Programs & Examples On #Idictionary

System.Collections.IDictionary and System.Collections.Generic.IDictionary interfaces in the BCL (Base Class Library) of the .NET framework represent a collection of key-value pairs.

Recreating a Dictionary from an IEnumerable<KeyValuePair<>>

If you're using .NET 3.5 or .NET 4, it's easy to create the dictionary using LINQ:

Dictionary<string, ArrayList> result = target.GetComponents()
                                      .ToDictionary(x => x.Key, x => x.Value);

There's no such thing as an IEnumerable<T1, T2> but a KeyValuePair<TKey, TValue> is fine.

Is it better in C++ to pass by value or pass by constant reference?

Simple difference :- In function we have input and output parameter , so if your passing input and out parameter is same then use call by reference else if input and output parameter are different then better to use call by value .

example void amount(int account , int deposit , int total )

input parameter : account , deposit output paramteter: total

input and out is different use call by vaule

  1. void amount(int total , int deposit )

input total deposit output total

Rotation of 3D vector?

Using the Euler-Rodrigues formula:

import numpy as np
import math

def rotation_matrix(axis, theta):
    Return the rotation matrix associated with counterclockwise rotation about
    the given axis by theta radians.
    axis = np.asarray(axis)
    axis = axis / math.sqrt(, axis))
    a = math.cos(theta / 2.0)
    b, c, d = -axis * math.sin(theta / 2.0)
    aa, bb, cc, dd = a * a, b * b, c * c, d * d
    bc, ad, ac, ab, bd, cd = b * c, a * d, a * c, a * b, b * d, c * d
    return np.array([[aa + bb - cc - dd, 2 * (bc + ad), 2 * (bd - ac)],
                     [2 * (bc - ad), aa + cc - bb - dd, 2 * (cd + ab)],
                     [2 * (bd + ac), 2 * (cd - ab), aa + dd - bb - cc]])

v = [3, 5, 0]
axis = [4, 4, 1]
theta = 1.2 

print(, theta), v)) 
# [ 2.74911638  4.77180932  1.91629719]

How can I delay a method call for 1 second?

You can also:

[UIView animateWithDuration:1.0
                 animations:^{ self.view.alpha = 1.1; /* Some fake chages */ }
                 completion:^(BOOL finished)
    NSLog(@"A second lapsed.");

This case you have to fake some changes to some view to get the animation work. It is hacky indeed, but I love the block based stuff. Or wrap up @mcfedr answer below.

waitFor(1.0, ^
    NSLog(@"A second lapsed");

typedef void (^WaitCompletionBlock)();
void waitFor(NSTimeInterval duration, WaitCompletionBlock completion)
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, duration * NSEC_PER_SEC),
                   dispatch_get_main_queue(), ^
    { completion(); });

JavaScript closures vs. anonymous functions

You are both using closures.

I 'm going with the Wikipedia definition here:

In computer science, a closure (also lexical closure or function closure) is a function or reference to a function together with a referencing environment—a table storing a reference to each of the non-local variables (also called free variables) of that function. A closure—unlike a plain function pointer—allows a function to access those non-local variables even when invoked outside of its immediate lexical scope.

Your friend's attempt clearly uses the variable i, which is non-local, by taking its value and making a copy to store into the local i2.

Your own attempt passes i (which at the call site is in scope) to an anonymous function as an argument. This is not a closure so far, but then that function returns another function that references the same i2. Since inside the inner anonymous function i2 is not a local, this creates a closure.

How to find a whole word in a String in java

Try to match using regular expressions. Match for "\b123wood\b", \b is a word break.

change type of input field with jQuery

An ultimate way to use jQuery:

Leave the original input field hidden from the screen.

$("#Password").hide(); //Hide it first
var old_id = $("#Password").attr("id"); //Store ID of hidden input for later use
$("#Password").attr("id","Password_hidden"); //Change ID for hidden input

Create new input field on the fly by JavaScript.

var new_input = document.createElement("input");

Migrate the ID and value from hidden input field to the new input field.

new_input.setAttribute("id", old_id); //Assign old hidden input ID to new input
new_input.setAttribute("type","text"); //Set proper type
new_input.value = $("#Password_hidden").val(); //Transfer the value to new input
$("#Password_hidden").after(new_input); //Add new input right behind the hidden input

To get around the error on IE like type property cannot be changed, you may find this useful as belows:

Attach click/focus/change event to new input element, in order to trigger the same event on hidden input.

//Replicate above line for all other events like focus, change and so on...

Old hidden input element is still inside the DOM so will react with the event triggered by new input element. As ID is swapped, new input element will act like the old one and respond to any function call to old hidden input's ID, but looks different.

A little bit tricky but WORKS!!! ;-)

GitLab git user password

This can happen if the host has a '-' in its name. (Even though this is legal according to RFC 952.) (Tested using Git Bash under Windows 10 using git 2.13.2.)

ssh prompts me for a password for any host that happens to have a '-' in its name. This would seem to be purely a problem with ssh configuration file parsing because adding an alias to ~/.ssh/config (and using that alias in my git remote urls) resolved the problem.

In other words try putting something like the following in your C:/Users/{username}/.ssh/config

Host {a}
    User git
    Hostname {a-b.domain}
    IdentityFile C:/Users/{username}/.ssh/id_rsa

and where you have a remote of the form

origin  [email protected]:repo-name.git

change the url to use the following the form

git remote set-url origin git@a:repo-name.git

Difference between SelectedItem, SelectedValue and SelectedValuePath

Their names can be a bit confusing :). Here's a summary:

  • The SelectedItem property returns the entire object that your list is bound to. So say you've bound a list to a collection of Category objects (with each Category object having Name and ID properties). eg. ObservableCollection<Category>. The SelectedItem property will return you the currently selected Category object. For binding purposes however, this is not always what you want, as this only enables you to bind an entire Category object to the property that the list is bound to, not the value of a single property on that Category object (such as its ID property).

  • Therefore we have the SelectedValuePath property and the SelectedValue property as an alternative means of binding (you use them in conjunction with one another). Let's say you have a Product object, that your view is bound to (with properties for things like ProductName, Weight, etc). Let's also say you have a CategoryID property on that Product object, and you want the user to be able to select a category for the product from a list of categories. You need the ID property of the Category object to be assigned to the CategoryID property on the Product object. This is where the SelectedValuePath and the SelectedValue properties come in. You specify that the ID property on the Category object should be assigned to the property on the Product object that the list is bound to using SelectedValuePath='ID', and then bind the SelectedValue property to the property on the DataContext (ie. the Product).

The example below demonstrates this. We have a ComboBox bound to a list of Categories (via ItemsSource). We're binding the CategoryID property on the Product as the selected value (using the SelectedValue property). We're relating this to the Category's ID property via the SelectedValuePath property. And we're saying only display the Name property in the ComboBox, with the DisplayMemberPath property).

<ComboBox ItemsSource="{Binding Categories}" 
          SelectedValue="{Binding CategoryID, Mode=TwoWay}" 
          DisplayMemberPath="Name" />
public class Category
    public int ID { get; set; }
    public string Name { get; set; }

public class Product
    public int CategoryID { get; set; }

It's a little confusing initially, but hopefully this makes it a bit clearer... :)


How to pip or easy_install tkinter on Windows

Well I can see two solutions here:

1) Follow the Docs-Tkinter install for Python (for Windows):

Tkinter (and, since Python 3.1, ttk) are included with all standard Python distributions. It is important that you use a version of Python supporting Tk 8.5 or greater, and ttk. We recommend installing the "ActivePython" distribution from ActiveState, which includes everything you'll need.

In your web browser, go to, and follow along the links to download the Community Edition of ActivePython for Windows. Make sure you're downloading a 3.1 or newer version, not a 2.x version.

Run the installer, and follow along. You'll end up with a fresh install of ActivePython, located in, e.g. C:\python32. From a Windows command prompt, or the Start Menu's "Run..." command, you should then be able to run a Python shell via:

% C:\python32\python

This should give you the Python command prompt. From the prompt, enter these two commands:

>>> import tkinter
>>> tkinter._test()

This should pop up a small window; the first line at the top of the window should say "This is Tcl/Tk version 8.5"; make sure it is not 8.4!

2) Uninstall 64-bit Python and install 32 bit Python.

How to get a product's image in Magento?

If you have the product collection object like:

$collection = Mage::getModel('catalog/product')->getCollection(); 

Now you can get product sku using $_product->getSku() if you can't get image path with

echo $this->helper('catalog/image')->init($_product,'small_image')->resize(135);



Then you can add a little code

$productModel = Mage::getModel('catalog/product');
$_prod = $productModel->loadByAttribute('sku', $_product->getSku()); 

Detecting the character encoding of an HTTP POST request

the default encoding of a HTTP POST is ISO-8859-1.

else you have to look at the Content-Type header that will then look like

Content-Type: application/x-www-form-urlencoded ; charset=UTF-8

You can maybe declare your form with

<form enctype="application/x-www-form-urlencoded;charset=UTF-8">


<form accept-charset="UTF-8">

to force the encoding.

Some references :

How do I get the max and min values from a set of numbers entered?

//for excluding zero
public class SmallestInt {

    public static void main(String[] args) {

        Scanner input= new Scanner(;

        System.out.println("enter number");
        int val=input.nextInt();
        int min=val;

        //String notNull;

        System.out.println("min is: "+min);

Best way to handle list.index(might-not-exist) in python?

It's been quite some time but it's a core part of the stdlib and has dozens of potential methods so I think it's useful to have some benchmarks for the different suggestions and include the numpy method which can be by far the fastest.

import random
from timeit import timeit
import numpy as np

l = [random.random() for i in range(10**4)]
l[10**4 - 100] = 5

# method 1
def fun1(l:list, x:int, e = -1) -> int:
    return [[i for i,elem in enumerate(l) if elem == x] or [e]][0]

# method 2
def fun2(l:list, x:int, e = -1) -> int:
    for i,elem in enumerate(l):
        if elem == x:
            return i
        return e

# method 3
def fun3(l:list, x:int, e = -1) -> int:
        idx = l.index(x)
    except ValueError:
        idx = e
    return idx

# method 4
def fun4(l:list, x:int, e = -1) -> int:
    return l.index(x) if x in l else e

l2 = np.array(l)
# method 5
def fun5(l:list or np.ndarray, x:int, e = -1) -> int:
    res = np.where(np.equal(l, x))
    if res[0].any():
        return res[0][0]
        return e

if __name__ == "__main__":
    print("Method 1:")
    print(timeit(stmt = "fun1(l, 5)", number = 1000, globals = globals()))
    print("Method 2:")
    print(timeit(stmt = "fun2(l, 5)", number = 1000, globals = globals()))
    print("Method 3:")
    print(timeit(stmt = "fun3(l, 5)", number = 1000, globals = globals()))
    print("Method 4:")
    print(timeit(stmt = "fun4(l, 5)", number = 1000, globals = globals()))
    print("Method 5, numpy given list:")
    print(timeit(stmt = "fun5(l, 5)", number = 1000, globals = globals()))
    print("Method 6, numpy given np.ndarray:")
    print(timeit(stmt = "fun5(l2, 5)", number = 1000, globals = globals()))

When run as main, this results in the following printout on my machine indicating time in seconds to complete 1000 trials of each function:

Method 1: 0.7502102799990098

Method 2: 0.7291318440002215

Method 3: 0.24142152300009911

Method 4: 0.5253471979995084

Method 5, numpy given list: 0.5045417560013448

Method 6, numpy given np.ndarray: 0.011147511999297421

Of course the question asks specifically about lists so the best solution is to use the try-except method, however the speed improvements (at least 20x here compared to try-except) offered by using the numpy data structures and operators instead of python data structures is significant and if building something on many arrays of data that is performance critical then the author should try to use numpy throughout to take advantage of the superfast C bindings. (CPython interpreter, other interpreter performances may vary)

Btw, the reason Method 5 is much slower than Method 6 is because numpy first has to convert the given list to it's own numpy array, so giving it a list doesn't break it it just doesn't fully utilise the speed possible.

Reading file line by line (with space) in Unix Shell scripting - Issue

You want to read raw lines to avoid problems with backslashes in the input (use -r):

while read -r line; do
   printf "<%s>\n" "$line"
done < file.txt

This will keep whitespace within the line, but removes leading and trailing whitespace. To keep those as well, set the IFS empty, as in

while IFS= read -r line; do
   printf "%s\n" "$line"
done < file.txt

This now is an equivalent of cat < file.txt as long as file.txt ends with a newline.

Note that you must double quote "$line" in order to keep word splitting from splitting the line into separate words--thus losing multiple whitespace sequences.

How to Scroll Down - JQuery

If you want to scroll down to the div (id="div1"). Then you can use this code.

 $('html, body').animate({
     scrollTop: $("#div1").offset().top
 }, 1500);

Fit Image in ImageButton in Android

You can make your ImageButton widget as I did. In my case, I needed a widget with a fixed icon size. Let's start from custom attributes:

<?xml version="1.0" encoding="utf-8"?>
    <declare-styleable name="ImageButtonFixedIconSize">
        <attr name="imageButton_icon" format="reference" />
        <attr name="imageButton_iconWidth" format="dimension" />
        <attr name="imageButton_iconHeight" format="dimension" />

Widget class is quite simple (the key point is padding calculations in onLayout method):

class ImageButtonFixedIconSize
    context: Context,
    attrs: AttributeSet? = null,
    defStyleAttr: Int = android.R.attr.imageButtonStyle
) : ImageButton(context, attrs, defStyleAttr) {

    private lateinit var icon: Drawable

    private var iconWidth: Int = 0
    private var iconHeight: Int = 0

    init {
        scaleType = ScaleType.FIT_XY
        attrs?.let { retrieveAttributes(it) }

    override fun onLayout(changed: Boolean, left: Int, top: Int, right: Int, bottom: Int) {
        val width = right - left
        val height = bottom - top

        val horizontalPadding = if(width > iconWidth) (width - iconWidth) / 2 else 0
        val verticalPadding = if(height > iconHeight) (height - iconHeight) / 2 else 0

        setPadding(horizontalPadding, verticalPadding, horizontalPadding, verticalPadding)


        super.onLayout(changed, left, top, right, bottom)

    private fun retrieveAttributes(attrs: AttributeSet) {
        val typedArray = context.obtainStyledAttributes(attrs, R.styleable.ImageButtonFixedIconSize)

        icon = typedArray.getDrawable(R.styleable.ImageButtonFixedIconSize_imageButton_icon)!!

        iconWidth = typedArray.getDimension(R.styleable.ImageButtonFixedIconSize_imageButton_iconWidth, 0f).toInt()
        iconHeight = typedArray.getDimension(R.styleable.ImageButtonFixedIconSize_imageButton_iconHeight, 0f).toInt()


And at last you should use your widget like this:




PHP regular expression - filter number only

Using is_numeric or intval is likely the best way to validate a number here, but to answer your question you could try using preg_replace instead. This example removes all non-numeric characters:

$output = preg_replace( '/[^0-9]/', '', $string );

How does Facebook Sharer select Images and other metadata when sharing my URL?

For secure HTTPS

<meta property="og:image:secure_url" content="https://image.path.png" />

How to sparsely checkout only one single file from a git repository?

Very simple:

git checkout from-branch-name -- path/to/the/file/you/want

This will not checkout the from-branch-name branch. You will stay on whatever branch you are on, and only that single file will be checked out from the specified branch.

Here's the relevant part of the manpage for git-checkout

git checkout [-p|--patch] [<tree-ish>] [--] <pathspec>...
       When <paths> or --patch are given, git checkout does not switch
       branches. It updates the named paths in the working tree from the
       index file or from a named <tree-ish> (most often a commit). In
       this case, the -b and --track options are meaningless and giving
       either of them results in an error. The <tree-ish> argument can be
       used to specify a specific tree-ish (i.e. commit, tag or tree) to
       update the index for the given paths before updating the working

Hat tip to Ariejan de Vroom who taught me this from this blog post.

Use a loop to plot n charts Python

We can create a for loop and pass all the numeric columns into it. The loop will plot the graphs one by one in separate pane as we are including plt.figure() into it.

import pandas as pd
import seaborn as sns
import numpy as np

numeric_features=[x for x in data.columns if data[x].dtype!="object"]
#taking only the numeric columns from the dataframe.

for i in data[numeric_features].columns:

How do I create a new user in a SQL Azure database?

Check out this link for all of the information :

First you need to create a login for SQL Azure, its syntax is as follows:

CREATE LOGIN username WITH password='password';

This command needs to run in master db. Only afterwards can you run commands to create a user in the database. The way SQL Azure or SQL Server works is that there is a login created first at the server level and then it is mapped to a user in every database.


How to run a script at a certain time on Linux?

The at command exists specifically for this purpose (unlike cron which is intended for scheduling recurring tasks).

at $(cat file) </path/to/script

How to check if an object is a list or tuple (but not string)?

I do this in my testcases.

def assertIsIterable(self, item):
    #add types here you don't want to mistake as iterables
    if isinstance(item, basestring): 
        raise AssertionError("type %s is not iterable" % type(item))

    #Fake an iteration.
        for x in item:
    except TypeError:
        raise AssertionError("type %s is not iterable" % type(item))

Untested on generators, I think you are left at the next 'yield' if passed in a generator, which may screw things up downstream. But then again, this is a 'unittest'

visual c++: #include files from other projects in the same solution

Expanding on @Benav's answer, my preferred approach is to:

  1. Add the solution directory to your include paths:
    • right click on your project in the Solution Explorer
    • select Properties
    • select All Configurations and All Platforms from the drop-downs
    • select C/C++ > General
    • add $(SolutionDir) to the Additional Include Directories
  2. Add references to each project you want to use:
    • right click on your project's References in the Solution Explorer
    • select Add Reference...
    • select the project(s) you want to refer to

Now you can include headers from your referenced projects like so:

#include "OtherProject/Header.h"


  • This assumes that your solution file is stored one folder up from each of your projects, which is the default organization when creating projects with Visual Studio.
  • You could now include any file from a path relative to the solution folder, which may not be desirable but for the simplicity of the approach I'm ok with this.
  • Step 2 isn't necessary for #includes, but it sets the correct build dependencies, which you probably want.

Accessing Redux state in an action creator?

I know I'm late to the party here, but I came here for opinions on my own desire to use state in actions, and then formed my own, when I realized what I think is the correct behavior.

This is where a selector makes the most sense to me. Your component that issues this request should be told wether it's time to issue it through selection.

export const SOME_ACTION = 'SOME_ACTION';
export function someAction(items) {
  return (dispatch) => {

It might feel like leaking abstractions, but your component clearly needs to send a message and the message payload should contain pertinent state. Unfortunately your question doesn't have a concrete example because we could work through a 'better model' of selectors and actions that way.

How to enable directory listing in apache web server

Once I changed Options -Index to Options +Index in my conf file, I removed the welcome page and restarted services.

$ sudo rm -f /etc/httpd/conf.d/welcome.conf
$ sudo service httpd restart

I was able to see directory listings after that.

Difference between exit() and sys.exit() in Python

If I use exit() in a code and run it in the shell, it shows a message asking whether I want to kill the program or not. It's really disturbing. See here

But sys.exit() is better in this case. It closes the program and doesn't create any dialogue box.

How to export plots from matplotlib with transparent background?

Use the matplotlib savefig function with the keyword argument transparent=True to save the image as a png file.

In [30]: x = np.linspace(0,6,31)

In [31]: y = np.exp(-0.5*x) * np.sin(x)

In [32]: plot(x, y, 'bo-')
Out[32]: [<matplotlib.lines.Line2D at 0x3f29750>]            

In [33]: savefig('demo.png', transparent=True)

Result: demo.png

Of course, that plot doesn't demonstrate the transparency. Here's a screenshot of the PNG file displayed using the ImageMagick display command. The checkerboard pattern is the background that is visible through the transparent parts of the PNG file.

display screenshot

How to use cookies in Python Requests

From the documentation:

  1. get cookie from response

    url = ''
    r = requests.get(url)

    {'example_cookie_name': 'example_cookie_value'}

  2. give cookie back to server on subsequent request

    url = ''
    cookies = dict(cookies_are='working')
    r = requests.get(url, cookies=cookies)`

CSS change button style after click

Try to check outline on button's focus:

button:focus {
    outline: blue auto 5px; 

If you have it, just set it to none.

How to resolve symbolic links in a shell script

Another way:

# Gets the real path of a link, following all links
myreadlink() { [ ! -h "$1" ] && echo "$1" || (local link="$(expr "$(command ls -ld -- "$1")" : '.*-> \(.*\)$')"; cd $(dirname $1); myreadlink "$link" | sed "s|^\([^/].*\)\$|$(dirname $1)/\1|"); }

# Returns the absolute path to a command, maybe in $PATH (which) or not. If not found, returns the same
whereis() { echo $1 | sed "s|^\([^/].*/.*\)|$(pwd)/\1|;s|^\([^/]*\)$|$(which -- $1)|;s|^$|$1|"; } 

# Returns the realpath of a called command.
whereis_realpath() { local SCRIPT_PATH=$(whereis $1); myreadlink ${SCRIPT_PATH} | sed "s|^\([^/].*\)\$|$(dirname ${SCRIPT_PATH})/\1|"; } 

Can I set a TTL for @Cacheable

Spring 3.1 and Guava 1.13.1:

public class CacheConfiguration implements CachingConfigurer {

    public CacheManager cacheManager() {
        ConcurrentMapCacheManager cacheManager = new ConcurrentMapCacheManager() {

            protected Cache createConcurrentMapCache(final String name) {
                return new ConcurrentMapCache(name,
                    CacheBuilder.newBuilder().expireAfterWrite(30, TimeUnit.MINUTES).maximumSize(100).build().asMap(), false);

        return cacheManager;

    public KeyGenerator keyGenerator() {
        return new DefaultKeyGenerator();


'Static readonly' vs. 'const'

One thing to note is const is restricted to primitive/value types (the exception being strings).

How to find which columns contain any NaN value in Pandas dataframe

This worked for me,

1. For getting Columns having at least 1 null value. (column names)


2. For getting Columns with count, with having at least 1 null value.


[Optional] 3. For getting percentage of the null count.

data[data.columns[data.isnull().any()]].isnull().sum() * 100 / data.shape[0]

How return error message in spring mvc @Controller

return new ResponseEntity<>(GenericResponseBean.newGenericError("Error during the calling the service", -1L), HttpStatus.EXPECTATION_FAILED);

Use JavaScript to place cursor at end of text in text input element

var valsrch = $('#search').val();

Eclipse will not start and I haven't changed anything


$ rm YOUR_PROJECT_DIR/.metadata/.plugins/org.eclipse.core.resources/.snap

Original source: Job found still running after platform shutdown eclipse

Check if String / Record exists in DataTable

Use the Find method if item_manuf_id is a primary key:

var result = dtPs.Rows.Find("some value");

If you only want to know if the value is in there then use the Contains method.

if (dtPs.Rows.Contains("some value"))

Primary key restriction applies to Contains aswell.

Arrays vs Vectors: Introductory Similarities and Differences


  • are a builtin language construct;
  • come almost unmodified from C89;
  • provide just a contiguous, indexable sequence of elements; no bells and whistles;
  • are of fixed size; you can't resize an array in C++ (unless it's an array of POD and it's allocated with malloc);
  • their size must be a compile-time constant unless they are allocated dynamically;
  • they take their storage space depending from the scope where you declare them;
  • if dynamically allocated, you must explicitly deallocate them;
  • if they are dynamically allocated, you just get a pointer, and you can't determine their size; otherwise, you can use sizeof (hence the common idiom sizeof(arr)/sizeof(*arr), that however fails silently when used inadvertently on a pointer);
  • automatically decay to a pointers in most situations; in particular, this happens when passing them to a function, which usually requires passing a separate parameter for their size;
  • can't be returned from a function;
  • can't be copied/assigned directly;
  • dynamical arrays of objects require a default constructor, since all their elements must be constructed first;


  • is a template class;
  • is a C++ only construct;
  • is implemented as a dynamic array;
  • grows and shrinks dynamically;
  • automatically manage their memory, which is freed on destruction;
  • can be passed to/returned from functions (by value);
  • can be copied/assigned (this performs a deep copy of all the stored elements);
  • doesn't decay to pointers, but you can explicitly get a pointer to their data (&vec[0] is guaranteed to work as expected);
  • always brings along with the internal dynamic array its size (how many elements are currently stored) and capacity (how many elements can be stored in the currently allocated block);
  • the internal dynamic array is not allocated inside the object itself (which just contains a few "bookkeeping" fields), but is allocated dynamically by the allocator specified in the relevant template parameter; the default one gets the memory from the freestore (the so-called heap), independently from how where the actual object is allocated;
  • for this reason, they may be less efficient than "regular" arrays for small, short-lived, local arrays;
  • when reallocating, the objects are copied (moved, in C++11);
  • does not require a default constructor for the objects being stored;
  • is better integrated with the rest of the so-called STL (it provides the begin()/end() methods, the usual STL typedefs, ...)

Also consider the "modern alternative" to arrays - std::array; I already described in another answer the difference between std::vector and std::array, you may want to have a look at it.

How to set iframe size dynamically

I've found this to work the best across all browsers and devices (PC, tables & mobile).

<script type="text/javascript">
                      function iframeLoaded() {
                          var iFrameID = document.getElementById('idIframe');
                          if(iFrameID) {
                                // here you can make the height, I delete it first, then I make it again
                                iFrameID.height = "";
                                iFrameID.height = iFrameID.contentWindow.document.body.scrollHeight + "px";

<iframe id="idIframe" onload="iframeLoaded()" frameborder="0" src="yourpage.php" height="100%" width="100%" scrolling="no"></iframe>

How to add a hook to the application context initialization event?

I had a single page application on entering URL it was creating a HashMap (used by my webpage) which contained data from multiple databases. I did following things to load everything during server start time-

1- Created ContextListenerClass

public class MyAppContextListener implements ServletContextListener

    private  MyDataProviderBean myDataProviderBean; 

    public MyDataProviderBean getMyDataProviderBean() {

        return MyDataProviderBean;


    public void setMyDataProviderBean(MyDataProviderBean MyDataProviderBean) {

        this.myDataProviderBean = MyDataProviderBean;


    public void contextDestroyed(ServletContextEvent arg0) {

        System.out.println("ServletContextListener destroyed");



    public void contextInitialized(ServletContextEvent context) {

        System.out.println("ServletContextListener started");

        ServletContext sc = context.getServletContext();

        WebApplicationContext springContext = WebApplicationContextUtils.getWebApplicationContext(sc);

        MyDataProviderBean MyDataProviderBean = (MyDataProviderBean)springContext.getBean("myDataProviderBean");

        Map<String, Object> myDataMap = MyDataProviderBean.getDataMap();

        sc.setAttribute("myMap", myDataMap);


2- Added below entry in web.xml


3- In my Controller Class updated code to first check for Map in servletContext

    @RequestMapping(value = "/index", method = RequestMethod.GET)
        public String index(@ModelAttribute("model") ModelMap model) {

            Map<String, Object> myDataMap = new HashMap<String, Object>();
            if (context != null && context.getAttribute("myMap")!=null)

                myDataMap=(Map<String, Object>)context.getAttribute("myMap");


                myDataMap = myDataProviderBean.getDataMap();

            for (String key : myDataMap.keySet())
                model.addAttribute(key, myDataMap.get(key));
            return "myWebPage";


With this much change when I start my tomcat it loads dataMap during startTime and puts everything in servletContext which is then used by Controller Class to get results from already populated servletContext .

How is a non-breaking space represented in a JavaScript string?

The jQuery docs for text() says

Due to variations in the HTML parsers in different browsers, the text returned may vary in newlines and other white space.

I'd use $td.html() instead.

Cannot call getSupportFragmentManager() from activity

This worked for me. Running android API 19 and above.

FragmentManager fragMan = getFragmentManager();

Keyboard shortcut to comment lines in Sublime Text 2

Ctrl+d and Ctrl+Shift+d....


{ "keys": ["ctrl+d"], "command": "toggle_comment", "args": { "block": false } },

{ "keys": ["ctrl+shift+d"], "command": "toggle_comment", "args": { "block": true } },


How to generate .env file for laravel?

There's another explanation for why .env doesn't exist, and it happens when you move all the Laravel files.

Take this workflow: in your project directory you do laravel new whatever, Laravel is installed in whatever, you do mv * .. to move all the files to your project folder, and you remove whatever. The problem is, mv doesn't move hidden files by default, so the .env files are left behind, and are removed!

Escape text for HTML

nobody has mentioned yet, in ASP.NET 4.0 there's new syntax to do this. instead of

<%= HttpUtility.HtmlEncode(unencoded) %>

you can simply do

<%: unencoded %>

read more here:

Convert a string to a double - is this possible?

Just use floatval().


$var = '122.34343';
$float_value_of_var = floatval($var);
echo $float_value_of_var; // 122.34343

And in case you wonder doubleval() is just an alias for floatval().

And as the other say, in a financial application, float values are critical as these are not precise enough. E.g. adding two floats could result in something like 12.30000000001 and this error could propagate.

How to use glyphicons in bootstrap 3.0

There you go:

<i class="glyphicon glyphicon-search"></i>

More information:

Btw. you can use this conversion tool, this will also update the code for the icons:

How do I write a RGB color value in JavaScript?

this is better function

function RGB2HTML(red, green, blue)
    var decColor =0x1000000+ blue + 0x100 * green + 0x10000 *red ;
    return '#'+decColor.toString(16).substr(1);

Is there a math nCr function in python?

Do you want iteration? itertools.combinations. Common usage:

>>> import itertools
>>> itertools.combinations('abcd',2)
<itertools.combinations object at 0x01348F30>
>>> list(itertools.combinations('abcd',2))
[('a', 'b'), ('a', 'c'), ('a', 'd'), ('b', 'c'), ('b', 'd'), ('c', 'd')]
>>> [''.join(x) for x in itertools.combinations('abcd',2)]
['ab', 'ac', 'ad', 'bc', 'bd', 'cd']

If you just need to compute the formula, use math.factorial:

import math

def nCr(n,r):
    f = math.factorial
    return f(n) / f(r) / f(n-r)

if __name__ == '__main__':
    print nCr(4,2)

In Python 3, use the integer division // instead of / to avoid overflows:

return f(n) // f(r) // f(n-r)



XMLHttpRequest (Ajax) Error

The problem is likely to lie with the line:

window.onload = onPageLoad();

By including the brackets you are saying onload should equal the return value of onPageLoad(). For example:

/*Example function*/
function onPageLoad()
    return "science";
/*Set on load*/
window.onload = onPageLoad()

If you print out the value of window.onload to the console it will be:


The solution is remove the brackets:

window.onload = onPageLoad;

So, you're using onPageLoad as a reference to the so-named function.

Finally, in order to get the response value you'll need a readystatechange listener for your XMLHttpRequest object, since it's asynchronous:

xmlDoc = xmlhttp.responseXML;
parser = new DOMParser(); // This code is untested as it doesn't run this far.

Here you add the listener:

xmlHttp.onreadystatechange = function() {
    if(this.readyState == 4) {
        // Do something

How can I make an entire HTML form "readonly"?

There's no fully compliant, official HTML way to do it, but a little javascript can go a long way. Another problem you'll run into is that disabled fields don't show up in the POST data

Receiver not registered exception error?

Be careful, when you register by


you can't unregister by


you must use


or app will crash, log as follow:

09-30 14:00:55.458 19064-19064/com.jialan.guangdian.view E/AndroidRuntime: FATAL EXCEPTION: main Process: com.jialan.guangdian.view, PID: 19064 java.lang.RuntimeException: Unable to stop service java.lang.IllegalArgumentException: Receiver not registered:$PlayStatusReceiver@19538584 at at$2200( at$H.handleMessage( at android.os.Handler.dispatchMessage( at android.os.Looper.loop( at at java.lang.reflect.Method.invoke(Native Method) at java.lang.reflect.Method.invoke( at$ at Caused by: java.lang.IllegalArgumentException: Receiver not registered:$PlayStatusReceiver@19538584 at at at android.content.ContextWrapper.unregisterReceiver( at at at$2200(  at$H.handleMessage(  at android.os.Handler.dispatchMessage(  at android.os.Looper.loop(  at  at java.lang.reflect.Method.invoke(Native Method)  at java.lang.reflect.Method.invoke(  at$  at 

"X-UA-Compatible" content="IE=9; IE=8; IE=7; IE=EDGE"

If you support IE, for versions of Internet Explorer 8 and above, this:

<meta http-equiv="X-UA-Compatible" content="IE=9; IE=8; IE=7" />

Forces the browser to render as that particular version's standards. It is not supported for IE7 and below.

If you separate with semi-colon, it sets compatibility levels for different versions. For example:

<meta http-equiv="X-UA-Compatible" content="IE=7; IE=9" />

Renders IE7 and IE8 as IE7, but IE9 as IE9. It allows for different levels of backwards compatibility. In real life, though, you should only chose one of the options:

<meta http-equiv="X-UA-Compatible" content="IE=8" />

This allows for much easier testing and maintenance. Although generally the more useful version of this is using Emulate:

<meta http-equiv="X-UA-Compatible" content="IE=EmulateIE8" />

For this:

<meta http-equiv="X-UA-Compatible" content="IE=Edge" />

It forces the browser the render at whatever the most recent version's standards are.

For more information, there is plenty to read about on MSDN,

PDO mysql: How to know if insert was successful

Try looking at the return value of execute, which is TRUE on success, and FALSE on failure.

How to convert entire dataframe to numeric while preserving decimals?

You might need to do some checking. You cannot safely convert factors directly to numeric. as.character must be applied first. Otherwise, the factors will be converted to their numeric storage values. I would check each column with is.factor then coerce to numeric as necessary.

df1[] <- lapply(df1, function(x) {
    if(is.factor(x)) as.numeric(as.character(x)) else x
sapply(df1, class)
#         a         b 
# "numeric" "numeric" 

How to avoid a System.Runtime.InteropServices.COMException?

I got this exception while coping a object(variable) Matrix Array into Excel sheet. The solution to this is, Matrix array Index(i,j) must start from (0,0) whereas Excel sheet should start with Matrix Array index (i,j) from (1,1) .

I hope you this concept.

how to get session id of client in Client

On Server side

io.on('connection', socket => {

On Client side

import io from '';

socket = io.connect('http://localhost:5000');
socket.on('connect', () => {

If, doesn't work, make sure you call it in on('connect') or after the connection.

Html attributes for EditorFor() in ASP.NET MVC

You can still use EditorFor. Just pass the style/whichever html attribute as ViewData.

@Html.EditorFor(model => model.YourProperty, new { style = "Width:50px" })

Because EditorFor uses templates to render, you could override the default template for your property and simply pass the style attribute as ViewData.

So your EditorTemplate would like the following:

@inherits System.Web.Mvc.WebViewPage<object>

@Html.TextBoxFor(m => m, new { @class = "text ui-widget-content", style=ViewData["style"] })

Execute SQL script from command line

If you want to run the script file then use below in cmd

sqlcmd -U user -P pass  -S servername -d databasename -i "G:\Hiren\Lab_Prodution.sql"

XML shape drawable not rendering desired color

I had a similar problem and found that if you remove the size definition, it works for some reason.


    android:height="40dp" />

from the shape.

Let me know if this works!

All ASP.NET Web API controllers return 404

One thing I ran into was having my configurations registered in the wrong order in my GLobal.asax file for instance:

Right Order:


Wrong Order:


Just saying, this was my problem and changing the order is obvious, but sometimes overlooked and can cause much frustration.

How do I open a new fragment from another fragment?

 Fragment fr = new Fragment_class();
             FragmentManager fm = getFragmentManager();
            FragmentTransaction fragmentTransaction = fm.beginTransaction();
            fragmentTransaction.add(, fr);

Just to be precise, is cretaed in your current class layout, upon calling, the new fragment automatically gets infiltrated.

How to export data to an excel file using PHPExcel

Work 100%. maybe not relation to creator answer but i share it for users have a problem with export mysql query to excel with phpexcel. Good Luck.



$filename = 'userReport'; //your file name

    $objPHPExcel = new PHPExcel();
    /*********************Add column headings START**********************/
                ->setCellValue('A1', 'username')
                ->setCellValue('B1', 'city_name');

    /*********************Add data entries START**********************/
//get_result_array_from_class**You can replace your sql code with this line.
$result = $get_report_clas->get_user_report();
//set variable for count table fields.
$num_row = 1;
foreach ($result as $value) {
  $user_name = $value['username'];
  $c_code = $value['city_name'];
                ->setCellValue('A'.$num_row, $user_name )
                ->setCellValue('B'.$num_row, $c_code );

    /*********************Autoresize column width depending upon contents START**********************/
    foreach(range('A','B') as $columnID) {

//Make heading font bold

        /*********************Add color to heading START**********************/

        $objPHPExcel->getActiveSheet()->setTitle('userReport'); //give title to sheet
        header('Content-Type: application/');
        header("Content-Disposition: attachment;Filename=$filename.xls");
        header('Cache-Control: max-age=0');
        $objWriter = PHPExcel_IOFactory::createWriter($objPHPExcel, 'Excel5');

Choosing a jQuery datagrid plugin?

The three most used and well supported jQuery grid plugins today are SlickGrid, jqGrid and DataTables. See for more info.

Is it possible to apply CSS to half of a character?

How about something like this for shorter text?

It could even work for longer text if you did something with a loop, repeating the characters with JavaScript. Anyway, the result is something like this:

Is it possible to apply CSS to half of a character?

p.char {_x000D_
  position: relative;_x000D_
  display: inline-block;_x000D_
  font-size: 60px;_x000D_
  color: red;_x000D_
p.char:before {_x000D_
  position: absolute;_x000D_
  content: attr(char);_x000D_
  width: 50%;_x000D_
  overflow: hidden;_x000D_
  color: black;_x000D_
<p class="char" char="S">S</p>_x000D_
<p class="char" char="t">t</p>_x000D_
<p class="char" char="a">a</p>_x000D_
<p class="char" char="c">c</p>_x000D_
<p class="char" char="k">k</p>_x000D_
<p class="char" char="o">o</p>_x000D_
<p class="char" char="v">v</p>_x000D_
<p class="char" char="e">e</p>_x000D_
<p class="char" char="r">r</p>_x000D_
<p class="char" char="f">f</p>_x000D_
<p class="char" char="l">l</p>_x000D_
<p class="char" char="o">o</p>_x000D_
<p class="char" char="w">w</p>

How can I change the value of the elements in a vector?

You might want to consider using some algorithms instead:

// read in the data:

sum = std::accumulate(v.begin(), v.end(), 0);
average = sum / v.size();

You can modify the values with std::transform, though until we get lambda expressions (C++0x) it may be more trouble than it's worth:

class difference { 
    double base;
    difference(double b) : base(b) {}
    double operator()(double v) { return v-base; }

std::transform(v.begin(), v.end(), v.begin(), difference(average));

Composer require runs out of memory. PHP Fatal error: Allowed memory size of 1610612736 bytes exhausted

In my case:

Windows 10 and Docker Desktop works:

docker-compose -f .docker/docker-compose.yml exec php env COMPOSER_MEMORY_LIMIT=-1 composer require fideloper/proxy

Getting all file names from a folder using C#

I would recommend you google 'Read objects in folder'. You might need to create a reader and a list and let the reader read all the object names in the folder and add them to the list in n loops.

Convert date to another timezone in JavaScript

For moment.js users, you can now use moment-timezone. Using it, your function would look something like this:

function toTimeZone(time, zone) {
    var format = 'YYYY/MM/DD HH:mm:ss ZZ';
    return moment(time, format).tz(zone).format(format);

Component based game engine design

I researched and implemented this last semester for a game development course. Hopefully this sample code can point you in the right direction of how you might approach this.

class Entity {
    Entity(const unsigned int id, const std::string& enttype);

    //Component Interface
    const Component* GetComponent(const std::string& family) const;
    void SetComponent(Component* newComp);
    void RemoveComponent(const std::string& family);
    void ClearComponents();

    //Property Interface
    bool HasProperty(const std::string& propName) const;
    template<class T> T& GetPropertyDataPtr(const std::string& propName);
    template<class T> const T& GetPropertyDataPtr(const std::string& propName) const;

    //Entity Interface
    const unsigned int GetID() const;
    void Update(float dt);

    void RemoveProperty(const std::string& propName);
    void ClearProperties();
    template<class T> void AddProperty(const std::string& propName);
    template<class T> Property<T>* GetProperty(const std::string& propName);
    template<class T> const Property<T>* GetProperty(const std::string& propName) const;

    unsigned int m_Id;
    std::map<const string, IProperty*> m_Properties;
    std::map<const string, Component*> m_Components;

Components specify behavior and operate on properties. Properties are shared between all components by a reference and get updates for free. This means no large overhead for message passing. If there's any questions I'll try to answer as best I can.

HTML if image is not found

The usual way to handle this scenario is by setting the alt tag to something meaningful.

If you want a default image instead, then I suggest using a server-side technology to serve up your images, called using a similar format to:

<img src="ImageHandler.aspx?Img=Blue.jpg" alt="I am a picture" />

In the ImageHandler.aspx code, catch any file-not-found errors and serve up your default.jpg instead.

Test iOS app on device without apple developer program or jailbreak

Seven years after the inception of the App Store (July 10, 2008), Apple has finally introduced a new feature in Xcode 7 that allows you to deploy and run any number of apps on any of your devices, simply by logging in with your Apple ID. You will no longer need a paid Program membership to deploy apps on your own device (and you certainly no longer have to jailbreak your device if you're not comfortable doing so).

Well, not for the majority of use cases anyway. For obvious reasons, certain capabilities and entitlements that require Program membership such as Game Center and in-app purchases will not be available to apps deployed using this method. From Apple's developer documentation:

Launch Your App on Devices Using Free Provisioning (iOS, watchOS)

If you don’t join the Apple Developer Program, you can still build and run your app on your devices using free provisioning. However, the capabilities available to your app, described in Adding Capabilities, are restricted when you don’t belong to the Apple Developer Program.

The precise steps to getting your app onto your iOS device or Apple Watch follow immediately thus (screenshots omitted for ease of skimming):

  1. In Xcode, add your Apple ID to Accounts preferences, described in Adding Your Apple ID Account in Xcode.

  2. In the project navigator, select the project and your target to display the project editor.

  3. Click General and choose your name from the Team pop-up menu.

  4. Connect the device to your Mac and choose your device from the Scheme toolbar menu.

  5. Below the Team pop-up menu, click Fix Issue.

    Xcode creates a free provisioning profile for you and the warning text under the Team pop-up menu disappears.

  6. Click the Run button.

    Xcode installs the app on the device before launching the app.

Prior to Xcode 7, a Program membership was indeed required in order to sign the provisioning certificates required to deploy apps to devices. The only other alternative was jailbreaking. With Xcode 7, you no longer need to jailbreak your device just to run apps distributed outside the App Store, or to test apps if you cannot afford to join the Program, or to deploy and use apps that you have developed for your own personal use if you do not intend to distribute them through the App Store (in which case you probably don't need the entitlements offered by Program membership anyway).

Difference between null and empty ("") Java String

Difference between null & empty string. For example: you have a variable named x. If you write in JS,

var x = "";

this means that you have assigned a value which is empty string (length is 0). Actually this is like something but which is feel of nothing :) On the other hand,

var y = null;

this means you've not assigned a value to y that clearly said by writing null to y at the time of declaration. If you write y.length; it will throw an error which indicates that no value assigned to y and as a result can't read length of y.

Scope 'session' is not active for the current thread; IllegalStateException: No thread-bound request found

As per documentation:

If you are accessing scoped beans within Spring Web MVC, i.e. within a request that is processed by the Spring DispatcherServlet, or DispatcherPortlet, then no special setup is necessary: DispatcherServlet and DispatcherPortlet already expose all relevant state.

If you are runnning outside of Spring MVC ( Not processed by DispatchServlet) you have to use the RequestContextListener Not just ContextLoaderListener .

Add the following in your web.xml


That will provide session to Spring in order to maintain the beans in that scope

Update : As per other answers , the @Controller only sensible when you are with in Spring MVC Context, So the @Controller is not serving actual purpose in your code. Still you can inject your beans into any where with session scope / request scope ( you don't need Spring MVC / Controller to just inject beans in particular scope) .

Update : RequestContextListener exposes the request to the current Thread only.
You have autowired ReportBuilder in two places

1. ReportPage - You can see Spring injected the Report builder properly here, because we are still in Same web Thread. i did changed the order of your code to make sure the ReportBuilder injected in ReportPage like this."ReportBuilder name: {}", reportBuilder.getName());

i knew the log should go after as per your logic , just for debug purpose i added .

2. UselessTasklet - We got exception , here because this is different thread created by Spring Batch , where the Request is not exposed by RequestContextListener.

You should have different logic to create and inject ReportBuilder instance to Spring Batch ( May Spring Batch Parameters and using Future<ReportBuilder> you can return for future reference)

How can I inspect element in an Android browser?

You can inspect elements of a website in your Android device using Chrome browser.

Open your Chrome browser and go to the website you want to inspect.

Go to the address bar and type "view-source:" before the "HTTP" and reload the page.

The whole elements of the page will be shown.

Read specific columns from a csv file with csv module?

Context: For this type of work you should use the amazing python petl library. That will save you a lot of work and potential frustration from doing things 'manually' with the standard csv module. AFAIK, the only people who still use the csv module are those who have not yet discovered better tools for working with tabular data (pandas, petl, etc.), which is fine, but if you plan to work with a lot of data in your career from various strange sources, learning something like petl is one of the best investments you can make. To get started should only take 30 minutes after you've done pip install petl. The documentation is excellent.

Answer: Let's say you have the first table in a csv file (you can also load directly from the database using petl). Then you would simply load it and do the following.

from petl import fromcsv, look, cut, tocsv 

#Load the table
table1 = fromcsv('table1.csv')
# Alter the colums
table2 = cut(table1, 'Song_Name','Artist_ID')
#have a quick look to make sure things are ok. Prints a nicely formatted table to your console
print look(table2)
# Save to new file
tocsv(table2, 'new.csv')

Instantiate and Present a viewController in Swift

If you want to present it modally, you should have something like bellow:

let vc = self.storyboard!.instantiateViewControllerWithIdentifier("YourViewControllerID")
self.showDetailViewController(vc as! YourViewControllerClassName, sender: self)

How can I get Maven to stop attempting to check for updates for artifacts from a certain group from maven-central-repo?

Something that is now available in maven as well is

mvn goal --no-snapshot-updates

or in short

mvn goal -nsu

How to set a background image in Xcode using swift?

I am beginner to iOS development so I would like to share whole info I got in this section.

First from image assets (images.xcassets) create image set .

According to Documentation here is all sizes need to create background image.

For iPhone 5:
   640 x 1136

   For iPhone 6:
   750 x 1334 (@2x) for portrait
   1334 x 750 (@2x) for landscape

   For iPhone 6 Plus:
   1242 x 2208 (@3x) for portrait
   2208 x 1242 (@3x) for landscape

   iPhone 4s (@2x)      
   640 x 960

   iPad and iPad mini (@2x) 
   1536 x 2048 (portrait)
   2048 x 1536 (landscape)

   iPad 2 and iPad mini (@1x)
   768 x 1024 (portrait)
   1024 x 768 (landscape)

   iPad Pro (@2x)
   2048 x 2732 (portrait)
   2732 x 2048 (landscape)

call the image background we can call image from image assets by using this method UIImage(named: "background") here is full code example

  override func viewDidLoad() {
            // Do any additional setup after loading the view.

  func assignbackground(){
        let background = UIImage(named: "background")

        var imageView : UIImageView!
        imageView = UIImageView(frame: view.bounds)
        imageView.contentMode =  UIViewContentMode.ScaleAspectFill
        imageView.clipsToBounds = true
        imageView.image = background =

Git: copy all files in a directory from another branch

If there are no spaces in paths, and you are interested, like I was, in files of specific extension only, you can use

git checkout otherBranch -- $(git ls-tree --name-only -r otherBranch | egrep '*.java')

Setting focus on an HTML input box on page load

This line:

<input type="password" name="PasswordInput"/>

should have an id attribute, like so:

<input type="password" name="PasswordInput" id="PasswordInput"/>

Http 415 Unsupported Media type error with JSON

This is because charset=utf8 should be without a space after application/json. That will work fine. Use it like application/json;charset=utf-8

JQuery Error: cannot call methods on dialog prior to initialization; attempted to call method 'close'

Create a separate JavaScript function that can be called to close the dialog using the specific object id, and place the function outside of $(document).ready() like this:

function closeDialogWindow() { 

NOTE: The function must be declared outside of $(document).ready() so jQuery doesn't try to trigger the close event on the dialog before it is created in the DOM.

How to put an image in div with CSS?

With Javascript/Jquery:

  • load image with hidden img
  • when image has been loaded, get width and height
  • dynamically create a div and set width, height and background
  • remove the original img

      $(document).ready(function() {
        var image = $("<img>");
        var div = $("<div>")
        image.load(function() {
            "width": this.width,
            "height": this.height,
            "background-image": "url(" + this.src + ")"
        image.attr("src", "test0.png");

Conversion of a varchar data type to a datetime data type resulted in an out-of-range value in SQL query

hope this may help you:

         FROM    AuditTrail 

If you want to have some filters over this datetime or it's different parts, you can use built-in functions such as Year and Month

getFilesDir() vs Environment.getDataDirectory()


Returns the absolute path to the directory on the filesystem where files created with openFileOutput(String, int) are stored.


Return the user data directory.

Deleting specific rows from DataTable

To remove entire row from DataTable , do like this

DataTable dt = new DataTable();  //User DataTable
DataRow[] rows;
rows = dt.Select("UserName = 'KarthiK'");  //'UserName' is ColumnName
foreach (DataRow row in rows)

Remove Primary Key in MySQL

One Line:

ALTER TABLE  `user_customer_permission` DROP PRIMARY KEY , ADD PRIMARY KEY (  `id` )

You will also not lose the auto-increment and have to re-add it which could have side-effects.

PHP function use variable from outside

Alternatively, you can bring variables in from the outside scope by using closures with the use keyword.

$myVar = "foo";
$myFunction = function($arg1, $arg2) use ($myVar)
 return $arg1 . $myVar . $arg2;

Error: JavaFX runtime components are missing, and are required to run this application with JDK 11

This worked for me:

File >> Project Structure >> Modules >> Dependency >> + (on left-side of window)

clicking the "+" sign will let you designate the directory where you have unpacked JavaFX's "lib" folder.

Scope is Compile (which is the default.) You can then edit this to call it JavaFX by double-clicking on the line.

then in:

Run >> Edit Configurations

Add this line to VM Options:

--module-path /path/to/JavaFX/lib --add-modules=javafx.controls

(oh and don't forget to set the SDK)

Link and execute external JavaScript file hosted on GitHub

This is no longer possible. GitHub has explicitly disabled JavaScript hotlinking, and newer versions of browsers respect that setting.

Heads up: nosniff header support coming to Chrome and Firefox

Process.start: how to get the output?

How to launch a process (such as a bat file, perl script, console program) and have its standard output displayed on a windows form:

processCaller = new ProcessCaller(this);
//processCaller.FileName = @"..\..\hello.bat";
processCaller.FileName = @"commandline.exe";
processCaller.Arguments = "";
processCaller.StdErrReceived += new DataReceivedHandler(writeStreamInfo);
processCaller.StdOutReceived += new DataReceivedHandler(writeStreamInfo);
processCaller.Completed += new EventHandler(processCompletedOrCanceled);
processCaller.Cancelled += new EventHandler(processCompletedOrCanceled);
// processCaller.Failed += no event handler for this one, yet.

this.richTextBox1.Text = "Started function.  Please stand by.." + Environment.NewLine;

// the following function starts a process and returns immediately,
// thus allowing the form to stay responsive.

You can find ProcessCaller on this link: Launching a process and displaying its standard output

LINQ to Entities does not recognize the method

If anyone is looking for a VB.Net answer (as I was initially), here it is:

Public Function IsSatisfied() As Expression(Of Func(Of Charity, String, String, Boolean))

Return Function(charity, name, referenceNumber) (String.IsNullOrWhiteSpace(name) Or
                                                         charity.registeredName.ToLower().Contains(name.ToLower()) Or
                                                         charity.alias.ToLower().Contains(name.ToLower()) Or
                                                         charity.charityId.ToLower().Contains(name.ToLower())) And
                                                    (String.IsNullOrEmpty(referenceNumber) Or
End Function

Creating email templates with Django

send_emai() didn't work for me so I used EmailMessage here in django docs.

I have included two versions of the anser:

  1. With html email version only
  2. With plain text email and html email versions
from django.template.loader import render_to_string 
from django.core.mail import EmailMessage

# import file with html content
html_version = 'path/to/html_version.html'

html_message = render_to_string(html_version, { 'context': context, })

message = EmailMessage(subject, html_message, from_email, [to_email])
message.content_subtype = 'html' # this is required because there is no plain text email version

If you want to include a plain text version of your email, modify the above like this:

from django.template.loader import render_to_string 
from django.core.mail import EmailMultiAlternatives # <= EmailMultiAlternatives instead of EmailMessage

plain_version = 'path/to/plain_version.html' # import plain version. No html content
html_version = 'path/to/html_version.html' # import html version. Has html content

plain_message = render_to_string(plain_version, { 'context': context, })
html_message = render_to_string(html_version, { 'context': context, })

message = EmailMultiAlternatives(subject, plain_message, from_email, [to_email])
message.attach_alternative(html_message, "text/html") # attach html version

My plain and html versions look like this: plain_version.html:

Plain text {{ context }}


<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "">
<html xmlns="">
<table align="center" border="0" cellpadding="0" cellspacing="0" width="320" style="border: none; border-collapse: collapse; font-family:  Arial, sans-serif; font-size: 14px; line-height: 1.5;">
{{ context }}

How to compare two Carbon Timestamps?

Carbon has a bunch of comparison functions with mnemonic names:

  • equalTo()
  • notEqualTo()
  • greaterThan()
  • greaterThanOrEqualTo()
  • lessThan()
  • lessThanOrEqualTo()


     // edited at is newer than created at

Valid for nesbot/carbon 1.36.2

if you are not sure what Carbon version you are on, run this

$composer show "nesbot/carbon"


How to access child's state in React?

As the previous answers saids, try to move the state to a top component and modify the state through callbacks passed to it's children.

In case that you really need to access to a child state that is declared as a functional component (hooks) you can declare a ref in the parent component, then pass it as a ref attribute to the child but you need to use React.forwardRef and then the hook useImperativeHandle to declare a function you can call in the parent component.

Take a look at the following example:

const Parent = () => {
    const myRef = useRef();
    return <Child ref={myRef} />;

const Child = React.forwardRef((props, ref) => {
    const [myState, setMyState] = useState('This is my state!');
    useImperativeHandle(ref, () => ({getMyState: () => {return myState}}), [myState]);

Then you should be able to get myState in the Parent component by calling: myRef.current.getMyState();

How should I throw a divide by zero exception in Java without actually dividing by zero?

There are two ways you could do this. Either create your own custom exception class to represent a divide by zero error or throw the same type of exception the java runtime would throw in this situation.

Define custom exception

public class DivideByZeroException() extends ArithmeticException {

Then in your code you would check for a divide by zero and throw this exception:

if (divisor == 0) throw new DivideByZeroException();

Throw ArithmeticException

Add to your code the check for a divide by zero and throw an arithmetic exception:

if (divisor == 0) throw new java.lang.ArithmeticException("/ by zero");

Additionally, you could consider throwing an illegal argument exception since a divisor of zero is an incorrect argument to pass to your setKp() method:

if (divisor == 0) throw new java.lang.IllegalArgumentException("divisor == 0");

Getting reference to the top-most view/window in iOS application

Just use this code if you want to add a view above of everything in the screen.

[[UIApplication sharedApplication].keyWindow addSubView: yourView];

Call a function after previous function is complete

Try this :

function method1(){
   // some code


function method2(){
   // some code


How to start an Intent by passing some parameters to it?

I think you want something like this:

Intent foo = new Intent(this, viewContacts.class);
foo.putExtra("myFirstKey", "myFirstValue");
foo.putExtra("mySecondKey", "mySecondValue");

or you can combine them into a bundle first. Corresponding getExtra() routines exist for the other side. See the intent topic in the dev guide for more information.

Apache: client denied by server configuration

OK I am using the wrong syntax, I should be using

Allow from
Allow from ::1

How to put space character into a string name in XML?

You can use following as well

<string name="spelatonertext3"> "-4,  5, -5,   6,  -6, "> </string>

Put anything in " "(quotation) with space, and it should work

Background Image for Select (dropdown) does not work in Chrome

What Arne said - you can't reliably style select boxes and have them look anything like consistent across browsers.

Uniform: is a javascript solution which gives you good graphic control over your form elements - it's still Javascript, but it's about as nice as javascript gets for solving this problem.

How to get hex color value rather than RGB value?

Most browsers seem to return the RGB value when using:


Only I.E (only 6 tested so far) returns the Hex value.

To avoid error messages in I.E, you could wrap the function in an if statement:

function rgb2hex(rgb) {
     if ("rgb") == -1 ) {
          return rgb;
     } else {
          rgb = rgb.match(/^rgba?\((\d+),\s*(\d+),\s*(\d+)(?:,\s*(\d+))?\)$/);
          function hex(x) {
               return ("0" + parseInt(x).toString(16)).slice(-2);
          return "#" + hex(rgb[1]) + hex(rgb[2]) + hex(rgb[3]); 

Activity restart on rotation Android

what I did...

in the manifest, to the activity section, added:


in the code for the activity, implemented:

//used in onCreate() and onConfigurationChanged() to set up the UI elements
public void InitializeUI()
    //get views from ID's
    this.textViewHeaderMainMessage = (TextView) this.findViewById(;

    //etc... hook up click listeners, whatever you need from the Views

//Called when the activity is first created.
public void onCreate(Bundle savedInstanceState)


//this is called when the screen rotates.
// (onCreate is no longer called when screen rotates due to manifest, see: android:configChanges)
public void onConfigurationChanged(Configuration newConfig)


In Jenkins, how to checkout a project into a specific directory (using GIT)

The default git plugin for Jenkins does the job quite nicely.

After adding a new git repository (project configuration > Source Code Management > check the GIT option) to the project navigate to the bottom of the plugin settings, just above Repository browser region. There should be an Advanced button. After clicking it a new form should appear, with a value described as Local subdirectory for repo (optional). Setting this to folder will make the plugin to check out the repository into the folder relative to your workspace. This way you can have as many repositories in your project as you need, all in separate locations.

Alternatively, if the project you're using will allow that, you can use GIT sub modules, which are similar to external paths in SVN. In the GIT Book there is a section on that very topic. If that will not be against some policy, submodules are fairly simple to use, giving you powerful way to control the locations, versions/tags/branches that will be imported AND it will be available on your local repository as well giving you better portability.

Obviously the GIT plugin supports checking out submodules, so Jenkins can work with them quite effectively.

Decode UTF-8 with Javascript

Update @Albert's answer adding condition for emoji.

function Utf8ArrayToStr(array) {
    var out, i, len, c;
    var char2, char3, char4;

    out = "";
    len = array.length;
    i = 0;
    while(i < len) {
    c = array[i++];
    switch(c >> 4)
      case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7:
        // 0xxxxxxx
        out += String.fromCharCode(c);
      case 12: case 13:
        // 110x xxxx   10xx xxxx
        char2 = array[i++];
        out += String.fromCharCode(((c & 0x1F) << 6) | (char2 & 0x3F));
      case 14:
        // 1110 xxxx  10xx xxxx  10xx xxxx
        char2 = array[i++];
        char3 = array[i++];
        out += String.fromCharCode(((c & 0x0F) << 12) |
                       ((char2 & 0x3F) << 6) |
                       ((char3 & 0x3F) << 0));
     case 15:
        // 1111 0xxx 10xx xxxx 10xx xxxx 10xx xxxx
        char2 = array[i++];
        char3 = array[i++];
        char4 = array[i++];
        out += String.fromCodePoint(((c & 0x07) << 18) | ((char2 & 0x3F) << 12) | ((char3 & 0x3F) << 6) | (char4 & 0x3F));


    return out;

how to filter out a null value from spark dataframe

for the first question, it is correct you are filtering out nulls and hence count is zero.

for the second replacing: use like below:

val options = Map("path" -> "...\\ex.csv", "header" -> "true")
val dfNull = spark.sqlContext.load("com.databricks.spark.csv", options)


|   user_id|  event_id|invited|day_diff|interested|event_owner|friend_id|
|   4236494| 110357109|      0|      -1|         0|  937597069|     null|
|  78065188| 498404626|      0|       0|         0| 2904922087|     null|
| 282487230|2520855981|      0|      28|         0| 3749735525|     null|
| 335269852|1641491432|      0|       2|         0| 1490350911|     null|
| 437050836|1238456614|      0|       2|         0|  991277599|     null|
| 447244169|2095085551|      0|      -1|         0| 1579858878|        a|
| 516353916|1076364848|      0|       3|         1| 3597645735|        b|
| 528218683|1151525474|      0|       1|         0| 3433080956|        c|
| 531967718|3632072502|      0|       1|         0| 3863085861|     null|
| 627948360|2823119321|      0|       0|         0| 4092665803|     null|
| 811791433|3513954032|      0|       2|         0|  415464198|     null|
| 830686203|  99027353|      0|       0|         0| 3549822604|     null|
|1008893291|1115453150|      0|       2|         0| 2245155244|     null|
|1239364869|2824096896|      0|       2|         1| 2579294650|        d|
|1287950172|1076364848|      0|       0|         0| 3597645735|     null|
|1345896548|2658555390|      0|       1|         0| 2025118823|     null|
|1354205322|2564682277|      0|       3|         0| 2563033185|     null|
|1408344828|1255629030|      0|      -1|         1|  804901063|     null|
|1452633375|1334001859|      0|       4|         0| 1488588320|     null|
|1625052108|3297535757|      0|       3|         0| 1972598895|     null|

dfNull.withColumn("friend_idTmp", when($"friend_id".isNull, "1").otherwise("0")).drop($"friend_id").withColumnRenamed("friend_idTmp", "friend_id").show

|   user_id|  event_id|invited|day_diff|interested|event_owner|friend_id|
|   4236494| 110357109|      0|      -1|         0|  937597069|        1|
|  78065188| 498404626|      0|       0|         0| 2904922087|        1|
| 282487230|2520855981|      0|      28|         0| 3749735525|        1|
| 335269852|1641491432|      0|       2|         0| 1490350911|        1|
| 437050836|1238456614|      0|       2|         0|  991277599|        1|
| 447244169|2095085551|      0|      -1|         0| 1579858878|        0|
| 516353916|1076364848|      0|       3|         1| 3597645735|        0|
| 528218683|1151525474|      0|       1|         0| 3433080956|        0|
| 531967718|3632072502|      0|       1|         0| 3863085861|        1|
| 627948360|2823119321|      0|       0|         0| 4092665803|        1|
| 811791433|3513954032|      0|       2|         0|  415464198|        1|
| 830686203|  99027353|      0|       0|         0| 3549822604|        1|
|1008893291|1115453150|      0|       2|         0| 2245155244|        1|
|1239364869|2824096896|      0|       2|         1| 2579294650|        0|
|1287950172|1076364848|      0|       0|         0| 3597645735|        1|
|1345896548|2658555390|      0|       1|         0| 2025118823|        1|
|1354205322|2564682277|      0|       3|         0| 2563033185|        1|
|1408344828|1255629030|      0|      -1|         1|  804901063|        1|
|1452633375|1334001859|      0|       4|         0| 1488588320|        1|
|1625052108|3297535757|      0|       3|         0| 1972598895|        1|

MySQL > Table doesn't exist. But it does (or it should)

Came cross same problem today. This is a mysql "Identifier Case Sensitivity" issue.

Please check corresponding data file. It is very likely that file name is in lower case on file system but table name listed in "show tables" command is in upper case. If system variable "lower_case_table_names" is 0, the query will return "table not exist" because name comparisons are case sensitive when "lower_case_table_names" is 0.

How to secure database passwords in PHP?

Just putting it into a config file somewhere is the way it's usually done. Just make sure you:

  1. disallow database access from any servers outside your network,
  2. take care not to accidentally show the password to users (in an error message, or through PHP files accidentally being served as HTML, etcetera.)

How to asynchronously call a method in Java

You can use the Java8 syntax for CompletableFuture, this way you can perform additional async computations based on the result from calling an async function.

for example:

                     .thenApply(this:: intReturningMethod)

More details can be found in this article

Build a basic Python iterator

First of all the itertools module is incredibly useful for all sorts of cases in which an iterator would be useful, but here is all you need to create an iterator in python:


Isn't that cool? Yield can be used to replace a normal return in a function. It returns the object just the same, but instead of destroying state and exiting, it saves state for when you want to execute the next iteration. Here is an example of it in action pulled directly from the itertools function list:

def count(n=0):
    while True:
        yield n
        n += 1

As stated in the functions description (it's the count() function from the itertools module...) , it produces an iterator that returns consecutive integers starting with n.

Generator expressions are a whole other can of worms (awesome worms!). They may be used in place of a List Comprehension to save memory (list comprehensions create a list in memory that is destroyed after use if not assigned to a variable, but generator expressions can create a Generator Object... which is a fancy way of saying Iterator). Here is an example of a generator expression definition:

gen = (n for n in xrange(0,11))

This is very similar to our iterator definition above except the full range is predetermined to be between 0 and 10.

I just found xrange() (suprised I hadn't seen it before...) and added it to the above example. xrange() is an iterable version of range() which has the advantage of not prebuilding the list. It would be very useful if you had a giant corpus of data to iterate over and only had so much memory to do it in.


In my humble experience with postgres 9.6, cascade delete doesn't work in practice for tables that grow above a trivial size.

  • Even worse, while the delete cascade is going on, the tables involved are locked so those tables (and potentially your whole database) is unusable.
  • Still worse, it's hard to get postgres to tell you what it's doing during the delete cascade. If it's taking a long time, which table or tables is making it slow? Perhaps it's somewhere in the pg_stats information? It's hard to tell.

Select query to remove non-numeric characters

CREATE FUNCTION FN_RemoveNonNumeric (@Input NVARCHAR(512))

SELECT @Trimmed = @Input

WHILE PATINDEX('%[^0-9]%', @Trimmed) > 0
    SELECT @Trimmed = REPLACE(@Trimmed, SUBSTRING(@Trimmed, PATINDEX('%[^0-9]%', @Trimmed), 1), '')

RETURN @Trimmed


SELECT dbo.FN_RemoveNonNumeric('ABCDE# 123')

get and set in TypeScript

If you are working with TypeScript modules and are trying to add a getter that is exported, you can do something like this:

// dataStore.ts
export const myData: string = undefined;  // just for typing support
let _myData: string;  // for memoizing the getter results

Object.defineProperty(this, "myData", {
    get: (): string => {
        if (_myData === undefined) {
            _myData = "my data";  // pretend this took a long time

        return _myData;

Then, in another file you have:

import * as dataStore from "./dataStore"
console.log(dataStore.myData); // "my data"

How to calculate difference between two dates in oracle 11g SQL

You can use this:


  V_START_DATE  CHAR(17) := '28/03/16 17:20:00';
  V_END_DATE    CHAR(17) := '30/03/16 17:50:10';




Accessing session from TWIG template

A simple trick is to define the $_SESSION array as a global variable. For that, edit the core.php file in the extension folder by adding this function :

public function getGlobals() {
    return array(
        'session'   => $_SESSION,
    ) ;

Then, you'll be able to acces any session variable as :

{{ session.username }}

if you want to access to


Xcode 6 Storyboard the wrong size?

I had this issue in xcode 6 and there is a way to resolve the resize conflicts. If you select your view, at the bottom you will see an icon that looks like |-Δ-|. If you click on it, you're project will resize for different devices.

Dynamically create an array of strings with malloc

Given that your strings are all fixed-length (presumably at compile-time?), you can do the following:

char (*orderedIds)[ID_LEN+1]
    = malloc(variableNumberOfElements * sizeof(*orderedIds));

// Clear-up

A more cumbersome, but more general, solution, is to assign an array of pointers, and psuedo-initialising them to point at elements of a raw backing array:

char *raw = malloc(variableNumberOfElements * (ID_LEN + 1));
char **orderedIds = malloc(sizeof(*orderedIds) * variableNumberOfElements);

// Set each pointer to the start of its corresponding section of the raw buffer.
for (i = 0; i < variableNumberOfElements; i++)
    orderedIds[i] = &raw[i * (ID_LEN+1)];


// Clear-up pointer array
// Clear-up raw array

Why does configure say no C compiler found when GCC is installed?

try yum groupinstall "Development Tools"

if the installation is success then you will have a full set of development tools. Such as gcc, g++, make, ld ect. After that you can try the compilation of Code Blocks again.

Since yum is deprecated you can use dnf instead:

dnf groupinstall "Development Tools"

pandas: to_numeric for multiple columns

UPDATE: you don't need to convert your values afterwards, you can do it on-the-fly when reading your CSV:

In [165]: df=pd.read_csv(url, index_col=0, na_values=['(NA)']).fillna(0)

In [166]: df.dtypes
GeoName                    object
ComponentName              object
IndustryId                  int64
IndustryClassification     object
Description                object
2004                        int64
2005                        int64
2006                        int64
2007                        int64
2008                        int64
2009                        int64
2010                        int64
2011                        int64
2012                        int64
2013                        int64
2014                      float64
dtype: object

If you need to convert multiple columns to numeric dtypes - use the following technique:

Sample source DF:

In [271]: df
     id    a  b  c  d  e    f
0  id_3  AAA  6  3  5  8    1
1  id_9    3  7  5  7  3  BBB
2  id_7    4  2  3  5  4    2
3  id_0    7  3  5  7  9    4
4  id_0    2  4  6  4  0    2

In [272]: df.dtypes
id    object
a     object
b      int64
c      int64
d      int64
e      int64
f     object
dtype: object

Converting selected columns to numeric dtypes:

In [273]: cols = df.columns.drop('id')

In [274]: df[cols] = df[cols].apply(pd.to_numeric, errors='coerce')

In [275]: df
     id    a  b  c  d  e    f
0  id_3  NaN  6  3  5  8  1.0
1  id_9  3.0  7  5  7  3  NaN
2  id_7  4.0  2  3  5  4  2.0
3  id_0  7.0  3  5  7  9  4.0
4  id_0  2.0  4  6  4  0  2.0

In [276]: df.dtypes
id     object
a     float64
b       int64
c       int64
d       int64
e       int64
f     float64
dtype: object

PS if you want to select all string (object) columns use the following simple trick:

cols = df.columns[df.dtypes.eq('object')]

JPA mapping: "QuerySyntaxException: foobar is not mapped..."

There is also another possible source of this error. In some J2EE / web containers (in my experience under Jboss 7.x and Tomcat 7.x) You have to add each class You want to use as a hibernate Entity into the file persistence.xml as


In case of jboss this concerns every entity class (local - i.e. within the project You are developing or in a library). In case of Tomcat 7.x this concerns only entity classes within libraries.

How do I empty an input value with jQuery?

To make values empty you can do the following:


To get the selected value you can do:

var value = $("#element").val();

Where #element is the id of the element you wish to select.

Google Maps API V3 : How show the direction from a point A to point B (Blue line)?

Using Javascript

I created a working demo that shows how to use the Google Maps API Directions Service in Javascript through a

  • DirectionsService object to send and receive direction requests
  • DirectionsRenderer object to render the returned route on the map

function initMap() {_x000D_
  var pointA = new google.maps.LatLng(51.7519, -1.2578),_x000D_
    pointB = new google.maps.LatLng(50.8429, -0.1313),_x000D_
    myOptions = {_x000D_
      zoom: 7,_x000D_
      center: pointA_x000D_
    map = new google.maps.Map(document.getElementById('map-canvas'), myOptions),_x000D_
    // Instantiate a directions service._x000D_
    directionsService = new google.maps.DirectionsService,_x000D_
    directionsDisplay = new google.maps.DirectionsRenderer({_x000D_
      map: map_x000D_
    markerA = new google.maps.Marker({_x000D_
      position: pointA,_x000D_
      title: "point A",_x000D_
      label: "A",_x000D_
      map: map_x000D_
    markerB = new google.maps.Marker({_x000D_
      position: pointB,_x000D_
      title: "point B",_x000D_
      label: "B",_x000D_
      map: map_x000D_
  // get route from A to B_x000D_
  calculateAndDisplayRoute(directionsService, directionsDisplay, pointA, pointB);_x000D_
function calculateAndDisplayRoute(directionsService, directionsDisplay, pointA, pointB) {_x000D_
    origin: pointA,_x000D_
    destination: pointB,_x000D_
    travelMode: google.maps.TravelMode.DRIVING_x000D_
  }, function(response, status) {_x000D_
    if (status == google.maps.DirectionsStatus.OK) {_x000D_
    } else {_x000D_
      window.alert('Directions request failed due to ' + status);_x000D_
    body {_x000D_
      height: 100%;_x000D_
      margin: 0;_x000D_
      padding: 0;_x000D_
    #map-canvas {_x000D_
      height: 100%;_x000D_
      width: 100%;_x000D_
<script src=""></script>_x000D_
<div id="map-canvas"></div>

Also on Jsfiddle:

Using Google Maps Web Services

You can use the Web Services using an API_KEY issuing a request like this:

An API_KEY can be obtained in the Google Developer Console with a quota of 2,500 free requests/day.

A request can return JSON or XML results that can be used to draw a path on a map.

Official documentation for Web Services using the Google Maps Directions API are here

How can I list all tags for a Docker image on a remote registry?

As of Docker Registry V2, a simple GET suffice:

GET /v2/<name>/tags/list

See docs for more.

Apache shows PHP code instead of executing it

Wow, lots of solutions here! Here's what I did on Ubuntu 16.04:

sudo apt-get install php libapache2-mod-php
sudo a2enmod mpm_prefork && sudo a2enmod php7.0
sudo service apache2 restart

Error during SSL Handshake with remote server

I have 2 servers setup on docker, reverse proxy & web server. This error started happening for all my websites all of a sudden after 1 year. When setting up earlier, I generated a self signed certificate on the web server.

So, I had to generate the SSL certificate again and it started working...

openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout ssl.key -out ssl.crt

Visual Studio 2013 License Product Key

I solved this, without having to completely reinstall Visual Studio 2013.

For those who may come across this in the future, the following steps worked for me:

  1. Run the ISO (or vs_professional.exe).
  2. If you get the error below, you need to update the Windows Registry to trick the installer into thinking you still have the base version. If you don't get this error, skip to step 3 "The product version that you are trying to set up is earlier than the version already installed on this computer."

    • Click the link for 'examine the log file' and look near the bottom of the log, for this line: Detected related bundle ... operation: Downgrade

    • open regedit.exe and do an Edit > Find... for that GUID. In my case it was {6dff50d0-3bc3-4a92-b724-bf6d6a99de4f}. This was found in:


    • Edit the BundleVersion value and change it to a lower version. I changed mine from 12.0.21005.13 to 12.0.21000.13: BundleVersion for Visual Studio lower the version for BundleVersion

    • Exit the registry

  3. Run the ISO (or vs_professional.exe) again. If it has a repair button like the image below, you can skip to step 4.

    Visual Studio Repair button

    • Otherwise you have to let the installer fix the registry. I did this by "installing" at least one feature, even though I think I already had all features (they were not detected). This took about 20 minutes.
  4. Run the ISO (or vs_professional.exe) again. This time repair should be visible.

  5. Click Repair and let it update your installation and apply its embedded license key. This took about 20 minutes.

Now when you run Visual Studio 2013, it should indicate that a license key was applied, under Help > Register Product:

License: Product key applied

Hope this helps somebody in the future!

Reference blog 'story'

Is there a Python caching library?

From Python 3.2 you can use the decorator @lru_cache from the functools library. It's a Last Recently Used cache, so there is no expiration time for the items in it, but as a fast hack it's very useful.

from functools import lru_cache

def f(x):
  return x*x

for x in range(20):
  print f(x)
for x in range(20):
  print f(x)

Change Date Format(DD/MM/YYYY) in SQL SELECT Statement

There's also another way to do this-

select TO_CHAR(SA.[RequestStartDate] , 'DD/MM/YYYY') as RequestStartDate from ... ;

Git: How do I list only local branches?

One of the most straightforward ways to do it is

git for-each-ref --format='%(refname:short)' refs/heads/

This works perfectly for scripts as well.

How to check if a user is logged in (how to properly use user.is_authenticated)?

Update for Django 1.10+:

is_authenticated is now an attribute in Django 1.10.

The method was removed in Django 2.0.

For Django 1.9 and older:

is_authenticated is a function. You should call it like

if request.user.is_authenticated():
    # do something if the user is authenticated

As Peter Rowell pointed out, what may be tripping you up is that in the default Django template language, you don't tack on parenthesis to call functions. So you may have seen something like this in template code:

{% if user.is_authenticated %}

However, in Python code, it is indeed a method in the User class.

Get sum of MySQL column in PHP

I have replace your Code and it works well

while ($row = mysql_fetch_assoc($result)){
    $value = $row['Value'];

    $sum += $value;

echo $sum;

Conflict with dependency ''. Resolved versions for app (23.1.0) and test app (23.0.1) differ

Try this :

apply plugin: ''

android {
compileSdkVersion 27
defaultConfig {
    applicationId "com.example.yourpackagename"
    minSdkVersion 15
    targetSdkVersion 27
    versionCode 1
    versionName "1.0"
    testInstrumentationRunner ""
buildTypes {
    release {
        minifyEnabled false
        proguardFiles getDefaultProguardFile('proguard-android.txt'), ''

dependencies {
implementation fileTree(dir: 'libs', include: ['*.jar'])
implementation ''
implementation ''
testImplementation 'junit:junit:4.12'
androidTestImplementation ''
androidTestImplementation ''

How to use glOrtho() in OpenGL?

Have a look at this picture: Graphical Projections enter image description here

The glOrtho command produces an "Oblique" projection that you see in the bottom row. No matter how far away vertexes are in the z direction, they will not recede into the distance.

I use glOrtho every time I need to do 2D graphics in OpenGL (such as health bars, menus etc) using the following code every time the window is resized:

glOrtho(0.0f, windowWidth, windowHeight, 0.0f, 0.0f, 1.0f);

This will remap the OpenGL coordinates into the equivalent pixel values (X going from 0 to windowWidth and Y going from 0 to windowHeight). Note that I've flipped the Y values because OpenGL coordinates start from the bottom left corner of the window. So by flipping, I get a more conventional (0,0) starting at the top left corner of the window rather.

Note that the Z values are clipped from 0 to 1. So be careful when you specify a Z value for your vertex's position, it will be clipped if it falls outside that range. Otherwise if it's inside that range, it will appear to have no effect on the position except for Z tests.

Blur the edges of an image or background image with CSS

If you set the image in div, you also must set both height and width. This may cause the image to lose its proportion. In addition, you must set the image URL in CSS instead of HTML.

Instead, you can set the image using the IMG tag. In the container class you can only set the width in percent or pixel and the height will automatically maintain proportion.

This is also more effective for accessibility of search engines and reading engines to define an image using an IMG tag.

.container {_x000D_
 margin: auto;_x000D_
 width: 200px;_x000D_
 position: relative;_x000D_
img {_x000D_
 width: 100%;_x000D_
.block {_x000D_
 width: 100%;_x000D_
 position: absolute;_x000D_
 bottom: 0px;_x000D_
 top: 0px;_x000D_
 box-shadow: inset 0px 0px 10px 20px white;_x000D_
<div class="container">_x000D_
 <img src="">_x000D_
 <div class="block"></div>_x000D_

The Network Adapter could not establish the connection when connecting with Oracle DB

I had similar problem before. But this was resolved when I started using hostname instead of IP address in my connection string.

IntelliJ can't recognize JavaFX 11 with OpenJDK 11

As mentioned in the comments, the Starting Guide is the place to start with Java 11 and JavaFX 11.

The key to work as you did before Java 11 is to understand that:

  • JavaFX 11 is not part of the JDK anymore
  • You can get it in different flavors, either as an SDK or as regular dependencies (maven/gradle).
  • You will need to include it to the module path of your project, even if your project is not modular.

JavaFX project

If you create a regular JavaFX default project in IntelliJ (without Maven or Gradle) I'd suggest you download the SDK from here. Note that there are jmods as well, but for a non modular project the SDK is preferred.

These are the easy steps to run the default project:

  1. Create a JavaFX project
  2. Set JDK 11 (point to your local Java 11 version)
  3. Add the JavaFX 11 SDK as a library. The URL could be something like /Users/<user>/Downloads/javafx-sdk-11/lib/. Once you do this you will notice that the JavaFX classes are now recognized in the editor.

JavaFX 11 Project

  1. Before you run the default project, you just need to add these to the VM options:

    --module-path /Users/<user>/Downloads/javafx-sdk-11/lib --add-modules=javafx.controls,javafx.fxml

  2. Run


If you use Maven to build your project, follow these steps:

  1. Create a Maven project with JavaFX archetype
  2. Set JDK 11 (point to your local Java 11 version)
  3. Add the JavaFX 11 dependencies.


Once you do this you will notice that the JavaFX classes are now recognized in the editor.

JavaFX 11 Maven project

You will notice that Maven manages the required dependencies for you: it will add javafx.base and for javafx.controls, but most important, it will add the required classifier based on your platform. In my case, Mac.

This is why your jars org.openjfx:javafx-controls:11 are empty, because there are three possible classifiers (windows, linux and mac platforms), that contain all the classes and the native implementation.

In case you still want to go to your .m2 repo and take the dependencies from there manually, make sure you pick the right one (for instance .m2/repository/org/openjfx/javafx-controls/11/javafx-controls-11-mac.jar)

  1. Replace default maven plugins with those from here.

  2. Run mvn compile javafx:run, and it should work.

Similar works as well for Gradle projects, as explained in detail here.


The mentioned Getting Started guide contains updated documentation and sample projects for IntelliJ:

Getting data from Yahoo Finance

As from the answer from BrianC use the YQL console. But after selecting the "Show Community Tables" go to the bottom of the tables list and expand yahoo where you find plenty of tables:

Stock Quotes:


Fundamental analysis:


Technical analysis:


General financial information:


2/Nov/2017: Yahoo finance has apparently killed this API, for more info and alternative resources see

What happened to Lodash _.pluck?

If you really want _.pluck support back, you can use a mixin:

const _ = require("lodash")


Because map now supports a string (the "iterator") as an argument instead of a function.

Pseudo-terminal will not be allocated because stdin is not a terminal

I'm adding this answer because it solved a related problem that I was having with the same error message.

Problem: I had installed cygwin under Windows and was getting this error: Pseudo-terminal will not be allocated because stdin is not a terminal

Resolution: It turns out that I had not installed the openssh client program and utilities. Because of that cygwin was using the Windows implementation of ssh, not the cygwin version. The solution was to install the openssh cygwin package.

How to set the size of button in HTML

If using the following HTML:

<button id="submit-button"></button>

Style can be applied through JS using the style object available on an HTMLElement.

To set height and width to 200px of the above example button, this would be the JS:

var myButton = document.getElementById('submit-button'); = '200px'; '200px';

I believe with this method, you are not directly writing CSS (inline or external), but using JavaScript to programmatically alter CSS Declarations.

Recursive Lock (Mutex) vs Non-Recursive Lock (Mutex)

As written by Dave Butenhof himself:

"The biggest of all the big problems with recursive mutexes is that they encourage you to completely lose track of your locking scheme and scope. This is deadly. Evil. It's the "thread eater". You hold locks for the absolutely shortest possible time. Period. Always. If you're calling something with a lock held simply because you don't know it's held, or because you don't know whether the callee needs the mutex, then you're holding it too long. You're aiming a shotgun at your application and pulling the trigger. You presumably started using threads to get concurrency; but you've just PREVENTED concurrency."

How do I check if a number is a palindrome?

Just for fun, this one also works.

a = num;
b = 0;
if (a % 10 == 0)
  return a == 0;
do {
  b = 10 * b + a % 10;
  if (a == b)
    return true;
  a = a / 10;
} while (a > b);
return a == b;

Expression must be a modifiable L-value

lvalue means "left value" -- it should be assignable. You cannot change the value of text since it is an array, not a pointer.

Either declare it as char pointer (in this case it's better to declare it as const char*):

const char *text;
if(number == 2) 
    text = "awesome"; 
    text = "you fail";

Or use strcpy:

char text[60];
if(number == 2) 
    strcpy(text, "awesome"); 
    strcpy(text, "you fail");

Why are unnamed namespaces used and what are their benefits?

Unnamed namespaces are a utility to make an identifier translation unit local. They behave as if you would choose a unique name per translation unit for a namespace:

namespace unique { /* empty */ }
using namespace unique;
namespace unique { /* namespace body. stuff in here */ }

The extra step using the empty body is important, so you can already refer within the namespace body to identifiers like ::name that are defined in that namespace, since the using directive already took place.

This means you can have free functions called (for example) help that can exist in multiple translation units, and they won't clash at link time. The effect is almost identical to using the static keyword used in C which you can put in in the declaration of identifiers. Unnamed namespaces are a superior alternative, being able to even make a type translation unit local.

namespace { int a1; }
static int a2;

Both a's are translation unit local and won't clash at link time. But the difference is that the a1 in the anonymous namespace gets a unique name.

Read the excellent article at comeau-computing Why is an unnamed namespace used instead of static? ( mirror).

Could not load file or assembly 'System.Net.Http.Formatting' or one of its dependencies. The system cannot find the path specified

As originally suggested in a comment by GeoMac and documented on NuGet's docs the following worked for me when none of the other answers worked:

Tools / NuGet Package Manager / Package Manager Console

Update-Package -ProjectName MyProjectName -reinstall

force client disconnect from server with and nodejs uses the EventEmitter pattern to disconnect/connect/check heartbeats so you could do. Client.emit('disconnect');

Setting different color for each series in scatter plot on matplotlib

This question is a bit tricky before Jan 2013 and matplotlib 1.3.1 (Aug 2013), which is the oldest stable version you can find on matpplotlib website. But after that it is quite trivial.

Because present version of matplotlib.pylab.scatter support assigning: array of colour name string, array of float number with colour map, array of RGB or RGBA.

this answer is dedicate to @Oxinabox's endless passion for correcting the 2013 version of myself in 2015.

you have two option of using scatter command with multiple colour in a single call.

  1. as pylab.scatter command support use RGBA array to do whatever colour you want;

  2. back in early 2013, there is no way to do so, since the command only support single colour for the whole scatter point collection. When I was doing my 10000-line project I figure out a general solution to bypass it. so it is very tacky, but I can do it in whatever shape, colour, size and transparent. this trick also could be apply to draw path collection, line collection....

the code is also inspired by the source code of pyplot.scatter, I just duplicated what scatter does without trigger it to draw.

the command pyplot.scatter return a PatchCollection Object, in the file "matplotlib/" a private variable _facecolors in Collection class and a method set_facecolors.

so whenever you have a scatter points to draw you can do this:

# rgbaArr is a N*4 array of float numbers you know what I mean
# X is a N*2 array of coordinates
# axx is the axes object that current draw, you get it from
# axx = fig.gca()

# also import these, to recreate the within env of scatter command 
import matplotlib.markers as mmarkers
import matplotlib.transforms as mtransforms
from matplotlib.collections import PatchCollection
import matplotlib.markers as mmarkers
import matplotlib.patches as mpatches

# define this function
# m is a string of scatter marker, it could be 'o', 's' etc..
# s is the size of the point, use 1.0
# dpi, get it from axx.figure.dpi
def addPatch_point(m, s, dpi):
    marker_obj = mmarkers.MarkerStyle(m)
    path = marker_obj.get_path()
    trans = mtransforms.Affine2D().scale(np.sqrt(s*5)*dpi/72.0)
    ptch = mpatches.PathPatch(path, fill = True, transform = trans)
    return ptch

patches = []
# markerArr is an array of maker string, ['o', 's'. 'o'...]
# sizeArr is an array of size float, [1.0, 1.0. 0.5...]

for m, s in zip(markerArr, sizeArr):
    patches.append(addPatch_point(m, s, axx.figure.dpi))

pclt = PatchCollection(
                offsets = zip(X[:,0], X[:,1]),
                transOffset = axx.transData)

pclt.set_edgecolors('none') # it's up to you
pclt._facecolors = rgbaArr

# in the end, when you decide to draw
# and call axx's parent to draw_idle()

How to make program go back to the top of the code instead of closing

Use an infinite loop:

while True:
    print('Hello world!')

This certainly can apply to your start() function as well; you can exit the loop with either break, or use return to exit the function altogether, which also terminates the loop:

def start():
    print ("Welcome to the converter toolkit made by Alan.")

    while True:
        op = input ("Please input what operation you wish to perform. 1 for Fahrenheit to Celsius, 2 for meters to centimetres and 3 for megabytes to gigabytes")

        if op == "1":
            f1 = input ("Please enter your fahrenheit temperature: ")
            f1 = int(f1)

            a1 = (f1 - 32) / 1.8
            a1 = str(a1)

            print (a1+" celsius") 

        elif op == "2":
            m1 = input ("Please input your the amount of meters you wish to convert: ")
            m1 = int(m1)
            m2 = (m1 * 100)

            m2 = str(m2)
            print (m2+" m")

        if op == "3":
            mb1 = input ("Please input the amount of megabytes you want to convert")
            mb1 = int(mb1)
            mb2 = (mb1 / 1024)
            mb3 = (mb2 / 1024)

            mb3 = str(mb3)

            print (mb3+" GB")

            print ("Sorry, that was an invalid command!")

If you were to add an option to quit as well, that could be:

if op.lower() in {'q', 'quit', 'e', 'exit'}:

for example.

How do format a phone number as a String in Java?

Pattern phoneNumber = Pattern.compile("(\\d{3})(\\d{3})(\\d{4})");
// ...
Matcher matcher = phoneNumber(numberAsLineOf10Symbols);
if (matcher.matches) {
    return "(" + + ")-" + "-" +;

Get multiple elements by Id

If you can change the markup, you might want to use class instead.

<!-- html -->
<a class="test" name="Name 1"></a>
<a class="test" name="Name 2"></a>
<a class="test" name="Name 3"></a>

// javascript
var elements = document.getElementsByClassName("test");
var names = '';
for(var i=0; i<elements.length; i++) {
    names += elements[i].name;

jsfiddle demo

How to resolve git's "not something we can merge" error

The branch which you are tryin to merge may not be identified by you git at present so perform git branch and see if the branch which you want to merge exists are not, if not then perform git pull and now if you do git branch, the branch will be visible now, and now you perform git merge <BranchName>

Get push notification while App in foreground iOS

For swift 5 to parse PushNotification dictionary

    func application(_ application: UIApplication, didReceiveRemoteNotification data: [AnyHashable : Any]) {
            if application.applicationState == .active {
                if let aps1 = data["aps"] as? NSDictionary {
                    if let dict = aps1["alert"] as? NSDictionary {
                        if let strTitle = dict["title"] as? String , let strBody = dict["body"] as? String {
                            if let topVC = UIApplication.getTopViewController() {
                                //Apply your own logic as per requirement
                                print("strTitle ::\(strTitle) , strBody :: \(strBody)")

To fetch top viewController on which we show topBanner

extension UIApplication {

    class func getTopViewController(base: UIViewController? = UIApplication.shared.keyWindow?.rootViewController) -> UIViewController? {

        if let nav = base as? UINavigationController {
            return getTopViewController(base: nav.visibleViewController)

        } else if let tab = base as? UITabBarController, let selected = tab.selectedViewController {
            return getTopViewController(base: selected)

        } else if let presented = base?.presentedViewController {
            return getTopViewController(base: presented)
        return base

Enabling HTTPS on express.js

First, you need to create selfsigned.key and selfsigned.crt files. Go to Create a Self-Signed SSL Certificate Or do following steps.

Go to the terminal and run the following command.

sudo openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout ./selfsigned.key -out selfsigned.crt

  • After that put the following information
  • Country Name (2 letter code) [AU]: US
  • State or Province Name (full name) [Some-State]: NY
  • Locality Name (eg, city) []:NY
  • Organization Name (eg, company) [Internet Widgits Pty Ltd]: xyz (Your - Organization)
  • Organizational Unit Name (eg, section) []: xyz (Your Unit Name)
  • Common Name (e.g. server FQDN or YOUR name) []: (Your URL)
  • Email Address []: Your email

After creation adds key & cert file in your code, and pass the options to the server.

const express = require('express');
const https = require('https');
const fs = require('fs');
const port = 3000;

var key = fs.readFileSync(__dirname + '/../certs/selfsigned.key');
var cert = fs.readFileSync(__dirname + '/../certs/selfsigned.crt');
var options = {
  key: key,
  cert: cert

app = express()
app.get('/', (req, res) => {
   res.send('Now using https..');

var server = https.createServer(options, app);

server.listen(port, () => {
  console.log("server starting on port : " + port)
  • Finally run your application using https.

More information

Rotate label text in seaborn factorplot

Any seaborn plots suported by facetgrid won't work with (e.g. catplot)


however barplot, countplot, etc. will work as they are not supported by facetgrid. Below will work for them.

g.set_xticklabels(g.get_xticklabels(), rotation=30)

Also, in case you have 2 graphs overlayed on top of each other, try set_xticklabels on graph which supports it.

How to set a radio button in Android

Many times if your radio buttons belong to the same radioGroup then


will not select the radio button properly. So to solve this problem try using your radioGroup.


Objective-C ARC: strong vs retain and weak vs assign

From the Transitioning to ARC Release Notes (the example in the section on property attributes).

// The following declaration is a synonym for: @property(retain) MyClass *myObject;

@property(strong) MyClass *myObject;

So strong is the same as retain in a property declaration.

For ARC projects I would use strong instead of retain, I would use assign for C primitive properties and weak for weak references to Objective-C objects.

HTML5 Canvas vs. SVG vs. div

I agree with Simon Sarris's conclusions:

I have compared some visualization in Protovis (SVG) to Processingjs (Canvas) which display > 2000 points and processingjs is much faster than protovis.

Handling events with SVG is of course much easer because you can attach them to the objects. In Canvas you have to do it manually (check mouse position, etc) but for simple interaction it shouldn't be hard.

There is also the dojo.gfx library of the dojo toolkit. It provides an abstraction layer and you can specify the renderer (SVG, Canvas, Silverlight). That might be also an viable choice although I don't know how much overhead the additional abstraction layer adds but it makes it easy to code interactions and animations and is renderer-agnostic.

Here are some interesting benchmarks:

Omitting all xsi and xsd namespaces when serializing an object in .NET?

After reading Microsoft's documentation and several solutions online, I have discovered the solution to this problem. It works with both the built-in XmlSerializer and custom XML serialization via IXmlSerialiazble.

To wit, I'll use the same MyTypeWithNamespaces XML sample that's been used in the answers to this question so far.

[XmlRoot("MyTypeWithNamespaces", Namespace="urn:Abracadabra", IsNullable=false)]
public class MyTypeWithNamespaces
    // As noted below, per Microsoft's documentation, if the class exposes a public
    // member of type XmlSerializerNamespaces decorated with the 
    // XmlNamespacesDeclarationAttribute, then the XmlSerializer will utilize those
    // namespaces during serialization.
    public MyTypeWithNamespaces( )
        this._namespaces = new XmlSerializerNamespaces(new XmlQualifiedName[] {
            // Don't do this!! Microsoft's documentation explicitly says it's not supported.
            // It doesn't throw any exceptions, but in my testing, it didn't always work.

            // new XmlQualifiedName(string.Empty, string.Empty),  // And don't do this:
            // new XmlQualifiedName("", "")

            // DO THIS:
            new XmlQualifiedName(string.Empty, "urn:Abracadabra") // Default Namespace
            // Add any other namespaces, with prefixes, here.

    // If you have other constructors, make sure to call the default constructor.
    public MyTypeWithNamespaces(string label, int epoch) : this( )
        this._label = label;
        this._epoch = epoch;

    // An element with a declared namespace different than the namespace
    // of the enclosing type.
    public string Label
        get { return this._label; }
        set { this._label = value; }
    private string _label;

    // An element whose tag will be the same name as the property name.
    // Also, this element will inherit the namespace of the enclosing type.
    public int Epoch
        get { return this._epoch; }
        set { this._epoch = value; }
    private int _epoch;

    // Per Microsoft's documentation, you can add some public member that
    // returns a XmlSerializerNamespaces object. They use a public field,
    // but that's sloppy. So I'll use a private backed-field with a public
    // getter property. Also, per the documentation, for this to work with
    // the XmlSerializer, decorate it with the XmlNamespaceDeclarations
    // attribute.
    public XmlSerializerNamespaces Namespaces
        get { return this._namespaces; }
    private XmlSerializerNamespaces _namespaces;

That's all to this class. Now, some objected to having an XmlSerializerNamespaces object somewhere within their classes; but as you can see, I neatly tucked it away in the default constructor and exposed a public property to return the namespaces.

Now, when it comes time to serialize the class, you would use the following code:

MyTypeWithNamespaces myType = new MyTypeWithNamespaces("myLabel", 42);

   OK, I just figured I could do this to make the code shorter, so I commented out the
   below and replaced it with what follows:

// You have to use this constructor in order for the root element to have the right namespaces.
// If you need to do custom serialization of inner objects, you can use a shortened constructor.
XmlSerializer xs = new XmlSerializer(typeof(MyTypeWithNamespaces), new XmlAttributeOverrides(),
    new Type[]{}, new XmlRootAttribute("MyTypeWithNamespaces"), "urn:Abracadabra");

XmlSerializer xs = new XmlSerializer(typeof(MyTypeWithNamespaces),
    new XmlRootAttribute("MyTypeWithNamespaces") { Namespace="urn:Abracadabra" });

// I'll use a MemoryStream as my backing store.
MemoryStream ms = new MemoryStream();

// This is extra! If you want to change the settings for the XmlSerializer, you have to create
// a separate XmlWriterSettings object and use the XmlTextWriter.Create(...) factory method.
// So, in this case, I want to omit the XML declaration.
XmlWriterSettings xws = new XmlWriterSettings();
xws.OmitXmlDeclaration = true;
xws.Encoding = Encoding.UTF8; // This is probably the default
// You could use the XmlWriterSetting to set indenting and new line options, but the
// XmlTextWriter class has a much easier method to accomplish that.

// The factory method returns a XmlWriter, not a XmlTextWriter, so cast it.
XmlTextWriter xtw = (XmlTextWriter)XmlTextWriter.Create(ms, xws);
// Then we can set our indenting options (this is, of course, optional).
xtw.Formatting = Formatting.Indented;

// Now serialize our object.
xs.Serialize(xtw, myType, myType.Namespaces);

Once you have done this, you should get the following output:

    <Label xmlns="urn:Whoohoo">myLabel</Label>

I have successfully used this method in a recent project with a deep hierachy of classes that are serialized to XML for web service calls. Microsoft's documentation is not very clear about what to do with the publicly accesible XmlSerializerNamespaces member once you've created it, and so many think it's useless. But by following their documentation and using it in the manner shown above, you can customize how the XmlSerializer generates XML for your classes without resorting to unsupported behavior or "rolling your own" serialization by implementing IXmlSerializable.

It is my hope that this answer will put to rest, once and for all, how to get rid of the standard xsi and xsd namespaces generated by the XmlSerializer.

UPDATE: I just want to make sure I answered the OP's question about removing all namespaces. My code above will work for this; let me show you how. Now, in the example above, you really can't get rid of all namespaces (because there are two namespaces in use). Somewhere in your XML document, you're going to need to have something like xmlns="urn:Abracadabra" xmlns:w="urn:Whoohoo. If the class in the example is part of a larger document, then somewhere above a namespace must be declared for either one of (or both) Abracadbra and Whoohoo. If not, then the element in one or both of the namespaces must be decorated with a prefix of some sort (you can't have two default namespaces, right?). So, for this example, Abracadabra is the defalt namespace. I could inside my MyTypeWithNamespaces class add a namespace prefix for the Whoohoo namespace like so:

public MyTypeWithNamespaces
    this._namespaces = new XmlSerializerNamespaces(new XmlQualifiedName[] {
        new XmlQualifiedName(string.Empty, "urn:Abracadabra"), // Default Namespace
        new XmlQualifiedName("w", "urn:Whoohoo")

Now, in my class definition, I indicated that the <Label/> element is in the namespace "urn:Whoohoo", so I don't need to do anything further. When I now serialize the class using my above serialization code unchanged, this is the output:

<MyTypeWithNamespaces xmlns:w="urn:Whoohoo">

Because <Label> is in a different namespace from the rest of the document, it must, in someway, be "decorated" with a namespace. Notice that there are still no xsi and xsd namespaces.

Querying data by joining two tables in two database on different servers

Maybe hard-coded database names isn't the best approach always within an SQL-query. Thus, adding synonyms would be a better approach. It's not always the case that databases have the same name across several staging environments. They might consist by postfixes like PROD, UAT, SIT, QA and so forth. So be aware of hard-coded queries and make them more dynamic.

Approach #1: Use synonyms to link tables between databases on the same server.

Approach #2: Collect data separately from each database and join it in your code. Your database connection strings could be part of your App-server configuration through either a database or a config file.

SQL DROP TABLE foreign key constraint

If you are on a mysql server and if you don't mind loosing your tables, you can use a simple query to delete multiple tables at once:

SET foreign_key_checks = 0;
DROP TABLE IF EXISTS table_a,table_b,table_c,table_etc;
SET foreign_key_checks = 1;

In this way it doesn't matter in what order you use the table in you query.

If anybody is going to say something about the fact that this is not a good solution if you have a database with many tables: I agree!

No provider for Router?

Nothing works from this tread. "forRoot" doesn't help.

Sorry. Sorted this out. I've managed to make it work by setting correct "routes" for this "forRoot" router setup routine

    import {RouterModule, Routes} from '@angular/router';    
    import {AppComponent} from './app.component';
    const appRoutes: Routes = [
      {path: 'UI/part1/Details', component: DetailsComponent}
      declarations: [
      imports: [
      providers: [DetailsService],
      bootstrap: [AppComponent]

Also may be helpful (spent some time to realize this) Optional route part:

    const appRoutes: Routes = [
       {path: 'UI/part1/Details', component: DetailsComponent},
       {path: ':project/UI/part1/Details', component: DetailsComponent}

Second rule allows to open URLs like

Been working as a frontend developer since 2012 but never stuck in a such over-complicated thing as angular2 (I have 3 years experience with enterprise level ExtJS)

Can I bind an array to an IN() condition?

here is my solution. I have also extended the PDO class:

class Db extends PDO

     * SELECT ... WHERE fieldName IN (:paramName) workaround
     * @param array  $array
     * @param string $prefix
     * @return string
    public function CreateArrayBindParamNames(array $array, $prefix = 'id_')
        $newparams = [];
        foreach ($array as $n => $val)
            $newparams[] = ":".$prefix.$n;
        return implode(", ", $newparams);

     * Bind every array element to the proper named parameter
     * @param PDOStatement $stmt
     * @param array        $array
     * @param string       $prefix
    public function BindArrayParam(PDOStatement &$stmt, array $array, $prefix = 'id_')
        foreach($array as $n => $val)
            $val = intval($val);
            $stmt -> bindParam(":".$prefix.$n, $val, PDO::PARAM_INT);

Here is a sample usage for the above code:

$idList = [1, 2, 3, 4];
$stmt = $this -> db -> prepare("
    (`ID` IN (".$this -> db -> CreateArrayBindParamNames($idList)."))");
$this -> db -> BindArrayParam($stmt, $idList);
$stmt -> execute();
foreach($stmt as $row)
    echo $row['Name'];

Let me know what you think

Execute write on doc: It isn't possible to write into a document from an asynchronously-loaded external script unless it is explicitly opened.

A bit late to the party, but Krux has created a script for this, called Postscribe. We were able to use this to get past this issue.

Angular 2 Unit Tests: Cannot find name 'describe'

In order for TypeScript Compiler to use all visible Type Definitions during compilation, types option should be removed completely from compilerOptions field in tsconfig.json file.

This problem arises when there exists some types entries in compilerOptions field, where at the same time jest entry is missing.

So in order to fix the problem, compilerOptions field in your tscongfig.json should either include jest in types area or get rid of types comnpletely:

  "compilerOptions": {
    "esModuleInterop": true,
    "target": "es6",
    "module": "commonjs",
    "outDir": "dist",
    "types": ["reflect-metadata", "jest"],  //<--  add jest or remove completely
    "moduleResolution": "node",
    "sourceMap": true
  "include": [
  "exclude": [

Bootstrap - Uncaught TypeError: Cannot read property 'fn' of undefined

To solve this problem just call jQuery file before the bootstrap file

OraOLEDB.Oracle provider is not registered on the local machine

If you can't change compile use x64, try uninstall x64 version of odac and install 32bit version. Then, don't forget to add install directory like C:\oracle and also the child directory C:\oracle\bin to the PATH environment variable. This worked out for me in .net 4 application.

C default arguments

Yet another option uses structs:

struct func_opts {
  int    arg1;
  char * arg2;
  int    arg3;

void func(int arg, struct func_opts *opts)
    int arg1 = 0, arg3 = 0;
    char *arg2 = "Default";
            arg1 = opts->arg1;
            arg2 = opts->arg2;
            arg3 = opts->arg3;
    // do stuff

// call with defaults
func(3, NULL);

// also call with defaults
struct func_opts opts = {0};
func(3, &opts);

// set some arguments
opts.arg3 = 3;
opts.arg2 = "Yes";
func(3, &opts);

Android Studio Emulator and "Process finished with exit code 0"

None of the solutions worked for me. I upgraded my previous Android Studio to 3.0.1 and received this issue while trying to restart the emulator.

What worked for me was deleting Android Studio from Windows 'Add or Remove Programs'. Then go to C:\Users[User] and delete any android-related folders (.android, .AndroidStudioX.X, Android).

Next go to C:\Users[User]\AppData\Local and delete any Android-related folders there. Restart your system and re-download android studio from their official site ( Install Android Studio from fresh and don't import any old settings.

When Android Studio finishes installing, I launched AVD from 'Tools > Android > AVD Manager', created a pixel 2 device with 4096mb of RAM running Android API P x86. Start it up and it works!

Get docker container id from container name

Docker image inspect ImageName\ImageId --format={{'.ConatinerConfig.Hostname'}}

Is it possible to dynamically compile and execute C# code fragments?

I recently needed to spawn processes for unit testing. This post was useful as I created a simple class to do that with either code as a string or code from my project. To build this class, you'll need the ICSharpCode.Decompiler and Microsoft.CodeAnalysis NuGet packages. Here's the class:

using ICSharpCode.Decompiler;
using ICSharpCode.Decompiler.CSharp;
using ICSharpCode.Decompiler.TypeSystem;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;

public static class CSharpRunner
   public static object Run(string snippet, IEnumerable<Assembly> references, string typeName, string methodName, params object[] args) =>
      Invoke(Compile(Parse(snippet), references), typeName, methodName, args);

   public static object Run(MethodInfo methodInfo, params object[] args)
      var refs = methodInfo.DeclaringType.Assembly.GetReferencedAssemblies().Select(n => Assembly.Load(n));
      return Invoke(Compile(Decompile(methodInfo), refs), methodInfo.DeclaringType.FullName, methodInfo.Name, args);

   private static Assembly Compile(SyntaxTree syntaxTree, IEnumerable<Assembly> references = null)
      if (references is null) references = new[] { typeof(object).Assembly, typeof(Enumerable).Assembly };
      var mrefs = references.Select(a => MetadataReference.CreateFromFile(a.Location));
      var compilation = CSharpCompilation.Create(Path.GetRandomFileName(), new[] { syntaxTree }, mrefs, new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary));

      using (var ms = new MemoryStream())
         var result = compilation.Emit(ms);
         if (result.Success)
            ms.Seek(0, SeekOrigin.Begin);
            return Assembly.Load(ms.ToArray());
            throw new InvalidOperationException(string.Join("\n", result.Diagnostics.Where(diagnostic => diagnostic.IsWarningAsError || diagnostic.Severity == DiagnosticSeverity.Error).Select(d => $"{d.Id}: {d.GetMessage()}")));

   private static SyntaxTree Decompile(MethodInfo methodInfo)
      var decompiler = new CSharpDecompiler(methodInfo.DeclaringType.Assembly.Location, new DecompilerSettings());
      var typeInfo = decompiler.TypeSystem.MainModule.Compilation.FindType(methodInfo.DeclaringType).GetDefinition();
      return Parse(decompiler.DecompileTypeAsString(typeInfo.FullTypeName));

   private static object Invoke(Assembly assembly, string typeName, string methodName, object[] args)
      var type = assembly.GetType(typeName);
      var obj = Activator.CreateInstance(type);
      return type.InvokeMember(methodName, BindingFlags.Default | BindingFlags.InvokeMethod, null, obj, args);

   private static SyntaxTree Parse(string snippet) => CSharpSyntaxTree.ParseText(snippet);

To use it, call the Run methods as below:

void Demo1()
   const string code = @"
   public class Runner
      public void Run() { System.IO.File.AppendAllText(@""C:\Temp\NUnitTest.txt"", System.DateTime.Now.ToString(""o"") + ""\n""); }

   CSharpRunner.Run(code, null, "Runner", "Run");

void Demo2()

public class Runner
   public void Run() { System.IO.File.AppendAllText(@"C:\Temp\NUnitTest.txt", System.DateTime.Now.ToString("o") + "\n"); }

How to check if activity is in foreground or in visible background?

If targeting API level 14 or above, one can use

public class MyApplication extends Application implements ActivityLifecycleCallbacks {
    private static boolean isInterestingActivityVisible;

    public void onCreate() {

        // Register to be notified of activity state changes

    public boolean isInterestingActivityVisible() {
        return isInterestingActivityVisible;

    public void onActivityResumed(Activity activity) {
        if (activity instanceof MyInterestingActivity) {
             isInterestingActivityVisible = true;

    public void onActivityStopped(Activity activity) {
        if (activity instanceof MyInterestingActivity) {
             isInterestingActivityVisible = false;

    // Other state change callback stubs

Practical uses for the "internal" keyword in C#

I have a project which uses LINQ-to-SQL for the data back-end. I have two main namespaces: Biz and Data. The LINQ data model lives in Data and is marked "internal"; the Biz namespace has public classes which wrap around the LINQ data classes.

So there's Data.Client, and Biz.Client; the latter exposes all relevant properties of the data object, e.g.:

private Data.Client _client;
public int Id { get { return _client.Id; } set { _client.Id = value; } }

The Biz objects have a private constructor (to force the use of factory methods), and an internal constructor which looks like this:

internal Client(Data.Client client) {
    this._client = client;

That can be used by any of the business classes in the library, but the front-end (UI) has no way of directly accessing the data model, ensuring that the business layer always acts as an intermediary.

This is the first time I've really used internal much, and it's proving quite useful.

Getting "net::ERR_BLOCKED_BY_CLIENT" error on some AJAX calls

I find a case is if your url contains the key word banner, it will blocked too.

Open Source Alternatives to Reflector?

Well, Reflector itself is a .NET assembly so you can open Reflector.exe in Reflector to check out how it's built.

How to change an Android app's name?

follow the steps:(let I assuming you have chosen Android view) app>res>values>strings

<string name="app_name">Put your App's new name here</string>

How do you create a toggle button?

The good semantic way would be to use a checkbox, and then style it in different ways if it is checked or not. But there are no good ways do to it. You have to add extra span, extra div, and, for a really nice look, add some javascript.

So the best solution is to use a small jQuery function and two background images for styling the two different statuses of the button. Example with an up/down effect given by borders:

$(document).ready(function() {_x000D_
  $('a#button').click(function() {_x000D_
a {_x000D_
  background: #ccc;_x000D_
  cursor: pointer;_x000D_
  border-top: solid 2px #eaeaea;_x000D_
  border-left: solid 2px #eaeaea;_x000D_
  border-bottom: solid 2px #777;_x000D_
  border-right: solid 2px #777;_x000D_
  padding: 5px 5px;_x000D_
a.down {_x000D_
  background: #bbb;_x000D_
  border-top: solid 2px #777;_x000D_
  border-left: solid 2px #777;_x000D_
  border-bottom: solid 2px #eaeaea;_x000D_
  border-right: solid 2px #eaeaea;_x000D_
<script src=""></script>_x000D_
<a id="button" title="button">Press Me</a>

Obviously, you can add background images that represent button up and button down, and make the background color transparent.

what are the .map files used for in Bootstrap 3.x?

Map files (source maps) are there to de-reference minified code (css and javascript).

And they are mainly used to help developers debugging a production environment, because developers usually use minified files for production which makes it impossible to debug. Map files help them de-referencing the code to see how the original file looked like.

UIView background color in Swift

Try This, It worked like a charm! for me,

The simplest way to add backgroundColor programmatically by using ColorLiteral.

You need to add the property ColorLiteral, Xcode will prompt you with a whole list of colors in which you can choose any color. The advantage of doing this is we use lesser code, add HEX values or RGB. You will also get the recently used colors from the storyboard.

Follow steps ,

1) Add below line of code in viewDidLoad() ,

self.view.backgroundColor = ColorLiteral

and clicked on enter button .

2) Display square box next to =

enter image description here

3) When Clicked on Square Box Xcode will prompt you with a whole list of colors which you can choose any colors also you can set HEX values or RGB

enter image description here

4) You can successfully set the colors .

enter image description here

Hope this will help some one to set backgroundColor in different ways.

How to get the month name in C#?

If you just want to use MonthName then reference Microsoft.VisualBasic and it's in Microsoft.VisualBasic.DateAndTime

//eg. Get January
String monthName = Microsoft.VisualBasic.DateAndTime.MonthName(1);

Redirecting a request using servlets and the "setHeader" method not working

Alternatively, you could try the following,

resp.setHeader("Location", "index.jsp");
resp.setHeader("Connection", "close");

Web.Config Debug/Release

To make the transform work in development (using F5 or CTRL + F5) I drop ctt.exe ( in the packages folder (packages\ConfigTransform\ctt.exe).

Then I register a pre- or post-build event in Visual Studio...

$(SolutionDir)packages\ConfigTransform\ctt.exe source:"$(ProjectDir)connectionStrings.config" transform:"$(ProjectDir)connectionStrings.$(ConfigurationName).config" destination:"$(ProjectDir)connectionStrings.config"
$(SolutionDir)packages\ConfigTransform\ctt.exe source:"$(ProjectDir)web.config" transform:"$(ProjectDir)web.$(ConfigurationName).config" destination:"$(ProjectDir)web.config"

For the transforms I use SlowCheeta VS extension (

Spark specify multiple column conditions for dataframe join

As of Spark version 1.5.0 (which is currently unreleased), you can join on multiple DataFrame columns. Refer to SPARK-7990: Add methods to facilitate equi-join on multiple join keys.




The question asked for a Scala answer, but I don't use Scala. Here is my best guess....


Non-alphanumeric list order from os.listdir()

It's probably just the order that C's readdir() returns. Try running this C program:

#include <dirent.h>
#include <stdio.h>
int main(void)
{   DIR *dirp;
    struct dirent* de;
    dirp = opendir(".");
    while(de = readdir(dirp)) // Yes, one '='.
        printf("%s\n", de->d_name);
    return 0;

The build line should be something like gcc -o foo foo.c.

P.S. Just ran this and your Python code, and they both gave me sorted output, so I can't reproduce what you're seeing.

How can I tell when a MySQL table was last updated?

Just grab the file date modified from file system. In my language that is:

 tbl_updated = file.update_time(
        "C:\ProgramData\MySQL\MySQL Server 5.5\data\mydb\person.frm")


1/25/2013 06:04:10 AM

How to set the color of "placeholder" text?

Nobody likes the "refer to this answer" answers, but in this case it may help: Change an HTML5 input's placeholder color with CSS

Since it's only supported by a couple of browsers, you can try the jQuery placeholder plugin (assuming you can\are using jQuery). It allows you to style the placeholder text via CSS since it's really only a swap trick it does with focus events.

The plugin does not activate on browsers that support it, though, so you can have CSS that targets chrome\firefox and the jQuery plugin's CSS to catch the rest.

The plugin can be found here:

What does enumerate() mean?

The enumerate() function adds a counter to an iterable.

So for each element in cursor, a tuple is produced with (counter, element); the for loop binds that to row_number and row, respectively.


>>> elements = ('foo', 'bar', 'baz')
>>> for elem in elements:
...     print elem
>>> for count, elem in enumerate(elements):
...     print count, elem
0 foo
1 bar
2 baz

By default, enumerate() starts counting at 0 but if you give it a second integer argument, it'll start from that number instead:

>>> for count, elem in enumerate(elements, 42):
...     print count, elem
42 foo
43 bar
44 baz

If you were to re-implement enumerate() in Python, here are two ways of achieving that; one using itertools.count() to do the counting, the other manually counting in a generator function:

from itertools import count

def enumerate(it, start=0):
    # return an iterator that adds a counter to each element of it
    return zip(count(start), it)


def enumerate(it, start=0):
    count = start
    for elem in it:
        yield (count, elem)
        count += 1

The actual implementation in C is closer to the latter, with optimisations to reuse a single tuple object for the common for i, ... unpacking case and using a standard C integer value for the counter until the counter becomes too large to avoid using a Python integer object (which is unbounded).

How do you easily create empty matrices javascript?

Well, you can create an empty 1-D array using the explicit Array constructor:

a = new Array(9)

To create an array of arrays, I think that you'll have to write a nested loop as Marc described.

How to get child element by index in Jquery?


how to align img inside the div to the right?

<div style="width:300px; text-align:right;">
        <img src="someimgage.gif">

Python slice first and last element in list

first, last = some_list[0], some_list[-1]