(filter_var('', FILTER_VALIDATE_URL));

It is bad practice to use regular expressions when not necessary.

EDIT: Be careful, this solution is not unicode-safe and not XSS-safe. If you need a complex validation, maybe it's better to look somewhere else.

Get webpage contents with Python?

If you ask me. try this one

import urllib2
resp = urllib2.urlopen('')

and read the normal way ie

page =

Good luck though

How to call two methods on button's onclick method in HTML or JavaScript?


You can also do as like below... In this way, your both functions should call and if both functions return true then it will return true else return false.

<input type="button" 
     onclick="var valFunc1 = func1(); var valFunc2 = func2(); if(valFunc1 == true && valFunc2 ==true) {return true;} else{return false;}" 
     value="Call2Functions" />

Thank you, Vishal Patel

how to change php version in htaccess in server

To switch to PHP 4.4:

AddHandler application/x-httpd-php4 .php

To switch to PHP 5.0:

AddHandler application/x-httpd-php5 .php

To switch to PHP 5.1:

AddHandler application/x-httpd-php51 .php

To switch to PHP 5.2:

AddHandler application/x-httpd-php52 .php

To switch to PHP 5.3:

AddHandler application/x-httpd-php53 .php

To switch to PHP 5.4:

AddHandler application/x-httpd-php54 .php

To switch to PHP 5.5:

AddHandler application/x-httpd-php55 .php

To switch to PHP 5.6:

AddHandler application/x-httpd-php56 .php

To switch to PHP 7:

AddHandler application/x-httpd-php7 .php

To switch to PHP 7.1:

AddHandler application/x-httpd-php71 .php

Plot size and resolution with R markdown, knitr, pandoc, beamer

Figure sizes are specified in inches and can be included as a global option of the document output format. For example:

title: "My Document"
    fig_width: 6
    fig_height: 4

And the plot's size in the graphic device can be increased at the chunk level:

```{r, fig.width=14, fig.height=12}          #Expand the plot width to 14 inches

ggplot(aes(x=mycolumn1, y=mycolumn2)) +     #specify the x and y aesthetic
geom_line(size=2) +                         #makes the line thicker
theme_grey(base_size = 25)                  #increases the size of the font

You can also use the out.width and out.height arguments to directly define the size of the plot in the output file:

```{r, out.width="200px", out.height="200px"} #Expand the plot width to 200 pixels

ggplot(aes(x=mycolumn1, y=mycolumn2)) +     #specify the x and y aesthetic
geom_line(size=2) +                         #makes the line thicker
theme_grey(base_size = 25)                  #increases the size of the font

How to remove tab indent from several lines in IDLE?

If you're using IDLE, and the Norwegian keyboard makes Ctrl-[ a problem, you can change the key.

  1. Go Options->Configure IDLE.
  2. Click the Keys tab.
  3. If necessary, click Save as New Custom Key Set.
  4. With your custom key set, find "dedent-region" in the list.
  5. Click Get New Keys for Selection.
  6. etc

I tried putting in shift-Tab and that worked nicely.

How to create a table from select query result in SQL Server 2008

Select [Column Name] into [New Table] from [Source Table]

Store List to session

Yes, you can store any object (I assume you are using ASP.NET with default settings, which is in-process session state):

Session["test"] = myList;

You should cast it back to the original type for use:

var list = (List<int>)Session["test"];
// list.Add(something);

As Richard points out, you should take extra care if you are using other session state modes (e.g. SQL Server) that require objects to be serializable.

DataTables: Uncaught TypeError: Cannot read property 'defaults' of undefined

The problem is that dataTable is not defined at the point you are calling this method.

Ensure that you are loading the .js files in the correct order:

<script src="/Scripts/jquery.dataTables.js"></script>
<script src="/Scripts/dataTables.bootstrap.js"></script>

What is the difference between json.load() and json.loads() functions

Yes, s stands for string. The json.loads function does not take the file path, but the file contents as a string. Look at the documentation at!

I can't access http://localhost/phpmyadmin/

I had the same problem. Couldn't access http://localhost/joomla neither.
and I did not quite understand the other answers.
The simple solution for me:

  1. stop all actions in xampp (I had apache and mysql running. apache on port 80 and 7000something)
  2. quit firefox
  3. restart the actions (apache and mysql)
  4. restart firefox.
  5. open http://localhost/phpmyadmin (or http://localhost/joomla - whatever it be)
  6. voila!

Now apache runs on port 80 and 443 and mysql on 3306.

How to add LocalDB to Visual Studio 2015 Community's SQL Server Object Explorer?

My App.config looks as below:
<?xml version="1.0" encoding="utf-8"?>
    <!-- For more information on Entity Framework configuration, visit -->
    <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">
        <parameter value="v11.0" />
      <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />

I noticed that there is localDB in the path that you mentioned above and has the version v11.0. So I entered (LocalDB\V11.0) in Add Connection dialogue and it worked for me.

How do I add a new column to a Spark DataFrame (using PySpark)?

To add a column using a UDF:

df = sqlContext.createDataFrame(
    [(1, "a", 23.0), (3, "B", -23.0)], ("x1", "x2", "x3"))

from pyspark.sql.functions import udf
from pyspark.sql.types import *

def valueToCategory(value):
   if   value == 1: return 'cat1'
   elif value == 2: return 'cat2'
   else: return 'n/a'

# NOTE: it seems that calls to udf() must be after SparkContext() is called
udfValueToCategory = udf(valueToCategory, StringType())
df_with_cat = df.withColumn("category", udfValueToCategory("x1"))

## +---+---+-----+---------+
## | x1| x2|   x3| category|
## +---+---+-----+---------+
## |  1|  a| 23.0|     cat1|
## |  3|  B|-23.0|      n/a|
## +---+---+-----+---------+

How to uninstall Apache with command line

I've had this sort of problem.....

The solve: cmd / powershell run as ADMINISTRATOR! I always forget.

Notice: In powershell, you need to put .\ for example:

.\httpd -k shutdown .\httpd -k stop .\httpd -k uninstall

Result: Removing the apache2.4 service The Apache2.4 service has been removed successfully.

Android + Pair devices via bluetooth programmatically

if you have the BluetoothDevice object you can create bond(pair) from api 19 onwards with bluetoothDevice.createBond() method.


for callback, if the request was accepted or denied you will have to create a BroadcastReceiver with BluetoothDevice.ACTION_BOND_STATE_CHANGED action

How do I execute a file in Cygwin?

you should just be able to call it by typing in the file name. You may have to call ./a.exe as the current directory is usually not on the path for security reasons.

How can I get the client's IP address in ASP.NET MVC?

A lot of the code here was very helpful, but I cleaned it up for my purposes and added some tests. Here's what I ended up with:

using System;
using System.Linq;
using System.Net;
using System.Web;

public class RequestHelpers
    public static string GetClientIpAddress(HttpRequestBase request)
            var userHostAddress = request.UserHostAddress;

            // Attempt to parse.  If it fails, we catch below and return ""
            // Could use TryParse instead, but I wanted to catch all exceptions

            var xForwardedFor = request.ServerVariables["X_FORWARDED_FOR"];

            if (string.IsNullOrEmpty(xForwardedFor))
                return userHostAddress;

            // Get a list of public ip addresses in the X_FORWARDED_FOR variable
            var publicForwardingIps = xForwardedFor.Split(',').Where(ip => !IsPrivateIpAddress(ip)).ToList();

            // If we found any, return the last one, otherwise return the user host address
            return publicForwardingIps.Any() ? publicForwardingIps.Last() : userHostAddress;
        catch (Exception)
            // Always return all zeroes for any failure (my calling code expects it)
            return "";

    private static bool IsPrivateIpAddress(string ipAddress)
        // Private IP Addresses are: 
        //  24-bit block: through
        //  20-bit block: through
        //  16-bit block: through
        //  Link-local addresses: through (

        var ip = IPAddress.Parse(ipAddress);
        var octets = ip.GetAddressBytes();

        var is24BitBlock = octets[0] == 10;
        if (is24BitBlock) return true; // Return to prevent further processing

        var is20BitBlock = octets[0] == 172 && octets[1] >= 16 && octets[1] <= 31;
        if (is20BitBlock) return true; // Return to prevent further processing

        var is16BitBlock = octets[0] == 192 && octets[1] == 168;
        if (is16BitBlock) return true; // Return to prevent further processing

        var isLinkLocalAddress = octets[0] == 169 && octets[1] == 254;
        return isLinkLocalAddress;

And here are some NUnit tests against that code (I'm using Rhino Mocks to mock the HttpRequestBase, which is the M<HttpRequestBase> call below):

using System.Web;
using NUnit.Framework;
using Rhino.Mocks;
using Should;

public class HelpersTests : TestBase
    HttpRequestBase _httpRequest;

    private const string XForwardedFor = "X_FORWARDED_FOR";
    private const string MalformedIpAddress = "MALFORMED";
    private const string DefaultIpAddress = "";
    private const string GoogleIpAddress = "";
    private const string MicrosoftIpAddress = "";
    private const string Private24Bit = "";
    private const string Private20Bit = "";
    private const string Private16Bit = "";
    private const string PrivateLinkLocal = "";

    public void Setup()
        _httpRequest = M<HttpRequestBase>();

    public void Teardown()
        _httpRequest = null;

    public void PublicIpAndNullXForwardedFor_Returns_CorrectIp()
        // Arrange
        _httpRequest.Stub(x => x.UserHostAddress).Return(GoogleIpAddress);
        _httpRequest.Stub(x => x.ServerVariables[XForwardedFor]).Return(null);

        // Act
        var ip = RequestHelpers.GetClientIpAddress(_httpRequest);

        // Assert

    public void PublicIpAndEmptyXForwardedFor_Returns_CorrectIp()
        // Arrange
        _httpRequest.Stub(x => x.UserHostAddress).Return(GoogleIpAddress);
        _httpRequest.Stub(x => x.ServerVariables[XForwardedFor]).Return(string.Empty);

        // Act
        var ip = RequestHelpers.GetClientIpAddress(_httpRequest);

        // Assert

    public void MalformedUserHostAddress_Returns_DefaultIpAddress()
        // Arrange
        _httpRequest.Stub(x => x.UserHostAddress).Return(MalformedIpAddress);
        _httpRequest.Stub(x => x.ServerVariables[XForwardedFor]).Return(null);

        // Act
        var ip = RequestHelpers.GetClientIpAddress(_httpRequest);

        // Assert

    public void MalformedXForwardedFor_Returns_DefaultIpAddress()
        // Arrange
        _httpRequest.Stub(x => x.UserHostAddress).Return(GoogleIpAddress);
        _httpRequest.Stub(x => x.ServerVariables[XForwardedFor]).Return(MalformedIpAddress);

        // Act
        var ip = RequestHelpers.GetClientIpAddress(_httpRequest);

        // Assert

    public void SingleValidPublicXForwardedFor_Returns_XForwardedFor()
        // Arrange
        _httpRequest.Stub(x => x.UserHostAddress).Return(GoogleIpAddress);
        _httpRequest.Stub(x => x.ServerVariables[XForwardedFor]).Return(MicrosoftIpAddress);

        // Act
        var ip = RequestHelpers.GetClientIpAddress(_httpRequest);

        // Assert

    public void MultipleValidPublicXForwardedFor_Returns_LastXForwardedFor()
        // Arrange
        _httpRequest.Stub(x => x.UserHostAddress).Return(GoogleIpAddress);
        _httpRequest.Stub(x => x.ServerVariables[XForwardedFor]).Return(GoogleIpAddress + "," + MicrosoftIpAddress);

        // Act
        var ip = RequestHelpers.GetClientIpAddress(_httpRequest);

        // Assert

    public void SinglePrivateXForwardedFor_Returns_UserHostAddress()
        // Arrange
        _httpRequest.Stub(x => x.UserHostAddress).Return(GoogleIpAddress);
        _httpRequest.Stub(x => x.ServerVariables[XForwardedFor]).Return(Private24Bit);

        // Act
        var ip = RequestHelpers.GetClientIpAddress(_httpRequest);

        // Assert

    public void MultiplePrivateXForwardedFor_Returns_UserHostAddress()
        // Arrange
        _httpRequest.Stub(x => x.UserHostAddress).Return(GoogleIpAddress);
        const string privateIpList = Private24Bit + "," + Private20Bit + "," + Private16Bit + "," + PrivateLinkLocal;
        _httpRequest.Stub(x => x.ServerVariables[XForwardedFor]).Return(privateIpList);

        // Act
        var ip = RequestHelpers.GetClientIpAddress(_httpRequest);

        // Assert

    public void MultiplePublicXForwardedForWithPrivateLast_Returns_LastPublic()
        // Arrange
        _httpRequest.Stub(x => x.UserHostAddress).Return(GoogleIpAddress);
        const string privateIpList = Private24Bit + "," + Private20Bit + "," + MicrosoftIpAddress + "," + PrivateLinkLocal;
        _httpRequest.Stub(x => x.ServerVariables[XForwardedFor]).Return(privateIpList);

        // Act
        var ip = RequestHelpers.GetClientIpAddress(_httpRequest);

        // Assert

get current url in twig template?

{{ path(app.request.attributes.get('_route'),
     app.request.attributes.get('_route_params')) }}

If you want to read it into a view variable:

{% set currentPath = path(app.request.attributes.get('_route'),
                       app.request.attributes.get('_route_params')) %}

The app global view variable contains all sorts of useful shortcuts, such as app.session and, that reference the services you might use in a controller.

jQuery if div contains this text, replace that part of the text

You can use the contains selector to search for elements containing a specific text

var elem = $('div.text_div:contains("This div contains some text")')?;
elem.text(elem.text().replace("contains", "Hello everyone"));


Is there a typical state machine implementation pattern?

For a simple state machine just use a switch statement and an enum type for your state. Do your transitions inside the switch statement based on your input. In a real program you would obviously change the "if(input)" to check for your transition points. Hope this helps.

typedef enum
    STATE_1 = 0,
} my_state_t;

my_state_t state = STATE_1;

void foo(char input)
        case STATE_1:
                state = STATE_2;
        case STATE_2:
                state = STATE_3;
                state = STATE_1;
        case STATE_3:

How to redirect output to a file and stdout

tee is perfect for this, but this will also do the job

ls -lr / > output | cat output

Running AngularJS initialization code when view is loaded

Since AngularJS 1.5 we should use $onInit which is available on any AngularJS component. Taken from the component lifecycle documentation since v1.5 its the preffered way:

$onInit() - Called on each controller after all the controllers on an element have been constructed and had their bindings initialized (and before the pre & post linking functions for the directives on this element). This is a good place to put initialization code for your controller.

var myApp = angular.module('myApp',[]);
myApp.controller('MyCtrl', function ($scope) {

    //default state
    $ = '';

    //all your init controller goodness in here
    this.$onInit = function () {
      $ = 'Superhero';

>> Fiddle Demo

An advanced example of using component lifecycle:

The component lifecycle gives us the ability to handle component stuff in a good way. It allows us to create events for e.g. "init", "change" or "destroy" of an component. In that way we are able to manage stuff which is depending on the lifecycle of an component. This little example shows to register & unregister an $rootScope event listener $on. By knowing, that an event $on binded on $rootScope will not be undinded when the controller loses its reference in the view or getting destroyed we need to destroy a $rootScope.$on listener manually. A good place to put that stuff is $onDestroy lifecycle function of an component:

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

myApp.controller('MyCtrl', function ($scope, $rootScope) {

  var registerScope = null;

  this.$onInit = function () {
    //register rootScope event
    registerScope = $rootScope.$on('someEvent', function(event) {

  this.$onDestroy = function () {
    //unregister rootScope event by calling the return function

>> Fiddle demo

Regular expression to validate US phone numbers?

The easiest way to match both




is to use alternation ((...|...)): specify them as two mostly-separate options:


By the way, when Americans put the area code in parentheses, we actually put a space after that; for example, I'd write (123) 123-1234, not (123)123-1234. So you might want to write:

^(\([0-9]{3}\) |[0-9]{3}-)[0-9]{3}-[0-9]{4}$

(Though it's probably best to explicitly demonstrate the format that you expect phone numbers to be in.)

How do I enable TODO/FIXME/XXX task tags in Eclipse?

I'm using Eclipse Classic 3.7.1.

The solution is: Window > Preferences > General > Editors > Sctructured Text Editors > Task Tags and checking "Enable searching for Task Tags" checkbox.

Jquery click event not working after append method

** Problem Solved ** enter image description here // Changed to delegate() method to use delegation from the body

$("body").delegate("#boundOnPageLoaded", "click", function(){
   alert("Delegated Button Clicked")

How to have css3 animation to loop forever

Whilst Elad's solution will work, you can also do it inline:

   -moz-animation: fadeinphoto 7s 20s infinite;
-webkit-animation: fadeinphoto 7s 20s infinite;
     -o-animation: fadeinphoto 7s 20s infinite;
        animation: fadeinphoto 7s 20s infinite;

In Perl, how can I concisely check if a $variable is defined and contains a non zero length string?

The excellent library Type::Tiny provides an framework with which to build type-checking into your Perl code. What I show here is only the thinnest tip of the iceberg and is using Type::Tiny in the most simplistic and manual way.

Be sure to check out the Type::Tiny::Manual for more information.

use Types::Common::String qw< NonEmptyStr >;

if ( NonEmptyStr->check($name) ) {
    # Do something here.

NonEmptyStr->($name);  # Throw an exception if validation fails

SQL DELETE with JOIN another table for WHERE condition

I think, from your description, the following would suffice:

DELETE FROM guide_category 
WHERE id_guide NOT IN (SELECT id_guide FROM guide)

I assume, that there are no referential integrity constraints on the tables involved, are there?

Chrome dev tools fails to show response even the content returned has header Content-Type:text/html; charset=UTF-8

As described by Gideon, this is a known issue.
For use window.onunload = function() { debugger; } instead.
But you can add a breakpoint in Source tab, then can solve your problem. like this: enter image description here

virtualenvwrapper and Python 3

virtualenvwrapper now lets you specify the python executable without the path.

So (on OSX at least)mkvirtualenv --python=python3 nameOfEnvironment will suffice.

How to convert empty spaces into null values, using SQL Server?

A case statement should do the trick when selecting from your source table:

  WHEN col1 = ' ' THEN NULL
  ELSE col1
END col1

Also, one thing to note is that your LTRIM and RTRIM reduce the value from a space (' ') to blank (''). If you need to remove white space, then the case statement should be modified appropriately:

END col1

Converting a String to a List of Words?

Try this:

import re

mystr = 'This is a string, with words!'
wordList = re.sub("[^\w]", " ",  mystr).split()

How it works:

From the docs :

re.sub(pattern, repl, string, count=0, flags=0)

Return the string obtained by replacing the leftmost non-overlapping occurrences of pattern in string by the replacement repl. If the pattern isn’t found, string is returned unchanged. repl can be a string or a function.

so in our case :

pattern is any non-alphanumeric character.

[\w] means any alphanumeric character and is equal to the character set [a-zA-Z0-9_]

a to z, A to Z , 0 to 9 and underscore.

so we match any non-alphanumeric character and replace it with a space .

and then we split() it which splits string by space and converts it to a list

so 'hello-world'

becomes 'hello world'

with re.sub

and then ['hello' , 'world']

after split()

let me know if any doubts come up.

Do I commit the package-lock.json file created by npm 5?

I don't commit this file in my projects. What's the point ?

  1. It's generated
  2. It's the cause of a SHA1 code integrity err in gitlab with gitlab-ci.yml builds

Though it's true that I never use ^ in my package.json for libs because I had bad experiences with it.

SQL Server 2005 How Create a Unique Constraint?

ALTER TABLE [TableName] ADD CONSTRAINT  [constraintName] UNIQUE ([columns])

Adding a SVN repository in Eclipse

Do you have any working repositories in this instance of eclipse?

I've had problems in the past with the default Subclipse subversion client on Windows, you need to make sure the native subversion client is installed and correctly configured (I've got TortoiseSVN to work in the past) if you want to use the default client adapter.

On a recent install I tried the "beta" drivers (I have Eclipse Ganymede and "SVNKit (Pure Java) SVNKit v1.2.0.4502") that you can optionally install with Subclipse and they worked pretty much straight out of the box, although a colleague found he had to go through a few hoops to make sure Eclipse installed them (and their dependancies) correctly.

Here are the packages that appear in "Help" -> "Software Updates" -> "Installed Software":

Subclipse                  1.4.0
Subversion Client Adapter
SVNKit Client Adapter
SVNKit Library   

These are probably a little out of date now, and the latest version will probably work better, but this is what I can see working right now.

WebView showing ERR_CLEARTEXT_NOT_PERMITTED although site is HTTPS


Add the below line in your application tag:


As shown below:


UPDATE: If you have network security config such as: android:networkSecurityConfig="@xml/network_security_config"

No Need to set clear text traffic to true as shown above, instead use the below code:

<?xml version="1.0" encoding="utf-8"?>
    <domain-config cleartextTrafficPermitted="true">

    <base-config cleartextTrafficPermitted="false"/>

Set the cleartextTrafficPermitted to true

Hope it helps.

How do I get the base URL with PHP?

Here's one I just put together that works for me. It will return an array with 2 elements. The first element is everything before the ? and the second is an array containing all of the query string variables in an associative array.

function disectURL()
    $arr = array();
    $a = explode('?',sprintf(
        isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] != 'off' ? 'https' : 'http',

    $arr['base_url']     = $a[0];
    $arr['query_string'] = [];

    if(sizeof($a) == 2)
        $b = explode('&', $a[1]);
        $qs = array();

        foreach ($b as $c)
            $d = explode('=', $c);
            $qs[$d[0]] = $d[1];
        $arr['query_string'] = (count($qs)) ? $qs : '';

    return $arr;


Note: This is an expansion of the answer provided by macek above. (Credit where credit is due.)

How do I set a background-color for the width of text, not the width of the entire element, using CSS?

Option 1

display: table;

  • no parent required

h1 {_x000D_
    display: table; /* keep the background color wrapped tight */_x000D_
    margin: 0px auto 0px auto; /* keep the table centered */_x000D_
<h1>The Last Will and Testament of Eric Jones</h1>



display: table tells the element to behave as a normal HTML table would.

More about it at w3schools, CSS Tricks and here

Option 2

display: inline-flex;

  • requires text-align: center; on parent

.container {_x000D_
    text-align: center; /* center the child */_x000D_
h1 {_x000D_
    display: inline-flex; /* keep the background color wrapped tight */_x000D_
<div class="container">_x000D_
  <h1>The Last Will and Testament of Eric Jones</h1>_x000D_

Option 3

display: flex;

  • requires a flex parent container

.container {_x000D_
  display: flex;_x000D_
  justify-content: center; /* center the child */_x000D_
h1 {_x000D_
    display: flex;_x000D_
    /* margin: 0 auto; or use auto left/right margin instead of justify-content center */_x000D_
    <div class="container">_x000D_
      <h1>The Last Will and Testament of Eric Jones</h1>_x000D_


Probably the most popular guide to Flexbox and one I reference constantly is at CSS Tricks

Option 4

display: block;

  • requires a flex parent container

.container {_x000D_
  display: flex;_x000D_
  justify-content: center; /* centers child */_x000D_
h1 {_x000D_
    display: block;_x000D_
<div class="container">_x000D_
  <h1>The Last Will and Testament of Eric Jones</h1>_x000D_

Option 5


  • requires entering words in css file (not very practical)

h1 {_x000D_
    display: flex; /* set a flex box */_x000D_
    justify-content: center; /* so you can center the content like this */_x000D_
h1::before {_x000D_
    content:'The Last Will and Testament of Eric Jones'; /* the content */_x000D_
    padding: 5px;font-size: 20px;background-color: green;color: #ffffff;_x000D_



More about css pseudo elements ::before and ::after at CSS Tricks and pseudo elements in general at w3schools

Option 6

display: inline-block;

  • centering with position: absolute and translateX

  • requires a position: relative parent

.container {_x000D_
  position: relative; /* required for absolute positioned child */_x000D_
h1 {_x000D_
  display: inline-block; /* keeps container wrapped tight to content */_x000D_
  position: absolute; /* to absolutely position element */_x000D_
  top: 0;_x000D_
  left: 50%; /* part1 of centering with translateX/Y */_x000D_
  transform: translateX(-50%); /* part2 of centering with translateX/Y */_x000D_
  white-space: nowrap; /* text lines will collapse without this */_x000D_
  <h1>The Last Will and Testament of Eric Jones</h1>


More on centering with transform: translate(); (and centering in general) in this CSS tricks article

Option 7

text-shadow: and box-shadow:

  • not what the OP was looking for but maybe helpful to others finding their way here.

h1, h2, h3, h4, h5 {display: table;margin: 10px auto;padding: 5px;font-size: 20px;color: #ffffff;overflow:hidden;}_x000D_
h1 {_x000D_
    text-shadow: 0 0 5px green,0 0 5px green,_x000D_
                 0 0 5px green,0 0 5px green,_x000D_
                 0 0 5px green,0 0 5px green,_x000D_
                 0 0 5px green,0 0 5px green;_x000D_
h2 {_x000D_
    text-shadow: -5px -5px 5px green,-5px 5px 5px green,_x000D_
                  5px -5px 5px green,5px 5px 5px green;_x000D_
h3 {_x000D_
    color: hsla(0, 0%, 100%, 0.8);_x000D_
    text-shadow: 0 0 10px hsla(120, 100%, 25%, 0.5),_x000D_
                 0 0 10px hsla(120, 100%, 25%, 0.5),_x000D_
                 0 0 10px hsla(120, 100%, 25%, 0.5),_x000D_
                 0 0 5px hsla(120, 100%, 25%, 1),_x000D_
                 0 0 5px hsla(120, 100%, 25%, 1),_x000D_
                 0 0 5px hsla(120, 100%, 25%, 1);_x000D_
h4 { /* overflow:hidden is the key to this one */_x000D_
    text-shadow: 0px 0px 35px green,0px 0px 35px green,_x000D_
                 0px 0px 35px green,0px 0px 35px green;_x000D_
h5 { /* set the spread value to something larger than you'll need to use as I don't believe percentage values are accepted */_x000D_
  box-shadow: inset 0px 0px 0px 1000px green;_x000D_
<h1>The First Will and Testament of Eric Jones</h1>_x000D_
<h2>The 2nd Will and Testament of Eric Jones</h2>_x000D_
<h3>The 3rd Will and Testament of Eric Jones</h3>_x000D_
<h4>The Last Will and Testament of Eric Jones</h4>_x000D_
<h5>The Last Box and Shadow of Eric Jones</h5>


More Options

There are a few other ways to go about this by combining the different display options and centering methods above.

How can I convert an Integer to localized month name in Java?

Apparently in Android 2.2 there is a bug with SimpleDateFormat.

In order to use month names you have to define them yourself in your resources:

<string-array name="month_names">

And then use them in your code like this:

 * Get the month name of a Date. e.g. January for the Date 2011-01-01
 * @param date
 * @return e.g. "January"
public static String getMonthName(Context context, Date date) {

     * Android 2.2 has a bug in SimpleDateFormat. Can't use "MMMM" for
     * getting the Month name for the given Locale. Thus relying on own
     * values from string resources

    String result = "";

    Calendar cal = Calendar.getInstance();
    int month = cal.get(Calendar.MONTH);

    try {
        result = context.getResources().getStringArray(R.array.month_names)[month];
    } catch (ArrayIndexOutOfBoundsException e) {
        result = Integer.toString(month);

    return result;

How to enable LogCat/Console in Eclipse for Android?

In Eclipse, Goto Window-> Show View -> Other -> Android-> Logcat.

Logcat is nothing but a console of your Emulator or Device.

System.out.println does not work in Android. So you have to handle every thing in Logcat. More Info Look out this Documentation.

Edit 1: System.out.println is working on Logcat. If you use that the Tag will be like System.out and Message will be your message.

Pygame mouse clicking detection

The pygame documentation for mouse events is here. You can either use the pygame.mouse.get_pressed method in collaboration with the pygame.mouse.get_pos (if needed). But please use the mouse click event via a main event loop. The reason why the event loop is better is due to "short clicks". You may not notice these on normal machines, but computers that use tap-clicks on trackpads have excessively small click periods. Using the mouse events will prevent this.

EDIT: To perform pixel perfect collisions use pygame.sprite.collide_rect() found on their docs for sprites.

How to simulate a button click using code?

If you do not use the sender argument, why not refactor the button handler implementation to separate function, and call it from wherever you want (from the button handler and from the other place).

Anyway, it is a better and cleaner design - a code that needs to be called on button handler AND from some other places deserves to be refactored to own function. Plus it will help you separate UI handling from application logic code. You will also have a nice name to the function, not just onDateSelectedButtonClick().

How is a CSS "display: table-column" supposed to work?

The CSS table model is based on the HTML table model

A table is divided into ROWS, and each row contains one or more cells. Cells are children of ROWS, they are NEVER children of columns.

"display: table-column" does NOT provide a mechanism for making columnar layouts (e.g. newspaper pages with multiple columns, where content can flow from one column to the next).

Rather, "table-column" ONLY sets attributes that apply to corresponding cells within the rows of a table. E.g. "The background color of the first cell in each row is green" can be described.

The table itself is always structured the same way it is in HTML.

In HTML (observe that "td"s are inside "tr"s, NOT inside "col"s):

<table ..>
  <col .. />
  <col .. />
  <tr ..>
    <td ..></td>
    <td ..></td>
  <tr ..>
    <td ..></td>
    <td ..></td>

Corresponding HTML using CSS table properties (Note that the "column" divs do not contain any contents -- the standard does not allow for contents directly in columns):

.mytable {_x000D_
  display: table;_x000D_
.myrow {_x000D_
  display: table-row;_x000D_
.mycell {_x000D_
  display: table-cell;_x000D_
.column1 {_x000D_
  display: table-column;_x000D_
  background-color: green;_x000D_
.column2 {_x000D_
  display: table-column;_x000D_
<div class="mytable">_x000D_
  <div class="column1"></div>_x000D_
  <div class="column2"></div>_x000D_
  <div class="myrow">_x000D_
    <div class="mycell">contents of first cell in row 1</div>_x000D_
    <div class="mycell">contents of second cell in row 1</div>_x000D_
  <div class="myrow">_x000D_
    <div class="mycell">contents of first cell in row 2</div>_x000D_
    <div class="mycell">contents of second cell in row 2</div>_x000D_

OPTIONAL: both "rows" and "columns" can be styled by assigning multiple classes to each row and cell as follows. This approach gives maximum flexibility in specifying various sets of cells, or individual cells, to be styled:

//Useful css declarations, depending on what you want to affect, include:_x000D_
/* all cells (that have "class=mycell") */_x000D_
.mycell {_x000D_
/* class row1, wherever it is used */_x000D_
.row1 {_x000D_
/* all the cells of row1 (if you've put "class=mycell" on each cell) */_x000D_
.row1 .mycell {_x000D_
/* cell1 of row1 */_x000D_
.row1 .cell1 {_x000D_
/* cell1 of all rows */_x000D_
.cell1 {_x000D_
/* row1 inside class mytable (so can have different tables with different styles) */_x000D_
.mytable .row1 {_x000D_
/* all the cells of row1 of a mytable */_x000D_
.mytable .row1 .mycell {_x000D_
/* cell1 of row1 of a mytable */_x000D_
.mytable .row1 .cell1 {_x000D_
/* cell1 of all rows of a mytable */_x000D_
.mytable .cell1 {_x000D_
<div class="mytable">_x000D_
  <div class="column1"></div>_x000D_
  <div class="column2"></div>_x000D_
  <div class="myrow row1">_x000D_
    <div class="mycell cell1">contents of first cell in row 1</div>_x000D_
    <div class="mycell cell2">contents of second cell in row 1</div>_x000D_
  <div class="myrow row2">_x000D_
    <div class="mycell cell1">contents of first cell in row 2</div>_x000D_
    <div class="mycell cell2">contents of second cell in row 2</div>_x000D_

In today's flexible designs, which use <div> for multiple purposes, it is wise to put some class on each div, to help refer to it. Here, what used to be <tr> in HTML became class myrow, and <td> became class mycell. This convention is what makes the above CSS selectors useful.

PERFORMANCE NOTE: putting class names on each cell, and using the above multi-class selectors, is better performance than using selectors ending with *, such as .row1 * or even .row1 > *. The reason is that selectors are matched last first, so when matching elements are being sought, .row1 * first does *, which matches all elements, and then checks all the ancestors of each element, to find if any ancestor has class row1. This might be slow in a complex document on a slow device. .row1 > * is better, because only the immediate parent is examined. But it is much better still to immediately eliminate most elements, via .row1 .cell1. (.row1 > .cell1 is an even tighter spec, but it is the first step of the search that makes the biggest difference, so it usually isn't worth the clutter, and the extra thought process as to whether it will always be a direct child, of adding the child selector >.)

The key point to take away re performance is that the last item in a selector should be as specific as possible, and should never be *.

How do you find the first key in a dictionary?

Update: as of Python 3.7, insertion order is maintained, so you don't need an OrderedDict here. You can use the below approaches with a normal dict

Changed in version 3.7: Dictionary order is guaranteed to be insertion order. This behavior was an implementation detail of CPython from 3.6.


Python 3.6 and earlier*

If you are talking about a regular dict, then the "first key" doesn't mean anything. The keys are not ordered in any way you can depend on. If you iterate over your dict you will likely not get "banana" as the first thing you see.

If you need to keep things in order, then you have to use an OrderedDict and not just a plain dictionary.

import collections
prices  = collections.OrderedDict([
        ("banana", 4),
        ("apple", 2),
        ("orange", 1.5),
        ("pear", 3),

If you then wanted to see all the keys in order you could do so by iterating through it

for k in prices:

You could, alternatively put all of the keys into a list and then work with that

ks = list(prices)
print(ks[0]) # will print "banana"

A faster way to get the first element without creating a list would be to call next on the iterator. This doesn't generalize nicely when trying to get the nth element though

>>> next(iter(prices))

* CPython had guaranteed insertion order as an implementation detail in 3.6.

CSS Input with width: 100% goes outside parent's bound

Padding is essentially added to the width, therefore when you say width:100% and padding: 5px 10px you're actually adding 20px to the 100% width.

mysql SELECT IF statement with OR

Presumably this would work:

IF(compliment = 'set' OR compliment = 'Y' OR compliment = 1, 'Y', 'N') AS customer_compliment

How do I write data to csv file in columns and rows from a list in python?

>>> import csv
>>> with open('test.csv', 'wb') as f:
...     wtr = csv.writer(f, delimiter= ' ')
...     wtr.writerows( [[1, 2], [2, 3], [4, 5]])
>>> with open('test.csv', 'r') as f:
...     for line in f:
...         print line,
1 2 <<=== Exactly what you said that you wanted.
2 3
4 5

To get it so that it can be loaded sensibly by Excel, you need to use a comma (the csv default) as the delimiter, unless you are in a locale (e.g. Europe) where you need a semicolon.

Export to csv in jQuery

This is my implementation (based in:

Usage: HTML:

<table class="download">...</table>
<a href="" download="name.csv">DOWNLOAD CSV</a>




jQuery.fn.toCSV = function(link) {
  var $link = $(link);
  var data = $(this).first(); //Only one table
  var csvData = [];
  var tmpArr = [];
  var tmpStr = '';
  data.find("tr").each(function() {
      if($(this).find("th").length) {
          $(this).find("th").each(function() {
            tmpStr = $(this).text().replace(/"/g, '""');
            tmpArr.push('"' + tmpStr + '"');
      } else {
          tmpArr = [];
             $(this).find("td").each(function() {
                  if($(this).text().match(/^-{0,1}\d*\.{0,1}\d+$/)) {
                  } else {
                      tmpStr = $(this).text().replace(/"/g, '""');
                      tmpArr.push('"' + tmpStr + '"');
  var output = csvData.join('\n');
  var uri = 'data:application/csv;charset=UTF-8,' + encodeURIComponent(output);
  $link.attr("href", uri);


  • It uses "th" tags for headings. If they are not present, they are not added.
  • This code detects numbers in the format: -####.## (You will need modify the code in order to accept other formats, e.g. using commas).


My previous implementation worked fine but it didn't set the csv filename. The code was modified to use a filename but it requires an < a > element. It seems that you can't dynamically generate the < a > element and fire the "click" event (perhaps security reasons?).


(Unfortunately jsfiddle fails to generate the file and instead it throws an error: 'please use POST request', don't let that error stop you from testing this code in your application).

How do I name the "row names" column in r

It sounds like you want to convert the rownames to a proper column of the data.frame. eg:

# add the rownames as a proper column
myDF <- cbind(Row.Names = rownames(myDF), myDF)

#           Row.Names id val vr2
# row_one     row_one  A   1  23
# row_two     row_two  A   2  24
# row_three row_three  B   3  25
# row_four   row_four  C   4  26

If you want to then remove the original rownames:

rownames(myDF) <- NULL
#   Row.Names id val vr2
# 1   row_one  A   1  23
# 2   row_two  A   2  24
# 3 row_three  B   3  25
# 4  row_four  C   4  26

Alternatively, if all of your data is of the same class (ie, all numeric, or all string), you can convert to Matrix and name the dimnames

myMat <- as.matrix(myDF)
names(dimnames(myMat)) <- c("Names.of.Rows", "")

# Names.of.Rows id  val vr2 
#   row_one   "A" "1" "23"
#   row_two   "A" "2" "24"
#   row_three "B" "3" "25"
#   row_four  "C" "4" "26"

Setting DataContext in XAML in WPF

First of all you should create property with employee details in the Employee class:

public class Employee
    public Employee()
        EmployeeDetails = new EmployeeDetails();
        EmployeeDetails.EmpID = 123;
        EmployeeDetails.EmpName = "ABC";

    public EmployeeDetails EmployeeDetails { get; set; }

If you don't do that, you will create instance of object in Employee constructor and you lose reference to it.

In the XAML you should create instance of Employee class, and after that you can assign it to DataContext.

Your XAML should look like this:

<Window x:Class="SampleApplication.MainWindow"
    Title="MainWindow" Height="350" Width="525"
        <local:Employee x:Key="Employee" />
    <Grid DataContext="{StaticResource Employee}">
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
            <ColumnDefinition Width="Auto" />
            <ColumnDefinition Width="200" />

        <Label Grid.Row="0" Grid.Column="0" Content="ID:"/>
        <Label Grid.Row="1" Grid.Column="0" Content="Name:"/>
        <TextBox Grid.Column="1" Grid.Row="0" Margin="3" Text="{Binding EmployeeDetails.EmpID}" />
        <TextBox Grid.Column="1" Grid.Row="1" Margin="3" Text="{Binding EmployeeDetails.EmpName}" />

Now, after you created property with employee details you should binding by using this property:

Text="{Binding EmployeeDetails.EmpID}"

Understanding passport serialize deserialize

  1. Where does go after passport.serializeUser has been called?

The user id (you provide as the second argument of the done function) is saved in the session and is later used to retrieve the whole object via the deserializeUser function.

serializeUser determines which data of the user object should be stored in the session. The result of the serializeUser method is attached to the session as req.session.passport.user = {}. Here for instance, it would be (as we provide the user id as the key) req.session.passport.user = {id: 'xyz'}

  1. We are calling passport.deserializeUser right after it where does it fit in the workflow?

The first argument of deserializeUser corresponds to the key of the user object that was given to the done function (see 1.). So your whole object is retrieved with help of that key. That key here is the user id (key can be any key of the user object i.e. name,email etc). In deserializeUser that key is matched with the in memory array / database or any data resource.

The fetched object is attached to the request object as req.user

Visual Flow

passport.serializeUser(function(user, done) {
});              ¦
                 +--------------------? saved to session
                                   ¦    req.session.passport.user = {id: '..'}
passport.deserializeUser(function(id, done) {
    User.findById(id, function(err, user) {
        done(err, user);
    });            +--------------? user object attaches to the request as req.user   

JavaScript: Difference between .forEach() and .map()

forEach() :

return value : undefined

originalArray : not modified after the method call

newArray is not created after the end of method call.

map() :

return value : new Array populated with the results of calling a provided function on every element in the calling array

originalArray : not modified after the method call

newArray is created after the end of method call.

Since map builds a new array, using it when you aren't using the
returned array is an anti-pattern; use forEach or for-of instead.

AlertDialog styling - how to change style (color) of title, message, etc

I changed color programmatically in this way :

var builder = new AlertDialog.Builder (this);
var dialog = builder.Show ();
int textColorId = Resources.GetIdentifier ("alertTitle", "id", "android");
TextView textColor = dialog.FindViewById<TextView> (textColorId);
textColor?.SetTextColor (Color.DarkRed);

as alertTitle, you can change other data by this way (next example is for titleDivider):

int titleDividerId = Resources.GetIdentifier ("titleDivider", "id", "android");
View titleDivider = dialog.FindViewById (titleDividerId);
titleDivider?.SetBackgroundColor (Color.Red);

this is in C#, but in java it is the same.

jQuery: How can I show an image popup onclick of the thumbnail?

There are a lot of jQuery plugins available for this







Thickbox Examples

For a single image

  1. Create a link element ()
  2. Give the link a class attribute with a value of thickbox (class="thickbox")
  3. Provide a path in the href attribute to an image file (.jpg .jpeg .png .gif .bmp)

Invalid Host Header when ngrok tries to connect to React dev server

I used this set up in a react app that works. I created a config file named configstrp.js that contains the following:

module.exports = {
ngrok: {
// use the local frontend port to connect
enabled: process.env.NODE_ENV !== 'production',
port: process.env.PORT || 3000,
subdomain: process.env.NGROK_SUBDOMAIN,
authtoken: process.env.NGROK_AUTHTOKEN
},   }

Require the file in the server.

const configstrp      = require('./config/configstrp.js');
const ngrok = configstrp.ngrok.enabled ? require('ngrok') : null;

and connect as such

if (ngrok) {
console.log('If nGronk')
    addr: configstrp.ngrok.port,
    subdomain: configstrp.ngrok.subdomain,
    authtoken: configstrp.ngrok.authtoken,
  (err, url) => {
    if (err) {

    } else {


Do not pass a subdomain if you do not have a custom domain

Angularjs - simple form submit

var app = angular.module( "myApp", [] );_x000D_
app.controller( "myCtrl", ["$scope", function($scope) {_x000D_
    $scope.submit_form = function(formData) {_x000D_
        $scope.formData = formData;_x000D_
        console.log(formData); // object_x000D_
        console.log(JSON.stringify(formData)); // string_x000D_
        $scope.form = {}; // clear ng-model form_x000D_
}] );
<script src=""></script>_x000D_
<div ng-app="myApp" ng-controller="myCtrl">_x000D_
    <form ng-submit="submit_form(form)" >_x000D_
        Firstname: <input type="text" ng-model="form.firstname" /><br />_x000D_
        Lastname: <input type="text" ng-model="form.lastname" /><br />_x000D_
        <hr />_x000D_
        <input type="submit" value="Submit" />_x000D_
    <hr />          _x000D_
    <p>Firstname: {{ form.firstname }}</p>_x000D_
    <p>Lastname: {{ form.lastname }}</p>_x000D_
    <pre>Submit Form: {{ formData }} </pre>_x000D_


SQL: How to to SUM two values from different tables


'And so on and so forth.

"The COALESCE function basically says "return the first parameter, unless it's null in which case return the second parameter" - It's quite handy in these scenarios." Source

How can I extract a good quality JPEG image from a video file with ffmpeg?

Output the images in a lossless format such as PNG:

ffmpeg.exe -i 10fps.h264 -r 10 -f image2 10fps.h264_%03d.png

Edit/Update: Not quite sure why I originally gave a strange filename example (with a possibly made-up extension).

I have since found that -vsync 0 is simpler than -r 10 because it avoids needing to know the frame rate.

This is something like what I currently use:

mkdir stills
ffmpeg -i my-film.mp4 -vsync 0 -f image2 stills/my-film-%06d.png

To extract only the key frames (which are likely to be of higher quality post-edit):

ffmpeg -skip_frame nokey -i my-film.mp4 -vsync 0 -f image2 stills/my-film-%06d.png

Then use another program (where you can more precisely specify quality, subsampling and DCT method – e.g. GIMP) to convert the PNGs you want to JPEG.

It is possible to obtain slightly sharper images in JPEG format this way than is possible with -qmin 1 -q:v 1 and outputting as JPEG directly from ffmpeg.

How to get max value of a column using Entity Framework?

In VB.Net it would be

Dim maxAge As Integer = context.Persons.Max(Function(p) p.Age)

Position absolute and overflow hidden

What about position: relative for the outer div? In the example that hides the inner one. It also won't move it in its layout since you don't specify a top or left.

Selenium WebDriver can't find element by link text

The problem might be in the rest of the html, the part that you didn't post.

With this example (I just closed the open tags):

<a class="item" ng-href="#/catalog/90d9650a36988e5d0136988f03ab000f/category/DATABASE_SERVERS/service/90cefc7a42b3d4df0142b52466810026" href="#/catalog/90d9650a36988e5d0136988f03ab000f/category/DATABASE_SERVERS/service/90cefc7a42b3d4df0142b52466810026">
<div class="col-lg-2 col-sm-3 col-xs-4 item-list-image">
<img ng-src="csa/images/library/Service_Design.png" src="csa/images/library/Service_Design.png">
<div class="col-lg-8 col-sm-9 col-xs-8">
<div class="col-xs-12">
    <strong class="ng-binding">Smoke Sequential</strong>

I was able to find the element without trouble with:

driver.findElement(By.linkText("Smoke Sequential")).click();

If there is more text inside the element, you could try a find by partial link text:


How to clear gradle cache?

In android studio open View > Tool Windows > Terminal and execute the following commands

On Windows:

gradlew cleanBuildCache

On Mac or Linux:

./gradlew cleanBuildCache

if you want to disable the cache from your project add this into the gradle build properties

(Warning: this may slow your PC performance if there is no cache than same time will consume after every time during the run app)


Using Custom Domains With IIS Express

David's solution is good. But I found the <script>alert(document.domain);</script> in the page still alerts "localhost" because the Project Url is still localhost even if it has been override with Another issue I run into is that it alerts me the port 80 has already been in use even if I have disabled the Skype using the 80 port number as recommended by David Murdoch. So I have figured out another solution that is much easier:

  1. Run Notepad as administrator, and open the C:\Windows\System32\drivers\etc\hosts, add mydomain, and save the file;
  2. Open the web project with Visual Studio 2013 (Note: must also run as administrator), right-click the project -> Properties -> Web, (lets suppose the Project Url under the "IIS Express" option is http://localhost:33333/), then change it from http://localhost:33333/ to http://mydomain:333333/ Note: After this change, you should neither click the "Create Virtual Directory" button on the right of the Project Url box nor click the Save button of the Visual Studio as they won't be succeeded. You can save your settings after next step 3.
  3. Open %USERPROFILE%\My Documents\IISExpress\config\applicationhost.config, search for "33333:localhost", then update it to "33333:mydomain" and save the file.
  4. Save your setting as mentioned in step 2.
  5. Right click a web page in your visual studio, and click "View in Browser". Now the page will be opened under http://mydomain:333333/, and <script>alert(document.domain);</script> in the page will alert "mydomain".

Note: The port number listed above is assumed to be 33333. You need to change it to the port number set by your visual studio.

Post edited: Today I tried with another domain name and got the following error: Unable to launch the IIS Express Web server. Failed to register URL... Access is denied. (0x80070005). I exit the IIS Express by right clicking the IIS Express icon at the right corner in the Windows task bar, and then re-start my visual studio as administrator, and the issue is gone.

Selecting only numeric columns from a data frame

iris %>% dplyr::select(where(is.numeric)) #as per most recent updates

Another option with purrr would be to negate discard function:

iris %>% purrr::discard(~!is.numeric(.))

If you want the names of the numeric columns, you can add names or colnames:

iris %>% purrr::discard(~!is.numeric(.)) %>% names

What is the difference between loose coupling and tight coupling in the object oriented paradigm?

There is a lot of nice answers here using analogies but a friend at work gave me an example that I liked more than all of the ones mentioned here... Eyes and Glasses!

Tight Coupling

Tight coupling would be the eyes. If I want to fix my vision, I'ts very expensive to get an eye transplant and holds a fair amount of risk. But what if the designer (being the human race) found a better way. Add a feature that is loosely coupled to the body so it can be easily changed! (yes.. glasses)

Loose coupling

I can easily replace my glasses without breaking my underlying vision. I can take off the glasses and my vision will be how it was before (not better or worse). Using different pairs of glasses changes how we see the world through our eyes with little risk and easy maintainability.


So next time someone asks you "who cares if my code is tightly-coupled?" The answer is all about effort to change, effort to maintain and risk of change.

So how is this done in C#? Interfaces and Dependency Injection!


This a good example of the Decorator pattern as well, where the the eyes are the class we are decorating by meeting interface requirements but giving different functionality (e.g. sunglasses, reading glasses, magnifying glasses for jewelers e.t.c)

How to lay out Views in RelativeLayout programmatically?





CSS3 selector to find the 2nd div of the same class

First you must select the parent element and set :nth-of-type(n) for the parent and then select the element you want. something like this :

#topmenu li:nth-of-type(2) ul.childUl {

This will select the second submenu from topmenu. #topmenu li is the parent element.


<ul id="topmenu">
        <ul class="childUl">
        <ul class="childUl">
        <ul class="childUl">

Sending XML data using HTTP POST with PHP

Another option would be file_get_contents():

// $xml_str = your xml
// $url = target url

$post_data = array('xml' => $xml_str);
$stream_options = array(
    'http' => array(
        'method'  => 'POST',
        'header'  => 'Content-type: application/x-www-form-urlencoded' . "\r\n",
        'content' =>  http_build_query($post_data)));

$context  = stream_context_create($stream_options);
$response = file_get_contents($url, null, $context);

Strip out HTML and Special Characters

to allow periods and any other character just add them like so:

change: '#[^a-zA-Z ]#' to:'#[^a-zA-Z .()!]#'

Append text with .bat

You need to use ECHO. Also, put the quotes around the entire file path if it contains spaces.

One other note, use > to overwrite a file if it exists or create if it does not exist. Use >> to append to an existing file or create if it does not exist.

Overwrite the file with a blank line:

ECHO.>"C:\My folder\Myfile.log"

Append a blank line to a file:

ECHO.>>"C:\My folder\Myfile.log"

Append text to a file:

ECHO Some text>>"C:\My folder\Myfile.log"

Append a variable to a file:

ECHO %MY_VARIABLE%>>"C:\My folder\Myfile.log"

Default value of function parameter

If you put the declaration in a header file, and the definition in a separate .cpp file, and #include the header from a different .cpp file, you will be able to see the difference.

Specifically, suppose:


int Add(int a, int b);


int Add(int a, int b = 3) {


#include "lib.h"

int main() {

The compilation of test.cpp will not see the default parameter declaration, and will fail with an error.

For this reason, the default parameter definition is usually specified in the function declaration:


int Add(int a, int b = 3);

Java POI : How to read Excel cell value and not the formula computing it?

If you want to extract a raw-ish value from a HSSF cell, you can use something like this code fragment:

CellBase base = (CellBase) cell;
CellType cellType = cell.getCellType();
String result = cell.getStringCellValue();

At least for strings that are completely composed of digits (and automatically converted to numbers by Excel), this returns the original string (e.g. "12345") instead of a fractional value (e.g. "12345.0"). Note that setCellType is available in interface Cell(as of v. 4.1) but deprecated and announced to be eliminated in v 5.x, whereas this method is still available in class CellBase. Obviously, it would be nicer either to have getRawValue in the Cell interface or at least to be able use getStringCellValue on non STRING cell types. Unfortunately, all replacements of setCellType mentioned in the description won't cover this use case (maybe a member of the POI dev team reads this answer).

Understanding Apache's access log

I also don't under stand what the "-" means after the 200 140 section of the log

That value corresponds to the referer as described by Joachim. If you see a dash though, that means that there was no referer value to begin with (eg. the user went straight to a specific destination, like if he/she typed a URL in their browser)

How to check if a date is greater than another in Java?

You can use Date.before() or Date.after() or Date.equals() for date comparison.

Taken from here:

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class DateDiff {

    public static void main( String[] args )
        compareDates("2017-01-13 00:00:00", "2017-01-14 00:00:00");// output will be Date1 is before Date2
        compareDates("2017-01-13 00:00:00", "2017-01-12 00:00:00");//output will be Date1 is after Date2
        compareDates("2017-01-13 00:00:00", "2017-01-13 10:20:30");//output will be Date1 is before Date2 because date2 is ahead of date 1 by 10:20:30 hours
        compareDates("2017-01-13 00:00:00", "2017-01-13 00:00:00");//output will be Date1 is equal Date2 because both date and time are equal

    public static void compareDates(String d1,String d2)
            // If you already have date objects then skip 1

            // Create 2 dates starts
            SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
            Date date1 = sdf.parse(d1);
            Date date2 = sdf.parse(d2);


            // Create 2 dates ends

            // Date object is having 3 methods namely after,before and equals for comparing
            // after() will return true if and only if date1 is after date 2
                System.out.println("Date1 is after Date2");
            // before() will return true if and only if date1 is before date2
                System.out.println("Date1 is before Date2");

            //equals() returns true if both the dates are equal
                System.out.println("Date1 is equal Date2");

        catch(ParseException ex){

    public static void compareDates(Date date1,Date date2)
        // if you already have date objects then skip 1


        //date object is having 3 methods namely after,before and equals for comparing
        //after() will return true if and only if date1 is after date 2
            System.out.println("Date1 is after Date2");

        //before() will return true if and only if date1 is before date2
            System.out.println("Date1 is before Date2");

        //equals() returns true if both the dates are equal
            System.out.println("Date1 is equal Date2");


Eclipse Java Missing required source folder: 'src'

Right-Click Project --> Build Path --> Configure Build Path; unselect the SRC, save, select again.

This solved my problem.

The easiest way to transform collection to array?

If you use Guava in your project you can use Iterables::toArray.

Foo[] foos = Iterables.toArray(x, Foo.class);

Postgres "psql not recognized as an internal or external command"

If you tried all the answers and still spinning your heads, don't forget to change the version with your one which you downloaded.

For example, don't simply copy paste

;C:\Program Files\PostgreSQL\9.5\bin ;C:\Program Files\PostgreSQL\9.5\lib

More clearly,

;C:\Program Files\PostgreSQL\[Your Version]\bin ;C:\Program Files\PostgreSQL\[Your Version]\lib

I was spinning my heads. Hope this helps.

How to check if click event is already bound - JQuery

The best way I see is to use live() or delegate() to capture the event in a parent and not in each child element.

If your button is inside a #parent element, you can replace:

$('#myButton').bind('click', onButtonClicked);


$('#parent').delegate('#myButton', 'click', onButtonClicked);

even if #myButton doesn't exist yet when this code is executed.

Adding items to end of linked list

You want to navigate through the entire linked list using a loop and checking the "next" value for each node. The last node will be the one whose next value is null. Simply make this node's next value a new node which you create with the input data.

node temp = first; // starts with the first node.

    while ( != null)
       temp =;
    } = new Node(header, x);

That's the basic idea. This is of course, pseudo code, but it should be simple enough to implement.

Python update a key in dict if it doesn't exist

Since Python 3.9 you can use the merge operator | to merge two dictionaries. The dict on the right takes precedence:

new_dict = old_dict | { key: val }

For example:

new_dict = { 'a': 1, 'b': 2 } | { 'b': 42 }

print(new_dict} # {'a': 1, 'b': 42}

Note: this creates a new dictionary with the updated values.

How to display scroll bar onto a html table

Not sure why no one mentioned to just use the built-in sticky header style for elements. Worked great for me.

.tableContainerDiv {
   overflow: auto;
   max-height: 80em;
th {
   position: sticky;
   top: 0;
   background: white;

Put a min-width on the in @media if you need to make responsive (or similar).

see Table headers position:sticky or Position Sticky and Table Headers

Removing all unused references from a project in Visual Studio projects

All you need is stone and bare knuckle then you can do it like a caveman.

  1. Remove unused namespaces (for each class)
  2. Run Debug build
  3. Copy your executable and remaining namespace references to new location
  4. Run the executable
  5. Missing Reference DLL error will occur
  6. Copy required DLL from Debug folder
  7. Repeat 4-6
  8. Gu Gu Ga Ga?
  9. Throw your stone

You can also rely on your build tools to let you know which reference is still required. It's the era of VS 2017, caveman still survived.

Error in <my code> : object of type 'closure' is not subsettable

I had this issue was trying to remove a ui element inside an event reactive:

myReactives <- eventReactive(input$execute, {
    ... # Some other long running function here
    removeUI(selector = "#placeholder2")

I was getting this error, but not on the removeUI element line, it was in the next observer after for some reason. Taking the removeUI method out of the eventReactive and placing it somewhere else removed this error for me.

BigDecimal setScale and round

There is indeed a big difference, which you should keep in mind. setScale really set the scale of your number whereas round does round your number to the specified digits BUT it "starts from the leftmost digit of exact result" as mentioned within the jdk. So regarding your sample the results are the same, but try 0.0034 instead. Here's my note about that on my blog:

Null vs. False vs. 0 in PHP

In PHP you can use === and !== operators to check not only if the values are equal but also if their types match. So for example: 0 == false is true, but 0 === false is false. The same goes for != versus !==. Also in case you compare null to the other two using the mentioned operators, expect similar results.

Now in PHP this quality of values is usually used when returning a value which sometimes can be 0 (zero), but sometimes it might be that the function failed. In such cases in PHP you return false and you have to check for these cases using the identity operator ===. For example if you are searching for a position of one string inside the other and you're using strpos(), this function will return the numeric position which can be 0 if the string is found at the very beginning, but if the string is not found at all, then strpos() will return false and you have to take this into account when dealing with the result.

If you will use the same technique in your functions, anybody familiar with the standard PHP library will understand what is going on and how to check if the returned value is what is wanted or did some error occur while processing. The same actually goes for function params, you can process them differently depending on if they are arrays or strings or what not, and this technique is used throughout PHP heavily too, so everybody will get it quite easily. So I guess that's the power.

keypress, ctrl+c (or some combo like that)

You cannot use Ctrl+C by jQuery , but you can with another library which is shortcut.js

Live Demo : Abdennour JSFiddle

$(document).ready(function() {
shortcut.add("Ctrl+C", function() {
    $('span').html("?????. ??? ???? ??? ???? : Ctrl+C");
    shortcut.add("Ctrl+V", function() {
    $('span').html("?????. ??? ???? ??? ???? : Ctrl+V");
       shortcut.add("Ctrl+X", function() {
    $('span').html("?????. ??? ???? ??? ???? : Ctrl+X");


How to analyse the heap dump using jmap in java

VisualVm does not come with Apple JDK. You can use VisualVM Mac Application bundle(dmg) as a separate application, to compensate for that.

How to strip comma in Python string

unicode('foo,bar').translate(dict([[ord(char), u''] for char in u',']))

Selecting an element in iFrame jQuery

Take a look at this post:

$("#iframeID").contents().find("[tokenid=" + token + "]").html();

Place your selector in the find method.

This may not be possible however if the iframe is not coming from your server. Other posts talk about permission denied errors.

jQuery/JavaScript: accessing contents of an iframe

Attach the Source in Eclipse of a jar

A .jar file usually only contains the .class files, not the .java files they were compiled from. That's why eclipse is telling you it doesn't know the source code of that class.

"Attaching" the source to a JAR means telling eclipse where the source code can be found. Of course, if you don't know yourself, that feature is of little help. Of course, you could try googling for the source code (or check wherever you got the JAR file from).

That said, you don't necessarily need the source to debug.

CSS no text wrap

Just use:

overflow: hidden;
white-space: nowrap;

In your item's divs

Usage of the backtick character (`) in JavaScript

A lot of the comments answer most of your questions, but I mainly wanted to contribute to this question:

Is there a way in which the behavior of the backtick actually differs from that of a single quote?

A difference I've noticed for template strings is the disability to set one as an object property. More information in this post; an interesting quote from the accepted answer:

Template strings are expressions, not literals1.

But basically, if you ever wanted to use it as an object property you'd have to use it wrapped with square brackets.

// Throws error
const object = {`templateString`: true};

// Works
const object = {[`templateString`]: true};

T-SQL: Using a CASE in an UPDATE statement to update certain columns depending on a condition

I believe that you can omit updating the "non-desired" columns by adjusting the other answers as follows:

update table set
    columnx = (case when condition1 then 25 end),
    columny = (case when condition2 then 25 end)`

As I understand it, this will update only when the condition is met.

After reading all the comments, this is the most efficient:

Update table set ColumnX = 25 where Condition1
 Update table set ColumnY = 25 where Condition1`

Sample Table:

CREATE TABLE [dbo].[tblTest](
    [ColX] [int] NULL,
    [ColY] [int] NULL,
    [ColConditional] [bit] NULL,
    [id] [int] IDENTITY(1,1) NOT NULL

Sample Data:

Insert into tblTest (ColX, ColY, ColConditional) values (null, null, 0)
Insert into tblTest (ColX, ColY, ColConditional) values (null, null, 0)
Insert into tblTest (ColX, ColY, ColConditional) values (null, null, 1)
Insert into tblTest (ColX, ColY, ColConditional) values (null, null, 1)
Insert into tblTest (ColX, ColY, ColConditional) values (1, null, null)
Insert into tblTest (ColX, ColY, ColConditional) values (2, null, null)
Insert into tblTest (ColX, ColY, ColConditional) values (null, 1, null)
Insert into tblTest (ColX, ColY, ColConditional) values (null, 2, null)

Now I assume you can write a conditional that handles nulls. For my example, I am assuming you have written such a conditional that evaluates to True, False or Null. If you need help with this, let me know and I will do my best.

Now running these two lines of code does infact change X to 25 if and only if ColConditional is True(1) and Y to 25 if and only if ColConditional is False(0)

Update tblTest set ColX = 25 where ColConditional = 1
Update tblTest set ColY = 25 where ColConditional = 0

P.S. The null case was never mentioned in the original question or any updates to the question, but as you can see, this very simple answer handles them anyway.

Ruby: What is the easiest way to remove the first element from an array?

You can use:


slice! generalizes to any index or range.

Add primary key to existing table

Please try this-


Multiple conditions in a C 'for' loop

The comma expression takes on the value of the last (eg. right-most) expression.

So in your first loop, the only controlling expression is i<=5; and j>=0 is ignored.

In the second loop, j>=0 controls the loop, and i<=5 is ignored.

As for a reason... there is no reason. This code is just wrong. The first part of the comma-expressions does nothing except confuse programmers. If a serious programmer wrote this, they should be ashamed of themselves and have their keyboard revoked.

Jenkins / Hudson environment variables

I tried /etc/profile, ~/.profile and ~/.bash_profile and none of those worked. I found that editing ~/.bashrc for the jenkins slave account did.

What is the meaning of Bus: error 10 in C

string literals are non-modifiable in C

How to join multiple lines of file names into one with custom delimiter?

You can use chomp to merge multiple line in single line:

perl -e 'while (<>) { if (/\$/ ) { chomp; } print ;}' bad0 >test

put line break condition in if statement.It can be special character or any delimiter.

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

this also might be relevant to anyone using React -

install react-moment (npm i react-moment)

import Moment from 'react-moment'

<Moment format="MM/DD/YYYY">{yourTimeStamp}</Moment>

(or any other format you'd like)

Remove blue border from css custom-styled button in Chrome

Don't forget the !important declaration, for a better result

button:focus {outline:0 !important;}

A rule that has the !important property will always be applied no matter where that rule appears in the CSS document.

Node.js connect only works on localhost

Binding to is half the battle. There is an ip firewall (different from the one in system preferences) that blocks TCP ports. Hence port must be unblocked there as well by doing:

sudo ipfw add <PORT NUMBER> allow tcp from any to any

List all liquibase sql types

For checking type conversions in version 3, you can go to their github and check into the different liquibase types and check the method toDatabaseDataType. For example, for Boolean, you can check here:

For version 2.0.x, the conversion seems to be into database specific classes. For example, for Mysql:

use of entityManager.createNativeQuery(query,foo.class)

Here is a DB2 Stored Procidure that receive a parameter


CREATE PROCEDURE getStateByName (IN StateName VARCHAR(128))
    -- Declare cursor
    -- #######################################################################
    -- # Replace the SQL statement with your statement.
    -- # Note: Be sure to end statements with the terminator character (usually ';')
    -- #
    -- # The example SQL statement SELECT NAME FROM SYSIBM.SYSTABLES
    -- # returns all names from SYSIBM.SYSTABLES.
    -- ######################################################################
    -- Cursor left open for client application
    OPEN Province_Cursor;


//Country is a db2 scheme

//Now here is a java Entity bean Method

public List<Province> getStateByName(String stateName) throws Exception {

    EntityManager em = this.em;
    List<State> states= null;
    try {
        Query query = em.createNativeQuery("call NGB.getStateByName(?1)", Province.class);
        query.setParameter(1, provinceName);
        states= (List<Province>) query.getResultList();
    } catch (Exception ex) {
        throw ex;

    return states;

How to download a file via FTP with Python ftplib

This is a Python code that is working fine for me. Comments are in Spanish but the app is easy to understand

# coding=utf-8

from ftplib import FTP                                                                      # Importamos la libreria ftplib desde FTP

import sys

def imprimirMensaje():                                                                      # Definimos la funcion para Imprimir el mensaje de bienvenida
    print "------------------------------------------------------"
    print "--               COMMAND LINE EXAMPLE               --"
    print "------------------------------------------------------"
    print ""
    print ">>>             Cliente FTP  en Python                "
    print ""
    print ">>> python <appname>.py <host> <port> <user> <pass>   "
    print "------------------------------------------------------"

def f(s):                                                                                   # Funcion para imprimir por pantalla los datos 
    print s

def download(j):                                                                            # Funcion para descargarnos el fichero que indiquemos según numero    
    print "Descargando=>",files[j]      
    fhandle = open(files[j], 'wb')
    ftp.retrbinary('RETR ' + files[j], fhandle.write)                                       # Imprimimos por pantalla lo que estamos descargando        #fhandle.close()

ip          = sys.argv[1]                                                                   # Recogemos la IP       desde la linea de comandos sys.argv[1] 
puerto      = sys.argv[2]                                                                   # Recogemos el PUERTO   desde la linea de comandos sys.argv[2]
usuario     = sys.argv[3]                                                                   # Recogemos el USUARIO  desde la linea de comandos sys.argv[3]
password    = sys.argv[4]                                                                   # Recogemos el PASSWORD desde la linea de comandos sys.argv[4]

ftp = FTP(ip)                                                                               # Creamos un objeto realizando una instancia de FTP pasandole la IP
ftp.login(usuario,password)                                                                 # Asignamos al objeto ftp el usuario y la contraseña

files = ftp.nlst()                                                                          # Ponemos en una lista los directorios obtenidos del FTP

for i,v in enumerate(files,1):                                                              # Imprimimos por pantalla el listado de directorios enumerados
    print i,"->",v

print ""
i = int(raw_input("Pon un Nº para descargar el archivo or pulsa 0 para descargarlos\n"))    # Introducimos algun numero para descargar el fichero que queramos. Lo convertimos en integer

if i==0:                                                                                    # Si elegimos el valor 0 nos decargamos todos los ficheros del directorio                                                                               
    for j in range(len(files)):                                                             # Hacemos un for para la lista files y
        download(j)                                                                         # llamamos a la funcion download para descargar los ficheros
if i>0 and i<=len(files):                                                                   # Si elegimos unicamente un numero para descargarnos el elemento nos lo descargamos. Comprobamos que sea mayor de 0 y menor que la longitud de files 
    download(i-1)                                                                           # Nos descargamos i-1 por el tema que que los arrays empiezan por 0 

Simple JavaScript Checkbox Validation

If the check box's ID "Delete" then for the "onclick" event of the submit button the javascript function can be as follows:

<input type="checkbox" name="Delete" value="Delete" id="Delete"></td>
<input type="button" value="Delete" name="delBtn" id="delBtn" onclick="deleteData()">

<script type="text/Javascript">
    function deleteData() {
            alert('Checkbox not checked');
            return false;

ActiveXObject in Firefox or Chrome (not IE!)

No for the moment.

I doubt it will be possible for the future for ActiveX support will be discontinued in near future (as MS stated).

Look here about HTML Object tag, but not anything will be accepted. You should try.

Where can I set environment variables that crontab will use?

All the above solutions work fine.

It will create issues when there are any special characters in your environment variable.

I have found the solution:

eval $(printenv | awk -F= '{print "export " "\""$1"\"""=""\""$2"\"" }' >> /etc/profile)

Removing "NUL" characters

Highlight a single null character, goto find replace - it usually automatically inserts the highlighted text into the find box. Enter a space into or leave blank the replace box.

How to convert number of minutes to hh:mm format in TSQL?

You can convert the duration to a date and then format it:

    @FirstDate datetime,
    @LastDate datetime

    @FirstDate = '2000-01-01 09:00:00',
    @LastDate = '2000-01-01 11:30:00'

SELECT CONVERT(varchar(12), 
       DATEADD(minute, DATEDIFF(minute, @FirstDate, @LastDate), 0), 114) 

/* Results: 02:30:00:000 */

For less precision, modify the size of the varchar:

SELECT CONVERT(varchar(5), 
       DATEADD(minute, DATEDIFF(minute, @FirstDate, @LastDate), 0), 114) 

/* Results: 02:30 */

Counting Number of Letters in a string variable

myString.Length; //will get you your result
//alternatively, if you only want the count of letters:
//however, if you want to display the words as ***_***** (where _ is a space)
//you can also use this:
//small note: that will fail with a repeated word, so check your repeats!
myString.Split(' ').ToDictionary(n => n, n => n.Length);
//or if you just want the strings and get the counts later:
myString.Split(' ');
//will not fail with repeats
//and neither will this, which will also get you the counts:
myString.Split(' ').Select(n => new KeyValuePair<string, int>(n, n.Length));

append to url and refresh page


window.location.href += (window.location.href.indexOf('?') > -1 ? '&' : '?') + 'param=1'

Just one liner of Shlomi answer usable in bookmarklets

Adjust list style image position?

My solution:_x000D_
ul {_x000D_
    line-height: 1.3 !important;_x000D_
    li {_x000D_
        font-size: x-large;_x000D_
        position: relative;_x000D_
        &:before {_x000D_
            content: '';_x000D_
            display: block;_x000D_
            position: absolute;_x000D_
            top: 5px;_x000D_
            left: -25px;_x000D_
            height: 23px;_x000D_
            width: 23px;_x000D_
            background-image: url(../img/list-char.png) !important;_x000D_
            background-size: 23px;_x000D_
            background-repeat: no-repeat;_x000D_

How to find third or n?? maximum salary from salary table?

//you can find n' th salary from table.if you want to retrive 2nd highest salary then put n=2,if 3rd hs then out n=3 as so on..

SELECT *  FROM tablename t1 
 FROM tablename t2
WHERE t2.Salary > t1.Salary)

Refused to load the script because it violates the following Content Security Policy directive

Full permission string

The previous answers did not fix my issue, because they don't include blob: data: gap: keywords at the same time; so here is a string that does:

<meta http-equiv="Content-Security-Policy" content="default-src * self blob: data: gap:; style-src * self 'unsafe-inline' blob: data: gap:; script-src * 'self' 'unsafe-eval' 'unsafe-inline' blob: data: gap:; object-src * 'self' blob: data: gap:; img-src * self 'unsafe-inline' blob: data: gap:; connect-src self * 'unsafe-inline' blob: data: gap:; frame-src * self blob: data: gap:;">

Warning: This exposes the document to many exploits. Be sure to prevent users from executing code in the console or to be in a closed environment like a Cordova application.

Set background image in CSS using jquery

You have to remove the semicolon in the css rule string:

$(this).parent().css("background", "url(/images/r-srchbg_white.png) no-repeat");

Parsing a JSON string in Ruby

Just to extend the answers a bit with what to do with the parsed object:

# JSON Parsing example
require "rubygems" # don't need this if you're Ruby v1.9.3 or higher
require "json"

string = '{"desc":{"someKey":"someValue","anotherKey":"value"},"main_item":{"stats":{"a":8,"b":12,"c":10}}}'
parsed = JSON.parse(string) # returns a hash

p parsed["desc"]["someKey"]
p parsed["main_item"]["stats"]["a"]

# Read JSON from a file, iterate over objects
file = open("shops.json")
json =

parsed = JSON.parse(json)

parsed["shop"].each do |shop|
  p shop["id"]

python ignore certificate validation urllib2

urllib2 does not verify server certificate by default. Check this documentation.

Edit: As pointed out in below comment, this is not true anymore for newer versions (seems like >= 2.7.9) of Python. Refer the below ANSWER

How do you remove Subversion control for a folder?

On Windows 10, we need to go to Windows Explorer, and then go to View and check the checkbox for View hidden files.

Then navigate to the folder that has the SVN linked on Windows Explorer and delete the .svn folder/file.

importing external ".txt" file in python

Import gives you access to other modules in your program. You can't decide to import a text file. If you want to read from a file that's in the same directory, you can look at this. Here's another StackOverflow post about it.

Split function equivalent in T-SQL?

This simple CTE will give what's needed:

DECLARE @csv varchar(max) = '1,2,3,4,5,6,7,8,9,10,11,12,13,14,15';
--append comma to the list for CTE to work correctly
SET @csv = @csv + ',';
--remove double commas (empty entries)
SET @csv = replace(@csv, ',,', ',');
WITH CteCsv AS (
    SELECT CHARINDEX(',', @csv) idx, SUBSTRING(@csv, 1, CHARINDEX(',', @csv) - 1) [Value]
    SELECT CHARINDEX(',', @csv, idx + 1), SUBSTRING(@csv, idx + 1, CHARINDEX(',', @csv, idx + 1) - idx - 1) FROM CteCsv
    WHERE CHARINDEX(',', @csv, idx + 1) > 0

SELECT [Value] FROM CteCsv

How can I create a copy of an Oracle table without copying the data?

Just use a where clause that won't select any rows:

create table xyz_new as select * from xyz where 1=0;


The following things will not be copied to the new table:

  • sequences
  • triggers
  • indexes
  • some constraints may not be copied
  • materialized view logs

This also does not handle partitions

Show popup after page load

If you don't want to use jquery, use this:

 // without jquery
document.addEventListener("DOMContentLoaded", function() {
 setTimeout(function() {
  // run your open popup function after 5 sec = 5000
 }, 5000)

OR With jquery

   // open popup after 5 seconds

Auto generate function documentation in Visual Studio

Visual Assist has a nice solution too, and is highly costumizable.

After tweaking it to generate doxygen-style comments, these two clicks would produce -

* Method:    FindTheFoo
* FullName:  FindTheFoo
* Access:    private 
* Qualifier:
* @param    int numberOfFoos
* @return   bool
private bool FindTheFoo(int numberOfFoos)


(Under default settings, its a bit different.)

Edit: The way to customize the 'document method' text is under VassistX->Visual Assist Options->Suggestions, select 'Edit VA Snippets', Language: C++, Type: Refactoring, then go to 'Document Method' and customize. The above example is generated by:


How to insert special characters into a database?

use mysql_real_escape_string

So what does mysql_real_escape_string do?

This PHP library function prepends backslashes to the following characters: \n, \r, \, \x00, \x1a, ‘ and “. The important part is that the single and double quotes are escaped, because these are the characters most likely to open up vulnerabilities.

Please inform yourself about sql_injection. You can use this link as a start

What is the garbage collector in Java?

The garbage collector allows your computer to simulate a computer with infinite memory. The rest is just mechanism.

It does this by detecting when chunks of memory are no longer accessible from your code, and returning those chunks to the free store.

EDIT: Yes, the link is for C#, but C# and Java are identical in this regard.

Flash CS4 refuses to let go

Use a grep analog to find the strings oldnamespace and Jenine inside the files in your whole project folder. Then you'd know what step to do next.

C++ - unable to start correctly (0xc0150002)

I take it that is a Vista Window! I often got this when first trying to port a DirectX program from XPsp3 to Vista.

It's a .dll problem. The OpenCV runtime.dll will call upon a system.dll that will be no longer shipped Vista, so unfortunately you will have to to a bit of hunting to find which system.dll it's trying to find. (system.dll could be vc2010 or vista)

This error is also caused by incorrect installation of .dlls (i.e not rolling out) hth Happy hunting

React-Redux: Actions must be plain objects. Use custom middleware for async actions

Make use of Arrow functions it improves the readability of code. No need to return anything in API.fetchComments, Api call is asynchronous when the request is completed then will get the response, there you have to just dispatch type and data.

Below code does the same job by making use of Arrow functions.

export const bindComments = postId => {
  return dispatch => {
    API.fetchComments(postId).then(comments => {
        type: BIND_COMMENTS,

SQL INSERT INTO from multiple tables

You only need one INSERT:

INSERT INTO table4 ( name, age, sex, city, id, number, nationality)
SELECT name, age, sex, city,, number, n.nationality
FROM table1 p
INNER JOIN table2 c ON c.Id = p.Id
INNER JOIN table3 n ON p.Id = n.Id

Deserialize JSON to ArrayList<POJO> using Jackson

You can deserialize directly to a list by using the TypeReference wrapper. An example method:

public static <T> T fromJSON(final TypeReference<T> type,
      final String jsonPacket) {
   T data = null;

   try {
      data = new ObjectMapper().readValue(jsonPacket, type);
   } catch (Exception e) {
      // Handle the problem
   return data;

And is used thus:

final String json = "";
Set<POJO> properties = fromJSON(new TypeReference<Set<POJO>>() {}, json);

TypeReference Javadoc

How can I escape square brackets in a LIKE clause?

Let's say you want to match the literal its[brac]et.

You don't need to escape the ] as it has special meaning only when it is paired with [.

Therefore escaping [ suffices to solve the problem. You can escape [ by replacing it with [[].

Find out if string ends with another string in C++

Simply compare the last n characters using std::string::compare:

#include <iostream>

bool hasEnding (std::string const &fullString, std::string const &ending) {
    if (fullString.length() >= ending.length()) {
        return (0 == (fullString.length() - ending.length(), ending.length(), ending));
    } else {
        return false;

int main () {
    std::string test1 = "binary";
    std::string test2 = "unary";
    std::string test3 = "tertiary";
    std::string test4 = "ry";
    std::string ending = "nary";

    std::cout << hasEnding (test1, ending) << std::endl;
    std::cout << hasEnding (test2, ending) << std::endl;
    std::cout << hasEnding (test3, ending) << std::endl;
    std::cout << hasEnding (test4, ending) << std::endl;

    return 0;

MySQL 'Order By' - sorting alphanumeric correctly

MySQL ORDER BY Sorting alphanumeric on correct order


SELECT `alphanumericCol` FROM `tableName` ORDER BY 
  SUBSTR(`alphanumericCol` FROM 1 FOR 1), 
  LPAD(lower(`alphanumericCol`), 10,0) ASC



SQL - Query to get server's IP address

A simpler way to get the machine name without the \InstanceName is:


PowerShell Connect to FTP server and get files

Remote pick directory path should be the exact path on the ftp server you are tryng to access.. here is the script to download files from the server.. you can add or modify with SSLMode..

#ftp server 
$ftp = "" 
$user = "XX" 
$pass = "XXX"
$SetType = "bin"  
$remotePickupDir = Get-ChildItem 'c:\test' -recurse
$webclient = New-Object System.Net.WebClient 

$webclient.Credentials = New-Object System.Net.NetworkCredential($user,$pass)  
foreach($item in $remotePickupDir){ 
    $uri = New-Object System.Uri($ftp+$item.Name) 

How do I make a list of data frames?

Very simple ! Here is my suggestion :

If you want to select dataframes in your workspace, try this :

Filter(function(x) , ls())


ls()[sapply(ls(), function(x)]

all these will give the same result.

You can change to check other types of variables like is.function

Injecting $scope into an angular service function()

Got into the same predicament. I ended up with the following. So here I am not injecting the scope object into the factory, but setting the $scope in the controller itself using the concept of promise returned by $http service.

(function () {
    getDataFactory = function ($http)
        return {
            callWebApi: function (reqData)
                var dataTemp = {
                    Page: 1, Take: 10,
                    PropName: 'Id', SortOrder: 'Asc'

                return $http({
                    method: 'GET',
                    url: '/api/PatientCategoryApi/PatCat',
                    params: dataTemp, // Parameters to pass to external service
                    headers: { 'Content-Type': 'application/Json' }
    patientCategoryController = function ($scope, getDataFactory) {
        var promise = getDataFactory.callWebApi('someDataToPass');
            function successCallback(response) {
                // Set this response data to scope to use it in UI
                $ =;
            }, function errorCallback(response) {
                alert('Some problem while fetching data!!');
    patientCategoryController.$inject = ['$scope', 'getDataFactory'];
    getDataFactory.$inject = ['$http'];
    angular.module('demoApp', []);
    angular.module('demoApp').controller('patientCategoryController', patientCategoryController);
    angular.module('demoApp').factory('getDataFactory', getDataFactory);    

How to form a correct MySQL connection string?

string MyConString = "Data Source='';" +
"Port=3306;" +
"Database='a455555_test';" +
"UID='a455555_me';" +

How to set 'X-Frame-Options' on iframe?

X-Frame-Options is a header included in the response to the request to state if the domain requested will allow itself to be displayed within a frame. It has nothing to do with javascript or HTML, and cannot be changed by the originator of the request.

This website has set this header to disallow it to be displayed in an iframe. There is nothing a client can do to stop this behaviour.

Further reading on X-Frame-Options

JSF rendered multiple combined conditions

Assuming that "a" and "b" are bean properties

rendered="#{bean.a==12 and (bean.b==13 or bean.b==15)}"

You may look at JSF EL operators

Accessing UI (Main) Thread safely in WPF

Use [Dispatcher.Invoke(DispatcherPriority, Delegate)] to change the UI from another thread or from background.

Step 1. Use the following namespaces

using System.Windows;
using System.Threading;
using System.Windows.Threading;

Step 2. Put the following line where you need to update UI

Application.Current.Dispatcher.Invoke(DispatcherPriority.Background, new ThreadStart(delegate
    //Update UI here


public object Invoke(
  DispatcherPriority priority,
  Delegate method



Type: System.Windows.Threading.DispatcherPriority

The priority, relative to the other pending operations in the Dispatcher event queue, the specified method is invoked.


Type: System.Delegate

A delegate to a method that takes no arguments, which is pushed onto the Dispatcher event queue.

Return Value

Type: System.Object

The return value from the delegate being invoked or null if the delegate has no return value.

Version Information

Available since .NET Framework 3.0

convert nan value to zero

For your purposes, if all the items are stored as str and you just use sorted as you are using and then check for the first element and replace it with '0'

>>> l1 = ['88','NaN','67','89','81']
>>> n = sorted(l1,reverse=True)
['NaN', '89', '88', '81', '67']
>>> import math
>>> if math.isnan(float(n[0])):
...     n[0] = '0'
>>> n
['0', '89', '88', '81', '67']

Fastest way to write huge data in text file Java

You might try removing the BufferedWriter and just using the FileWriter directly. On a modern system there's a good chance you're just writing to the drive's cache memory anyway.

It takes me in the range of 4-5 seconds to write 175MB (4 million strings) -- this is on a dual-core 2.4GHz Dell running Windows XP with an 80GB, 7200-RPM Hitachi disk.

Can you isolate how much of the time is record retrieval and how much is file writing?

import java.util.ArrayList;
import java.util.List;

public class FileWritingPerfTest {

private static final int ITERATIONS = 5;
private static final double MEG = (Math.pow(1024, 2));
private static final int RECORD_COUNT = 4000000;
private static final String RECORD = "Help I am trapped in a fortune cookie factory\n";
private static final int RECSIZE = RECORD.getBytes().length;

public static void main(String[] args) throws Exception {
    List<String> records = new ArrayList<String>(RECORD_COUNT);
    int size = 0;
    for (int i = 0; i < RECORD_COUNT; i++) {
        size += RECSIZE;
    System.out.println(records.size() + " 'records'");
    System.out.println(size / MEG + " MB");
    for (int i = 0; i < ITERATIONS; i++) {
        System.out.println("\nIteration " + i);
        writeBuffered(records, 8192);
        writeBuffered(records, (int) MEG);
        writeBuffered(records, 4 * (int) MEG);

private static void writeRaw(List<String> records) throws IOException {
    File file = File.createTempFile("foo", ".txt");
    try {
        FileWriter writer = new FileWriter(file);
        System.out.print("Writing raw... ");
        write(records, writer);
    } finally {
        // comment this out if you want to inspect the files afterward

private static void writeBuffered(List<String> records, int bufSize) throws IOException {
    File file = File.createTempFile("foo", ".txt");
    try {
        FileWriter writer = new FileWriter(file);
        BufferedWriter bufferedWriter = new BufferedWriter(writer, bufSize);
        System.out.print("Writing buffered (buffer size: " + bufSize + ")... ");
        write(records, bufferedWriter);
    } finally {
        // comment this out if you want to inspect the files afterward

private static void write(List<String> records, Writer writer) throws IOException {
    long start = System.currentTimeMillis();
    for (String record: records) {
    // writer.flush(); // close() should take care of this
    long end = System.currentTimeMillis();
    System.out.println((end - start) / 1000f + " seconds");

deny directory listing with htaccess

Options -Indexes

I have to try create .htaccess file that current directory that i want to disallow directory index listing. But, sorry i don't know about recursive in .htaccess code.

Try it.

Which Android phones out there do have a gyroscope?

Since I have recently developed an Android application using gyroscope data (steady compass), I tried to collect a list with such devices. This is not an exhaustive list at all, but it is what I have so far:

*** Phones:

  • HTC Sensation
  • HTC Sensation XL
  • HTC Evo 3D
  • HTC One S
  • HTC One X
  • Huawei Ascend P1
  • Huawei Ascend X (U9000)
  • Huawei Honor (U8860)
  • LG Nitro HD (P930)
  • LG Optimus 2x (P990)
  • LG Optimus Black (P970)
  • LG Optimus 3D (P920)
  • Samsung Galaxy S II (i9100)
  • Samsung Galaxy S III (i9300)
  • Samsung Galaxy R (i9103)
  • Samsung Google Nexus S (i9020)
  • Samsung Galaxy Nexus (i9250)
  • Samsung Galaxy J3 (2017) model
  • Samsung Galaxy Note (n7000)
  • Sony Xperia P (LT22i)
  • Sony Xperia S (LT26i)

*** Tablets:

  • Acer Iconia Tab A100 (7")
  • Acer Iconia Tab A500 (10.1")
  • Asus Eee Pad Transformer (TF101)
  • Asus Eee Pad Transformer Prime (TF201)
  • Motorola Xoom (mz604)
  • Samsung Galaxy Tab (p1000)
  • Samsung Galaxy Tab 7 plus (p6200)
  • Samsung Galaxy Tab 10.1 (p7100)
  • Sony Tablet P
  • Sony Tablet S
  • Toshiba Thrive 7"
  • Toshiba Trhive 10"

Hope the list keeps growing and hope that gyros will be soon available on mid and low price smartphones.

Play audio file from the assets directory

enter image description here

start sound



private void startSound(String filename) {
    AssetFileDescriptor afd = null;
    try {
        afd = getResources().getAssets().openFd(filename);
    } catch (IOException e) {
    MediaPlayer player = new MediaPlayer();
    try {
        assert afd != null;
        player.setDataSource(afd.getFileDescriptor(), afd.getStartOffset(), afd.getLength());
    } catch (IOException e) {
    try {
    } catch (IOException e) {

MYSQL order by both Ascending and Descending sorting

I don't understand what the meaning of ordering with the same column ASC and DESC in the same ORDER BY, but this how you can do it: naam DESC, naam ASC like so:

ORDER BY `product_category_id` DESC,`naam` DESC, `naam` ASC

Convert string to variable name in JavaScript

You can access the window object as an associative array and set it that way

window["onlyVideo"] = "TEST";

Bootstrap date time picker

All scripts should be imported in order:

  1. jQuery and Moment.js
  2. Bootstrap js file
  3. Bootstrap datepicker js file

Bootstrap-datetimepicker requires moment.js to be loaded before datepicker.js.

Working snippet:

$(function() {_x000D_
<script src=""></script>_x000D_
<script src=""></script>_x000D_
<script src=""></script>_x000D_
<script src=""></script>_x000D_
<link rel="stylesheet" href="">_x000D_
<link rel="stylesheet" href="">_x000D_
<div class="container">_x000D_
  <div class="row">_x000D_
    <div class='col-sm-6'>_x000D_
      <div class="form-group">_x000D_
        <div class='input-group date' id='datetimepicker1'>_x000D_
          <input type='text' class="form-control" />_x000D_
          <span class="input-group-addon">_x000D_
            <span class="glyphicon glyphicon-calendar"></span>_x000D_

How to use Apple's new .p8 certificate for APNs in firebase console

Apple have recently made new changes in APNs and now apple insist us to use "Token Based Authentication" instead of the traditional ways which we are using for push notification.

So does not need to worry about their expiration and this p8 certificates are for both development and production so again no need to generate 2 separate certificate for each mode.

To generate p8 just go to your developer account and select this option "Apple Push Notification Authentication Key (Sandbox & Production)"

enter image description here

Then will generate directly p8 file.

I hope this will solve your issue.

Read this new APNs changes from apple:

Also you can read this:

How do I convert ticks to minutes?

TimeSpan.FromTicks( 28000000000 ).TotalMinutes;

VBA check if object is set

If obj Is Nothing Then
    ' need to initialize obj: '
    Set obj = ...
    ' obj already set / initialized. '
End If

Or, if you prefer it the other way around:

If Not obj Is Nothing Then
    ' obj already set / initialized. '
    ' need to initialize obj: '
    Set obj = ...
End If

long long int vs. long int vs. int64_t in C++

You don't need to go to 64-bit to see something like this. Consider int32_t on common 32-bit platforms. It might be typedef'ed as int or as a long, but obviously only one of the two at a time. int and long are of course distinct types.

It's not hard to see that there is no workaround which makes int == int32_t == long on 32-bit systems. For the same reason, there's no way to make long == int64_t == long long on 64-bit systems.

If you could, the possible consequences would be rather painful for code that overloaded foo(int), foo(long) and foo(long long) - suddenly they'd have two definitions for the same overload?!

The correct solution is that your template code usually should not be relying on a precise type, but on the properties of that type. The whole same_type logic could still be OK for specific cases:

long foo(long x);
std::tr1::disable_if(same_type(int64_t, long), int64_t)::type foo(int64_t);

I.e., the overload foo(int64_t) is not defined when it's exactly the same as foo(long).

[edit] With C++11, we now have a standard way to write this:

long foo(long x);
std::enable_if<!std::is_same<int64_t, long>::value, int64_t>::type foo(int64_t);

[edit] Or C++20

long foo(long x);
int64_t foo(int64_t) requires (!std::is_same_v<int64_t, long>);

Using with React components

First argument in update method is SyntheticEvent object that contains common properties and methods to any event, it is not reference to React component where there is property props.

if you need pass argument to update method you can do it like this

onClick={ (e) => this.props.onClick(e, 'home', 'Home') }

and get these arguments inside update method

update(e, space, txt){
   console.log(, space, txt);

Example gives you the native DOMNode, then you need to use the regular DOM APIs to access attributes. For instance getAttribute or dataset

  onClick={ this.props.onClick } 

onClick(e) {


Throw keyword in function's signature

Jalf already linked to it, but the GOTW puts it quite nicely why exception specifications are not as useful as one might hope:

int Gunc() throw();    // will throw nothing (?)
int Hunc() throw(A,B); // can only throw A or B (?)

Are the comments correct? Not quite. Gunc() may indeed throw something, and Hunc() may well throw something other than A or B! The compiler just guarantees to beat them senseless if they do… oh, and to beat your program senseless too, most of the time.

That's just what it comes down to, you probably just will end up with a call to terminate() and your program dying a quick but painful death.

The GOTWs conclusion is:

So here’s what seems to be the best advice we as a community have learned as of today:

  • Moral #1: Never write an exception specification.
  • Moral #2: Except possibly an empty one, but if I were you I’d avoid even that.


WHERE clause introduces a condition on individual rows; HAVING clause introduces a condition on aggregations, i.e. results of selection where a single result, such as count, average, min, max, or sum, has been produced from multiple rows. Your query calls for a second kind of condition (i.e. a condition on an aggregation) hence HAVING works correctly.

As a rule of thumb, use WHERE before GROUP BY and HAVING after GROUP BY. It is a rather primitive rule, but it is useful in more than 90% of the cases.

While you're at it, you may want to re-write your query using ANSI version of the join:

SELECT  L.LectID, Fname, Lname
FROM Lecturers L
JOIN Lecturers_Specialization S ON L.LectID=S.LectID
GROUP BY L.LectID, Fname, Lname
(SELECT COUNT(Expertise) FROM Lecturers_Specialization GROUP BY LectID)

This would eliminate WHERE that was used as a theta join condition.

Maximum value for long integer

A) For a cheap comparison / arithmetics dummy use math.inf. Or math.nan, which compares FALSE in any direction (including nan == nan) except identity check (is) and renders any arithmetics (like nan - nan) nan. Or a reasonably high real integer number according to your use case (e.g. sys.maxsize). For a bitmask dummy (e.g. in mybits & bitmask) use -1.

B) To get the platform primitive maximum signed long int (or long long):

>>> 256 ** sys.int_info.sizeof_digit // 2 - 1  # Python’s internal primitive
>>> 256 ** ctypes.sizeof(ctypes.c_long) // 2 - 1  # CPython
>>> 256 ** ctypes.sizeof(ctypes.c_longlong) // 2 - 1  # CPython
>>> 2**63 - 1  # Java / JPython primitive long

C) The maximum Python integer could be estimated by a long running loop teasing for a memory overflow (try 256**int(8e9) - can be stopped by KeyboardInterrupt). But it cannot not be used reasonably, because its representation already consumes all the memory and its much greater than sys.float_info.max.

"Unknown class <MyClass> in Interface Builder file" error at runtime

In my case I get this error message by a very stupid mistake by me: on interface builder I wanted to set the identifier of a UITableViewCell, but I typed the identifier accidentally to the 'Custom class' entry in interface builder.

I made cells 1000 times before....

Create a BufferedImage from file and make it TYPE_INT_ARGB

BufferedImage in =;

BufferedImage newImage = new BufferedImage(
    in.getWidth(), in.getHeight(), BufferedImage.TYPE_INT_ARGB);

Graphics2D g = newImage.createGraphics();
g.drawImage(in, 0, 0, null);

Best practices with STDIN in Ruby?

Something like this perhaps?

#/usr/bin/env ruby

if $stdin.tty?
  ARGV.each do |file|
    puts "do something with this file: #{file}"
  $stdin.each_line do |line|
    puts "do something with this line: #{line}"


> cat input.txt | ./myprog.rb
do something with this line: this
do something with this line: is
do something with this line: a
do something with this line: test
> ./myprog.rb < input.txt 
do something with this line: this
do something with this line: is
do something with this line: a
do something with this line: test
> ./myprog.rb arg1 arg2 arg3
do something with this file: arg1
do something with this file: arg2
do something with this file: arg3

How to implement a binary search tree in Python?

Another Python BST with sort key (defaulting to value)

LEFT = 0

class BinarySearchTree(object):

    def __init__(self, sort_key=None):
        self._root = []  
        self._sort_key = sort_key
        self._len = 0  

def insert(self, val):
    if self._sort_key is None:
        sort_key = val // if no sort key, sort key is value
        sort_key = self._sort_key(val)

    node = self._root
    while node:
        if sort_key < node[_SORT_KEY]:
            node = node[LEFT]
            node = node[RIGHT]

    if sort_key is val:
        node[:] = [[], [], val]
        node[:] = [[], [], val, sort_key]
    self._len += 1

def minimum(self):
    return self._extreme_node(LEFT)[VALUE]

def maximum(self):
    return self._extreme_node(RIGHT)[VALUE]

def find(self, sort_key):
    return self._find(sort_key)[VALUE]

def _extreme_node(self, side):
    if not self._root:
        raise IndexError('Empty')
    node = self._root
    while node[side]:
        node = node[side]
    return node

def _find(self, sort_key):
    node = self._root
    while node:
        node_key = node[SORT_KEY]
        if sort_key < node_key:
            node = node[LEFT]
        elif sort_key > node_key:
            node = node[RIGHT]
            return node
    raise KeyError("%r not found" % sort_key)

Equivalent function for DATEADD() in Oracle



Method 2: Interval

SYSDATE - interval '6' month

Note: if you want to do the operations from start of the current month always, TRUNC(SYSDATE,'MONTH') would give that. And it expects a Date datatype as input.

Calculating Page Load Time In JavaScript

Don't ever use the setInterval or setTimeout functions for time measuring! They are unreliable, and it is very likely that the JS execution scheduling during a documents parsing and displaying is delayed.

Instead, use the Date object to create a timestamp when you page began loading, and calculate the difference to the time when the page has been fully loaded:

<doctype html>
        <script type="text/javascript">
            var timerStart =;
        <!-- do all the stuff you need to do -->
        <!-- put everything you need in here -->

        <script type="text/javascript">
             $(document).ready(function() {
                 console.log("Time until DOMready: ",;
             $(window).load(function() {
                 console.log("Time until everything loaded: ",;

How can I make an "are you sure" prompt in a Windows batchfile?

Here a bit easier:

@echo off
set /p var=Are You Sure?[Y/N]: 
if %var%== Y goto ...
if not %var%== Y exit


@echo off
echo Are You Sure?[Y/N]
choice /c YN
if %errorlevel%==1 goto yes
if %errorlevel%==2 goto no
echo yes
goto :EOF
echo no

How does strtok() split the string into tokens in C?

The first time you call it, you provide the string to tokenize to strtok. And then, to get the following tokens, you just give NULL to that function, as long as it returns a non NULL pointer.

The strtok function records the string you first provided when you call it. (Which is really dangerous for multi-thread applications)

Adding custom radio buttons in android

Add a background drawable that references to an image, or a selector (like below), and make the button transparent:

    android:text="RadioButton1" />

If you would like your radio buttons to have a different resource when checked, create a selector background drawable:


<selector xmlns:android="" >
        android:state_pressed="true" />
        android:state_pressed="true" />
        android:state_checked="true" />
        android:drawable="@drawable/b" />

In the selector above, we reference two drawables, a and b, here's how we create them:

res/drawable/a.xml - Selected State

    android:shape="rectangle" >
        android:radius="5dp" />
        android:color="#fff" />
        android:color="#53aade" />

res/drawable/b.xml - Regular State

    android:shape="rectangle" >
        android:radius="5dp" />
        android:color="#fff" />
        android:color="#555555" />

More on drawables here:

Tricks to manage the available memory in an R session

With only 4GB of RAM (running Windows 10, so make that about 2 or more realistically 1GB) I've had to be real careful with the allocation.

I use data.table almost exclusively.

The 'fread' function allows you to subset information by field names on import; only import the fields that are actually needed to begin with. If you're using base R read, null the spurious columns immediately after import.

As 42- suggests, where ever possible I will then subset within the columns immediately after importing the information.

I frequently rm() objects from the environment as soon as they're no longer needed, e.g. on the next line after using them to subset something else, and call gc().

'fread' and 'fwrite' from data.table can be very fast by comparison with base R reads and writes.

As kpierce8 suggests, I almost always fwrite everything out of the environment and fread it back in, even with thousand / hundreds of thousands of tiny files to get through. This not only keeps the environment 'clean' and keeps the memory allocation low but, possibly due to the severe lack of RAM available, R has a propensity for frequently crashing on my computer; really frequently. Having the information backed up on the drive itself as the code progresses through various stages means I don't have to start right from the beginning if it crashes.

As of 2017, I think the fastest SSDs are running around a few GB per second through the M2 port. I have a really basic 50GB Kingston V300 (550MB/s) SSD that I use as my primary disk (has Windows and R on it). I keep all the bulk information on a cheap 500GB WD platter. I move the data sets to the SSD when I start working on them. This, combined with 'fread'ing and 'fwrite'ing everything has been working out great. I've tried using 'ff' but prefer the former. 4K read/write speeds can create issues with this though; backing up a quarter of a million 1k files (250MBs worth) from the SSD to the platter can take hours. As far as I'm aware, there isn't any R package available yet that can automatically optimise the 'chunkification' process; e.g. look at how much RAM a user has, test the read/write speeds of the RAM / all the drives connected and then suggest an optimal 'chunkification' protocol. This could produce some significant workflow improvements / resource optimisations; e.g. split it to ... MB for the ram -> split it to ... MB for the SSD -> split it to ... MB on the platter -> split it to ... MB on the tape. It could sample data sets beforehand to give it a more realistic gauge stick to work from.

A lot of the problems I've worked on in R involve forming combination and permutation pairs, triples etc, which only makes having limited RAM more of a limitation as they will often at least exponentially expand at some point. This has made me focus a lot of attention on the quality as opposed to quantity of information going into them to begin with, rather than trying to clean it up afterwards, and on the sequence of operations in preparing the information to begin with (starting with the simplest operation and increasing the complexity); e.g. subset, then merge / join, then form combinations / permutations etc.

There do seem to be some benefits to using base R read and write in some instances. For instance, the error detection within 'fread' is so good it can be difficult trying to get really messy information into R to begin with to clean it up. Base R also seems to be a lot easier if you're using Linux. Base R seems to work fine in Linux, Windows 10 uses ~20GB of disc space whereas Ubuntu only needs a few GB, the RAM needed with Ubuntu is slightly lower. But I've noticed large quantities of warnings and errors when installing third party packages in (L)Ubuntu. I wouldn't recommend drifting too far away from (L)Ubuntu or other stock distributions with Linux as you can loose so much overall compatibility it renders the process almost pointless (I think 'unity' is due to be cancelled in Ubuntu as of 2017). I realise this won't go down well with some Linux users but some of the custom distributions are borderline pointless beyond novelty (I've spent years using Linux alone).

Hopefully some of that might help others out.

What does Maven do, in theory and in practice? When is it worth to use it?

From the Sonatype doc:

The answer to this question depends on your own perspective. The great majority of Maven users are going to call Maven a “build tool”: a tool used to build deployable artifacts from source code. Build engineers and project managers might refer to Maven as something more comprehensive: a project management tool. What is the difference? A build tool such as Ant is focused solely on preprocessing, compilation, packaging, testing, and distribution. A project management tool such as Maven provides a superset of features found in a build tool. In addition to providing build capabilities, Maven can also run reports, generate a web site, and facilitate communication among members of a working team.

I'd strongly recommend looking at the Sonatype doc and spending some time looking at the available plugins to understand the power of Maven.

Very briefly, it operates at a higher conceptual level than (say) Ant. With Ant, you'd specify the set of files and resources that you want to build, then specify how you want them jarred together, and specify the order that should occur in (clean/compile/jar). With Maven this is all implicit. Maven expects to find your files in particular places, and will work automatically with that. Consequently setting up a project with Maven can be a lot simpler, but you have to play by Maven's rules!

How to add one column into existing SQL Table

What about something like:

Alter Table Products
Add LastUpdate varchar(200) null

Do you need something more complex than this?

Easiest way to ignore blank lines when reading a file in Python

Why are you all going the hard way?

with open("myfile") as myfile:
    nonempty = filter(str.rstrip, myfile)

Convert nonempty into a list if you have the urge to do so, although I highly suggest keeping nonempty a generator as it is in Python 3.x

In Python 2.x you may use itertools.ifilter to do your bidding instead.

With MySQL, how can I generate a column containing the record index in a table?

Here comes the structure of template I used:

          /*this is a row number counter*/
          ( select @rownum := @rownum + 1 from ( select @rownum := 0 ) d2 ) 
          as rownumber,
  ( select d1.* from table_name d1 ) d3

And here is my working code:

           ( select @rownum := @rownum + 1 from ( select @rownum := 0 ) d2 ) 
           as rownumber,
(   select     year( ), month( ), count( )
    from       maindatabase d1
    where      ( ( >= '2013-01-01' ) and ( <= '2014-12-31' ) )
    group by   YEAR( ), MONTH( ) ) d3

Iterating through directories with Python

From python >= 3.5 onward, you can use **, glob.iglob(path/**, recursive=True) and it seems the most pythonic solution, i.e.:

import glob, os

for filename in glob.iglob('/pardadox-music/**', recursive=True):
    if os.path.isfile(filename): # filter dirs



1 - glob.iglob

glob.iglob(pathname, recursive=False)

Return an iterator which yields the same values as glob() without actually storing them all simultaneously.

2 - If recursive is True, the pattern '**' will match any files and zero or more directories and subdirectories.

3 - If the directory contains files starting with . they won’t be matched by default. For example, consider a directory containing card.gif and .card.gif:

>>> import glob
>>> glob.glob('*.gif') ['card.gif'] 
>>> glob.glob('.c*')['.card.gif']

4 - You can also use rglob(pattern), which is the same as calling glob() with **/ added in front of the given relative pattern.

Concatenate two string literals

Your second example does not work because there is no operator + for two string literals. Note that a string literal is not of type string, but instead is of type const char *. Your second example will work if you revise it like this:

const string message = string("Hello") + ",world" + exclam;

Node update a specific package

Always you can do it manually. Those are the steps:

  • Go to the NPM package page, and search for the GitHub link.
  • Now download the latest version using GitHub download link, or by clonning. git clone github_url
  • Copy the package to your node_modules folder for e.g. node_modules/browser-sync

Now it should work for you. To be sure it will not break in the future when you do npm i, continue the upcoming two steps:

  • Check the version of the new package by reading the package.json file in it's folder.
  • Open your project package.json and set the same version for where it's appear in the dependencies part of your package.json

While it's not recommened to do it manually. Sometimes it's good to understand how things are working under the hood, to be able to fix things. I found myself doing it from time to time.

Import an Excel worksheet into Access using VBA

Pass the sheet name with the Range parameter of the DoCmd.TransferSpreadsheet Method. See the box titled "Worksheets in the Range Parameter" near the bottom of that page.

This code imports from a sheet named "temp" in a workbook named "temp.xls", and stores the data in a table named "tblFromExcel".

Dim strXls As String
strXls = CurrentProject.Path & Chr(92) & "temp.xls"
DoCmd.TransferSpreadsheet acImport, , "tblFromExcel", _
    strXls, True, "temp!"

How can a Javascript object refer to values in itself?

You can't refer to a property of an object before you have initialized that object; use an external variable.

var key1 = "it";
var obj = {
  key1 : key1,
  key2 : key1 + " works!"

Also, this is not a "JSON object"; it is a Javascript object. JSON is a method of representing an object with a string (which happens to be valid Javascript code).

html5 <input type="file" accept="image/*" capture="camera"> display as image rather than "choose file" button

You can trigger a file input element by sending it a Javascript click event, e.g.

<input type="file" ... id="file-input">


You could put this in a click event handler for the image, for instance, then hide the file input with CSS. It'll still work even if it's invisible.

Once you've got that part working, you can set a change event handler on the input element to see when the user puts a file into it. This event handler can create a temporary "blob" URL for the image by using window.URL.createObjectURL, e.g.:

var file = document.getElementById("file-input").files[0];
var blob_url = window.URL.createObjectURL(file);

That URL can be set as the src for an image on the page. (It only works on that page, though. Don't try to save it anywhere.)

Note that not all browsers currently support camera capture. (In fact, most desktop browsers don't.) Make sure your interface still makes sense if the user gets asked to pick a file.

Is a new line = \n OR \r\n?

\n is used for Unix systems (including Linux, and OSX).

\r\n is mainly used on Windows.

\r is used on really old Macs.

PHP_EOL constant is used instead of these characters for portability between platforms.

Jackson and generic type reference

This is a well-known problem with Java type erasure: T is just a type variable, and you must indicate actual class, usually as Class argument. Without such information, best that can be done is to use bounds; and plain T is roughly same as 'T extends Object'. And Jackson will then bind JSON Objects as Maps.

In this case, tester method needs to have access to Class, and you can construct

JavaType type = mapper.getTypeFactory().
  constructCollectionType(List.class, Foo.class)

and then

List<Foo> list = mapper.readValue(new File("input.json"), type);