Programs & Examples On #Callbyname

What is a unix command for deleting the first N characters of a line?

tail -f logfile | grep org.springframework | cut -c 900-

would remove the first 900 characters

cut uses 900- to show the 900th character to the end of the line

however when I pipe all of this through grep I don't get anything

JavaScript replace \n with <br />

You need the /g for global matching

replace(/\n/g, "<br />");

This works for me for \n - see this answer if you might have \r\n

NOTE: The dupe is the most complete answer for any combination of \r\n, \r or \n

var messagetoSend = document.getElementById('x').value.replace(/\n/g, "<br />");_x000D_
<textarea id="x" rows="9">_x000D_
    Line 1_x000D_
    Line 2_x000D_
    Line 3_x000D_


It seems some visitors of this question have text with the breaklines escaped as

some text\r\nover more than one line"

In that case you need to escape the slashes:

replace(/\\r\\n/g, "<br />");

NOTE: All browsers will ignore \r in a string when rendering.

IIS Manager in Windows 10

I arrived here because I was having the same issue.

If you are here and everything above didn't work, it's likely that you butchered your path somehow.

Go to System -> Advanced System Settings -> Advanced -> Environment Variables -> Machine or User and add the following entry to the end, or append to the existing, separating with a semi-colon:


After closing and opening your shell, you should now be able to access inetmgr from the command line.

How to open an Excel file in C#?

For opening a file, try this:

    missing, missing, missing, missing, missing, missing, missing,
    missing, missing, missing, missing, missing,missing, missing);

You must supply those stupid looking 'missing' arguments. If you were writing the same code in VB.Net you wouldn't have needed them, but you can't avoid them in C#.

How to add border around linear layout except at the bottom?

Kenny is right, just want to clear some things out.

  1. Create the file border.xml and put it in the folder res/drawable/
  2. add the code

    <shape xmlns:android=""> 
       <stroke android:width="4dp" android:color="#FF00FF00" /> 
       <solid android:color="#ffffff" /> 
       <padding android:left="7dp" android:top="7dp" 
            android:right="7dp" android:bottom="0dp" /> 
       <corners android:radius="4dp" /> 
  3. set back ground like android:background="@drawable/border" wherever you want the border

Mine first didn't work cause i put the border.xml in the wrong folder!

How to dynamically add rows to a table in ASP.NET?

You can use the asp:Table in your web form and build it via code:

Also, check out for tutorials and such.

Selection with .loc in python

This is using dataframes from the pandas package. The "index" part can be either a single index, a list of indices, or a list of booleans. This can be read about in the documentation:

So the index part specifies a subset of the rows to pull out, and the (optional) column_name specifies the column you want to work with from that subset of the dataframe. So if you want to update the 'class' column but only in rows where the class is currently set as 'versicolor', you might do something like what you list in the question:

iris_data.loc[iris_data['class'] == 'versicolor', 'class'] = 'Iris-versicolor'

Capturing URL parameters in request.GET

You might as well check request.META dictionary to access many useful things like PATH_INFO, QUERY_STRING

# for example

# or to avoid any exceptions provide a fallback

request.META.get('QUERY_STRING', False)

you said that it returns empty query dict

I think you need to tune your url to accept required or optional args or kwargs Django got you all the power you need with regrex like:


more about this at django-optional-url-parameters

Difference between npx and npm?

Introducing npx: an npm package runner

NPM - Manages packages but doesn't make life easy executing any.
NPX - A tool for executing Node packages.

NPX comes bundled with NPM version 5.2+

NPM by itself does not simply run any package. it doesn't run any package in a matter of fact. If you want to run a package using NPM, you must specify that package in your package.json file.

When executables are installed via NPM packages, NPM links to them:

  1. local installs have "links" created at ./node_modules/.bin/ directory.
  2. global installs have "links" created from the global bin/ directory (e.g. /usr/local/bin) on Linux or at %AppData%/npm on Windows.

Documentation you should read


One might install a package locally on a certain project:

npm install some-package

Now let's say you want NodeJS to execute that package from the command line:

$ some-package

The above will fail. Only globally installed packages can be executed by typing their name only.

To fix this, and have it run, you must type the local path:

$ ./node_modules/.bin/some-package

You can technically run a locally installed package by editing your packages.json file and adding that package in the scripts section:

  "name": "whatever",
  "version": "1.0.0",
  "scripts": {
    "some-package": "some-package"

Then run the script using npm run-script (or npm run):

npm run some-package


npx will check whether <command> exists in $PATH, or in the local project binaries, and execute it. So, for the above example, if you wish to execute the locally-installed package some-package all you need to do is type:

npx some-package

Another major advantage of npx is the ability to execute a package which wasn't previously installed:

$ npx create-react-app my-app

The above example will generate a react app boilerplate within the path the command had run in, and ensures that you always use the latest version of a generator or build tool without having to upgrade each time you’re about to use it.

Use-Case Example:

npx command may be helpful in the script section of a package.json file, when it is unwanted to define a dependency which might not be commonly used or any other reason:

"scripts": {
    "start": "npx [email protected]",
    "serve": "npx http-server"

Call with: npm run serve

Related questions:

  1. How to use package installed locally in node_modules?
  2. NPM: how to source ./node_modules/.bin folder?
  3. How do you run a js file using npm scripts?

How to create JSON string in C#

If you can't or don't want to use the two built-in JSON serializers (JavaScriptSerializer and DataContractJsonSerializer) you can try the JsonExSerializer library - I use it in a number of projects and works quite well.

Python 3 print without parenthesis

No. That will always be a syntax error in Python 3. Consider using 2to3 to translate your code to Python 3

How can I list ALL DNS records?

Many DNS servers refuse ‘ANY’ queries. So the only way is to query for every type individually. Luckily there are sites that make this simpler. For example, shows the most popular record types by default, and has support for all existing record types.

MySql Error: 1364 Field 'display_name' doesn't have default value

I also had this issue using Lumen, but fixed by setting DB_STRICT_MODE=false in .env file.

How to get subarray from array?

For a simple use of slice, use my extension to Array Class:

Array.prototype.subarray = function(start, end) {
    if (!end) { end = -1; } 
    return this.slice(start, this.length + 1 - (end * -1));


var bigArr = ["a", "b", "c", "fd", "ze"];


bigArr.subarray(1, -1);

< ["b", "c", "fd", "ze"]


bigArr.subarray(2, -2);

< ["c", "fd"]



< ["c", "fd","ze"]

Might be easier for developers coming from another language (i.e. Groovy).

How do I completely remove root password

Did you try passwd -d root? Most likely, this will do what you want.

You can also manually edit /etc/shadow: (Create a backup copy. Be sure that you can log even if you mess up, for example from a rescue system.) Search for "root". Typically, the root entry looks similar to


There, delete the second field (everything between the first and second colon):


Some systems will make you put an asterisk (*) in the password field instead of blank, where a blank field would allow no password (CentOS 8 for example)


Save the file, and try logging in as root. It should skip the password prompt. (Like passwd -d, this is a "no password" solution. If you are really looking for a "blank password", that is "ask for a password, but accept if the user just presses Enter", look at the manpage of mkpasswd, and use mkpasswd to create the second field for the /etc/shadow.)

Are there any HTTP/HTTPS interception tools like Fiddler for mac OS X?

I know this is an old question, but I wanted to add ServiceCapture to the list, for those who may come across this.

I've been using ServiceCapture for about 4 years and love it. It's not free, but it is a great tool and not very expensive. If you debug a lot of Flash or AJAX apps it is invaluable.

Extracting the top 5 maximum values in excel

Put the data into a Pivot Table and do a top n filter on it

Excel Demo

How do I create an empty array/matrix in NumPy?

For creating an empty NumPy array without defining its shape:

  1. arr = np.array([])

    (this is preferred, because you know you will be using this as a NumPy array)

  2.  arr = []   # and use it as NumPy array later by converting it
     arr = np.asarray(arr)

NumPy converts this to np.ndarray type afterward, without extra [] 'dimension'.

Get the data received in a Flask request

To get JSON posted without the application/json content type, use request.get_json(force=True).

@app.route('/process_data', methods=['POST'])
def process_data():
    req_data = request.get_json(force=True)
    language = req_data['language']
    return 'The language value is: {}'.format(language)

SQLDataReader Row Count

Maybe you can try this: though please note - This pulls the column count, not the row count

 using (SqlDataReader reader = command.ExecuteReader())
     while (reader.Read())
         int count = reader.VisibleFieldCount;

How to restart a node.js server

If I am just run the node app from console (not using forever etc) I use control + C, not sure if OSX has the same key combination to terminate but much faster than finding the process id and killing it, you could also add the following code to the chat app you are using and then type 'exit' in the console whenever you want to close down the app.


process.stdin.on('data', function(data) {
  if (data == 'exit\n') process.exit();

SQL Count for each date

You can use:

     count(created_date) as counted_leads,
     created_date as count_date
group by

Generate random number between two numbers in JavaScript

This is about nine years late, but makes this a simple one-liner:

rando(1, 6)

You just need to add this to the head of your html document, and you can do pretty much whatever you want with randomness easily. Random values from arrays, random jquery elements, random properties from objects, and even preventing repetitions if needed.

<script src=""></script>

Android studio: emulator is running but not showing up in Run App "choose a running device"

try to open the emulator and run it parallel with android studio/eclipse and the option will be displayed to select in the choose the device(emuator name, mine is Genymotion).

How do I make CMake output into a 'bin' dir?

To add on to this:

If you're using CMAKE to generate a Visual Studio solution, and you want Visual Studio to output compiled files into /bin, Peter's answer needs to be modified a bit:

# set output directories for all builds (Debug, Release, etc.)

Where do I call the BatchNormalization function in Keras?

Just to answer this question in a little more detail, and as Pavel said, Batch Normalization is just another layer, so you can use it as such to create your desired network architecture.

The general use case is to use BN between the linear and non-linear layers in your network, because it normalizes the input to your activation function, so that you're centered in the linear section of the activation function (such as Sigmoid). There's a small discussion of it here

In your case above, this might look like:

# import BatchNormalization
from keras.layers.normalization import BatchNormalization

# instantiate model
model = Sequential()

# we can think of this chunk as the input layer
model.add(Dense(64, input_dim=14, init='uniform'))

# we can think of this chunk as the hidden layer    
model.add(Dense(64, init='uniform'))

# we can think of this chunk as the output layer
model.add(Dense(2, init='uniform'))

# setting up the optimization of our weights 
sgd = SGD(lr=0.1, decay=1e-6, momentum=0.9, nesterov=True)
model.compile(loss='binary_crossentropy', optimizer=sgd)

# running the fitting, y_train, nb_epoch=20, batch_size=16, show_accuracy=True, validation_split=0.2, verbose = 2)

Hope this clarifies things a bit more.

Make text wrap in a cell with FPDF?

Text Wrap:

The MultiCell is used for print text with multiple lines. It has the same atributes of Cell except for ln and link.

$pdf->MultiCell( 200, 40, $reportSubtitle, 1);

Line Height:

What multiCell does is to spread the given text into multiple cells, this means that the second parameter defines the height of each line (individual cell) and not the height of all cells (collectively).

MultiCell(float w, float h, string txt [, mixed border [, string align [, boolean fill]]])

You can read the full documentation here.

View HTTP headers in Google Chrome?

For me, as of Google Chrome Version 46.0.2490.71 m, the Headers info area is a little hidden. To access:

  1. While the browser is open, press F12 to access Web Developer tools

  2. When opened, click the "Network" option

  3. Initially, it is possible the page data is not present/up to date. Refresh the page if necessary

  4. Observe the page information appears in the listing. (Also, make sure "All" is selected next to the "Hide data URLs" checkbox)

see screenshot

A generic error occurred in GDI+, JPEG Image to MemoryStream

I have strange solution for this problem. I was fased to this during coding. I thought that Bitmap is struct and wrap around it with method. In my imagination Bitmap will be copies inside method and returned out of method. But later I checked that it's class, and i have no idea why is it helped me, but it Works! Maybe someone have time and have fun to look at IL code of this ;) Not sure maybe it's working cause this method is static inside static method, I don't know.

        public SomeClass
            public byte[] _screenShotByte;
            public Bitmap _screenShotByte;
            public Bitmap ScreenShot 
                    if (_screenShot == null)
                        _screenShotByte = ScreenShot();
                        using (var ms = new MemoryStream(_screenShotByte))
                            _screenShot = (Bitmap)Image.FromStream(ms);
                        ImageUtils.GetBitmap(_screenShot).Save(Path.Combine(AppDomain.CurrentDomain.BaseDirectory) ,$"{DateTime.Now.ToFileTimeUtc()}.png"));
                    return ImageUtils.GetBitmap(_screenShot);
            public byte[] ScreenShot()
                ///....return byte array for image in my case implementedd like selenium screen shot 
        public static ImageUtils
            public static Bitmap GetBitmap(Bitmap image)
                return Bitmap;

p.s. It's not trolling this solution solved problem of keep using bitmap after saving in another places.

c# datatable insert column at position 0

You can use the following code to add column to Datatable at postion 0:

    DataColumn Col   = datatable.Columns.Add("Column Name", System.Type.GetType("System.Boolean"));
    Col.SetOrdinal(0);// to put the column in position 0;

An internal error occurred during: "Updating Maven Project". Unsupported IClasspathEntry kind=4

I have that problem and my solution is going source folder and run command line: mvn clean install -DskipTests eclipse:eclipse then return eclipse workspace and refresh project. Hope that help!

Calculate Pandas DataFrame Time Difference Between Two Columns in Hours and Minutes

Pandas timestamp differences returns a datetime.timedelta object. This can easily be converted into hours by using the *as_type* method, like so

import pandas
df = pandas.DataFrame(columns=['to','fr','ans']) = [pandas.Timestamp('2014-01-24 13:03:12.050000'), pandas.Timestamp('2014-01-27 11:57:18.240000'), pandas.Timestamp('2014-01-23 10:07:47.660000')] = [pandas.Timestamp('2014-01-26 23:41:21.870000'), pandas.Timestamp('2014-01-27 15:38:22.540000'), pandas.Timestamp('2014-01-23 18:50:41.420000')]

to yield,

0    58
1     3
2     8
dtype: float64

How to check if a view controller is presented modally or pushed on a navigation stack?

For some one who's wondering, How to tell ViewController that it is being presented

if A is presenting/pushing B

  1. Define an enum and property in B

    enum ViewPresentationStyle {
        case Push
        case Present
    //and write property 
    var vcPresentationStyle : ViewPresentationStyle = .Push //default value, considering that B is pushed 
  2. Now in A view controller, tell B if it is being presented/pushed by assigning presentationStyle

    func presentBViewController() {
        let bViewController = B()
        bViewController.vcPresentationStyle = .Present //telling B that it is being presented
        self.presentViewController(bViewController, animated: true, completion: nil)
  3. Usage in B View Controller

    override func viewDidLoad() {
        if self.vcPresentationStyle == .Present {
            //is being presented 
        else {
            //is being pushed

How to place a JButton at a desired location in a JFrame using Java

I have figured it out lol. for the button do .setBounds(0, 0, 220, 30) The .setBounds layout is like this (int x, int y, int width, int height)

How to enable mod_rewrite for Apache 2.2

New apache version has change in some way. If your apache version is 2.4 then you have to go to /etc/apache2/. There will be a file named apache2.conf. You have to edit that one(you should have root permission). Change directory text like this

<Directory /var/www/>
    Options Indexes FollowSymLinks
    AllowOverride All
    Require all granted

Now restart apache.

service apache2 reload

Hope it works.

String.replaceAll single backslashes with double backslashes

TLDR: use theString = theString.replace("\\", "\\\\"); instead.


replaceAll(target, replacement) uses regular expression (regex) syntax for target and partially for replacement.

Problem is that \ is special character in regex (it can be used like \d to represents digit) and in String literal (it can be used like "\n" to represent line separator or \" to escape double quote symbol which normally would represent end of string literal).

In both these cases to create \ symbol we can escape it (make it literal instead of special character) by placing additional \ before it (like we escape " in string literals via \").

So to target regex representing \ symbol will need to hold \\, and string literal representing such text will need to look like "\\\\".

So we escaped \ twice:

  • once in regex \\
  • once in String literal "\\\\" (each \ is represented as "\\").

In case of replacement \ is also special there. It allows us to escape other special character $ which via $x notation, allows us to use portion of data matched by regex and held by capturing group indexed as x, like "012".replaceAll("(\\d)", "$1$1") will match each digit, place it in capturing group 1 and $1$1 will replace it with its two copies (it will duplicate it) resulting in "001122".

So again, to let replacement represent \ literal we need to escape it with additional \ which means that:

  • replacement must hold two backslash characters \\
  • and String literal which represents \\ looks like "\\\\"

BUT since we want replacement to hold two backslashes we will need "\\\\\\\\" (each \ represented by one "\\\\").

So version with replaceAll can look like

replaceAll("\\\\", "\\\\\\\\");

Easier way

To make out life easier Java provides tools to automatically escape text into target and replacement parts. So now we can focus only on strings, and forget about regex syntax:

replaceAll(Pattern.quote(target), Matcher.quoteReplacement(replacement))

which in our case can look like

replaceAll(Pattern.quote("\\"), Matcher.quoteReplacement("\\\\"))

Even better

If we don't really need regex syntax support lets not involve replaceAll at all. Instead lets use replace. Both methods will replace all targets, but replace doesn't involve regex syntax. So you could simply write

theString = theString.replace("\\", "\\\\");

Integer value in TextView

TextView tv = new TextView(this);
tv.setText("" + 4);

importing external ".txt" file in python

The "import" keyword is for attaching python definitions that are created external to the current python program. So in your case, where you just want to read a file with some text in it, use:

text = open("words.txt", "rb").read()

Built in Python hash() function

At a guess, AppEngine is using a 64-bit implementation of Python (-5768830964305142685 won't fit in 32 bits) and your implementation of Python is 32 bits. You can't rely on object hashes being meaningfully comparable between different implementations.

Return the characters after Nth character in a string

Mid(strYourString, 4) (i.e. without the optional length argument) will return the substring starting from the 4th character and going to the end of the string.

invalid multibyte char (US-ASCII) with Rails and Ruby 1.9

Just a note that as of Ruby 2.0 there is no need to add # encoding: utf-8. UTF-8 is automatically detected.

Cast to generic type in C#

I had a similar problem. I have a class;


which has a property of type T.

How do I get the property when I don't know T? I can't cast to Action<> unless I know T.


Implement a non-generic interface;

public interface IGetGenericTypeInstance
    object GenericTypeInstance();

Now I can cast the object to IGetGenericTypeInstance and GenericTypeInstance will return the property as type object.

Check if certain value is contained in a dataframe column in pandas

You can simply use this:

'07311954' in which returns True or False

Here is the further explanation:

In pandas, using in check directly with DataFrame and Series (e.g. val in df or val in series ) will check whether the val is contained in the Index.

BUT you can still use in check for their values too (instead of Index)! Just using val in df.col_name.values or val in series.values. In this way, you are actually checking the val with a Numpy array.

And .isin(vals) is the other way around, it checks whether the DataFrame/Series values are in the vals. Here vals must be set or list-like. So this is not the natural way to go for the question.

Adding and reading from a Config file

Configuration configManager = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
KeyValueConfigurationCollection confCollection = configManager.AppSettings.Settings;

confCollection["YourKey"].Value = "YourNewKey";


Formatting struct timespec

You could use a std::stringstream. You can stream anything into it:

std::stringstream stream;
stream << 5.7;
stream <<;

std::string s = stream.str();

That should be a quite general approach. (Works only for C++, but you asked the question for this language too.)

Formula px to dp, dp to px android

In most of the cases, conversion functions are called frequently. We can optimize it by adding memoization. So,it does not calculate every-time the function is called.

Let's declare a HashMap which will store the calculated values.

private static Map<Float, Float> pxCache = new HashMap<>();

A function which calculates pixel values :

public static float calculateDpToPixel(float dp, Context context) {

        Resources resources = context.getResources();
        DisplayMetrics metrics = resources.getDisplayMetrics();
        float px = dp * (metrics.densityDpi / 160f);
        return px;


A memoization function which returns the value from HashMap and maintains the record of previous values.

Memoization can be implemented in different ways in Java. For Java 7 :

public static float convertDpToPixel(float dp, final Context context) {

        Float f = pxCache.get(dp);
        if (f == null) {
            synchronized (pxCache) {
                f = calculateDpToPixel(dp, context);
                pxCache.put(dp, f);


        return f;

Java 8 supports Lambda function :

public static float convertDpToPixel(float dp, final Context context) {

        pxCache.computeIfAbsent(dp, y ->calculateDpToPixel(dp,context));


how to get request path with express req object

After having a bit of a play myself, you should use:


Regular expression for address field validation

Regular expression for simple address validation


E.g. for Address match case

#1, North Street, Chennai - 11 

E.g. for Address not match case

$1, North Street, Chennai @ 11

Invalid application of sizeof to incomplete type with a struct

It means the file containing main doesn't have access to the player structure definition (i.e. doesn't know what it looks like).

Try including it in header.h or make a constructor-like function that allocates it if it's to be an opaque object.


If your goal is to hide the implementation of the structure, do this in a C file that has access to the struct:

struct player *
    struct player *p = calloc(1, sizeof *p);

    /* ... */
    return p;

However if the implementation shouldn't be hidden - i.e. main should legally say p->canPlay = 1 it would be better to put the definition of the structure in header.h.

How can I make a menubar fixed on the top while scrolling

This should get you started

 <div class="menuBar">
        <img class="logo" src="logo.jpg"/>
        <div class="nav"> 
                <li>Menu 2</li>
                <li>Menu 3</li>

.nav ul li{

Explain the concept of a stack frame in a nutshell

If you understand stack very well then you will understand how memory works in program and if you understand how memory works in program you will understand how function store in program and if you understand how function store in program you will understand how recursive function works and if you understand how recursive function works you will understand how compiler works and if you understand how compiler works your mind will works as compiler and you will debug any program very easily

Let me explain how stack works:

First you have to know how functions are represented in stack :

Heap stores dynamically allocated values.
Stack stores automatic allocation and deletion values.

enter image description here

Let's understand with example :

def hello(x):
    if x==1:
        return "op"
    return e


Now understand parts of this program :

enter image description here

Now let's see what is stack and what are stack parts:

enter image description here

Allocation of the stack :

Remember one thing: if any function's return condition gets satisfied, no matter it has loaded the local variables or not, it will immediately return from stack with it's stack frame. It means that whenever any recursive function get base condition satisfied and we put a return after base condition, the base condition will not wait to load local variables which are located in the “else” part of program. It will immediately return the current frame from the stack following which the next frame is now in the activation record.

See this in practice:

enter image description here

Deallocation of the block:

So now whenever a function encounters return statement, it delete the current frame from the stack.

While returning from the stack, values will returned in reverse of the original order in which they were allocated in stack.

enter image description here

commands not found on zsh

For me just restarting my terminal seemed to fix the issue.

Python - How to concatenate to a string in a for loop?

endstring = ''
for s in list:
    endstring += s

Angular ng-if="" with multiple arguments

It is possible.

<span ng-if="checked && checked2">
  I'm removed when the checkbox is unchecked.

How to find time complexity of an algorithm

I know this question goes a way back and there are some excellent answers here, nonetheless I wanted to share another bit for the mathematically-minded people that will stumble in this post. The Master theorem is another usefull thing to know when studying complexity. I didn't see it mentioned in the other answers.

How to do fade-in and fade-out with JavaScript and CSS

Heres my code for a fade in/out toggle functions.

fadeIn: function (len) {
                var obj = this.e;
       = '';
                var op = 0; 
                var timer = setInterval(function () {
                    if (op >= 1 || op >= 1.0){
                        console.log('done', op)
           = op.toFixed(1);
                    op += 0.1;
                }, len);
                return this;
    fadeOut: function (len) {
                var obj = this.e;
                var op = 1; 
                var timer = setInterval(function () {
                    if (op <= 0){
                        console.log('done', op)
               = 'none';
           = op.toFixed(1);
                    op -= 0.1;
                }, len);
                return this;

This was from a jQuery style lib i did. hope it's helpfull. link to lib on cloud9:

How can I see the raw SQL queries Django is running?

Just to add, in django, if you have a query like:






to get the sql string

Ignore .pyc files in git repository

Put it in .gitignore. But from the gitignore(5) man page:

  ·   If the pattern does not contain a slash /, git treats it as a shell
       glob pattern and checks for a match against the pathname relative
       to the location of the .gitignore file (relative to the toplevel of
       the work tree if not from a .gitignore file).

  ·   Otherwise, git treats the pattern as a shell glob suitable for
       consumption by fnmatch(3) with the FNM_PATHNAME flag: wildcards in
       the pattern will not match a / in the pathname. For example,
       "Documentation/*.html" matches "Documentation/git.html" but not
       "Documentation/ppc/ppc.html" or

So, either specify the full path to the appropriate *.pyc entry, or put it in a .gitignore file in any of the directories leading from the repository root (inclusive).

Sass nth-child nesting

I'd be careful about trying to get too clever here. I think it's confusing as it is and using more advanced nth-child parameters will only make it more complicated. As for the background color I'd just set that to a variable.

Here goes what I came up with before I realized trying to be too clever might be a bad thing.

#romtest {
 $bg: #e5e5e5;
 .detailed {
    th {
      &:nth-child(-2n+6) {
        background-color: $bg;
    td {
      &:nth-child(3n), &:nth-child(2), &:nth-child(7) {
        background-color: $bg;
      &.last {
          background-color: $bg;

and here is a quick demo:


Here's another approach to avoid retyping background-color:

#romtest {
  %highlight {
    background-color: #e5e5e5; 
  .detailed {
    th {
      &:nth-child(-2n+6) {
        @extend %highlight;

    td {
      &:nth-child(3n), &:nth-child(2), &:nth-child(7) {
        @extend %highlight;
      &.last {
          @extend %highlight;

How can I convert radians to degrees with Python?

Python includes two functions in the math package; radians converts degrees to radians, and degrees converts radians to degrees.

To match the output of your calculator you need:

>>> math.cos(math.radians(1))

Note that all of the trig functions convert between an angle and the ratio of two sides of a triangle. cos, sin, and tan take an angle in radians as input and return the ratio; acos, asin, and atan take a ratio as input and return an angle in radians. You only convert the angles, never the ratios.

Has Facebook sharer.php changed to no longer accept detailed parameters?

Your problem is caused by the lack of markers OpenGraph, as you say it is not possible that you implement for some reason.

For you, the only solution is to use the PHP Facebook API.

  1. First you must create the application in your facebook account.
  2. When creating the application you will have two key data for your code:

  3. Download the Facebook PHP SDK from here.

  4. You can start with this code for share content from your site:

      // Remember to copy files from the SDK's src/ directory to a
      // directory in your application on the server, such as php-sdk/
      $config = array(
        'appId' => 'YOUR_APP_ID',
        'secret' => 'YOUR_APP_SECRET',
        'allowSignedRequest' => false // optional but should be set to false for non-canvas apps
      $facebook = new Facebook($config);
      $user_id = $facebook->getUser();
        if($user_id) {
          // We have a user ID, so probably a logged in user.
          // If not, we'll get an exception, which we handle below.
          try {
            $ret_obj = $facebook->api('/me/feed', 'POST',
                                          'link' => '',
                                          'message' => 'Posting with the PHP SDK!'
            echo '<pre>Post ID: ' . $ret_obj['id'] . '</pre>';
            // Give the user a logout link 
            echo '<br /><a href="' . $facebook->getLogoutUrl() . '">logout</a>';
          } catch(FacebookApiException $e) {
            // If the user is logged out, you can have a 
            // user ID even though the access token is invalid.
            // In this case, we'll get an exception, so we'll
            // just ask the user to login again here.
            $login_url = $facebook->getLoginUrl( array(
                           'scope' => 'publish_stream'
            echo 'Please <a href="' . $login_url . '">login.</a>';
        } else {
          // No user, so print a link for the user to login
          // To post to a user's wall, we need publish_stream permission
          // We'll use the current URL as the redirect_uri, so we don't
          // need to specify it here.
          $login_url = $facebook->getLoginUrl( array( 'scope' => 'publish_stream' ) );
          echo 'Please <a href="' . $login_url . '">login.</a>';

You can find more examples in the Facebook Developers site:

Visual Studio Code includePath

I solved this issue by uninstalling Visual Studio that I had installed recently.

utf-8 special characters not displaying

If all the other answers didn't work for you, try disabling HTTP input encoding translation.

This is a setting related to PHP extension mbstring. This was the problem in my case. This setting was enabled by default in my server.

What is the difference between 'typedef' and 'using' in C++11?

I know the original poster has a great answer, but for anyone stumbling on this thread like I have there's an important note from the proposal that I think adds something of value to the discussion here, particularly to concerns in the comments about if the typedef keyword is going to be marked as deprecated in the future, or removed for being redundant/old:

It has been suggested to (re)use the keyword typedef ... to introduce template aliases:

template<class T>
  typedef std::vector<T, MyAllocator<T> > Vec;

That notation has the advantage of using a keyword already known to introduce a type alias. However, it also displays several disavantages [sic] among which the confusion of using a keyword known to introduce an alias for a type-name in a context where the alias does not designate a type, but a template; Vec is not an alias for a type, and should not be taken for a typedef-name. The name Vec is a name for the family std::vector<•, MyAllocator<•> > – where the bullet is a placeholder for a type-name.Consequently we do not propose the “typedef” syntax.On the other hand the sentence

template<class T>
  using Vec = std::vector<T, MyAllocator<T> >;

can be read/interpreted as: from now on, I’ll be using Vec<T> as a synonym for std::vector<T, MyAllocator<T> >. With that reading, the new syntax for aliasing seems reasonably logical.

To me, this implies continued support for the typedef keyword in C++ because it can still make code more readable and understandable.

Updating the using keyword was specifically for templates, and (as was pointed out in the accepted answer) when you are working with non-templates using and typedef are mechanically identical, so the choice is totally up to the programmer on the grounds of readability and communication of intent.

Email address validation using ASP.NET MVC data type attributes

If you are using .NET Framework 4.5, the solution is to use EmailAddressAttribute which resides inside System.ComponentModel.DataAnnotations.

Your code should look similar to this:

[Display(Name = "Email address")]
[Required(ErrorMessage = "The email address is required")]
[EmailAddress(ErrorMessage = "Invalid Email Address")]
public string Email { get; set; }

gradle build fails on lint task

if abortOnError false will not resolve your problem, you can try this.

lintOptions {
    checkReleaseBuilds false

Pointers, smart pointers or shared pointers?

To avoid memory leaks you may use smart pointers whenever you can. There are basically 2 different types of smart pointers in C++

  • Reference counted (e.g. boost::shared_ptr / std::tr1:shared_ptr)
  • non reference counted (e.g. boost::scoped_ptr / std::auto_ptr)

The main difference is that reference counted smart pointers can be copied (and used in std:: containers) while scoped_ptr cannot. Non reference counted pointers have almost no overhead or no overhead at all. Reference counting always introduces some kind of overhead.

(I suggest to avoid auto_ptr, it has some serious flaws if used incorrectly)

SQL server query to get the list of columns in a table along with Data types, NOT NULL, and PRIMARY KEY constraints

wite the table name in the query editor select the name and press Alt+F1 and it will bring all the information of the table.

Initialize array of strings

This example program illustrates initialization of an array of C strings.

#include <stdio.h>

const char * array[] = {
    "First entry",
    "Second entry",
    "Third entry",

#define n_array (sizeof (array) / sizeof (const char *))

int main ()
    int i;

    for (i = 0; i < n_array; i++) {
        printf ("%d: %s\n", i, array[i]);
    return 0;

It prints out the following:

0: First entry
1: Second entry
2: Third entry

No Persistence provider for EntityManager named

If you're using Maven, it could be that it is not looking at the right place for the META-INF folder. Others have mentioned copying the folder, but another way that worked for me was to tell Maven where to look for it, using the <resources> tag. See:

Pass array to ajax request in $.ajax()

Just use the JSON.stringify method and pass it through as the "data" parameter for the $.ajax function, like follows:

    type: "POST",
    url: "index.php",
    dataType: "json",
    data: JSON.stringify({ paramName: info }),
    success: function(msg){

You just need to make sure you include the JSON2.js file in your page...

How do I compile a .c file on my Mac?

You'll need to get a compiler. The easiest way is probably to install XCode development environment from the CDs/DVDs you got with your Mac, which will give you gcc. Then you should be able compile it like

gcc -o mybinaryfile mysourcefile.c

Memory Allocation "Error: cannot allocate vector of size 75.1 Mb"

R has gotten to the point where the OS cannot allocate it another 75.1Mb chunk of RAM. That is the size of memory chunk required to do the next sub-operation. It is not a statement about the amount of contiguous RAM required to complete the entire process. By this point, all your available RAM is exhausted but you need more memory to continue and the OS is unable to make more RAM available to R.

Potential solutions to this are manifold. The obvious one is get hold of a 64-bit machine with more RAM. I forget the details but IIRC on 32-bit Windows, any single process can only use a limited amount of RAM (2GB?) and regardless Windows will retain a chunk of memory for itself, so the RAM available to R will be somewhat less than the 3.4Gb you have. On 64-bit Windows R will be able to use more RAM and the maximum amount of RAM you can fit/install will be increased.

If that is not possible, then consider an alternative approach; perhaps do your simulations in batches with the n per batch much smaller than N. That way you can draw a much smaller number of simulations, do whatever you wanted, collect results, then repeat this process until you have done sufficient simulations. You don't show what N is, but I suspect it is big, so try smaller N a number of times to give you N over-all.

How to get the nth occurrence in a string?

function getStringReminder(str, substr, occ) {
   let index = str.indexOf(substr);
   let preindex = '';
   let i = 1;
   while (index !== -1) {
      preIndex = index;
      if (occ == i) {
      index = str.indexOf(substr, index + 1)
   return preIndex;
console.log(getStringReminder('bcdefgbcdbcd', 'bcd', 3));

How can I get a file's size in C++?

If you have the file descriptor fstat() returns a stat structure which contain the file size.

#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>

// fd = fileno(f); //if you have a stream (e.g. from fopen), not a file descriptor.
struct stat buf;
fstat(fd, &buf);
off_t size = buf.st_size;

How do I iterate through the files in a directory in Java?

You can also misuse File.list(FilenameFilter) (and variants) for file traversal. Short code and works in early java versions, e.g:

// list files in dir
new File(dir).list(new FilenameFilter() {
    public boolean accept(File dir, String name) {
        String file = dir.getAbsolutePath() + File.separator + name;
        return false;

How to resolve ORA-011033: ORACLE initialization or shutdown in progress

I faced the same problem. I restarted the oracle service for that DB instance and the error is gone.

How can I trigger a Bootstrap modal programmatically?

You should't write data-toggle="modal" in the element which triggered the modal (like a button), and you manually can show the modal with:


and hide with:


UITableView load more when scrolling to bottom like Facebook application


  • Swift 5.1, Xcode 11.2.1


Worked with UIScrollView / UICollectionView / UITableView

import UIKit

class LoadMoreActivityIndicator {

    private let spacingFromLastCell: CGFloat
    private let spacingFromLastCellWhenLoadMoreActionStart: CGFloat
    private weak var activityIndicatorView: UIActivityIndicatorView?
    private weak var scrollView: UIScrollView?

    private var defaultY: CGFloat {
        guard let height = scrollView?.contentSize.height else { return 0.0 }
        return height + spacingFromLastCell

    deinit { activityIndicatorView?.removeFromSuperview() }

    init (scrollView: UIScrollView, spacingFromLastCell: CGFloat, spacingFromLastCellWhenLoadMoreActionStart: CGFloat) {
        self.scrollView = scrollView
        self.spacingFromLastCell = spacingFromLastCell
        self.spacingFromLastCellWhenLoadMoreActionStart = spacingFromLastCellWhenLoadMoreActionStart
        let size:CGFloat = 40
        let frame = CGRect(x: (scrollView.frame.width-size)/2, y: scrollView.contentSize.height + spacingFromLastCell, width: size, height: size)
        let activityIndicatorView = UIActivityIndicatorView(frame: frame)
        if #available(iOS 13.0, *)
            activityIndicatorView.color = .label
            activityIndicatorView.color = .black
        activityIndicatorView.autoresizingMask = [.flexibleLeftMargin, .flexibleRightMargin]
        activityIndicatorView.hidesWhenStopped = true
        self.activityIndicatorView = activityIndicatorView

    private var isHidden: Bool {
        guard let scrollView = scrollView else { return true }
        return scrollView.contentSize.height < scrollView.frame.size.height

    func start(closure: (() -> Void)?) {
        guard let scrollView = scrollView, let activityIndicatorView = activityIndicatorView else { return }
        let offsetY = scrollView.contentOffset.y
        activityIndicatorView.isHidden = isHidden
        if !isHidden && offsetY >= 0 {
            let contentDelta = scrollView.contentSize.height - scrollView.frame.size.height
            let offsetDelta = offsetY - contentDelta
            let newY = defaultY-offsetDelta
            if newY < scrollView.frame.height {
                activityIndicatorView.frame.origin.y = newY
            } else {
                if activityIndicatorView.frame.origin.y != defaultY {
                    activityIndicatorView.frame.origin.y = defaultY

            if !activityIndicatorView.isAnimating {
                if offsetY > contentDelta && offsetDelta >= spacingFromLastCellWhenLoadMoreActionStart && !activityIndicatorView.isAnimating {

            if scrollView.isDecelerating {
                if activityIndicatorView.isAnimating && scrollView.contentInset.bottom == 0 {
                    UIView.animate(withDuration: 0.3) { [weak self] in
                        if let bottom = self?.spacingFromLastCellWhenLoadMoreActionStart {
                            scrollView.contentInset = UIEdgeInsets(top: 0, left: 0, bottom: bottom, right: 0)

    func stop(completion: (() -> Void)? = nil) {
        guard let scrollView = scrollView , let activityIndicatorView = activityIndicatorView else { return }
        let contentDelta = scrollView.contentSize.height - scrollView.frame.size.height
        let offsetDelta = scrollView.contentOffset.y - contentDelta
        if offsetDelta >= 0 {
            UIView.animate(withDuration: 0.3, animations: {
                scrollView.contentInset = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)
            }) { _ in completion?() }
        } else {
            scrollView.contentInset = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)



activityIndicator = LoadMoreActivityIndicator(scrollView: tableView, spacingFromLastCell: 10, spacingFromLastCellWhenLoadMoreActionStart: 60)


extension ViewController: UITableViewDelegate {
    func scrollViewDidScroll(_ scrollView: UIScrollView) {
        activityIndicator.start {
   .utility).async {
                DispatchQueue.main.async { [weak self] in

Full Sample

Do not forget to paste the solution code.

import UIKit

class ViewController: UIViewController {
    fileprivate var activityIndicator: LoadMoreActivityIndicator!
    override func viewDidLoad() {
        let tableView = UITableView(frame: view.frame)
        tableView.translatesAutoresizingMaskIntoConstraints = false
        tableView.topAnchor.constraint(equalTo: view.topAnchor).isActive = true
        tableView.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true
        tableView.leftAnchor.constraint(equalTo: view.leftAnchor).isActive = true
        tableView.rightAnchor.constraint(equalTo: view.rightAnchor).isActive = true
        tableView.dataSource = self
        tableView.delegate = self
        tableView.tableFooterView = UIView()
        activityIndicator = LoadMoreActivityIndicator(scrollView: tableView, spacingFromLastCell: 10, spacingFromLastCellWhenLoadMoreActionStart: 60)

extension ViewController: UITableViewDataSource {
    func numberOfSections(in tableView: UITableView) -> Int {
        return 1
    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return 30
    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = UITableViewCell()
        cell.textLabel?.text = "\(indexPath)"
        return cell

extension ViewController: UITableViewDelegate {
    func scrollViewDidScroll(_ scrollView: UIScrollView) {
        activityIndicator.start {
   .utility).async {
                for i in 0..<3 {
                    print("!!!!!!!!! \(i)")
                DispatchQueue.main.async { [weak self] in


enter image description here

Python error: TypeError: 'module' object is not callable for HeadFirst Python code

You module and class AthleteList have the same name. Change:

import AthleteList


from AthleteList import AthleteList

This now means that you are importing the module object and will not be able to access any module methods you have in AthleteList

Android: Force EditText to remove focus?

To hide the keyboard when activity starts.. write the following code in onCreate()..

InputMethodManager imm = (InputMethodManager)
imm.hideSoftInputFromWindow(getWindow().getDecorView().getWindowToken(), 0);

To clear focus and remove cursor from edittext.....



Display Python datetime without time

For me, I needed to KEEP a timetime object because I was using UTC and it's a bit of a pain. So, this is what I ended up doing:

date = datetime.datetime.utcnow()

start_of_day = date - datetime.timedelta(

end_of_day = start_of_day + datetime.timedelta(

Example output:

>>> date
datetime.datetime(2016, 10, 14, 17, 21, 5, 511600)
>>> start_of_day
datetime.datetime(2016, 10, 14, 0, 0)
>>> end_of_day
datetime.datetime(2016, 10, 14, 23, 59, 59)

startsWith() and endsWith() functions in PHP

If speed is important for you, try this.(I believe it is the fastest method)

Works only for strings and if $haystack is only 1 character

function startsWithChar($needle, $haystack)
   return ($needle === $haystack[0]);

function endsWithChar($needle, $haystack)
   return ($needle === $haystack[strlen($haystack) - 1]);

echo startsWithChar('|',$str); //Returns true
echo endsWithChar('}',$str); //Returns true
echo startsWithChar('=',$str); //Returns false
echo endsWithChar('#',$str); //Returns false

C++ trying to swap values in a vector

I think what you are looking for is iter_swap which you can find also in <algorithm>.
all you need to do is just pass two iterators each pointing at one of the elements you want to exchange.
since you have the position of the two elements, you can do something like this:

// assuming your vector is called v
iter_swap(v.begin() + position, v.begin() + next_position);
// position, next_position are the indices of the elements you want to swap

How can I get city name from a latitude and longitude point?

In node.js we can use node-geocoder npm module to get address from lat, lng.,


var NodeGeocoder = require('node-geocoder');

var options = {
  provider: 'google',
  httpAdapter: 'https', // Default
  apiKey: ' ', // for Mapquest, OpenCage, Google Premier
  formatter: 'json' // 'gpx', 'string', ...

var geocoder = NodeGeocoder(options);

geocoder.reverse({lat:28.5967439, lon:77.3285038}, function(err, res) {


node geo.js

[ { formattedAddress: 'C-85B, C Block, Sector 8, Noida, Uttar Pradesh 201301, India',
    latitude: 28.5967439,
    longitude: 77.3285038,
     { googlePlaceId: 'ChIJkTdx9vzkDDkRx6LVvtz1Rhk',
       confidence: 1,
       premise: 'C-85B',
       subpremise: null,
       neighborhood: 'C Block',
       establishment: null },
     { level2long: 'Gautam Buddh Nagar',
       level2short: 'Gautam Buddh Nagar',
       level1long: 'Uttar Pradesh',
       level1short: 'UP' },
    city: 'Noida',
    country: 'India',
    countryCode: 'IN',
    zipcode: '201301',
    provider: 'google' } ]

Regular expressions inside SQL Server

SQL Wildcards are enough for this purpose. Follow this link:

you need to use a query like this:

select * from mytable where msisdn like '%7%'


select * from mytable where msisdn like '56655%'

MySQL combine two columns and add into a new column

Are you sure you want to do this? In essence, you're duplicating the data that is in the three original columns. From that point on, you'll need to make sure that the data in the combined field matches the data in the first three columns. This is more overhead for your application, and other processes that update the system will need to understand the relationship.

If you need the data, why not select in when you need it? The SQL for selecting what would be in that field would be:

SELECT CONCAT(zipcode, ' - ', city, ', ', state) FROM Table;

This way, if the data in the fields changes, you don't have to update your combined field.

Delete a database in phpMyAdmin

After successful login to cPanel, near to the phpMyAdmin icon there is another icon MySQL Databases; click on that.

enter image description here

That brings you to the database listing page.

In the action column you can find the delete database option click on that to delete your database!

How to access private data members outside the class without making "friend"s?

access private members outside class ....only for study purpose .... This program accepts all the below conditions "I dont want to create member function for above class A. And also i dont want to inherit the above class A. I dont want to change the specifier of iData."

//here member function is used only to input and output the private values ... //void hack() is defined outside the class...

//GEEK MODE....;)

    class A
    private :int iData,x;
    public: void get()             //enter the values
        {cout<<"Enter iData : ";
            cin>>iData;cout<<"Enter x : ";cin>>x;}

        void put()                               //displaying values
    {cout<<endl<<"sum = "<<iData+x;}

void hack();        //hacking function

void main()
{A obj;clrscr();

void hack()         //hack begins
{int hck,*ptr=&hck;
cout<<endl<<"Enter value of private data (iData or x) : ";
cin>>hck;     //enter the value assigned for iData or x
for(int i=0;i<5;i++)
{cout<<"Private data hacked...!!!\nChange the value : ";
cin>>*ptr;cout<<hck<<" Is chaged to : "<<*ptr;
}cout<<"Sorry value not found.....";

JQuery wait for page to finish loading before starting the slideshow?

did you try this ?

$("#yourdiv").load(url, function(){ 

         your functions goes here !!!


TSQL How do you output PRINT in a user defined function?

Tip: generate error.

declare @Day int, @Config_Node varchar(50)

    set @Config_Node = 'value to trace'

    set @Day = @Config_Node

You will get this message:

Conversion failed when converting the varchar value 'value to trace' to data type int.

How to AUTO_INCREMENT in db2?

Added a few optional parameters for creating "future safe" sequences.

  CACHE 10;

How to use ClassLoader.getResources() correctly?

There is no way to recursively search through the classpath. You need to know the Full pathname of a resource to be able to retrieve it in this way. The resource may be in a directory in the file system or in a jar file so it is not as simple as performing a directory listing of "the classpath". You will need to provide the full path of the resource e.g. '/com/mypath/bla.xml'.

For your second question, getResource will return the first resource that matches the given resource name. The order that the class path is searched is given in the javadoc for getResource.

Font scaling based on width of container

I don't see any answer with reference to CSS flex property, but it can be very useful too.

Apache 2.4 - Request exceeded the limit of 10 internal redirects due to probable configuration error

This problem can be caused by requests for certain files that don't exist. For example, requests for files in wp-content/uploads/ where the file does not exist.

If this is the situation you're seeing, you can solve the problem by going to .htaccess and changing this line:

RewriteRule ^(wp-(content|admin|includes).*) $1 [L]


RewriteRule ^(wp-(content|admin|includes).*) - [L]

The underlying issue is that the rule above triggers a rewrite to the exact same url with a slash in front and because there was a rewrite, the newly rewritten request goes back through the rules again and the same rule is triggered. By changing that line's "$1" to "-", no rewrite happens and so the rewriting process does not start over again with the same URL.

It's possible that there's a difference in how apache 2.2 and 2.4 handle this situation of only-difference-is-a-slash-in-front and that's why the default rules provided by WordPress aren't working perfectly.

Getting all selected checkboxes in an array

Pure JS

For those who don't want to use jQuery

var array = []
var checkboxes = document.querySelectorAll('input[type=checkbox]:checked')

for (var i = 0; i < checkboxes.length; i++) {

Function to calculate R2 (R-squared) in R

Why not this:

rsq <- function(x, y) summary(lm(y~x))$r.squared
rsq(obs, mod)
#[1] 0.8560185

Python UTC datetime object's ISO format doesn't include Z (Zulu or Zero offset)

I use pendulum:

import pendulum

d ="UTC").to_iso8601_string()

>>> 2019-10-30T00:11:21.818265Z

Random element from string array

Just store the index generated in a variable, and then access the array using this varaible:

int idx = new Random().nextInt(fruits.length);
String random = (fruits[idx]);

P.S. I usually don't like generating new Random object per randoization - I prefer using a single Random in the program - and re-use it. It allows me to easily reproduce a problematic sequence if I later find any bug in the program.

According to this approach, I will have some variable Random r somewhere, and I will just use:

int idx = r.nextInt(fruits.length)

However, your approach is OK as well, but you might have hard time reproducing a specific sequence if you need to later on.

Reducing video size with same format and reducing frame size

ffmpeg -i <input.mp4> -b:v 2048k -s 1000x600 -fs 2048k -vcodec mpeg4 -acodec copy <output.mp4>
  • -i input file

  • -b:v videobitrate of output video in kilobytes (you have to try)

  • -s dimensions of output video

  • -fs FILESIZE of output video in kilobytes

  • -vcodec videocodec (use ffmpeg -codecs to list all available codecs)

  • -acodec audio codec for output video (only copy the audiostream, don't temper)

How to add SHA-1 to android application

If you are using Google Play App Signing, you don't need to add your SHA-1 keys manually, just login into Firebase go into "project settings"->"integration" and press a button to link Google Play with firebase, SHA-1 will be added automatically.

C# DropDownList with a Dictionary as DataSource

If the DropDownList is declared in your aspx page and not in the codebehind, you can do it like this.


<asp:DropDownList ID="ddlStatus" runat="server" DataSource="<%# Statuses %>"
     DataValueField="Key" DataTextField="Value"></asp:DropDownList>


protected void Page_Load(object sender, EventArgs e)
    // or use Page.DataBind() to bind everything

public Dictionary<int, string> Statuses
        // do database/webservice lookup here to populate Dictionary

How to set standard encoding in Visual Studio

The Problem is Windows and Microsoft applications put byte order marks at the beginning of all your files so other applications often break or don't read these UTF-8 encoding marks. I perfect example of this problem was triggering quirsksmode in old IE web browsers when encoding in UTF-8 as browsers often display web pages based on what encoding falls at the start of the page. It makes a mess when other applications view those UTF-8 Visual Studio pages.

I usually do not recommend Visual Studio Extensions, but I do this one to fix that issue:

Fix File Encoding:

The FixFileEncoding above install REMOVES the byte order mark and forces VS to save ALL FILES without signature in UTF-8. After installing go to Tools > Option then choose "FixFileEncoding". It should allow you to set all saves as UTF-8 . Add "cshtml to the list of files to always save in UTF-8 without the byte order mark as so: ".(htm|html|cshtml)$)".

Now open one of your files in Visual Studio. To verify its saving as UTF-8 go to File > Save As, then under the Save button choose "Save With Encoding". It should choose "UNICODE (Save without Signature)" by default from the list of encodings. Now when you save that page it should always save as UTF-8 without byte order mark at the beginning of the file when saving in Visual Studio.

How To Set Text In An EditText

If you check the docs for EditText, you'll find a setText() method. It takes in a String and a TextView.BufferType. For example:

EditText editText = (EditText)findViewById(;
editText.setText("This sets the text.", TextView.BufferType.EDITABLE);

It also inherits TextView's setText(CharSequence) and setText(int) methods, so you can set it just like a regular TextView:

editText.setText("Hello world!");

Oracle SQL convert date format from DD-Mon-YY to YYYYMM

Am I missing something? You can just convert offer_date in the comparison:

FROM offers
WHERE to_char(offer_date, 'YYYYMM') = (SELECT to_date(create_date, 'YYYYMM') FROM customers where id = '12345678') AND
      offer_rate > 0 

What is the best way to prevent session hijacking?

// Collect this information on every request

// Do this each time the user successfully logs in.
$_SESSION['ident'] = hash("sha256", $aip . $bip . $agent);

// Do this every time the client makes a request to the server, after authenticating
$ident = hash("sha256", $aip . $bip . $agent);
if ($ident != $_SESSION['ident'])
    header("Location: login.php");
    // add some fancy pants GET/POST var headers for login.php, that lets you
    // know in the login page to notify the user of why they're being challenged
    // for login again, etc.

What this does is capture 'contextual' information about the user's session, pieces of information which should not change during the life of a single session. A user isn't going to be at a computer in the US and in China at the same time, right? So if the IP address changes suddenly within the same session that strongly implies a session hijacking attempt, so you secure the session by ending the session and forcing the user to re-authenticate. This thwarts the hack attempt, the attacker is also forced to login instead of gaining access to the session. Notify the user of the attempt (ajax it up a bit), and vola, Slightly annoyed+informed user and their session/information is protected.

We throw in User Agent and X-FORWARDED-FOR to do our best to capture uniqueness of a session for systems behind proxies/networks. You may be able to use more information then that, feel free to be creative.

It's not 100%, but it's pretty damn effective.

There's more you can do to protect sessions, expire them, when a user leaves a website and comes back force them to login again maybe. You can detect a user leaving and coming back by capturing a blank HTTP_REFERER (domain was typed in the URL bar), or check if the value in the HTTP_REFERER equals your domain or not (the user clicked an external/crafted link to get to your site).

Expire sessions, don't let them remain valid indefinitely.

Don't rely on cookies, they can be stolen, it's one of the vectors of attack for session hijacking.

How to get dictionary values as a generic list

How about:

var values = myDico.Values.ToList();

How to make war file in Eclipse

File -> Export -> Web -> WAR file

OR in Kepler follow as shown below :

enter image description here

Add a column in a table in HIVE QL

You cannot add a column with a default value in Hive. You have the right syntax for adding the column ALTER TABLE test1 ADD COLUMNS (access_count1 int);, you just need to get rid of default sum(max_count). No changes to that files backing your table will happen as a result of adding the column. Hive handles the "missing" data by interpreting NULL as the value for every cell in that column.

So now your have the problem of needing to populate the column. Unfortunately in Hive you essentially need to rewrite the whole table, this time with the column populated. It may be easier to rerun your original query with the new column. Or you could add the column to the table you have now, then select all of its columns plus value for the new column.

You also have the option to always COALESCE the column to your desired default and leave it NULL for now. This option fails when you want NULL to have a meaning distinct from your desired default. It also requires you to depend on always remembering to COALESCE.

If you are very confident in your abilities to deal with the files backing Hive, you could also directly alter them to add your default. In general I would recommend against this because most of the time it will be slower and more dangerous. There might be some case where it makes sense though, so I've included this option for completeness.

Super-simple example of C# observer/observable with delegates

    /**********************Simple Example ***********************/    

class Program
            static void Main(string[] args)
                Parent p = new Parent();


        public delegate void DelegateName(string data);

        class Child
            public event DelegateName delegateName;

            public void call()


        class Parent
            public Parent()
                Child c = new Child();
                c.delegateName += new DelegateName(print);
                //or like this
                //c.delegateName += print;

            public void print(string name)
                Console.WriteLine("yes we got the name : " + name);

What does a question mark represent in SQL queries?

It normally represents a parameter to be supplied by client.

java.lang.ClassNotFoundException: javax.servlet.jsp.jstl.core.Config

Probably the jstl libraries are missing from your classpath/not accessible by tomcat.

You need to add at least the following jar files in your WEB-INF/lib directory:

  • jsf-impl.jar
  • jsf-api.jar
  • jstl.jar

How do I get java logging output to appear on a single line?

This logging is specific to your application and not a general Java feature. What application(s) are you running?

It might be that this is coming from a specific logging library that you are using within your own code. If so, please post the details of which one you are using.

Missing maven .m2 folder

When you first install maven, .m2 folder will not be present in C:\Users\ {user} path. To generate the folder you have to run any maven command e.g. mvn clean, mvn install etc. so that it searches for settings.xml in .m2 folder and when not found creates one.

So long story cur short, open cmd -> mvn install

It will show could not find any projects(Don't worry maven is working fine :P) now check your user folder.

P.S. If still not able to view .m2 folder try unhiding hidden items.

Conda command not found

Sometimes, if you don't restart your terminal after you have installed anaconda also, it gives this error.

Close your terminal window and restart it.

It worked for me now!

Send Email to multiple Recipients with MailMessage?

I've tested this using the following powershell script and using (,) between the addresses. It worked for me!

$EmailFrom = "<[email protected]>";
$EmailPassword = "<password>";
$EmailTo = "<[email protected]>,<[email protected]>";
$SMTPServer = "<>";
$SMTPPort = <port>;
$SMTPClient = New-Object Net.Mail.SmtpClient($SmtpServer,$SMTPPort);
$SMTPClient.EnableSsl = $true;
$SMTPClient.Credentials = New-Object System.Net.NetworkCredential($EmailFrom, $EmailPassword);
$Subject = "Notification from XYZ";
$Body = "this is a notification from XYZ Notifications..";
$SMTPClient.Send($EmailFrom, $EmailTo, $Subject, $Body);

Is it possible to force Excel recognize UTF-8 CSV files automatically?

It is incredible that there are so many answers but none answers the question:

"When I was asking this question, I asked for a way of opening a UTF-8 CSV file in Excel without any problems for a user,..."

The answer marked as the accepted answer with 200+ up-votes is useless for me because I don't want to give my users a manual how to configure Excel. Apart from that: this manual will apply to one Excel version but other Excel versions have different menus and configuration dialogs. You would need a manual for each Excel version.

So the question is how to make Excel show UTF8 data with a simple double click?

Well at least in Excel 2007 this is not possible if you use CSV files because the UTF8 BOM is ignored and you will see only garbage. This is already part of the question of Lyubomyr Shaydariv:

"I also tried specifying UTF-8 BOM EF BB BF, but Excel ignores that."

I make the same experience: Writing russian or greek data into a UTF8 CSV file with BOM results in garbage in Excel:

Content of UTF8 CSV file:


Result in Excel 2007:

CSV UTF8 Excel

A solution is to not use CSV at all. This format is implemented so stupidly by Microsoft that it depends on the region settings in control panel if comma or semicolon is used as separator. So the same CSV file may open correctly on one computer but on anther computer not. "CSV" means "Comma Separated Values" but for example on a german Windows by default semicolon must be used as separator while comma does not work. (Here it should be named SSV = Semicolon Separated Values) CSV files cannot be interchanged between different language versions of Windows. This is an additional problem to the UTF-8 problem.

Excel exists since decades. It is a shame that Microsoft was not able to implement such a basic thing as CSV import in all these years.

However, if you put the same values into a HTML file and save that file as UTF8 file with BOM with the file extension XLS you will get the correct result.

Content of UTF8 XLS file:


Result in Excel 2007:


You can even use colors in HTML which Excel will show correctly.

.Head { background-color:gray; color:white; }
.Red  { color:red; }
<table border=1>
<tr><td class=Head>Colum1</td><td class=Head>Column2</td></tr>
<tr><td class=Red>?????????</td><td class=Red>T??????</td></tr>

Result in Excel 2007:


In this case only the table itself has a black border and lines. If you want ALL cells to display gridlines this is also possible in HTML:

<html xmlns:x="urn:schemas-microsoft-com:office:excel">
        <meta http-equiv="content-type" content="text/plain; charset=UTF-8"/>

This code even allows to specify the name of the worksheet (here "MySuperSheet")

Result in Excel 2007:

enter image description here

Difference between rake db:migrate db:reset and db:schema:load

Rails 5

db:create - Creates the database for the current RAILS_ENV environment. If RAILS_ENV is not specified it defaults to the development and test databases.

db:create:all - Creates the database for all environments.

db:drop - Drops the database for the current RAILS_ENV environment. If RAILS_ENV is not specified it defaults to the development and test databases.

db:drop:all - Drops the database for all environments.

db:migrate - Runs migrations for the current environment that have not run yet. By default it will run migrations only in the development environment.

db:migrate:redo - Runs db:migrate:down and db:migrate:up or db:migrate:rollback and db:migrate:up depending on the specified migration.

db:migrate:up - Runs the up for the given migration VERSION.

db:migrate:down - Runs the down for the given migration VERSION.

db:migrate:status - Displays the current migration status.

db:migrate:rollback - Rolls back the last migration.

db:version - Prints the current schema version.

db:forward - Pushes the schema to the next version.

db:seed - Runs the db/seeds.rb file.

db:schema:load Recreates the database from the schema.rb file. Deletes existing data.

db:schema:dump Dumps the current environment’s schema to db/schema.rb.

db:structure:load - Recreates the database from the structure.sql file.

db:structure:dump - Dumps the current environment’s schema to db/structure.sql. (You can specify another file with SCHEMA=db/my_structure.sql)

db:setup Runs db:create, db:schema:load and db:seed.

db:reset Runs db:drop and db:setup. db:migrate:reset - Runs db:drop, db:create and db:migrate.

db:test:prepare - Check for pending migrations and load the test schema. (If you run rake without any arguments it will do this by default.)

db:test:clone - Recreate the test database from the current environment’s database schema.

db:test:clone_structure - Similar to db:test:clone, but it will ensure that your test database has the same structure, including charsets and collations, as your current environment’s database.

db:environment:set - Set the current RAILS_ENV environment in the ar_internal_metadata table. (Used as part of the protected environment check.)

db:check_protected_environments - Checks if a destructive action can be performed in the current RAILS_ENV environment. Used internally when running a destructive action such as db:drop or db:schema:load.

A required class was missing while executing org.apache.maven.plugins:maven-war-plugin:2.1.1:war

Make sure your Java version matches the project's Java version requirement. This could be an another cause for such kinds of issues.

How to make space between LinearLayout children?

Android now supports adding a Space view between views. It's available from 4.0 ICS onwards.

How to validate phone number using PHP?

Since phone numbers must conform to a pattern, you can use regular expressions to match the entered phone number against the pattern you define in regexp.

php has both ereg and preg_match() functions. I'd suggest using preg_match() as there's more documentation for this style of regex.

An example

$phone = '000-0000-0000';

if(preg_match("/^[0-9]{3}-[0-9]{4}-[0-9]{4}$/", $phone)) {
  // $phone is valid

Font awesome is not showing icon

All the above are correct however on top of that my issue was that I downloaded the free version of FA5 which doesn't have:


I could not get v5 to work so I reverted to 4.7.0 with the help of the posts above and it fixed my issue.

fatal error LNK1104: cannot open file 'libboost_system-vc110-mt-gd-1_51.lib'

I had same issue reported here. I solved the issue moving the mainTest.cpp from a subfolder src/mainTest/ to the main folder src/ I guess this was your problem too.

Angular2 module has no exported member

Also some of common cases :

maybe you export class with "default" prefix like so

export default class Module {}

just remove it

export class Module {}

this is solve the issue for me

Python 3.1.1 string to hex

The hex codec has been chucked in 3.x. Use binascii instead:

>>> binascii.hexlify(b'hello')

How To Get Selected Value From UIPickerView

You have to use the didSelectRow delegate method, because a UIPickerView can have an arbitrary number of components. There is no "objectValue" or anything like that, because that's entirely up to you.

Javascript callback when IFRAME is finished loading?

I am using jQuery and surprisingly this seems to load as I just tested and loaded a heavy page and I didn't get the alert for a few seconds until I saw the iframe load:


So if you don't want to use jQuery take a look at their source code and see if this function behaves differently with iframe DOM elements, I will look at it myself later as I am interested and post here. Also I only tested in the latest chrome.

Reloading/refreshing Kendo Grid

If you do not want to have a reference to the grid in the handler, you can use this code:


This will refresh the grid, if there is a refresh button. The button can be enabled like so:

[MVC GRID DECLARATION].Pageable(p=> p.Refresh(true))

How to resolve this JNI error when trying to run LWJGL "Hello World"?

I had same issue using different dependancy what helped me is to set scope to compile.


Some dates recognized as dates, some dates not recognized. Why?

It's not that hard...

Check out this forum post:

The steps in short:

  1. Select only the column of "dates"
  2. Click Data > Text to Columns
  3. Click Next
  4. Click Next
  5. In step 3 of the wizard, check "Date" under Col data format, then choose: "DMY" from the droplist.
  6. Click Finish

Getting java.lang.ClassNotFoundException: org.apache.commons.logging.LogFactory exception

I have also faced the same issues, to fix, download the jar files from the below url

and copy to your lib folder, will resolve your issue.

How to remove duplicates from Python list and keep order?

If your input is already sorted, then there may be a simpler way to do it:

from operator import itemgetter
from itertools import groupby
unique_list = list(map(itemgetter(0), groupby(yourList)))

Is System.nanoTime() completely useless?

This doesn't seem to be a problem on a Core 2 Duo running Windows XP and JRE 1.5.0_06.

In a test with three threads I don't see System.nanoTime() going backwards. The processors are both busy, and threads go to sleep occasionally to provoke moving threads around.

[EDIT] I would guess that it only happens on physically separate processors, i.e. that the counters are synchronized for multiple cores on the same die.

Most recent previous business day in Python

timeboard package does this.

Suppose your date is 04 Sep 2017. In spite of being a Monday, it was a holiday in the US (the Labor Day). So, the most recent business day was Friday, Sep 1.

>>> import timeboard.calendars.US as US
>>> clnd = US.Weekly8x5()
>>> clnd('04 Sep 2017').rollback().to_timestamp().date(), 9, 1)

In UK, 04 Sep 2017 was the regular business day, so the most recent business day was itself.

>>> import timeboard.calendars.UK as UK
>>> clnd = UK.Weekly8x5()
>>> clnd('04 Sep 2017').rollback().to_timestamp().date(), 9, 4)

DISCLAIMER: I am the author of timeboard.

CREATE FILE encountered operating system error 5(failed to retrieve text for this error. Reason: 15105)

Giving admin rights or full control to my database install location solved my problem

Way to *ngFor loop defined number of times instead of repeating over array?

Within your component, you can define an array of number (ES6) as described below:

export class SampleComponent {
  constructor() {
    this.numbers = Array(5).fill(0).map((x,i)=>i);

See this link for the array creation: Tersest way to create an array of integers from 1..20 in JavaScript.

You can then iterate over this array with ngFor:

  template: `
      <li *ngFor="let number of numbers">{{number}}</li>
export class SampleComponent {

Or shortly:

  template: `
      <li *ngFor="let number of [0,1,2,3,4]">{{number}}</li>
export class SampleComponent {

Hope it helps you, Thierry

Edit: Fixed the fill statement and template syntax.

Excel formula to remove space between words in a cell

It is SUBSTITUTE(B1," ",""), not REPLACE(xx;xx;xx).

C++ Convert string (or char*) to wstring (or wchar_t*)

Here's a way to combining string, wstring and mixed string constants to wstring. Use the wstringstream class.

This does NOT work for multi-byte character encodings. This is just a dumb way of throwing away type safety and expanding 7 bit characters from std::string into the lower 7 bits of each character of std:wstring. This is only useful if you have a 7-bit ASCII strings and you need to call an API that requires wide strings.

#include <sstream>

std::string narrow = "narrow";
std::wstring wide = L"wide";

std::wstringstream cls;
cls << " abc " << narrow.c_str() << L" def " << wide.c_str();
std::wstring total= cls.str();

Referencing a string in a string array resource with xml

In short: I don't think you can, but there seems to be a workaround:.

If you take a look into the Android Resource here:

You see than under the array section (string array, at least), the "RESOURCE REFERENCE" (as you get from an XML) does not specify a way to address the individual items. You can even try in your XML to use "@array/yourarrayhere". I know that in design time you will get the first item. But that is of no practical use if you want to use, let's say... the second, of course.

HOWEVER, there is a trick you can do. See here:

Referencing an XML string in an XML Array (Android)

You can "cheat" (not really) the array definition by addressing independent strings INSIDE the definition of the array. For example, in your strings.xml:

<string name="earth">Earth</string>
<string name="moon">Moon</string>

<string-array name="system">

By using this, you can use "@string/earth" and "@string/moon" normally in your "android:text" and "android:title" XML fields, and yet you won't lose the ability to use the array definition for whatever purposes you intended in the first place.

Seems to work here on my Eclipse. Why don't you try and tell us if it works? :-)

SQL Server: Filter output of sp_who2

A really easy way to do it is to create an ODBC link in EXCEL and run SP_WHO2 from there.

You can Refresh whenever you like and because it's EXCEL everything can be manipulated easily!

org.apache.tomcat.util.bcel.classfile.ClassFormatException: Invalid byte tag in constant pool: 15

The "offical answer" is that Tomcat 7 runs on Java 8, see ("Java version 6 and later").

However, if annotation scanning is enabled (metadata-complete="true" in web.xml) there are some issues due to BCEL (not able to process the new Java 8 byte codes). You will get exceptions like (at least with Tomcat 7.0.28):

SEVERE: Unable to process Jar entry [jdk/nashorn/internal/objects/NativeString.class] from Jar [jar:file:/usr/lib/jvm/jdk1.8.0_5/jre/lib/ext/nashorn.jar!/] for annotations
org.apache.tomcat.util.bcel.classfile.ClassFormatException: Invalid byte tag in constant pool: 15
    at org.apache.tomcat.util.bcel.classfile.Constant.readConstant(

If not using annotation scanning, everything works fine, starting release 7.0.53 (updated compiler with better Java 8 support).

(UPDATE 2014-10-17) If your are using annotation scanning and your own code is not Java 8 based, another solution is to add the following line in /etc/tomcat7/ (text added after "ant-launcher.jar" so part of property tomcat.util.scan.DefaultJarScanner.jarsToSkip):


Tested with Tomcat 7.0.28 and Oracle JDK 8_25 on Debian 7.6.

Using a global variable with a thread

In a function:

a += 1

will be interpreted by the compiler as assign to a => Create local variable a, which is not what you want. It will probably fail with a a not initialized error since the (local) a has indeed not been initialized:

>>> a = 1
>>> def f():
...     a += 1
>>> f()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 2, in f
UnboundLocalError: local variable 'a' referenced before assignment

You might get what you want with the (very frowned upon, and for good reasons) global keyword, like so:

>>> def f():
...     global a
...     a += 1
>>> a
>>> f()
>>> a

In general however, you should avoid using global variables which become extremely quickly out of hand. And this is especially true for multithreaded programs, where you don't have any synchronization mechanism for your thread1 to know when a has been modified. In short: threads are complicated, and you cannot expect to have an intuitive understanding of the order in which events are happening when two (or more) threads work on the same value. The language, compiler, OS, processor... can ALL play a role, and decide to modify the order of operations for speed, practicality or any other reason.

The proper way for this kind of thing is to use Python sharing tools (locks and friends), or better, communicate data via a Queue instead of sharing it, e.g. like this:

from threading import Thread
from queue import Queue
import time

def thread1(threadname, q):
    #read variable "a" modify by thread 2
    while True:
        a = q.get()
        if a is None: return # Poison pill
        print a

def thread2(threadname, q):
    a = 0
    for _ in xrange(10):
        a += 1
    q.put(None) # Poison pill

queue = Queue()
thread1 = Thread( target=thread1, args=("Thread-1", queue) )
thread2 = Thread( target=thread2, args=("Thread-2", queue) )


Mythical man month 10 lines per developer day - how close on large projects?

How are other people doing?

I am the only full-time dev at our company and have written 500,000 lines of OCaml and F# code over the past 7 years, which equates to about 200 lines of code per day. However, the vast majority of that code is tutorial examples consisting of hundreds of separate projects each a few hundred lines long. Also, there is a lot of duplication between the OCaml and the F#. We are not maintaining any in-house code bases larger than 50kLOC.

In addition to developing and maintaining our own software, I have also consulted for many clients in industry over the past 7 years. For the first client, I wrote 2,000 lines of OCaml over 3 months which is 20 lines of code per day. For the next client, four of us wrote a compiler that generated millions of lines of C/C++/Python/Java/OCaml code as well as documentation in 6 months which is 2,000 lines of code per day per developer. For another client, I replaced 50kLOC of C++ with 6kLOC of F# in 6 months which is -352 lines of code per day. For yet another client, I am rewriting 15kLOC of OCaml in F# which will be the same size so 0 lines of code per day.

For our current client, I will replace 1,600,000 lines of C++ and Mathematica code with ~160kLOC of F# in 1 year (by writing a bespoke compiler) which will be -6,000 lines of code per day. This will be my most successful project to date and will save our client millions of dollars a year in on-going costs. I think everyone should aim to write -6,000 lines of code per day.

How To Raise Property Changed events on a Dependency Property?

I think the OP is asking the wrong question. The code below will show that it not necessary to manually raise the PropertyChanged EVENT from a dependency property to achieve the desired result. The way to do it is handle the PropertyChanged CALLBACK on the dependency property and set values for other dependency properties there. The following is a working example. In the code below, MyControl has two dependency properties - ActiveTabInt and ActiveTabString. When the user clicks the button on the host (MainWindow), ActiveTabString is modified. The PropertyChanged CALLBACK on the dependency property sets the value of ActiveTabInt. The PropertyChanged EVENT is not manually raised by MyControl.


/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window, INotifyPropertyChanged
    public MainWindow()
        DataContext = this;
        ActiveTabString = "zero";

    private string _ActiveTabString;
    public string ActiveTabString
        get { return _ActiveTabString; }
            if (_ActiveTabString != value)
                _ActiveTabString = value;

    private int _ActiveTabInt;
    public int ActiveTabInt
        get { return _ActiveTabInt; }
            if (_ActiveTabInt != value)
                _ActiveTabInt = value;

    #region INotifyPropertyChanged implementation
    public event PropertyChangedEventHandler PropertyChanged;

    public void RaisePropertyChanged(string propertyName)
        if (PropertyChanged != null)
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));

    private void Button_Click(object sender, RoutedEventArgs e)
        ActiveTabString = (ActiveTabString == "zero") ? "one" : "zero";


public class MyControl : Control
    public static List<string> Indexmap = new List<string>(new string[] { "zero", "one" });

    public string ActiveTabString
        get { return (string)GetValue(ActiveTabStringProperty); }
        set { SetValue(ActiveTabStringProperty, value); }

    public static readonly DependencyProperty ActiveTabStringProperty = DependencyProperty.Register(
        typeof(MyControl), new FrameworkPropertyMetadata(

    public int ActiveTabInt
        get { return (int)GetValue(ActiveTabIntProperty); }
        set { SetValue(ActiveTabIntProperty, value); }
    public static readonly DependencyProperty ActiveTabIntProperty = DependencyProperty.Register(
        typeof(MyControl), new FrameworkPropertyMetadata(
            new Int32(),

    static MyControl()
        DefaultStyleKeyProperty.OverrideMetadata(typeof(MyControl), new FrameworkPropertyMetadata(typeof(MyControl)));


    public override void OnApplyTemplate()

    private static void ActiveTabStringChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
        MyControl thiscontrol = sender as MyControl;

        if (Indexmap[thiscontrol.ActiveTabInt] != thiscontrol.ActiveTabString)
            thiscontrol.ActiveTabInt = Indexmap.IndexOf(e.NewValue.ToString());



    <StackPanel Orientation="Vertical">
    <Button Content="Change Tab Index" Click="Button_Click" Width="110" Height="30"></Button>
    <local:MyControl x:Name="myControl" ActiveTabInt="{Binding ActiveTabInt, Mode=TwoWay}" ActiveTabString="{Binding ActiveTabString}"></local:MyControl>


<Style TargetType="local:MyControl">
        <Setter Property="Template">
                <ControlTemplate TargetType="local:MyControl">
                    <TabControl SelectedIndex="{Binding ActiveTabInt, Mode=TwoWay}">
                        <TabItem Header="Tab Zero">
                            <TextBlock Text="{Binding ActiveTabInt}"></TextBlock>
                        <TabItem Header="Tab One">
                            <TextBlock Text="{Binding ActiveTabInt}"></TextBlock>

How to trigger the onclick event of a marker on a Google Maps V3?

I've found out the solution! Thanks to Firebug ;)

//"markers" is an array that I declared which contains all the marker of the map
//"i" is the index of the marker in the array that I want to trigger the OnClick event

//V2 version is:
GEvent.trigger(markers[i], 'click');

//V3 version is:
google.maps.event.trigger(markers[i], 'click');

Initialize a byte array to a certain value, other than the default null?

Use this to create the array in the first place:

byte[] array = Enumerable.Repeat((byte)0x20, <number of elements>).ToArray();

Replace <number of elements> with the desired array size.

javascript date to string

A little bit simpler using regex and toJSON().

var now = new Date();
var timeRegex = /^.*T(\d{2}):(\d{2}):(\d{2}).*$/
var dateRegex = /^(\d{4})-(\d{2})-(\d{2})T.*$/
var dateData = dateRegex.exec(now.toJSON());
var timeData = timeRegex.exec(now.toJSON());
var myFormat = dateData[1]+dateData[2]+dateData[3]+timeData[1]+timeData[2]+timeData[3]

Which at the time of writing gives you "20151111180924".

The good thing of using toJSON() is that everything comes already padded.

Open application after clicking on Notification

Use my example...

 public void createNotification() {
        NotificationManager notificationManager = (NotificationManager) 
        Notification notification = new Notification(R.drawable.icon,
            "message", System.currentTimeMillis());
        // Hide the notification after its selected
        notification.flags |= Notification.FLAG_AUTO_CANCEL;
        Vibrator vibrator = (Vibrator)getSystemService(Context.VIBRATOR_SERVICE);
        long[] pattern = { 0, 100, 600, 100, 700};
        vibrator.vibrate(pattern, -1);
     Intent intent = new Intent(this, Main.class);
     PendingIntent activity = PendingIntent.getActivity(this, 0, intent, 0);
     String sms = getSharedPreferences("SMSPREF", MODE_PRIVATE).getString("incoming", "EMPTY");
        notification.setLatestEventInfo(this, "message" ,
            sms, activity);
        notification.number += 1;
        notificationManager.notify(0, notification);


Nested Recycler view height doesn't wrap its content

Yes the workaround shown in all answer is correct , that is we need to customize the linear layout manager to calculate the height of its child items dynamically at run time. But all answers not working as expected .Please the below answer for custom layout manger with all orientation support.

public class MyLinearLayoutManager extends {

private static boolean canMakeInsetsDirty = true;
private static Field insetsDirtyField = null;

private static final int CHILD_WIDTH = 0;
private static final int CHILD_HEIGHT = 1;
private static final int DEFAULT_CHILD_SIZE = 100;

private final int[] childDimensions = new int[2];
private final RecyclerView view;

private int childSize = DEFAULT_CHILD_SIZE;
private boolean hasChildSize;
private int overScrollMode = ViewCompat.OVER_SCROLL_ALWAYS;
private final Rect tmpRect = new Rect();

public MyLinearLayoutManager(Context context) {
    this.view = null;

public MyLinearLayoutManager(Context context, int orientation, boolean reverseLayout) {
    super(context, orientation, reverseLayout);
    this.view = null;

public MyLinearLayoutManager(RecyclerView view) {
    this.view = view;
    this.overScrollMode = ViewCompat.getOverScrollMode(view);

public MyLinearLayoutManager(RecyclerView view, int orientation, boolean reverseLayout) {
    super(view.getContext(), orientation, reverseLayout);
    this.view = view;
    this.overScrollMode = ViewCompat.getOverScrollMode(view);

public void setOverScrollMode(int overScrollMode) {
    if (overScrollMode < ViewCompat.OVER_SCROLL_ALWAYS || overScrollMode > ViewCompat.OVER_SCROLL_NEVER)
        throw new IllegalArgumentException("Unknown overscroll mode: " + overScrollMode);
    if (this.view == null) throw new IllegalStateException("view == null");
    this.overScrollMode = overScrollMode;
    ViewCompat.setOverScrollMode(view, overScrollMode);

public static int makeUnspecifiedSpec() {
    return View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED);

public void onMeasure(RecyclerView.Recycler recycler, RecyclerView.State state, int widthSpec, int heightSpec) {
    final int widthMode = View.MeasureSpec.getMode(widthSpec);
    final int heightMode = View.MeasureSpec.getMode(heightSpec);

    final int widthSize = View.MeasureSpec.getSize(widthSpec);
    final int heightSize = View.MeasureSpec.getSize(heightSpec);

    final boolean hasWidthSize = widthMode != View.MeasureSpec.UNSPECIFIED;
    final boolean hasHeightSize = heightMode != View.MeasureSpec.UNSPECIFIED;

    final boolean exactWidth = widthMode == View.MeasureSpec.EXACTLY;
    final boolean exactHeight = heightMode == View.MeasureSpec.EXACTLY;

    final int unspecified = makeUnspecifiedSpec();

    if (exactWidth && exactHeight) {
        // in case of exact calculations for both dimensions let's use default "onMeasure" implementation
        super.onMeasure(recycler, state, widthSpec, heightSpec);

    final boolean vertical = getOrientation() == VERTICAL;

    initChildDimensions(widthSize, heightSize, vertical);

    int width = 0;
    int height = 0;

    // it's possible to get scrap views in recycler which are bound to old (invalid) adapter entities. This
    // happens because their invalidation happens after "onMeasure" method. As a workaround let's clear the
    // recycler now (it should not cause any performance issues while scrolling as "onMeasure" is never
    // called whiles scrolling)

    final int stateItemCount = state.getItemCount();
    final int adapterItemCount = getItemCount();
    // adapter always contains actual data while state might contain old data (f.e. data before the animation is
    // done). As we want to measure the view with actual data we must use data from the adapter and not from  the
    // state
    for (int i = 0; i < adapterItemCount; i++) {
        if (vertical) {
            if (!hasChildSize) {
                if (i < stateItemCount) {
                    // we should not exceed state count, otherwise we'll get IndexOutOfBoundsException. For such items
                    // we will use previously calculated dimensions
                    measureChild(recycler, i, widthSize, unspecified, childDimensions);
                } else {
            height += childDimensions[CHILD_HEIGHT];
            if (i == 0) {
                width = childDimensions[CHILD_WIDTH];
            if (hasHeightSize && height >= heightSize) {
        } else {
            if (!hasChildSize) {
                if (i < stateItemCount) {
                    // we should not exceed state count, otherwise we'll get IndexOutOfBoundsException. For such items
                    // we will use previously calculated dimensions
                    measureChild(recycler, i, unspecified, heightSize, childDimensions);
                } else {
            width += childDimensions[CHILD_WIDTH];
            if (i == 0) {
                height = childDimensions[CHILD_HEIGHT];
            if (hasWidthSize && width >= widthSize) {

    if (exactWidth) {
        width = widthSize;
    } else {
        width += getPaddingLeft() + getPaddingRight();
        if (hasWidthSize) {
            width = Math.min(width, widthSize);

    if (exactHeight) {
        height = heightSize;
    } else {
        height += getPaddingTop() + getPaddingBottom();
        if (hasHeightSize) {
            height = Math.min(height, heightSize);

    setMeasuredDimension(width, height);

    if (view != null && overScrollMode == ViewCompat.OVER_SCROLL_IF_CONTENT_SCROLLS) {
        final boolean fit = (vertical && (!hasHeightSize || height < heightSize))
                || (!vertical && (!hasWidthSize || width < widthSize));

        ViewCompat.setOverScrollMode(view, fit ? ViewCompat.OVER_SCROLL_NEVER : ViewCompat.OVER_SCROLL_ALWAYS);

private void logMeasureWarning(int child) {
    if (BuildConfig.DEBUG) {
        Log.w("MyLinearLayoutManager", "Can't measure child #" + child + ", previously used dimensions will be reused." +
                "To remove this message either use #setChildSize() method or don't run RecyclerView animations");

private void initChildDimensions(int width, int height, boolean vertical) {
    if (childDimensions[CHILD_WIDTH] != 0 || childDimensions[CHILD_HEIGHT] != 0) {
        // already initialized, skipping
    if (vertical) {
        childDimensions[CHILD_WIDTH] = width;
        childDimensions[CHILD_HEIGHT] = childSize;
    } else {
        childDimensions[CHILD_WIDTH] = childSize;
        childDimensions[CHILD_HEIGHT] = height;

public void setOrientation(int orientation) {
    // might be called before the constructor of this class is called
    //noinspection ConstantConditions
    if (childDimensions != null) {
        if (getOrientation() != orientation) {
            childDimensions[CHILD_WIDTH] = 0;
            childDimensions[CHILD_HEIGHT] = 0;

public void clearChildSize() {
    hasChildSize = false;

public void setChildSize(int childSize) {
    hasChildSize = true;
    if (this.childSize != childSize) {
        this.childSize = childSize;

private void measureChild(RecyclerView.Recycler recycler, int position, int widthSize, int heightSize, int[] dimensions) {
    final View child;
    try {
        child = recycler.getViewForPosition(position);
    } catch (IndexOutOfBoundsException e) {
        if (BuildConfig.DEBUG) {
            Log.w("MyLinearLayoutManager", "MyLinearLayoutManager doesn't work well with animations. Consider switching them off", e);

    final RecyclerView.LayoutParams p = (RecyclerView.LayoutParams) child.getLayoutParams();

    final int hPadding = getPaddingLeft() + getPaddingRight();
    final int vPadding = getPaddingTop() + getPaddingBottom();

    final int hMargin = p.leftMargin + p.rightMargin;
    final int vMargin = p.topMargin + p.bottomMargin;

    // we must make insets dirty in order calculateItemDecorationsForChild to work
    // this method should be called before any getXxxDecorationXxx() methods
    calculateItemDecorationsForChild(child, tmpRect);

    final int hDecoration = getRightDecorationWidth(child) + getLeftDecorationWidth(child);
    final int vDecoration = getTopDecorationHeight(child) + getBottomDecorationHeight(child);

    final int childWidthSpec = getChildMeasureSpec(widthSize, hPadding + hMargin + hDecoration, p.width, canScrollHorizontally());
    final int childHeightSpec = getChildMeasureSpec(heightSize, vPadding + vMargin + vDecoration, p.height, canScrollVertically());

    child.measure(childWidthSpec, childHeightSpec);

    dimensions[CHILD_WIDTH] = getDecoratedMeasuredWidth(child) + p.leftMargin + p.rightMargin;
    dimensions[CHILD_HEIGHT] = getDecoratedMeasuredHeight(child) + p.bottomMargin + p.topMargin;

    // as view is recycled let's not keep old measured values

private static void makeInsetsDirty(RecyclerView.LayoutParams p) {
    if (!canMakeInsetsDirty) {
    try {
        if (insetsDirtyField == null) {
            insetsDirtyField = RecyclerView.LayoutParams.class.getDeclaredField("mInsetsDirty");
        insetsDirtyField.set(p, true);
    } catch (NoSuchFieldException e) {
    } catch (IllegalAccessException e) {

private static void onMakeInsertDirtyFailed() {
    canMakeInsetsDirty = false;
    if (BuildConfig.DEBUG) {
        Log.w("MyLinearLayoutManager", "Can't make LayoutParams insets dirty, decorations measurements might be incorrect");

Where does Android emulator store SQLite database?

For Android Studio 3.5, fount it using instructions here: (View -> Tool Windows -> Device File Explorer -> -> databases

Aggregate / summarize multiple variables per group (e.g. sum, mean)

With the dplyr package, you can use summarise_all, summarise_at or summarise_if functions to aggregate multiple variables simultaneously. For the example dataset you can do this as follows:

# summarising all non-grouping variables
df2 <- df1 %>% group_by(year, month) %>% summarise_all(sum)

# summarising a specific set of non-grouping variables
df2 <- df1 %>% group_by(year, month) %>% summarise_at(vars(x1, x2), sum)
df2 <- df1 %>% group_by(year, month) %>% summarise_at(vars(-date), sum)

# summarising a specific set of non-grouping variables using select_helpers
# see ?select_helpers for more options
df2 <- df1 %>% group_by(year, month) %>% summarise_at(vars(starts_with('x')), sum)
df2 <- df1 %>% group_by(year, month) %>% summarise_at(vars(matches('.*[0-9]')), sum)

# summarising a specific set of non-grouping variables based on condition (class)
df2 <- df1 %>% group_by(year, month) %>% summarise_if(is.numeric, sum)

The result of the latter two options:

    year month        x1         x2
   <dbl> <dbl>     <dbl>      <dbl>
1   2000     1 -73.58134  -92.78595
2   2000     2 -57.81334 -152.36983
3   2000     3 122.68758  153.55243
4   2000     4 450.24980  285.56374
5   2000     5 678.37867  384.42888
6   2000     6 792.68696  530.28694
7   2000     7 908.58795  452.31222
8   2000     8 710.69928  719.35225
9   2000     9 725.06079  914.93687
10  2000    10 770.60304  863.39337
# ... with 14 more rows

Note: summarise_each is deprecated in favor of summarise_all, summarise_at and summarise_if.

As mentioned in my comment above, you can also use the recast function from the reshape2-package:

recast(df1, year + month ~ variable, sum, id.var = c("date", "year", "month"))

which will give you the same result.

Pointer-to-pointer dynamic two-dimensional array

What you describe for the second method only gives you a 1D array:

int *board = new int[10];

This just allocates an array with 10 elements. Perhaps you meant something like this:

int **board = new int*[4];
for (int i = 0; i < 4; i++) {
  board[i] = new int[10];

In this case, we allocate 4 int*s and then make each of those point to a dynamically allocated array of 10 ints.

So now we're comparing that with int* board[4];. The major difference is that when you use an array like this, the number of "rows" must be known at compile-time. That's because arrays must have compile-time fixed sizes. You may also have a problem if you want to perhaps return this array of int*s, as the array will be destroyed at the end of its scope.

The method where both the rows and columns are dynamically allocated does require more complicated measures to avoid memory leaks. You must deallocate the memory like so:

for (int i = 0; i < 4; i++) {
  delete[] board[i];
delete[] board;

I must recommend using a standard container instead. You might like to use a std::array<int, std::array<int, 10> 4> or perhaps a std::vector<std::vector<int>> which you initialise to the appropriate size.

Remove excess whitespace from within a string

I wrote recently a simple function which removes excess white space from string without regular expression implode(' ', array_filter(explode(' ', $str))).

Loading inline content using FancyBox

The way I figured this out was going through the example index.html/style.css that comes packaged with the Fancybox installation.

If you view the code that is used for the demo website and basically copy/paste, you'll be fine.

To get an inline Fancybox working, you will need to have this code present in your index.html file:

    <link href="./fancybox/jquery.fancybox-1.3.4.css" rel="stylesheet" type="text/css" media="screen" />
    <script>!window.jQuery && document.write('<script src="jquery-1.4.3.min.js"><\/script>');</script>
    <script type="text/javascript" src=""></script>
    <script type="text/javascript" src="./fancybox/jquery.fancybox-1.3.4.pack.js"></script>
    <script type="text/javascript">
    $(document).ready(function() {

            'titlePosition'     : 'inside',
            'transitionIn'      : 'none',
            'transitionOut'     : 'none'


    <a id="various1" href="#inline1" title="Put a title here">Name of Link Here</a>
    <div style="display: none;">
        <div id="inline1" style="width:400px;height:100px;overflow:auto;">
                   Write whatever text you want right here!!


Remember to be precise about what folders your script files are placed in and where you are pointing to in the Head tag; they must correspond.

Cloning git repo causes error - Host key verification failed. fatal: The remote end hung up unexpectedly

Resolved the issue... you need to add the ssh public key to your github account.

  1. Verify that the ssh keys have been setup correctly.
    1. Run ssh-keygen
    2. Enter the password (keep the default path - ~/.ssh/id_rsa)
  2. Add the public key (~/.ssh/ to github account
  3. Try git clone. It works!

Initial status (public key not added to git hub account)

foo@bn18-251:~$ rm -rf test
foo@bn18-251:~$ ls
foo@bn18-251:~$ git clone [email protected]:devendra-d-chavan/test.git
Cloning into 'test'...
Permission denied (publickey).
fatal: The remote end hung up unexpectedly

Now, add the public key ~/.ssh/ to the github account (I used cat ~/.ssh/

foo@bn18-251:~$ ssh-keygen 
Generating public/private rsa key pair.
Enter file in which to save the key (/home/foo/.ssh/id_rsa): 
Created directory '/home/foo/.ssh'.
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /home/foo/.ssh/id_rsa.
Your public key has been saved in /home/foo/.ssh/
The key fingerprint is:
The key's randomart image is:
+--[ RSA 2048]----+
foo@bn18-251:~$ cat ./.ssh/ 
foo@bn18-251:~$ git clone [email protected]:devendra-d-chavan/test.git
Cloning into 'test'...
The authenticity of host ' (' can't be established.
RSA key fingerprint is 16:27:ac:a5:76:28:2d:36:63:1b:56:4d:eb:df:a6:48.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added ',' (RSA) to the list of known hosts.
Enter passphrase for key '/home/foo/.ssh/id_rsa': 
warning: You appear to have cloned an empty repository.
foo@bn18-251:~$ ls
foo@bn18-251:~/test$ git status
# On branch master
# Initial commit
nothing to commit (create/copy files and use "git add" to track)

wget ssl alert handshake failure

Basically your OpenSSL uses SSLv3 and the site you are accessing does not support that protocol.

Just update your wget:

sudo apt-get install wget

Or if it is already supporting another secure protocol, just add it as argument:

wget --secure-protocol=PROTOCOL_v1

ReactJS: Maximum update depth exceeded error

onClick you should call function, thats called your function toggle.

onClick={() => this.toggle()}

Is it possible to overwrite a function in PHP

You could use the PECL extension

but that is bad practise in my opinion. You are using functions, but check out the Decorator design pattern. Can borrow the basic idea from it.

How can I compare time in SQL Server?

Adding to the other answers:

you can create a function for trimming the date from a datetime

CREATE FUNCTION dbo.f_trimdate (@dat datetime) RETURNS DATETIME AS BEGIN

So this:

SELECT @dat = '20080201 02:25:46.000'
SELECT dbo.f_trimdate(@dat)

Will return 1900-01-01 02:25:46.000

Check if a Bash array contains a value

Using grep and printf

Format each array member on a new line, then grep the lines.

if printf '%s\n' "${array[@]}" | grep -x -q "search string"; then echo true; else echo false; fi
$ array=("word", "two words")
$ if printf '%s\n' "${array[@]}" | grep -x -q "two words"; then echo true; else echo false; fi

Note that this has no problems with delimeters and spaces.

Round float to x decimals?

I coded a function (used in Django project for DecimalField) but it can be used in Python project :

This code :

  • Manage integers digits to avoid too high number
  • Manage decimals digits to avoid too low number
  • Manage signed and unsigned numbers

Code with tests :

def convert_decimal_to_right(value, max_digits, decimal_places, signed=True):

    integer_digits = max_digits - decimal_places
    max_value = float((10**integer_digits)-float(float(1)/float((10**decimal_places))))

    if signed:
        min_value = max_value*-1
        min_value = 0

    if value > max_value:
        value = max_value

    if value < min_value:
        value = min_value

    return round(value, decimal_places)

value = 12.12345
nb = convert_decimal_to_right(value, 4, 2)
# nb : 12.12

value = 12.126
nb = convert_decimal_to_right(value, 4, 2)
# nb : 12.13

value = 1234.123
nb = convert_decimal_to_right(value, 4, 2)
# nb : 99.99

value = -1234.123
nb = convert_decimal_to_right(value, 4, 2)
# nb : -99.99

value = -1234.123
nb = convert_decimal_to_right(value, 4, 2, signed = False)
# nb : 0

value = 12.123
nb = convert_decimal_to_right(value, 8, 4)
# nb : 12.123

Required attribute on multiple checkboxes with the same name?

To provide another approach similar to the answer by @IvanCollantes. It works by additionally filtering the required checkboxes by name. I also simplified the code a bit and checks for a default checked checkbox.

jQuery(function($) {_x000D_
  var requiredCheckboxes = $(':checkbox[required]');_x000D_
  requiredCheckboxes.on('change', function(e) {_x000D_
    var checkboxGroup = requiredCheckboxes.filter('[name="' + $(this).attr('name') + '"]');_x000D_
    var isChecked =':checked');_x000D_
    checkboxGroup.prop('required', !isChecked);_x000D_
<script src=""></script>_x000D_
<form target="_blank">_x000D_
    At least one checkbox from each group is required..._x000D_
    <legend>Checkboxes Group test</legend>_x000D_
      <input type="checkbox" name="test[]" value="1" checked="checked" required="required">test-1_x000D_
      <input type="checkbox" name="test[]" value="2" required="required">test-2_x000D_
      <input type="checkbox" name="test[]" value="3" required="required">test-3_x000D_
    <legend>Checkboxes Group test2</legend>_x000D_
      <input type="checkbox" name="test2[]" value="1" required="required">test2-1_x000D_
      <input type="checkbox" name="test2[]" value="2" required="required">test2-2_x000D_
      <input type="checkbox" name="test2[]" value="3" required="required">test2-3_x000D_
  <button type="submit" value="submit">Submit</button>_x000D_

How to use multiple @RequestMapping annotations in spring?

The following is acceptable as well:

@GetMapping(path = { "/{pathVariable1}/{pathVariable1}/somePath", 
                     "/fixedPath/{some-name}/{some-id}/fixed" }, 
            produces = "application/json")

Same can be applied to @RequestMapping as well

How to use parameters with HttpPost

You can also use this approach in case you want to pass some http parameters and send a json request:

(note: I have added in some extra code just incase it helps any other future readers)

public void postJsonWithHttpParams() throws URISyntaxException, UnsupportedEncodingException, IOException {

    //add the http parameters you wish to pass
    List<NameValuePair> postParameters = new ArrayList<>();
    postParameters.add(new BasicNameValuePair("param1", "param1_value"));
    postParameters.add(new BasicNameValuePair("param2", "param2_value"));

    //Build the server URI together with the parameters you wish to pass
    URIBuilder uriBuilder = new URIBuilder("");

    HttpPost postRequest = new HttpPost(;
    postRequest.setHeader("Content-Type", "application/json");

    //this is your JSON string you are sending as a request
    String yourJsonString = "{\"str1\":\"a value\",\"str2\":\"another value\"} ";

    //pass the json string request in the entity
    HttpEntity entity = new ByteArrayEntity(yourJsonString.getBytes("UTF-8"));

    //create a socketfactory in order to use an http connection manager
    PlainConnectionSocketFactory plainSocketFactory = PlainConnectionSocketFactory.getSocketFactory();
    Registry<ConnectionSocketFactory> connSocketFactoryRegistry = RegistryBuilder.<ConnectionSocketFactory>create()
            .register("http", plainSocketFactory)

    PoolingHttpClientConnectionManager connManager = new PoolingHttpClientConnectionManager(connSocketFactoryRegistry);


    RequestConfig defaultRequestConfig = RequestConfig.custom()

    // Build the http client.
    CloseableHttpClient httpclient = HttpClients.custom()

    CloseableHttpResponse response = httpclient.execute(postRequest);

    //Read the response
    String responseString = "";

    int statusCode = response.getStatusLine().getStatusCode();
    String message = response.getStatusLine().getReasonPhrase();

    HttpEntity responseHttpEntity = response.getEntity();

    InputStream content = responseHttpEntity.getContent();

    BufferedReader buffer = new BufferedReader(new InputStreamReader(content));
    String line;

    while ((line = buffer.readLine()) != null) {
        responseString += line;

    //release all resources held by the responseHttpEntity

    //close the stream

    // Close the connection manager.

PowerShell try/catch/finally

-ErrorAction Stop is changing things for you. Try adding this and see what you get:

Catch [System.Management.Automation.ActionPreferenceStopException] {
"caught a StopExecution Exception" 

Convert interface{} to int

You need to do type assertion for converting your interface{} to int value.

iAreaId := val.(int)
iAreaId, ok := val.(int)

More information is available.

How do I insert an image in an activity with android studio?

since you followed the tutorial, I presume you have a screen that says Hello World.

that means you have some code in your layout xml that looks like this

    android:text="@string/hello_world" />

you want to display an image, so instead of TextView you want to have ImageView. and instead of a text attribute you want an src attribute, that links to your drawable resource


scrollTop jquery, scrolling to div with id?

instead of

$('html, body').animate({scrollTop:xxx}, 'slow');


$('html, body').animate({scrollTop:$('#div_id').position().top}, 'slow');

this will return the absolute top position of whatever element you select as #div_id

Detect if a jQuery UI dialog box is open

If you want to check if the dialog's open on a particular element you can do this:

if ($('#elem').closest('.ui-dialog').is(':visible')) { 
  // do something

Or if you just want to check if the element itself is visible you can do:

if ($('#elem').is(':visible')) { 
  // do something


if ($('#elem:visible').length) { 
  // do something

How to add spacing between columns?

Simple Way

.row div{
  padding-left: 8px;
  padding-right: 8px;

Can an ASP.NET MVC controller return an Image?

To expland on Dyland's response slightly:

Three classes implement the FileResult class:


They're all fairly self explanatory:

  • For file path downloads where the file exists on disk, use FilePathResult - this is the easiest way and avoids you having to use Streams.
  • For byte[] arrays (akin to Response.BinaryWrite), use FileContentResult.
  • For byte[] arrays where you want the file to download (content-disposition: attachment), use FileStreamResult in a similar way to below, but with a MemoryStream and using GetBuffer().
  • For Streams use FileStreamResult. It's called a FileStreamResult but it takes a Stream so I'd guess it works with a MemoryStream.

Below is an example of using the content-disposition technique (not tested):

    public ActionResult GetFile()
        // No need to dispose the stream, MVC does it for you
        string path = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "App_Data", "myimage.png");
        FileStream stream = new FileStream(path, FileMode.Open);
        FileStreamResult result = new FileStreamResult(stream, "image/png");
        result.FileDownloadName = "image.png";
        return result;

ECMAScript 6 arrow function that returns an object

You can always check this out for more custom solutions:

x => ({}[] = x);

RegEx match open tags except XHTML self-contained tags

Disclaimer: use a parser if you have the option. That said...

This is the regex I use (!) to match HTML tags:


It may not be perfect, but I ran this code through a lot of HTML. Note that it even catches strange things like <a name="badgenerator"">, which show up on the web.

I guess to make it not match self contained tags, you'd either want to use Kobi's negative look-behind:


or just combine if and if not.

To downvoters: This is working code from an actual product. I doubt anyone reading this page will get the impression that it is socially acceptable to use regexes on HTML.

Caveat: I should note that this regex still breaks down in the presence of CDATA blocks, comments, and script and style elements. Good news is, you can get rid of those using a regex...

Conda: Installing / upgrading directly from github

I found a reference to this in condas issues. The following should now work.

name: sample_env
   - requests
   - bokeh>=0.10.0
   - pip:
     - git+

Shortcut to exit scale mode in VirtualBox

I was having the similar issue when using VirtualBox on Ubuntu 12.04LTS. Now if anyone is using or has ever used Ubuntu, you might be aware that how things are hard sometimes when using shortcut keys in Ubuntu. For me, when i was trying to revert back the Host key, it was just not happening and the shortcut keys won't just work. I even tried the command line option to revert back the scale mode and it won't work either. Finally i found the following when all the other options fails:

Fix the Scale Mode Issue in Oracle VirtualBox in Ubuntu using the following steps:

  1. Close all virtual machines and VirtualBox windows.
  2. Find your machine config files (i.e. /home/<username>/VirtualBox VMs/ANKSVM) where ANKSVM is your VM Name and edit and change the following in ANKSVM.vbox and ANKSVM.vbox-prev files:

  3. Edit the line: <ExtraDataItem name="GUI/Scale" value="on"/> to <ExtraDataItem name="GUI/Scale" value="off"/>

  4. Restart VirtualBox

You are done.

This works every time specially when all other options fails like how it happened for me.

Center image using text-align center?

To center a non background image depends on whether you want to display the image as an inline (default behavior) or a block element.

Case of inline

If you want to keep the default behavior of the image's display CSS property, you will need to wrap your image inside another block element to which you must set text-align: center;

Case of block

If you want to consider the image as a block element of its own, then text-align property does not make a sens, and you should do this instead:

IMG.display {
    display: block;
    margin-left: auto;
    margin-right: auto;

The answer to your question:

Is the property text-align: center; a good way to center an image using CSS?

Yes and no.

  • Yes, if the image is the only element inside its wrapper.
  • No, in case you have other elements inside the image's wrapper because all the children elements which are siblings of the image will inherit the text-align property: and may be you would not like this side effect.


  1. List of inline elements
  2. Centering things

Docker official registry (Docker Hub) URL

For those trying to create a Google Cloud instance using the "Deploy a container image to this VM instance." option then the correct url format would be<dockerimagename>:version

The suggestion above of<dockerimagename> did not work for me.

I finally found the solution here (in my case, i was trying to run

How do I make the return type of a method generic?

You need to make it a generic method, like this:

public static T ConfigSetting<T>(string settingName)
    return /* code to convert the setting to T... */

But the caller will have to specify the type they expect. You could then potentially use Convert.ChangeType, assuming that all the relevant types are supported:

public static T ConfigSetting<T>(string settingName)
    object value = ConfigurationManager.AppSettings[settingName];
    return (T) Convert.ChangeType(value, typeof(T));

I'm not entirely convinced that all this is a good idea, mind you...

Populating a dictionary using for loops (python)

>>> dict(zip(keys, values))
{0: 'Hi', 1: 'I', 2: 'am', 3: 'John'}

Gradle failed to resolve library in Android Studio

You go File->Settings->Gradle Look at the "Offline work" inbox, if it's checked u uncheck and try to sync again I have the same problem and i try this , the problem resolved. Good luck !

How to make picturebox transparent?

Try using an ImageList

ImageList imgList = new ImageList;

imgList.TransparentColor = Color.White;

Load the image like this:

picturebox.Image = imgList.Images[img_index];

Difference between readFile() and readFileSync()

readFileSync() is synchronous and blocks execution until finished. These return their results as return values. readFile() are asynchronous and return immediately while they function in the background. You pass a callback function which gets called when they finish. let's take an example for non-blocking.

following method read a file as a non-blocking way

var fs = require('fs');
fs.readFile(filename, "utf8", function(err, data) {
        if (err) throw err;

following is read a file as blocking or synchronous way.

var data = fs.readFileSync(filename);

LOL...If you don't want readFileSync() as blocking way then take reference from the following code. (Native)

var fs = require('fs');
function readFileAsSync(){
    new Promise((resolve, reject)=>{
        fs.readFile(filename, "utf8", function(err, data) {
                if (err) throw err;

async function callRead(){
    let data = await readFileAsSync();


it's mean behind scenes readFileSync() work same as above(promise) base.

What does it mean to inflate a view from an xml file?

Inflating is the process of adding a view (.xml) to activity on runtime. When we create a listView we inflate each of its items dynamically. If we want to create a ViewGroup with multiple views like buttons and textview, we can create it like so:

Button but = new Button();
but.setText ="button text";
but.background ...
but.leftDrawable.. and so on...

TextView txt = new TextView();
txt.setText ="button text";
txt.background ... and so on...

Then we have to create a layout where we can add above views:

RelativeLayout rel = new RelativeLayout();


And now if we want to add a button in the right-corner and a textview on the bottom, we have to do a lot of work. First by instantiating the view properties and then applying multiple constraints. This is time consuming.

Android makes it easy for us to create a simple .xml and design its style and attributes in xml and then simply inflate it wherever we need it without the pain of setting constraints programatically.

LayoutInflater inflater = 
View menuLayout = inflater.inflate(R.layout.your_menu_layout, mainLayout, true);
//now add menuLayout to wherever you want to add like


How to force a web browser NOT to cache images

I use PHP's file modified time function, for example:

echo <img  src='Images/image.png?" . filemtime('Images/image.png') . "'  />";

If you change the image then the new image is used rather than the cached one, due to having a different modified timestamp.

How to add column to numpy array

If you have an array, a of say 210 rows by 8 columns:

a = numpy.empty([210,8])

and want to add a ninth column of zeros you can do this:

b = numpy.append(a,numpy.zeros([len(a),1]),1)

Want to download a Git repository, what do I need (windows machine)?

Install mysysgit. (Same as Greg Hewgill's answer.)

Install Tortoisegit. (Tortoisegit requires mysysgit or something similiar like Cygwin.)

After TortoiseGit is installed, right-click on a folder, select Git Clone..., then enter the Url of the repository, then click Ok.

This answer is not any better than just installing mysysgit, but you can avoid the dreaded command line. :)

Syntax error: Illegal return statement in JavaScript

If you want to return some value then wrap your statement in function

function my_function(){ 

 return my_thing; 

Problem is with the statement on the 1st line if you are trying to use PHP

var ask = confirm ('".$message."'); 

IF you are trying to use PHP you should use

 var ask = confirm (<?php echo "'".$message."'" ?>); //now message with be the javascript string!!

How to do a subquery in LINQ?

Ok, here's a basic join query that gets the correct records:

   int[] selectedRolesArr = GetSelectedRoles();
    if( selectedRolesArr != null && selectedRolesArr.Length > 0 ) 

    //this join version requires the use of distinct to prevent muliple records
        //being returned for users with more than one company role.
    IQueryable retVal = (from u in context.Users
                        join c in context.CompanyRolesToUsers
                          on u.Id equals c.UserId
                        where u.LastName.Contains( "fra" ) &&
                            selectedRolesArr.Contains( c.CompanyRoleId )
                        select  u).Distinct();

But here's the code that most easily integrates with the algorithm that we already had in place:

int[] selectedRolesArr = GetSelectedRoles(); 
if ( useAnd ) 
          predicateAnd = predicateAnd.And( u => (from c in context.CompanyRolesToUsers 
                       where selectedRolesArr.Contains(c.CompanyRoleId) 
                       select c.UserId).Contains(u.Id)); 
           predicateOr = predicateOr.Or( u => (from c in context.CompanyRolesToUsers 
                          where selectedRolesArr.Contains(c.CompanyRoleId) 
                         select c.UserId).Contains(u.Id) ); 

which is thanks to a poster at the LINQtoSQL forum

Return file in ASP.Net Core Web API

Here is a simplistic example of streaming a file:

using System.IO;
using Microsoft.AspNetCore.Mvc;
public async Task<FileStreamResult> Download(int id)
    var path = "<Get the file path using the ID>";
    var stream = File.OpenRead(path);
    return new FileStreamResult(stream, "application/octet-stream");


Be sure to use FileStreamResult from Microsoft.AspNetCore.Mvc and not from System.Web.Mvc.

Center icon in a div - horizontally and vertically

Here is a way to center content both vertically and horizontally in any situation, which is useful when you do not know the width or height or both:


#container {
    display: table;
    width: 300px; /* not required, just for example */
    height: 400px; /* not required, just for example */

#update {
    display: table-cell;
    vertical-align: middle;
    text-align: center;


<div id="container">
    <a id="update" href="#">
        <i class="icon-refresh"></i>


Note that the width and height values are just for demonstration here, you can change them to anything you want (or remove them entirely) and it will still work because the vertical centering here is a product of the way the table-cell display property works.

php is null or empty?

This is not a bug but PHP normal behavior. It happens because the == operator in PHP doesn't check for type.

'' == null == 0 == false

If you want also to check if the values have the same type, use === instead. To study in deep this difference, please read the official documentation.

Is there a way to break a list into columns?

The mobile-first way is to use CSS Columns to create an experience for smaller screens then use Media Queries to increase the number of columns at each of your layout's defined breakpoints.

ul {_x000D_
  column-count: 2;_x000D_
  column-gap: 2rem;_x000D_
@media screen and (min-width: 768px)) {_x000D_
  ul {_x000D_
    column-count: 3;_x000D_
    column-gap: 5rem;_x000D_

Python: maximum recursion depth exceeded while calling a Python object

Instead of doing recursion, the parts of the code with checkNextID(ID + 18) and similar could be replaced with ID+=18, and then if you remove all instances of return 0, then it should do the same thing but as a simple loop. You should then put a return 0 at the end and make your variables non-global.

Spring Boot: How can I set the logging level with

You can do that using your

logging.level.=ERROR -> Sets the root logging level to error
logging.level.=DEBUG -> Sets the root logging level to DEBUG

logging.file=${}/myapp.log -> Sets the absolute log file path to TMPDIR/myapp.log

A sane default set of regarding logging using profiles would be:<your app name here>


When you develop inside your favourite IDE you just add a as VM argument to the run/debug configuration of your app.

This will give you error only logging in production and debug logging during development WITHOUT writing the output to a log file. This will improve the performance during development ( and save SSD drives some hours of operation ;) ).

Using Java 8 to convert a list of objects into a string obtained from the toString() method

String actual =, u) -> t + "," + u).get();

Error 0x80005000 and DirectoryServices

On IIS hosted sites, try recycling the app pool. It fixed my issue. Thanks

java.lang.IllegalStateException: Fragment not attached to Activity

This error happens due to the combined effect of two factors:

  • The HTTP request, when complete, invokes either onResponse() or onError() (which work on the main thread) without knowing whether the Activity is still in the foreground or not. If the Activity is gone (the user navigated elsewhere), getActivity() returns null.
  • The Volley Response is expressed as an anonymous inner class, which implicitly holds a strong reference to the outer Activity class. This results in a classic memory leak.

To solve this problem, you should always do:

Activity activity = getActivity();
if(activity != null){

    // etc ...


and also, use isAdded() in the onError() method as well:

public void onError(VolleyError error) {

    Activity activity = getActivity(); 
    if(activity != null && isAdded())
        if (error instanceof NoConnectionError) {
           String errormsg = getResources().getString(R.string.no_internet_error_msg);
           Toast.makeText(activity, errormsg, Toast.LENGTH_LONG).show();

jQuery make global variable

You can avoid declaration of global variables by adding them directly to the global object:

(function(global) {


  global.varName = someValue;



A disadvantage of this method is that global.varName won't exist until that specific line of code is executed, but that can be easily worked around.

You might also consider an application architecture where such globals are held in a closure common to all functions that need them, or as properties of a suitably accessible data storage object.

Pycharm does not show plot

One property need to set for pycharm.

import matplotlib.pyplot as plt

plt.interactive(False)  #need to set to False

dataset.plot(kind='box', subplots=True, layout=(2,2), sharex=False, sharey=False)