Programs & Examples On #Design by contract

Design by Contract (DbC) or Programming by Contract is an approach to designing computer software. It prescribes that software designers should define formal, precise and verifiable interface specifications for software components, which extend the ordinary definition of abstract data types with preconditions, postconditions and invariants. These specifications are referred to as "contracts", in accordance with a conceptual metaphor with the conditions and

Zookeeper connection error

Unable to read additional data from server sessionid 0x0, likely server has closed socket, closing socket connection and attempting reconnect (org.apache.zookeeper.ClientCnxn)

I changed just the number of brokers in the zoo.cfg file and restart zookeeper and kafka service

How to replace case-insensitive literal substrings in Java

Not as elegant perhaps as other approaches but it's pretty solid and easy to follow, esp. for people newer to Java. One thing that gets me about the String class is this: It's been around for a very long time and while it supports a global replace with regexp and a global replace with Strings (via CharSequences), that last doesn't have a simple boolean parameter: 'isCaseInsensitive'. Really, you'd've thought that just by adding that one little switch, all the trouble its absence causes for beginners especially could have been avoided. Now on JDK 7, String still doesn't support this one little addition!

Well anyway, I'll stop griping. For everyone in particular newer to Java, here's your cut-and-paste deus ex machina. As I said, not as elegant and won't win you any slick coding prizes, but it works and is reliable. Any comments, feel free to contribute. (Yes, I know, StringBuffer is probably a better choice of managing the two character string mutation lines, but it's easy enough to swap the techniques.)

public String replaceAll(String findtxt, String replacetxt, String str, 
        boolean isCaseInsensitive) {
    if (str == null) {
        return null;
    if (findtxt == null || findtxt.length() == 0) {
        return str;
    if (findtxt.length() > str.length()) {
        return str;
    int counter = 0;
    String thesubstr = "";
    while ((counter < str.length()) 
            && (str.substring(counter).length() >= findtxt.length())) {
        thesubstr = str.substring(counter, counter + findtxt.length());
        if (isCaseInsensitive) {
            if (thesubstr.equalsIgnoreCase(findtxt)) {
                str = str.substring(0, counter) + replacetxt 
                    + str.substring(counter + findtxt.length());
                // Failing to increment counter by replacetxt.length() leaves you open
                // to an infinite-replacement loop scenario: Go to replace "a" with "aa" but
                // increment counter by only 1 and you'll be replacing 'a's forever.
                counter += replacetxt.length();
            } else {
                counter++; // No match so move on to the next character from
                           // which to check for a findtxt string match.
        } else {
            if (thesubstr.equals(findtxt)) {
                str = str.substring(0, counter) + replacetxt 
                    + str.substring(counter + findtxt.length());
                counter += replacetxt.length();
            } else {
    return str;

html 5 audio tag width

You can use html and be a boss with simple things :

<embed src="music.mp3" width="3000" height="200" controls>

How to make a dropdown readonly using jquery?

Try to make empty string when "keypress up"

The Html is:

<input id="cf_1268591" style="width:60px;line-height:16px;border:1px solid #ccc">

The Jquery is:

  url:"your url",
  panelWidth: "350",
  panelHeight: "200",

// make after keyup with empty string

var tb = $("#cf_1268591").combobox("textbox");
  this.value = "";

What version of Java is running in Eclipse?

Eclipse uses the default Java on the system to run itself. This can also be changed in the eclipse.ini file in your eclipse install folder.

To find out the version of java that your eclipse project is using, see Project->properties->build path->Libraries tab and see the JRE system library thats being used. You can also check it out at Window->Preferences->Java->Installed JREs. This is a list of all JREs that eclipse knows about

To find out using code, use the System.getProperty(...) method. See for supported properties.

How to check if a string starts with a specified string?

You can use a simple regex (updated version from user viriathus as eregi is deprecated)

if (preg_match('#^http#', $url) === 1) {
    // Starts with http (case sensitive).

or if you want a case insensitive search

if (preg_match('#^http#i', $url) === 1) {
    // Starts with http (case insensitive).

Regexes allow to perform more complex tasks

if (preg_match('#^https?://#i', $url) === 1) {
    // Starts with http:// or https:// (case insensitive).

Performance wise, you don't need to create a new string (unlike with substr) nor parse the whole string if it doesn't start with what you want. You will have a performance penalty though the 1st time you use the regex (you need to create/compile it).

This extension maintains a global per-thread cache of compiled regular expressions (up to 4096).

Find if variable is divisible by 2

You don't need jQuery. Just use JavaScript's Modulo operator.

Import SQL dump into PostgreSQL database

psql databasename < data_base_dump

That's the command you are looking for.

Beware: databasename must be created before importing. Have a look at the PostgreSQL Docs Chapter 23. Backup and Restore.

jQuery Upload Progress and AJAX file upload

Here are some options for using AJAX to upload files:

UPDATE: Here is a JQuery plug-in for Multiple File Uploading.

Change Volley timeout duration

See Request.setRetryPolicy() and the constructor for DefaultRetryPolicy, e.g.

JsonObjectRequest myRequest = new JsonObjectRequest(Method.GET,
        url, null,
        new Response.Listener<JSONObject>() {

            public void onResponse(JSONObject response) {
                Log.d(TAG, response.toString());
        }, new Response.ErrorListener() {

            public void onErrorResponse(VolleyError error) {
                Log.d(TAG, "Error: " + error.getMessage());

myRequest.setRetryPolicy(new DefaultRetryPolicy(

Apache HttpClient 4.0.3 - how do I set cookie with sessionID for POST request?

HttpContext localContext = new BasicHttpContext();
localContext.setAttribute(HttpClientContext.COOKIE_STORE, cookieStore);
response = client.execute(httppost, localContext);

doesn't work in 4.5 version without

cookie.setAttribute(ClientCookie.DOMAIN_ATTR, "true");

How to split CSV files as per number of rows specified?

This should do it for you - all your files will end up called Part1-Part500.

HDR=$(head -1 $FILENAME)   # Pick up CSV header line to apply to each file
split -l 20 $FILENAME xyz  # Split the file into chunks of 20 lines each
for f in xyz*              # Go through all newly created chunks
   echo $HDR > Part${n}    # Write out header to new file called "Part(n)"
   cat $f >> Part${n}      # Add in the 20 lines from the "split" command
   rm $f                   # Remove temporary file
   ((n++))                 # Increment name of output part

How to squash commits in git after they have been pushed?

For squashing two commits, one of which was already pushed, on a single branch the following worked:

git rebase -i HEAD~2
    [ pick     older-commit  ]
    [ squash   newest-commit ]
git push --force

By default, this will include the commit message of the newest commit as a comment on the older commit.

Newline in markdown table?

Just for those that are trying to do this on Jira. Just add \\ at the end of each line and a new line will be created:

|Something|Something else \\ that's rather long|Something else|

Will render this:

enter image description here

Source: Text breaks on Jira

Default values for Vue component props & how to check if a user did not set the prop?

Vue allows for you to specify a default prop value and type directly, by making props an object (see:

props: {
  year: {
    default: 2016,
    type: Number

If the wrong type is passed then it throws an error and logs it in the console, here's the fiddle:

Pure Javascript listen to input value change

Another approach in 2020 could be using document.querySelector():

const myInput = document.querySelector('input[name="exampleInput"]');

myInput.addEventListener("change", (e) => {
  // here we do something

How to disable back swipe gesture in UINavigationController on iOS 7

swift 5, swift 4.2 can use the code in the below.

// disable
self.navigationController?.interactivePopGestureRecognizer?.isEnabled = false
// enable
self.navigationController?.interactivePopGestureRecognizer?.isEnabled = true

How can I tell where mongoDB is storing data? (its not in the default /data/db!)

If you could somehow locate mongod.log and the do a grep over it

grep dbpath mongod.log

The value for dbpath is the data location for mongodb!! All the best :)

JSON Java 8 LocalDateTime format in Spring Boot

simply use:


or you can use pattern as you like for e.g: ('-' in place of '/')

Add a "sort" to a =QUERY statement in Google Spreadsheets

Sorting by C and D needs to be put into number form for the corresponding column, ie 3 and 4, respectively. Eg Order By 2 asc")

C# Example of AES256 encryption using System.Security.Cryptography.Aes

Once I'd discovered all the information of how my client was handling the encryption/decryption at their end it was straight forward using the AesManaged example suggested by dtb.

The finally implemented code started like this:

        // Create a new instance of the AesManaged class.  This generates a new key and initialization vector (IV).
        AesManaged myAes = new AesManaged();

        // Override the cipher mode, key and IV
        myAes.Mode = CipherMode.ECB;
        myAes.IV = new byte[16] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }; // CRB mode uses an empty IV
        myAes.Key = CipherKey;  // Byte array representing the key
        myAes.Padding = PaddingMode.None;

        // Create a encryption object to perform the stream transform.
        ICryptoTransform encryptor = myAes.CreateEncryptor();

        // TODO: perform the encryption / decryption as required...

    catch (Exception ex)
        // TODO: Log the error 
        throw ex;

Count number of matches of a regex in Javascript

As mentioned in my earlier answer, you can use RegExp.exec() to iterate over all matches and count each occurrence; the advantage is limited to memory only, because on the whole it's about 20% slower than using String.match().

var re = /\s/g,
count = 0;

while (re.exec(text) !== null) {

return count;

Converting video to HTML5 ogg / ogv and mpg4

The Miro video converter does a beautiful job and is drag-n-drop.

BTW it's FREE and also very good for mobile device encoding.

How to do sed like text replace with python?

If I want something like sed, then I usually just call sed itself using the sh library.

from sh import sed

sed(['-i', 's/^# deb/deb/', '/etc/apt/sources.list'])

Sure, there are downsides. Like maybe the locally installed version of sed isn't the same as the one you tested with. In my cases, this kind of thing can be easily handled at another layer (like by examining the target environment beforehand, or deploying in a docker image with a known version of sed).

Converting a SimpleXML Object to an Array

I found this in the PHP manual comments:

 * function xml2array
 * This function is part of the PHP manual.
 * The PHP manual text and comments are covered by the Creative Commons 
 * Attribution 3.0 License, copyright (c) the PHP Documentation Group
 * @author  k dot antczak at livedata dot pl
 * @date    2011-04-22 06:08 UTC
 * @link
 * @license
 * @license
 * @license CC-BY-3.0 <>
function xml2array ( $xmlObject, $out = array () )
    foreach ( (array) $xmlObject as $index => $node )
        $out[$index] = ( is_object ( $node ) ) ? xml2array ( $node ) : $node;

    return $out;

It could help you. However, if you convert XML to an array you will loose all attributes that might be present, so you cannot go back to XML and get the same XML.

Node Multer unexpected field

A follow up to vincent's answer.

Not a direct answer to the question since the question is using a form.

For me, it wasn't the name of the input tag that was used, but the name when appending the file to the formData.

front end file

   var formData = new FormData();

web service file:'/upload', upload.single('<NAME>'),...

Alter column, add default constraint

I use the stored procedure below to update the defaults on a column.

It automatically removes any prior defaults on the column, before adding the new default.

Examples of usage:

-- Update default to be a date.
exec [dbo].[AlterDefaultForColumn] '[dbo].[TableName]','Column','getdate()';
-- Update default to be a number.
exec [dbo].[AlterDefaultForColumn] '[dbo].[TableName]','Column,'6';
-- Update default to be a string. Note extra quotes, as this is not a function.
exec [dbo].[AlterDefaultForColumn] '[dbo].[TableName]','Column','''MyString''';

Stored procedure:


-- Sample function calls:
--exec [dbo].[AlterDefaultForColumn] '[dbo].[TableName]','ColumnName','getdate()';
--exec [dbol].[AlterDefaultForColumn] '[dbo].[TableName]','Column,'6';
--exec [dbo].[AlterDefaultForColumn] '[dbo].[TableName]','Column','''MyString''';
create PROCEDURE [dbo].[ColumnDefaultUpdate]
        -- Table name, including schema, e.g. '[dbo].[TableName]'
        @TABLE_NAME VARCHAR(100), 
        -- Column name, e.g. 'ColumnName'.
        @COLUMN_NAME VARCHAR(100),
        -- New default, e.g. '''MyDefault''' or 'getdate()'
        -- Note that if you want to set it to a string constant, the contents
        -- must be surrounded by extra quotes, e.g. '''MyConstant''' not 'MyConstant'
    -- Trim angle brackets so things work even if they are included.

    print 'Table name: ' + @TABLE_NAME;
    print 'Column name: ' + @COLUMN_NAME;
    DECLARE @ObjectName NVARCHAR(100)
    SELECT @ObjectName = OBJECT_NAME([default_object_id]) FROM SYS.COLUMNS
    WHERE [object_id] = OBJECT_ID(@TABLE_NAME) AND [name] = @COLUMN_NAME;

    IF @ObjectName <> '' 
        print 'Removed default: ' + @ObjectName;
        --print('ALTER TABLE ' + @TABLE_NAME + ' DROP CONSTRAINT ' + @ObjectName)
        EXEC('ALTER TABLE ' + @TABLE_NAME + ' DROP CONSTRAINT ' + @ObjectName)

    print 'Added default of: ' + @NEW_DEFAULT;

Errors this stored procedure eliminates

If you attempt to add a default to a column when one already exists, you will get the following error (something you will never see if using this stored proc):

-- Using the stored procedure eliminates this error:
Msg 1781, Level 16, State 1, Line 1
Column already has a DEFAULT bound to it.
Msg 1750, Level 16, State 0, Line 1
Could not create constraint. See previous errors.

TypeScript: Interfaces vs Types

One difference is that interfaces create a new name that is used everywhere. Type aliases don’t create a new name — for instance, error messages won’t use the alias name.

Best way to stress test a website

JMeter would be one such tool. Can be a bit hard to learn and configure, but it's usually worth it.

How do I get the coordinate position after using jQuery drag and drop?

Had the same problem. My solution is next:

    drop: function( event, ui ) {

        // position of the draggable minus position of the droppable
        // relative to the document
        var $newPosX = ui.offset.left - $(this).offset().left;
        var $newPosY = - $(this).offset().top;


Programmatically set left drawable in a TextView

Using Kotlin:

You can create an extension function or just use setCompoundDrawablesWithIntrinsicBounds directly.

fun TextView.leftDrawable(@DrawableRes id: Int = 0) {
   this.setCompoundDrawablesWithIntrinsicBounds(id, 0, 0, 0)

If you need to resize the drawable, you can use this extension function.

textView.leftDrawable(R.drawable.my_icon, R.dimen.icon_size)

fun TextView.leftDrawable(@DrawableRes id: Int = 0, @DimenRes sizeRes: Int) {
    val drawable = ContextCompat.getDrawable(context, id)
    val size = resources.getDimensionPixelSize(sizeRes)
    drawable?.setBounds(0, 0, size, size)
    this.setCompoundDrawables(drawable, null, null, null)

To get really fancy, create a wrapper that allows size and/or color modification.

textView.leftDrawable(R.drawable.my_icon, colorRes = R.color.white)

fun TextView.leftDrawable(@DrawableRes id: Int = 0, @DimenRes sizeRes: Int = 0, @ColorInt color: Int = 0, @ColorRes colorRes: Int = 0) {
    val drawable = drawable(id)
    if (sizeRes != 0) {
        val size = resources.getDimensionPixelSize(sizeRes)
        drawable?.setBounds(0, 0, size, size)
    if (color != 0) {
        drawable?.setColorFilter(color, PorterDuff.Mode.SRC_ATOP)
    } else if (colorRes != 0) {
        val colorInt = ContextCompat.getColor(context, colorRes)
        drawable?.setColorFilter(colorInt, PorterDuff.Mode.SRC_ATOP)
    this.setCompoundDrawables(drawable, null, null, null)

HTTP 400 (bad request) for logical error, not malformed request syntax

This is difficult.

I think we should;

  1. Return 4xx errors only when the client has the power to make a change to the request, headers or body, that will result in the request succeeding with the same intent.

  2. Return error range codes when the expected mutation has not occured, i.e. a DELETE didn't happen or a PUT didn't change anything. However, a POST is more interesting because the spec says it should be used to either create resources at a new location, or just process a payload.

Using the example in Vish's answer, if the request intends to add employee Priya to a department Marketing but Priya wasn't found or her account is archived, then this is an application error.

The request worked fine, it got to your application rules, the client did everything properly, the ETags matched etc. etc.

Because we're using HTTP we must respond based on the effect of the request on the state of the resource. And that depends on your API design.

Perhaps you designed this.

PUT { updated members list } /marketing/members

Returning a success code would indicate that the "replacement" of the resource worked; a GET on the resource would reflect your changes, but it wouldn't.

So now you have to choose a suitable negative HTTP code, and that's the tricky part, since the codes are strongly intended for the HTTP protocol, not your application.

When I read the official HTTP codes, these two look suitable.

The 409 (Conflict) status code indicates that the request could not be completed due to a conflict with the current state of the target resource. This code is used in situations where the user might be able to resolve the conflict and resubmit the request. The server SHOULD generate a payload that includes enough information for a user to recognize the source of the conflict.


The 500 (Internal Server Error) status code indicates that the server encountered an unexpected condition that prevented it from fulfilling the request.

Though we've traditionally considered the 500 to be like an unhandled exception :-/

I don't think its unreasonable to invent your own status code so long as its consistently applied and designed.

This design is easier to deal with.

PUT { membership add command } /accounts/groups/memberships/instructions/1739119

Then you could design your API to always succeed in creating the instruction, it returns 201 Created and a Location header and any problems with the instruction are held within that new resource.

A POST is more like that last PUT to a new location. A POST allows for any kind of server processing of a message, which opens up designs that say something like "The action successfully failed."

Probably you already wrote an API that does this, a website. You POST the payment form and it was successfully rejected because the credit card number was wrong.

With a POST, whether you return 200 or 201 along with your rejection message depends on whether a new resource was created and is available to GET at another location, or not.

With that all said, I'd be inclined to design APIs that need fewer PUTs, perhaps just updating data fields, and actions and stuff that invokes rules and processing or just have a higher chance of expected failures, can be designed to POST an instruction form.

What is a singleton in C#?

E.X You can use Singleton for global information that needs to be injected.

In my case, I was keeping the Logged user detail(username, permissions etc.) in Global Static Class. And when I tried to implement the Unit Test, there was no way I could inject dependency into Controller classes. Thus I have changed my Static Class to Singleton pattern.

public class SysManager
    private static readonly SysManager_instance = new SysManager();

    static SysManager() {}

    private SysManager(){}

    public static SysManager Instance
        get {return _instance;}

Fitting empirical distribution to theoretical ones with Scipy (Python)?

fit() method mentioned by @Saullo Castro provides maximum likelihood estimates (MLE). The best distribution for your data is the one give you the highest can be determined by several different ways: such as

1, the one that gives you the highest log likelihood.

2, the one that gives you the smallest AIC, BIC or BICc values (see wiki:, basically can be viewed as log likelihood adjusted for number of parameters, as distribution with more parameters are expected to fit better)

3, the one that maximize the Bayesian posterior probability. (see wiki:

Of course, if you already have a distribution that should describe you data (based on the theories in your particular field) and want to stick to that, you will skip the step of identifying the best fit distribution.

scipy does not come with a function to calculate log likelihood (although MLE method is provided), but hard code one is easy: see Is the build-in probability density functions of `scipy.stat.distributions` slower than a user provided one?

Convert a secure string to plain text

In PS 7, you can use ConvertFrom-SecureString and -AsPlainText:

 $UnsecurePassword = ConvertFrom-SecureString -SecureString $SecurePassword -AsPlainText

           [-SecureString] <SecureString>

The Import cannot be resolved

I tried the answer described here but it doesn´t worked for me. I have the last Android SDK tools ver. 23.0.2 and Android SDK Platform-tools ver. 20

The support library android-support-v4.jar is causing this conflict, just delete the library under /libs folder of your project, don´t be scared, the library is already contained in the library appcompat_v7, clean and build your project, and your project will work like a charm!

enter image description here

Get loop counter/index using for…of syntax in JavaScript

To use for..of loop on array and retrieve index you can you use array1.indexOf(element) which will return the index value of an element in the loop. You can return both the index and the value using this method.

array1 = ['a', 'b', 'c']
for (element of array1) {
    console.log(array1.indexOf(element), element) // 0 a 1 b 2 c

Shorthand for if-else statement

Using the ternary :? operator [spec].

var hasName = (name === 'true') ? 'Y' :'N';

The ternary operator lets us write shorthand if..else statements exactly like you want.

It looks like:

(name === 'true') - our condition

? - the ternary operator itself

'Y' - the result if the condition evaluates to true

'N' - the result if the condition evaluates to false

So in short (question)?(result if true):(result is false) , as you can see - it returns the value of the expression so we can simply assign it to a variable just like in the example above.

How to convert an integer to a character array using C

Make use of the log10 function to determine the number of digits and do like below:

char * toArray(int number)
    int n = log10(number) + 1;
    int i;
    char *numberArray = calloc(n, sizeof(char));
    for (i = n-1; i >= 0; --i, number /= 10)
        numberArray[i] = (number % 10) + '0';
    return numberArray;

Or the other option is sprintf(yourCharArray,"%ld", intNumber);

Double % formatting question for printf in Java

Yes, %d is for decimal (integer), double expect %f. But simply using %f will default to up to precision 6. To print all of the precision digits for a double, you can pass it via string as:

System.out.printf("%s \r\n",String.valueOf(d));


System.out.printf("%s \r\n",Double.toString(d));

This is what println do by default:


(and terminates the line)

JavaFX How to set scene background image

In addition to @Elltz answer, we can use both fill and image for background:

            new Background(
                    Collections.singletonList(new BackgroundFill(
                            new CornerRadii(500), 
                            new Insets(10))),
                    Collections.singletonList(new BackgroundImage(
                            new Image("image/logo.png", 100, 100, false, true),


                new Background(
                        Collections.singletonList(new BackgroundFill(
                                new CornerRadii(0),
                                new Insets(0))),
                        Collections.singletonList(new BackgroundImage(
                                new Image("file:clouds.jpg", 100, 100, false, true),
                                new BackgroundSize(1.0, 1.0, true, true, false, false)

(different last argument) to make the image full-window size.

How to check if an object is an array?

Here's a code snippet that'll explain an important fact of arrays that should be known early on while learning JS (unlike me).

// this functions puts a string inside an array_x000D_
var stringInsideArray = function(input) {_x000D_
  if (typeof input === 'string') {_x000D_
    return [input];_x000D_
  else if (Array.isArray(input)) {_x000D_
    return input;_x000D_
  } _x000D_
  else {_x000D_
    throw new Error("Input is not a string!");_x000D_
var output = stringInsideArray('hello');_x000D_
console.log('step one output: ', output); // ["hello"]_x000D_
// use typeof method to verify output is an object_x000D_
console.log('step two output: ', typeof output); // object_x000D_
// use Array.isArray() method to verify output is an array_x000D_
console.log('step three output: ', Array.isArray(output)); // true

Arrays, are in fact, objects.

Using the typeof operator, the output of stringInsideArray('hello') proves that ["hello"] is really an object. This baffled me for the longest time because I assumed that arrays would be a JavaScript data type...

There are only 7 JS data types and arrays are NOT one of them.

To answer your question, using the Array.isArray() method determines that the output is an array.

What is the difference between bindParam and bindValue?

From Prepared statements and stored procedures

Use bindParam to insert multiple rows with one time binding:


$stmt = $dbh->prepare("INSERT INTO REGISTRY (name, value) VALUES (?, ?)");
$stmt->bindParam(1, $name);
$stmt->bindParam(2, $value);

// insert one row
$name = 'one';
$value = 1;

// insert another row with different values
$name = 'two';
$value = 2;

Hibernate SessionFactory vs. JPA EntityManagerFactory

Prefer EntityManagerFactory and EntityManager. They are defined by the JPA standard.

SessionFactory and Session are hibernate-specific. The EntityManager invokes the hibernate session under the hood. And if you need some specific features that are not available in the EntityManager, you can obtain the session by calling:

Session session = entityManager.unwrap(Session.class);

How can I use Helvetica Neue Condensed Bold in CSS?

In case anyone is still looking for Helvetica Neue Condensed Bold, you essentially have two options.

  1. License the real font as a webfont from Free (with a badge), $10/month for 250k pageviews and $100/month for 2.5M pageviews. You can download the font to your desktop with the most expensive plan (but if you're on a Mac you already have it).
  2. / Buy a pretty close alternative like Nimbus Sans Novus D from MyFont ($160 for unlimited pageviews), or Franklin Gothic FS Demi Condensed, from (about $21.95, flat one time fee with unlimited pageviews). In both cases you also get to download the font for your desktop so you can use it in Photoshop for comps.

A very cheap compromise is to buy Franklin from fontspring and then use "HelveticaNeue-CondensedBold" as the preferred font in your CSS.

h2 {"HelveticaNeue-CondensedBold", "FranklinGothicFSDemiCondensed", Arial, sans-serif;}

Then if a Mac user loads your site they see Helvetica Neue, but if they're on another platform they see Franklin.

UPDATE: I discovered a much closer match to Helvetica Neue Condensed Bold is Nimbus Sans Novus D Condensed bold. In fact, it is also derived from Helvetica. You can get it at for $20 (desktop) and $20 (web, 10k pageviews). Web with unlimited pageviews is $160. I have used this font throughout (i.e. NOT exploiting the Mac's built in "NimbusSansNovusDBoldCondensed" at all) because it leads to a design that is more uniform across browsers. Built in HN and Nimbus Sans are very similar in all respects but point size. Nimbus needs a few extra points to get an identical size match.

Bootstrap 3 modal responsive

I had the same problem, and a easy way i found to solve that was to make everything in the modal's body responsive(using boostrap classes) and my problem were solved.

Dealing with timestamps in R

You want the (standard) POSIXt type from base R that can be had in 'compact form' as a POSIXct (which is essentially a double representing fractional seconds since the epoch) or as long form in POSIXlt (which contains sub-elements). The cool thing is that arithmetic etc are defined on this -- see help(DateTimeClasses)

Quick example:

R> now <- Sys.time()
R> now
[1] "2009-12-25 18:39:11 CST"
R> as.numeric(now)
[1] 1.262e+09
R> now + 10  # adds 10 seconds
[1] "2009-12-25 18:39:21 CST"
R> as.POSIXlt(now)
[1] "2009-12-25 18:39:11 CST"
R> str(as.POSIXlt(now))
 POSIXlt[1:9], format: "2009-12-25 18:39:11"
R> unclass(as.POSIXlt(now))
[1] 11.79

[1] 39

[1] 18

[1] 25

[1] 11

[1] 109

[1] 5

[1] 358

[1] 0

[1] "America/Chicago" "CST"             "CDT"            

As for reading them in, see help(strptime)

As for difference, easy too:

R> Jan1 <- strptime("2009-01-01 00:00:00", "%Y-%m-%d %H:%M:%S")
R> difftime(now, Jan1, unit="week")
Time difference of 51.25 weeks

Lastly, the zoo package is an extremely versatile and well-documented container for matrix with associated date/time indices.

How can I upgrade specific packages using pip and a requirements file?

This solved the issue for me:

pip install -I --upgrade psutil --force

Afterwards just uninstall psutil with the new version and hop you can suddenly install the older version (:

How to create a dotted <hr/> tag?

You can do:

<hr style="border: 1px dashed black;" />


How do I pass an object to HttpClient.PostAsync and serialize as a JSON body?

New .NET 5 Solution:

In .NET 5, a new class has been introduced called JsonContent, which derives from HttpContent. See in Microsoft docs

This class has a static method called Create(), which takes an object as a parameter.


var myObject = new
    foo = "Hello",
    bar = "World",

JsonContent content = JsonContent.Create(myObject);

HttpResponseMessage response = await _httpClient.PostAsync("https://...", content);

Simple java program of pyramid

enter image description here

 import java.util.Scanner;
    public class Print {
        public static void main(String[] args) {
            int row,temp,c,n;
            Scanner s=new Scanner(;
            temp = n;
            for ( row = 1 ; row <= n ; row++ )
                  for ( c = 1 ; c < temp ; c++ )
                    System.out.print(" ");


                  for ( c = 1 ; c <= 2*row - 1 ; c++ )



php exec() is not executing the command

I already said that I was new to exec() function. After doing some more digging, I came upon 2>&1 which needs to be added at the end of command in exec().

Thanks @mattosmat for pointing it out in the comments too. I did not try this at once because you said it is a Linux command, I am on Windows.

So, what I have discovered, the command is actually executing in the back-end. That is why I could not see it actually running, which I was expecting to happen.

For all of you, who had similar problem, my advise is to use that command. It will point out all the errors and also tell you info/details about execution.

exec('some_command 2>&1', $output);
print_r($output);  // to see the response to your command

Thanks for all the help guys, I appreciate it ;)

LINQ extension methods - Any() vs. Where() vs. Exists()

IEnumerable introduces quite a number of extensions to it which helps you to pass your own delegate and invoking the resultant from the IEnumerable back. Most of them are by nature of type Func

The Func takes an argument T and returns TResult.

In case of

Where - Func : So it takes IEnumerable of T and Returns a bool. The where will ultimately returns the IEnumerable of T's for which Func returns true.

So if you have 1,5,3,6,7 as IEnumerable and you write .where(r => r<5) it will return a new IEnumerable of 1,3.

Any - Func basically is similar in signature but returns true only when any of the criteria returns true for the IEnumerable. In our case, it will return true as there are few elements present with r<5.

Exists - Predicate on the other hand will return true only when any one of the predicate returns true. So in our case if you pass .Exists(r => 5) will return true as 5 is an element present in IEnumerable.

WCF error - There was no endpoint listening at

Different case but may help someone,

In my case Window firewall was enabled on Server,

Two thinks can be done,

1) Disable windows firewall (your on risk but it will get thing work)

2) Add port in inbound rule.

Thanks .

Use of alloc init instead of new

I am very late to this but I want to mention that that new is actually unsafe in the Obj-C with Swift world. Swift will only create a default init method if you do not create any other initializer. Calling new on a swift class with a custom initializer will cause a crash. If you use alloc/init then the compiler will properly complain that init does not exist.

How to log in to phpMyAdmin with WAMP, what is the username and password?

Sometimes it doesn't get login with username = root and password, then you can change the default settings or the reset settings.

Open file in the phpmyadmin folder

Instead of

$cfg['Servers'][$i]['AllowNoPassword'] = false;

change it to:

$cfg['Servers'][$i]['AllowNoPassword'] = true;

Do not specify any password and put the user name as it was before, which means root.


$cfg['Servers'][$i]['user'] = 'root';
$cfg['Servers'][$i]['password'] = '';

This worked for me after i had edited my file.

Timing a command's execution in PowerShell


Measure-Command { .\do_something.ps1 }

Note that one minor downside of Measure-Command is that you see no stdout output.

[Update, thanks to @JasonMArcher] You can fix that by piping the command output to some commandlet that writes to the host, e.g. Out-Default so it becomes:

Measure-Command { .\do_something.ps1 | Out-Default }

Another way to see the output would be to use the .NET Stopwatch class like this:

$sw = [Diagnostics.Stopwatch]::StartNew()

console.log timestamps in Chrome?

If you want to preserve line number information (each message pointing to its .log() call, not all pointing to our wrapper), you have to use .bind(). You can prepend an extra timestamp argument via console.log.bind(console, <timestamp>) but the problem is you need to re-run this every time to get a function bound with a fresh timestamp. An awkward way to do that is a function that returns a bound function:

function logf() {
  // console.log is native function, has no .bind in some browsers.
  // TODO: fallback to wrapping if .bind doesn't exist...
  return, console, yourTimeFormat());

which then has to be used with a double call:

logf()(object, "message...")

BUT we can make the first call implicit by installing a property with getter function:

var origLog = console.log;
// TODO: fallbacks if no `defineProperty`...
Object.defineProperty(console, "log", {
  get: function () { 
    return, console, yourTimeFormat()); 

Now you just call console.log(...) and automagically it prepends a timestamp!

> console.log(12)
71.919s 12 VM232:2
> console.log(12)
72.866s 12 VM233:2

You can even achieve this magical behavior with a simple log() instead of console.log() by doing Object.defineProperty(window, "log", ...).

See for a well-done safe console wrapper using .bind(), with compatibility fallbacks.

See for compatibility fallbacks from defineProperty() to legacy __defineGetter__ API. If neither property API works, you should fallback to a wrapper function that gets a fresh timestamp every time. (In this case you lose line number info, but timestamps will still show.)

Boilerplate: Time formatting the way I like it:

var timestampMs = ((window.performance && ?
                 function() { return; } :
                 function() { return new Date().getTime(); });
function formatDuration(ms) { return (ms / 1000).toFixed(3) + "s"; }
var t0 = timestampMs();
function yourTimeFormat() { return formatDuration(timestampMs() - t0); }

Side-by-side plots with ggplot2

Any ggplots side-by-side (or n plots on a grid)

The function grid.arrange() in the gridExtra package will combine multiple plots; this is how you put two side by side.

plot1 <- qplot(1)
plot2 <- qplot(1)
grid.arrange(plot1, plot2, ncol=2)

This is useful when the two plots are not based on the same data, for example if you want to plot different variables without using reshape().

This will plot the output as a side effect. To print the side effect to a file, specify a device driver (such as pdf, png, etc), e.g.

grid.arrange(plot1, plot2)

or, use arrangeGrob() in combination with ggsave(),

ggsave("foo.pdf", arrangeGrob(plot1, plot2))

This is the equivalent of making two distinct plots using par(mfrow = c(1,2)). This not only saves time arranging data, it is necessary when you want two dissimilar plots.

Appendix: Using Facets

Facets are helpful for making similar plots for different groups. This is pointed out below in many answers below, but I want to highlight this approach with examples equivalent to the above plots.

mydata <- data.frame(myGroup = c('a', 'b'), myX = c(1,1))

qplot(data = mydata, 
    x = myX, 
    facets = ~myGroup)

ggplot(data = mydata) + 
    geom_bar(aes(myX)) + 


the plot_grid function in the cowplot is worth checking out as an alternative to grid.arrange. See the answer by @claus-wilke below and this vignette for an equivalent approach; but the function allows finer controls on plot location and size, based on this vignette.

PHP Function Comments

That's phpDoc syntax.

Read more here: phpDocumentor

The given key was not present in the dictionary. Which key?

This exception is thrown when you try to index to something that isn't there, for example:

Dictionary<String, String> test = new Dictionary<String,String>();
string error = test["Key2"];

Often times, something like an object will be the key, which undoubtedly makes it harder to get. However, you can always write the following (or even wrap it up in an extension method):

if (test.ContainsKey(myKey))
   return test[myKey];
   throw new Exception(String.Format("Key {0} was not found", myKey));

Or more efficient (thanks to @ScottChamberlain)

T retValue;
if (test.TryGetValue(myKey, out retValue))
    return retValue;
   throw new Exception(String.Format("Key {0} was not found", myKey));

Microsoft chose not to do this, probably because it would be useless when used on most objects. Its simple enough to do yourself, so just roll your own!

Android Studio SDK location

macOS (Catalina or Mojave or Sierra):

After installing Android Studio (3.6+ or 2.3.x), by default

sdk path: "/Users/< username >/Library/Android/sdk"

Remember: may be Library folder is hidden.
To make it visible:- Hit Command+shift+. OR Open Terminal and type "chflags nohidden ~/Library/" then hit return.


After installing Android Studio, by default

sdk path: "C:\Users< username >\AppData\Local\Android\sdk"

Remember: by default AppData folder is hidden, make it visible first.

Cannot set some HTTP headers when using System.Net.WebRequest

I ran into this problem with a custom web client. I think people may be getting confused because of multiple ways to do this. When using WebRequest.Create() you can cast to an HttpWebRequest and use the property to add or modify a header. When using a WebHeaderCollection you may use the .Add("referer","my_url").

Ex 1

WebClient client = new WebClient();
client.Headers.Add("referer", "");
client.Headers.Add("user-agent", "Mozilla/5.0");

Ex 2

HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
request.Referer = "";
request.UserAgent = "Mozilla/5.0";
response = (HttpWebResponse)request.GetResponse();

R Markdown - changing font size and font type in html output

These answers are overly complicated. You can change the main body font size (as well as any other CSS you might want to change) simply by embedding CSS directly into the Rmarkdown document using the html <style> tag. You do not need an entire CSS file for something so simple. If you are doing a lot of CSS then use a separate CSS file. If you are just modifying a couple of simple things I would do it like this.

title: "Untitled"
author: "James"
date: "9/29/2020"
output: html_document

<style type="text/css">
  font-size: 12pt;

```{r setup, include = FALSE}
knitr::opts_chunk$set(echo = TRUE)

How can I view the Git history in Visual Studio Code?

Git Graph seems like a decent extension. After installing, you can open the graph view from the bottom status bar.

JavaScript listener, "keypress" doesn't detect backspace?

Use one of keyup / keydown / beforeinput events instead.

based on this reference, keypress is deprecated and no longer recommended.

The keypress event is fired when a key that produces a character value is pressed down. Examples of keys that produce a character value are alphabetic, numeric, and punctuation keys. Examples of keys that don't produce a character value are modifier keys such as Alt, Shift, Ctrl, or Meta.

if you use "beforeinput" be careful about it's Browser compatibility. the difference between "beforeinput" and the other two is that "beforeinput" is fired when input value is about to changed, so with characters that can't change the input value, it is not fired (e.g shift, ctr ,alt).

I had the same problem and by using keyup it was solved.

Codeigniter displays a blank page instead of error messages

In your index.php file add the line:

define('ENVIRONMENT', isset($_SERVER['CI_ENV']) ? $_SERVER['CI_ENV'] : 'development');

Git: How to squash all commits on branch

Git reset, as mentioned in many answers before, is by far the best and simplest way to achieve what you want. I use it in the following workflow:

(on development branch)

git fetch
git merge origin/master  #so development branch has all current changes from master
git reset origin/master  #will show all changes from development branch to master as unstaged
git gui # do a final review, stage all changes you really want
git commit # all changes in a single commit
git branch -f master #update local master branch
git push origin master #push it

Access files in /var/mobile/Containers/Data/Application without jailbreaking iPhone

If this is your app, if you connect the device to your computer, you can use the "Devices" option on Xcode's "Window" menu and then download the app's data container to your computer. Just select your app from the list of installed apps, and click on the "gear" icon and choose "Download Container".

enter image description here

Once you've downloaded it, right click on the file in the Finder and choose "Show Package Contents".

How to make rounded percentages add up to 100%

I'm not sure what level of accuracy you need, but what I would do is simply add 1 the first n numbers, n being the ceil of the total sum of decimals. In this case that is 3, so I would add 1 to the first 3 items and floor the rest. Of course this is not super accurate, some numbers might be rounded up or down when it shouldn't but it works okay and will always result in 100%.

So [ 13.626332, 47.989636, 9.596008, 28.788024 ] would be [14, 48, 10, 28] because Math.ceil(.626332+.989636+.596008+.788024) == 3

function evenRound( arr ) {
  var decimal = a ){ return a % 1 })
    .reduce(function( a,b ){ return a + b }); // Ceil of total sum of decimals
  for ( var i = 0; i < decimal; ++i ) {
    arr[ i ] = ++arr[ i ]; // compensate error by adding 1 the the first n items
  return a ){ return ~~a }); // floor all other numbers

var nums = evenRound( [ 13.626332, 47.989636, 9.596008, 28.788024 ] );
var total = nums.reduce(function( a,b ){ return a + b }); //=> 100

You can always inform users that the numbers are rounded and may not be super-accurate... Date without time

Either use one of the standard date and time format strings which only specifies the date (e.g. "D" or "d"), or a custom date and time format string which only uses the date parts (e.g. "yyyy/MM/dd").

Delete first character of a string in Javascript



console.log("0string  =>", "0string".replace(/^0/,'') );_x000D_
console.log("00string =>", "00string".replace(/^0/,'') );_x000D_
console.log("string00 =>", "string00".replace(/^0/,'') );

Android - Best and safe way to stop thread

You should make your thread support interrupts. Basically, you can call yourThread.interrupt() to stop the thread and, in your run() method you'd need to periodically check the status of Thread.interrupted()

There is a good tutorial here.

jump to line X in nano editor

I am using Linux raspi 4.19.118+ #1311 via ssh Powershell on Win 10 Pro 1909 with German keyboard. nano shortcut Goto Line with "Crtl + Shift + -" was not working Solution: Step 1 - Do Current Position with "Crtl + C" Step 2 - Goto Line with "Crtl + Shift + -" IS working!

I dont know what effects it. But now its working without step 1!

How to choose an AWS profile when using boto3 to connect to CloudFront

Do this to use a profile with name 'dev':

session = boto3.session.Session(profile_name='dev')
s3 = session.resource('s3')
for bucket in s3.buckets.all():

Convert String to Float in Swift

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

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

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

enumerate() for dictionary in python

dict1={'a':1, 'b':'banana'}

To list the dictionary in Python 2.x:

for k,v in dict1.iteritems():
        print k,v 

In Python 3.x use:

for k,v in dict1.items():
# a 1
# b banana

Finally, as others have indicated, if you want a running index, you can have that too:

for i  in enumerate(dict1.items()):

 # (0, ('a', 1))
 # (1, ('b', 'banana'))

But this defeats the purpose of a dictionary (map, associative array) , which is an efficient data structure for telephone-book-style look-up. Dictionary ordering could be incidental to the implementation and should not be relied upon. If you need the order, use OrderedDict instead.

Why is conversion from string constant to 'char*' valid in C but invalid in C++

You can declare like one of the below options:

char data[] = "Testing String";


const char* data = "Testing String";


char* data = (char*) "Testing String";

Using git to get just the latest revision

Use git clone with the --depth option set to 1 to create a shallow clone with a history truncated to the latest commit.

For example:

git clone --depth 1

To also initialize and update any nested submodules, also pass --recurse-submodules and to clone them shallowly, also pass --shallow-submodules.

For example:

git clone --depth 1 --recurse-submodules --shallow-submodules

Commit history on remote repository

I don't believe this is possible. I believe you have to clone that remote repo locally and perform git fetch on it before you can issue a git log against it.

Controlling number of decimal digits in print output in R

If you are producing the entire output yourself, you can use sprintf(), e.g.

> sprintf("%.10f",0.25)
[1] "0.2500000000"

specifies that you want to format a floating point number with ten decimal points (in %.10f the f is for float and the .10 specifies ten decimal points).

I don't know of any way of forcing R's higher level functions to print an exact number of digits.

Displaying 100 digits does not make sense if you are printing R's usual numbers, since the best accuracy you can get using 64-bit doubles is around 16 decimal digits (look at .Machine$double.eps on your system). The remaining digits will just be junk.

Raw SQL Query without DbSet - Entity Framework Core

It depends if you're using EF Core 2.1 or EF Core 3 and higher versions.

If you're using EF Core 2.1

If you're using EF Core 2.1 Release Candidate 1 available since 7 may 2018, you can take advantage of the proposed new feature which is Query type.

What is query type?

In addition to entity types, an EF Core model can contain query types, which can be used to carry out database queries against data that isn't mapped to entity types.

When to use query type?

Serving as the return type for ad hoc FromSql() queries.

Mapping to database views.

Mapping to tables that do not have a primary key defined.

Mapping to queries defined in the model.

So you no longer need to do all the hacks or workarounds proposed as answers to your question. Just follow these steps:

First you defined a new property of type DbQuery<T> where T is the type of the class that will carry the column values of your SQL query. So in your DbContext you'll have this:

public DbQuery<SomeModel> SomeModels { get; set; }

Secondly use FromSql method like you do with DbSet<T>:

var result = context.SomeModels.FromSql("SQL_SCRIPT").ToList();
var result = await context.SomeModels.FromSql("SQL_SCRIPT").ToListAsync();

Also note that DdContexts are partial classes, so you can create one or more separate files to organize your 'raw SQL DbQuery' definitions as best suits you.

If you're using EF Core 3.0 and higher versions

Query type is now known as Keyless entity type. As said above query types were introduced in EF Core 2.1. If you're using EF Core 3.0 or higher version you should now consider using keyless entity types because query types are now marked as obsolete.

This feature was added in EF Core 2.1 under the name of query types. In EF Core 3.0 the concept was renamed to keyless entity types. The [Keyless] Data Annotation became available in EFCore 5.0.

We still have the same scenarios as for query types for when to use keyless entity type.

So to use it you need to first mark your class SomeModel with [Keyless] data annotation or through fluent configuration with .HasNoKey() method call like below:

public DbSet<SomeModel> SomeModels { get; set; }

protected override void OnModelCreating(ModelBuilder modelBuilder)

After that configuration, you can use one of the methods explained here to execute your SQL query. For example you can use this one:

var result = context.SomeModels.FromSqlRaw("SQL SCRIPT").ToList();

React-router: How to manually invoke Link?

React Router 4 includes a withRouter HOC that gives you access to the history object via this.props:

import React, {Component} from 'react'
import {withRouter} from 'react-router-dom'

class Foo extends Component {
  constructor(props) {

    this.goHome = this.goHome.bind(this)

  goHome() {

  render() {
    <div className="foo">
      <button onClick={this.goHome} />

export default withRouter(Foo)

Cannot insert explicit value for identity column in table 'table' when IDENTITY_INSERT is set to OFF

You're inserting values for OperationId that is an identity column.

You can turn on identity insert on the table like this so that you can specify your own identity values.


/*Note the column list is REQUIRED here, not optional*/
VALUES      (20,
             'Hierachy Update',


How can I sort a dictionary by key?

from operator import itemgetter
# if you would like to play with multiple dictionaries then here you go:
# Three dictionaries that are composed of first name and last name.
user = [
    {'fname': 'Mo', 'lname': 'Mahjoub'},
    {'fname': 'Abdo', 'lname': 'Al-hebashi'},
    {'fname': 'Ali', 'lname': 'Muhammad'}
#  This loop will sort by the first and the last names.
# notice that in a dictionary order doesn't matter. So it could put the first name first or the last name first. 
for k in sorted (user, key=itemgetter ('fname', 'lname')):
    print (k)

# This one will sort by the first name only.
for x in sorted (user, key=itemgetter ('fname')):
    print (x)

Docker Repository Does Not Have a Release File on Running apt-get update on Ubuntu

This is what worked for me on LinuxMint 19.

curl -s | sudo apt-key add
apt-key fingerprint 58118E89F3A912897C070ADBF76221572C52609D
sudo add-apt-repository "deb ubuntu-$(lsb_release -cs) main"
sudo apt-get update
sudo apt-get install docker-ce docker-ce-cli

How to create an alert message in jsp page after submit process is complete

You can also create a new jsp file sayng that form is submited and in your main action file just write its file name

Eg. Your form is submited is in a file succes.jsp Then your action file will have


Android - Spacing between CheckBox and text

Checkbox image was overlapping when I used my own drawables from selector, I have solve this using below code :

CheckBox cb = new CheckBox(mActivity);
cb.setPadding(cb.getPaddingLeft(), padding, padding, padding);

Thanks to Alex Semeniuk

Efficient Algorithm for Bit Reversal (from MSB->LSB to LSB->MSB) in C

Well, this is basically the same as the first "reverse()" but it is 64 bit and only needs one immediate mask to be loaded from the instruction stream. GCC creates code without jumps, so this should be pretty fast.

#include <stdio.h>

static unsigned long long swap64(unsigned long long val)
#define ZZZZ(x,s,m) (((x) >>(s)) & (m)) | (((x) & (m))<<(s));
/* val = (((val) >>16) & 0xFFFF0000FFFF) | (((val) & 0xFFFF0000FFFF)<<16); */

val = ZZZZ(val,32,  0x00000000FFFFFFFFull );
val = ZZZZ(val,16,  0x0000FFFF0000FFFFull );
val = ZZZZ(val,8,   0x00FF00FF00FF00FFull );
val = ZZZZ(val,4,   0x0F0F0F0F0F0F0F0Full );
val = ZZZZ(val,2,   0x3333333333333333ull );
val = ZZZZ(val,1,   0x5555555555555555ull );

return val;
#undef ZZZZ

int main(void)
unsigned long long val, aaaa[16] =
 { 0xfedcba9876543210,0xedcba9876543210f,0xdcba9876543210fe,0xcba9876543210fed
 , 0xba9876543210fedc,0xa9876543210fedcb,0x9876543210fedcba,0x876543210fedcba9
 , 0x76543210fedcba98,0x6543210fedcba987,0x543210fedcba9876,0x43210fedcba98765
 , 0x3210fedcba987654,0x210fedcba9876543,0x10fedcba98765432,0x0fedcba987654321
unsigned iii;

for (iii=0; iii < 16; iii++) {
    val = swap64 (aaaa[iii]);
    printf("A[]=%016llX Sw=%016llx\n", aaaa[iii], val);
return 0;

Python extending with - using super() Python 3 vs Python 2

  • super() (without arguments) was introduced in Python 3 (along with __class__):

    super() -> same as super(__class__, self)

    so that would be the Python 2 equivalent for new-style classes:

    super(CurrentClass, self)
  • for old-style classes you can always use:

     class Classname(OldStyleParent):
        def __init__(self, *args, **kwargs):
            OldStyleParent.__init__(self, *args, **kwargs)

Get POST data in C#/ASP.NET

c.Request["AP"] will read posted values. Also you need to use a submit button to post the form:

<input type="submit" value="Submit" />

instead of

<input type=button value="Submit" />

How to empty the content of a div

If you're using jQuery ...




What does the shrink-to-fit viewport meta attribute do?

It is Safari specific, at least at time of writing, being introduced in Safari 9.0. From the "What's new in Safari?" documentation for Safari 9.0:

Viewport Changes

Viewport meta tags using "width=device-width" cause the page to scale down to fit content that overflows the viewport bounds. You can override this behavior by adding "shrink-to-fit=no" to your meta tag as shown below. The added value will prevent the page from scaling to fit the viewport.

<meta name="viewport" content="width=device-width, initial-scale=1.0, shrink-to-fit=no">

In short, adding this to the viewport meta tag restores pre-Safari 9.0 behaviour.


Here's a worked visual example which shows the difference upon loading the page in the two configurations.

The red section is the width of the viewport and the blue section is positioned outside the initial viewport (eg left: 100vw). Note how in the first example the page is zoomed to fit when shrink-to-fit=no is omitted (thus showing the out-of-viewport content) and the blue content remains off screen in the latter example.

The code for this example can be found at

Without shrink-to-fit specified

Without shrink-to-fit=no

With shrink-to-fit=no

With shrink-to-fit=no

Regex to get NUMBER only from String

Either [0-9] or \d1 should suffice if you only need a single digit. Append + if you need more.

1 The semantics are slightly different as \d potentially matches any decimal digit in any script out there that uses decimal digits.

How to display multiple images in one figure correctly?

Here is my approach that you may try:

import numpy as np
import matplotlib.pyplot as plt

fig=plt.figure(figsize=(8, 8))
columns = 4
rows = 5
for i in range(1, columns*rows +1):
    img = np.random.randint(10, size=(h,w))
    fig.add_subplot(rows, columns, i)

The resulting image:


(Original answer date: Oct 7 '17 at 4:20)

Edit 1

Since this answer is popular beyond my expectation. And I see that a small change is needed to enable flexibility for the manipulation of the individual plots. So that I offer this new version to the original code. In essence, it provides:-

  1. access to individual axes of subplots
  2. possibility to plot more features on selected axes/subplot

New code:

import numpy as np
import matplotlib.pyplot as plt

w = 10
h = 10
fig = plt.figure(figsize=(9, 13))
columns = 4
rows = 5

# prep (x,y) for extra plotting
xs = np.linspace(0, 2*np.pi, 60)  # from 0 to 2pi
ys = np.abs(np.sin(xs))           # absolute of sine

# ax enables access to manipulate each of subplots
ax = []

for i in range(columns*rows):
    img = np.random.randint(10, size=(h,w))
    # create subplot and append to ax
    ax.append( fig.add_subplot(rows, columns, i+1) )
    ax[-1].set_title("ax:"+str(i))  # set title
    plt.imshow(img, alpha=0.25)

# do extra plots on selected axes/subplots
# note: index starts with 0
ax[2].plot(xs, 3*ys)
ax[19].plot(ys**2, xs)  # finally, render the plot

The resulting plot:

enter image description here

Edit 2

In the previous example, the code provides access to the sub-plots with single index, which is inconvenient when the figure has many rows/columns of sub-plots. Here is an alternative of it. The code below provides access to the sub-plots with [row_index][column_index], which is more suitable for manipulation of array of many sub-plots.

import matplotlib.pyplot as plt
import numpy as np

# settings
h, w = 10, 10        # for raster image
nrows, ncols = 5, 4  # array of sub-plots
figsize = [6, 8]     # figure size, inches

# prep (x,y) for extra plotting on selected sub-plots
xs = np.linspace(0, 2*np.pi, 60)  # from 0 to 2pi
ys = np.abs(np.sin(xs))           # absolute of sine

# create figure (fig), and array of axes (ax)
fig, ax = plt.subplots(nrows=nrows, ncols=ncols, figsize=figsize)

# plot simple raster image on each sub-plot
for i, axi in enumerate(ax.flat):
    # i runs from 0 to (nrows*ncols-1)
    # axi is equivalent with ax[rowid][colid]
    img = np.random.randint(10, size=(h,w))
    axi.imshow(img, alpha=0.25)
    # get indices of row/column
    rowid = i // ncols
    colid = i % ncols
    # write row/col indices as axes' title for identification
    axi.set_title("Row:"+str(rowid)+", Col:"+str(colid))

# one can access the axes by ax[row_id][col_id]
# do additional plotting on ax[row_id][col_id] of your choice
ax[0][2].plot(xs, 3*ys, color='red', linewidth=3)
ax[4][3].plot(ys**2, xs, color='green', linewidth=3)


The resulting plot:


how to convert an RGB image to numpy array?

As of today, your best bet is to use:

img = cv2.imread(image_path)   # reads an image in the BGR format
img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)   # BGR -> RGB

You'll see img will be a numpy array of type:

<class 'numpy.ndarray'>

How to differentiate single click event and double click event?

Well in order to double click (click twice) you must first click once. The click() handler fires on your first click, and since the alert pops up, you don't have a chance to make the second click to fire the dblclick() handler.

Change your handlers to do something other than an alert() and you'll see the behaviour. (perhaps change the background color of the element):

$("#my_id").click(function() { 
    $(this).css('backgroundColor', 'red')

$("#my_id").dblclick(function() {
    $(this).css('backgroundColor', 'green')

How to build a query string for a URL in C#?

Just wanted to throw in my 2 cents:

public static class HttpClientExt
    public static Uri AddQueryParams(this Uri uri, string query)
        var ub = new UriBuilder(uri);
        ub.Query = string.IsNullOrEmpty(uri.Query) ? query : string.Join("&", uri.Query.Substring(1), query);
        return ub.Uri;

    public static Uri AddQueryParams(this Uri uri, IEnumerable<string> query)
        return uri.AddQueryParams(string.Join("&", query));

    public static Uri AddQueryParams(this Uri uri, string key, string value)
        return uri.AddQueryParams(string.Join("=", HttpUtility.UrlEncode(key), HttpUtility.UrlEncode(value)));

    public static Uri AddQueryParams(this Uri uri, params KeyValuePair<string,string>[] kvps)
        return uri.AddQueryParams(kvps.Select(kvp => string.Join("=", HttpUtility.UrlEncode(kvp.Key), HttpUtility.UrlEncode(kvp.Value))));

    public static Uri AddQueryParams(this Uri uri, IDictionary<string, string> kvps)
        return uri.AddQueryParams(kvps.Select(kvp => string.Join("=", HttpUtility.UrlEncode(kvp.Key), HttpUtility.UrlEncode(kvp.Value))));

    public static Uri AddQueryParams(this Uri uri, NameValueCollection nvc)
        return uri.AddQueryParams(nvc.AllKeys.SelectMany(nvc.GetValues, (key, value) => string.Join("=", HttpUtility.UrlEncode(key), HttpUtility.UrlEncode(value))));

The docs say that uri.Query will start with a ? if it's non-empty and you should trim it off if you're going to modify it.

Note that HttpUtility.UrlEncode is found in System.Web.


var uri = new Uri("").AddQueryParam("url","")

List of swagger UI alternatives

Yes, there are a few of them.

Hosted solutions that support swagger:

Check the following articles for more details:

Where do I find the current C or C++ standard documents?

PDF versions of the standard

As of 1st September 2014, the best locations by price for C and C++ standards documents in PDF are:

You cannot usually get old revisions of a standard (any standard) directly from the standards bodies shortly after a new edition of the standard is released. Thus, standards for C89, C90, C99, C++98, C++03 will be hard to find for purchase from a standards body. If you need an old revision of a standard, check Techstreet as one possible source. For example, it can still provide the Canadian version CAN/CSA-ISO/IEC 9899:1990 standard in PDF, for a fee.

Non-PDF electronic versions of the standard

Print versions of the standard

Print copies of the standards are available from national standards bodies and ISO but are very expensive.

If you want a hardcopy of the C90 standard for much less money than above, you may be able to find a cheap used copy of Herb Schildt's book The Annotated ANSI Standard at Amazon, which contains the actual text of the standard (useful) and commentary on the standard (less useful - it contains several dangerous and misleading errors).

The C99 and C++03 standards are available in book form from Wiley and the BSI (British Standards Institute):

Standards committee draft versions (free)

The working drafts for future standards are often available from the committee websites:

If you want to get drafts from the current or earlier C/C++ standards, there are some available for free on the internet:

For C:

(Almost the same as ANSI X3.159-198 (C89) except for the frontmatter and section numbering. Note that the conversion between ANSI and ISO/IEC Standard is seen inside this document, the document refers to its name as "ANSI/ISO: 9899/99" although this isn't the right name of the later made standard of it, the right name is "ISO/IEC 9899:1990")

For C++:

Note that these documents are not the same as the standard, though the versions just prior to the meetings that decide on a standard are usually very close to what is in the final standard. The FCD (Final Committee Draft) versions are password protected; you need to be on the standards committee to get them.

Even though the draft versions might be very close to the final ratified versions of the standards, some of this post's editors would strongly advise you to get a copy of the actual documents — especially if you're planning on quoting them as references. Of course, starving students should go ahead and use the drafts if strapped for cash.

It appears that, if you are willing and able to wait a few months after ratification of a standard, to search for "INCITS/ISO/IEC" instead of "ISO/IEC" when looking for a standard is the key. By doing so, one of this post's editors was able to find the C11 and C++11 standards at reasonable prices. For example, if you search for "INCITS/ISO/IEC 9899:2011" instead of "ISO/IEC 9899:2011" on you will find the reasonably priced PDF version.

The site provides short-URL links to the C++ current working draft and draft standards, and committee papers:

The current draft of the standard is maintained as LaTeX sources on Github. These sources can be converted to HTML using cxxdraft-htmlgen. The following sites maintain HTML pages so generated:

Tim Song also maintains generated HTML and PDF versions of the Networking TS and Ranges TS.

jQuery has deprecated synchronous XMLHTTPRequest

It was mentioned as a comment by @henri-chan, but I think it deserves some more attention:

When you update the content of an element with new html using jQuery/javascript, and this new html contains <script> tags, those are executed synchronously and thus triggering this error. Same goes for stylesheets.

You know this is happening when you see (multiple) scripts or stylesheets being loaded as XHR in the console window. (firefox).

Disabling browser print options (headers, footers, margins) from page?

Try this code, works 100% for me:
FOR Landscape:

<style type="text/css">

  size: auto A4 landscape;
  margin: 3mm;


FOR Portait:

<style type="text/css">

  size: auto;
  margin: 3mm;


Enabling CORS in Cloud Functions for Firebase

If you're testing firebase app locally then you need to point functions to localhost instead of cloud. By default, firebase serve or firebase emulators:start points the functions to server instead of localhost when you use it on your web app.

Add below script in html head after firebase init script:


Make sure to remove this snippet when deploying code to server.

Xcode is not currently available from the Software Update server

I just got the same error after I upgraded to 10.14 Mojave and had to reinstall command line tools (I don't use the full Xcode IDE and wanted command line tools a la carte).

My xcode-select -p path was right, per Basav's answer, so that wasn't the issue.

I also ran sudo softwareupdate --clear-catalog per Lambda W's answer and that reset to Apple Production, but did not make a difference.

What worked was User 92's answer to visit

From there I was able to download a .dmg file that had a GUI installer wizard for command line tools :)

I installed that, then I restarted terminal and everything was back to normal.

PHP Check for NULL

Make sure that the value of the column is really NULL and not an empty string or 0.

How to style a div to have a background color for the entire width of the content, and not just for the width of the display?

.success { background-color: #cffccc; overflow: scroll; min-width: 100%; }

You can try scroll or auto.

How can I show and hide elements based on selected option with jQuery?

You're running the code before the DOM is loaded.

Try this:

Live example:

$(function() {    // Makes sure the code contained doesn't run until
                  //     all the DOM elements have loaded

        $('#' + $(this).val()).show();


How to disable auto-play for local video in iframe

What do you think about video tag ? If you don't have to use iframe tag you can use video tag instead.

<video width="500" height="345" src="hey.mp4"  />

You should not use autoplay attribute in your video tag to disable autoplay.

Why I get 'list' object has no attribute 'items'?

More generic way in case qs has more than one dictionaries:

[int(v) for lst in qs for k, v in lst.items()]


>>> qs = [{u'a': 15L, u'b': 9L, u'a': 16L}, {u'a': 20, u'b': 35}]
>>> result_list = [int(v) for lst in qs for k, v in lst.items()]
>>> result_list
[16, 9, 20, 35]

How to store directory files listing into an array?

This might work for you:

OIFS=$IFS; IFS=$'\n'; array=($(ls -ls)); IFS=$OIFS; echo "${array[1]}"

How to undo a SQL Server UPDATE query?

If you already have a full backup from your database, fortunately, you have an option in SQL Management Studio. In this case, you can use the following steps:

  1. Right click on database -> Tasks -> Restore -> Database.

  2. In General tab, click on Timeline -> select Specific date and time option.

  3. Move the timeline slider to before update command time -> click OK.

  4. In the destination database name, type a new name.

  5. In the Files tab, check in Reallocate all files to folder and then select a new path to save your recovered database.

  6. In the options tab, check in Overwrite ... and remove Take tail-log... check option.

  7. Finally, click on OK and wait until the recovery process is over.

I have used this method myself in an operational database and it was very useful.

Python socket.error: [Errno 111] Connection refused

The problem obviously was (as you figured it out) that port 36250 wasn't open on the server side at the time you tried to connect (hence connection refused). I can see the server was supposed to open this socket after receiving SEND command on another connection, but it apparently was "not opening [it] up in sync with the client side".

Well, the main reason would be there was no synchronisation whatsoever. Calling:

cs.send("SEND " + FILE)

would just place the data into a OS buffer; close would probably flush the data and push into the network, but it would almost certainly return before the data would reach the server. Adding sleep after close might mitigate the problem, but this is not synchronisation.

The correct solution would be to make sure the server has opened the connection. This would require server sending you some message back (for example OK, or better PORT 36250 to indicate where to connect). This would make sure the server is already listening.

The other thing is you must check the return values of send to make sure how many bytes was taken from your buffer. Or use sendall.

(Sorry for disturbing with this late answer, but I found this to be a high traffic question and I really didn't like the sleep idea in the comments section.)

Android widget: How to change the text of a button

use the exchange using java. setText = "...", for class java there are many more methods for implementation.

    //button fechar
    View.OnClickListener close = new View.OnClickListener() {
        public void onClick(View view) {
            if (btnclose.isClickable()) {
            } else {

            Toast.makeText(getActivity(), "FECHADO", Toast.LENGTH_SHORT).show();


How to pass payload via JSON file for curl?

curl sends POST requests with the default content type of application/x-www-form-urlencoded. If you want to send a JSON request, you will have to specify the correct content type header:

$ curl -vX POST http://server/api/v1/places.json -d @testplace.json \
--header "Content-Type: application/json"

But that will only work if the server accepts json input. The .json at the end of the url may only indicate that the output is json, it doesn't necessarily mean that it also will handle json input. The API documentation should give you a hint on whether it does or not.

The reason you get a 401 and not some other error is probably because the server can't extract the auth_token from your request.

Is it acceptable and safe to run pip install under sudo?

It looks like your permissions are messed up. Type chown -R markwalker ~ in the Terminal and try pip again? Let me know if you're sorted.

How to delete a specific line in a file?

Probably, you already got a correct answer, but here is mine. Instead of using a list to collect unfiltered data (what readlines() method does), I use two files. One is for hold a main data, and the second is for filtering the data when you delete a specific string. Here is a code:

main_file = open('data_base.txt').read()    # your main dataBase file
filter_file = open('filter_base.txt', 'w')
main_file = open('data_base.txt', 'w')
for line in open('filter_base'):
    if 'your data to delete' not in line:    # remove a specific string
        main_file.write(line)                # put all strings back to your db except deleted
    else: pass

Hope you will find this useful! :)

Disable a Maven plugin defined in a parent POM

See if the plugin has a 'skip' configuration parameter. Nearly all do. if it does, just add it to a declaration in the child:


If not, then use:


Deserialize Java 8 LocalDateTime with JacksonMapper


Change to:

@Column(name = "start_date")
@DateTimeFormat(pattern = "yyyy-MM-dd HH:mm", iso = ISO.DATE_TIME)
@JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd HH:mm")
private LocalDateTime startDate;

JSON request:

 "startDate":"2019-04-02 11:45"

Get content of a DIV using JavaScript

You need to set Div2 to Div1's innerHTML. Also, JavaScript is case sensitive - in your HTML, the id Div2 is DIV2. Also, you should use document, not Document:

var MyDiv1 = document.getElementById('DIV1');
var MyDiv2 = document.getElementById('DIV2');
MyDiv2.innerHTML = MyDiv1.innerHTML; 

Here is a JSFiddle:

How to parse JSON response from Alamofire API in Swift?

 pod 'Alamofire'
 pod 'SwiftyJSON'
 pod 'ReachabilitySwift'

import UIKit
import Alamofire
import SwiftyJSON
import SystemConfiguration

class WebServiceHelper: NSObject {

    typealias SuccessHandler = (JSON) -> Void
    typealias FailureHandler = (Error) -> Void

    // MARK: - Internet Connectivity

    class func isConnectedToNetwork() -> Bool {

        var zeroAddress = sockaddr_in()
        zeroAddress.sin_len = UInt8(MemoryLayout<sockaddr_in>.size)
        zeroAddress.sin_family = sa_family_t(AF_INET)

        guard let defaultRouteReachability = withUnsafePointer(to: &zeroAddress, {
            $0.withMemoryRebound(to: sockaddr.self, capacity: 1) {
                SCNetworkReachabilityCreateWithAddress(nil, $0)
        }) else {
            return false

        var flags: SCNetworkReachabilityFlags = []
        if !SCNetworkReachabilityGetFlags(defaultRouteReachability, &flags) {
            return false

        let isReachable = flags.contains(.reachable)
        let needsConnection = flags.contains(.connectionRequired)

        return (isReachable && !needsConnection)

    // MARK: - Helper Methods

    class func getWebServiceCall(_ strURL : String, isShowLoader : Bool, success : @escaping SuccessHandler, failure : @escaping FailureHandler)
        if isConnectedToNetwork() {


            if isShowLoader == true {


            Alamofire.request(strURL).responseJSON { (resObj) -> Void in


                if resObj.result.isSuccess {
                    let resJson = JSON(resObj.result.value!)

                    if isShowLoader == true {

                if resObj.result.isFailure {
                    let error : Error = resObj.result.error!

                    if isShowLoader == true {
        }else {

            CommonMethods.showAlertWithError("", strMessage: Messages.NO_NETWORK, withTarget: (AppDelegate.getDelegate().window!.rootViewController)!)

    class func getWebServiceCall(_ strURL : String, params : [String : AnyObject]?, isShowLoader : Bool, success : @escaping SuccessHandler,  failure :@escaping FailureHandler){
        if isConnectedToNetwork() {

            if isShowLoader == true {

            Alamofire.request(strURL, method: .get, parameters: params, encoding: JSONEncoding.default, headers: nil).responseJSON(completionHandler: {(resObj) -> Void in


                if resObj.result.isSuccess {
                    let resJson = JSON(resObj.result.value!)

                    if isShowLoader == true {

                if resObj.result.isFailure {
                    let error : Error = resObj.result.error!

                    if isShowLoader == true {


    else {

            CommonMethods.showAlertWithError("", strMessage: Messages.NO_NETWORK, withTarget: (AppDelegate.getDelegate().window!.rootViewController)!)


    class func postWebServiceCall(_ strURL : String, params : [String : AnyObject]?, isShowLoader : Bool, success : @escaping SuccessHandler, failure :@escaping FailureHandler)
        if isConnectedToNetwork()

            if isShowLoader == true

            Alamofire.request(strURL, method: .post, parameters: params, encoding: JSONEncoding.default, headers: nil).responseJSON(completionHandler: {(resObj) -> Void in


                if resObj.result.isSuccess
                    let resJson = JSON(resObj.result.value!)

                    if isShowLoader == true


                if resObj.result.isFailure
                    let error : Error = resObj.result.error!

                    if isShowLoader == true

        }else {
            CommonMethods.showAlertWithError("", strMessage: Messages.NO_NETWORK, withTarget: (AppDelegate.getDelegate().window!.rootViewController)!)

    class func postWebServiceCallWithImage(_ strURL : String, image : UIImage!, strImageParam : String, params : [String : AnyObject]?, isShowLoader : Bool, success : @escaping SuccessHandler, failure : @escaping FailureHandler)
        if isConnectedToNetwork() {
            if isShowLoader == true

                multipartFormData: { multipartFormData in
                    if let imageData = UIImageJPEGRepresentation(image, 0.5) {
                        multipartFormData.append(imageData, withName: "Image.jpg")

                    for (key, value) in params! {

                        let data = value as! String

                        multipartFormData.append( String.Encoding.utf8)!, withName: key)
                to: strURL,
                encodingCompletion: { encodingResult in
                    switch encodingResult {
                    case .success(let upload, _, _):
                        upload.responseJSON { response in
                            //let datastring = String(data: response, encoding: String.Encoding.utf8)
                           // print(datastring)
                    case .failure(let encodingError):
                        if isShowLoader == true

                        let error : NSError = encodingError as NSError

                    switch encodingResult {
                    case .success(let upload, _, _):
                        upload.responseJSON { (response) -> Void in

                            if response.result.isSuccess
                                let resJson = JSON(response.result.value!)

                                if isShowLoader == true


                            if response.result.isFailure
                                let error : Error = response.result.error! as Error

                                if isShowLoader == true


                    case .failure(let encodingError):
                        if isShowLoader == true

                        let error : NSError = encodingError as NSError
            CommonMethods.showAlertWithError("", strMessage: Messages.NO_NETWORK, withTarget: (AppDelegate.getDelegate().window!.rootViewController)!)



Call Method

let aParams : [String : String] = [
                "ReqCode" : Constants.kRequestCodeLogin,

            WebServiceHelper.postWebServiceCall(Constants.BaseURL, params: aParams as [String : AnyObject]?, isShowLoader: true, success: { (responceObj) in

                if "\(responceObj["RespCode"])" != "1"
                    let alert = UIAlertController(title: Constants.kAppName, message: "\(responceObj["RespMsg"])", preferredStyle: UIAlertControllerStyle.alert)
                    let OKAction = UIAlertAction(title: "OK", style: .default) { (action:UIAlertAction!) in
                    self.present(alert, animated: true, completion: nil)
                    let aParams : [String : String] = [
                        "Password" : self.dictAddLogin[AddLoginConstants.kPassword]!,
                    CommonMethods.saveCustomObject(aParams as AnyObject?, key: Constants.kLoginData)

                }, failure:
                { (error) in

                    CommonMethods.showAlertWithError(Constants.kALERT_TITLE_Error, strMessage: error.localizedDescription,withTarget: (AppDelegate.getDelegate().window!.rootViewController)!)

How to detect my browser version and operating system using JavaScript?

Detecting browser's details:

var nVer = navigator.appVersion;
var nAgt = navigator.userAgent;
var browserName  = navigator.appName;
var fullVersion  = ''+parseFloat(navigator.appVersion); 
var majorVersion = parseInt(navigator.appVersion,10);
var nameOffset,verOffset,ix;

// In Opera, the true version is after "Opera" or after "Version"
if ((verOffset=nAgt.indexOf("Opera"))!=-1) {
 browserName = "Opera";
 fullVersion = nAgt.substring(verOffset+6);
 if ((verOffset=nAgt.indexOf("Version"))!=-1) 
   fullVersion = nAgt.substring(verOffset+8);
// In MSIE, the true version is after "MSIE" in userAgent
else if ((verOffset=nAgt.indexOf("MSIE"))!=-1) {
 browserName = "Microsoft Internet Explorer";
 fullVersion = nAgt.substring(verOffset+5);
// In Chrome, the true version is after "Chrome" 
else if ((verOffset=nAgt.indexOf("Chrome"))!=-1) {
 browserName = "Chrome";
 fullVersion = nAgt.substring(verOffset+7);
// In Safari, the true version is after "Safari" or after "Version" 
else if ((verOffset=nAgt.indexOf("Safari"))!=-1) {
 browserName = "Safari";
 fullVersion = nAgt.substring(verOffset+7);
 if ((verOffset=nAgt.indexOf("Version"))!=-1) 
   fullVersion = nAgt.substring(verOffset+8);
// In Firefox, the true version is after "Firefox" 
else if ((verOffset=nAgt.indexOf("Firefox"))!=-1) {
 browserName = "Firefox";
 fullVersion = nAgt.substring(verOffset+8);
// In most other browsers, "name/version" is at the end of userAgent 
else if ( (nameOffset=nAgt.lastIndexOf(' ')+1) < 
          (verOffset=nAgt.lastIndexOf('/')) ) 
 browserName = nAgt.substring(nameOffset,verOffset);
 fullVersion = nAgt.substring(verOffset+1);
 if (browserName.toLowerCase()==browserName.toUpperCase()) {
  browserName = navigator.appName;
// trim the fullVersion string at semicolon/space if present
if ((ix=fullVersion.indexOf(";"))!=-1)
if ((ix=fullVersion.indexOf(" "))!=-1)

majorVersion = parseInt(''+fullVersion,10);
if (isNaN(majorVersion)) {
 fullVersion  = ''+parseFloat(navigator.appVersion); 
 majorVersion = parseInt(navigator.appVersion,10);

 +'Browser name  = '+browserName+'<br>'
 +'Full version  = '+fullVersion+'<br>'
 +'Major version = '+majorVersion+'<br>'
 +'navigator.appName = '+navigator.appName+'<br>'
 +'navigator.userAgent = '+navigator.userAgent+'<br>'

Source JavaScript: browser name.
See JSFiddle to detect Browser Details.

Detecting OS:

// This script sets OSName variable as follows:
// "Windows"    for all versions of Windows
// "MacOS"      for all versions of Macintosh OS
// "Linux"      for all versions of Linux
// "UNIX"       for all other UNIX flavors 
// "Unknown OS" indicates failure to detect the OS

var OSName="Unknown OS";
if (navigator.appVersion.indexOf("Win")!=-1) OSName="Windows";
if (navigator.appVersion.indexOf("Mac")!=-1) OSName="MacOS";
if (navigator.appVersion.indexOf("X11")!=-1) OSName="UNIX";
if (navigator.appVersion.indexOf("Linux")!=-1) OSName="Linux";

document.write('Your OS: '+OSName);

source JavaScript: OS detection.
See JSFiddle to detect OS Details.

    var nVer = navigator.appVersion;_x000D_
    var nAgt = navigator.userAgent;_x000D_
    var browserName  = navigator.appName;_x000D_
    var fullVersion  = ''+parseFloat(navigator.appVersion); _x000D_
    var majorVersion = parseInt(navigator.appVersion,10);_x000D_
    var nameOffset,verOffset,ix;_x000D_
    // In Opera, the true version is after "Opera" or after "Version"_x000D_
    if ((verOffset=nAgt.indexOf("Opera"))!=-1) {_x000D_
     browserName = "Opera";_x000D_
     fullVersion = nAgt.substring(verOffset+6);_x000D_
     if ((verOffset=nAgt.indexOf("Version"))!=-1) _x000D_
       fullVersion = nAgt.substring(verOffset+8);_x000D_
    // In MSIE, the true version is after "MSIE" in userAgent_x000D_
    else if ((verOffset=nAgt.indexOf("MSIE"))!=-1) {_x000D_
     browserName = "Microsoft Internet Explorer";_x000D_
     fullVersion = nAgt.substring(verOffset+5);_x000D_
    // In Chrome, the true version is after "Chrome" _x000D_
    else if ((verOffset=nAgt.indexOf("Chrome"))!=-1) {_x000D_
     browserName = "Chrome";_x000D_
     fullVersion = nAgt.substring(verOffset+7);_x000D_
    // In Safari, the true version is after "Safari" or after "Version" _x000D_
    else if ((verOffset=nAgt.indexOf("Safari"))!=-1) {_x000D_
     browserName = "Safari";_x000D_
     fullVersion = nAgt.substring(verOffset+7);_x000D_
     if ((verOffset=nAgt.indexOf("Version"))!=-1) _x000D_
       fullVersion = nAgt.substring(verOffset+8);_x000D_
    // In Firefox, the true version is after "Firefox" _x000D_
    else if ((verOffset=nAgt.indexOf("Firefox"))!=-1) {_x000D_
     browserName = "Firefox";_x000D_
     fullVersion = nAgt.substring(verOffset+8);_x000D_
    // In most other browsers, "name/version" is at the end of userAgent _x000D_
    else if ( (nameOffset=nAgt.lastIndexOf(' ')+1) < _x000D_
              (verOffset=nAgt.lastIndexOf('/')) ) _x000D_
     browserName = nAgt.substring(nameOffset,verOffset);_x000D_
     fullVersion = nAgt.substring(verOffset+1);_x000D_
     if (browserName.toLowerCase()==browserName.toUpperCase()) {_x000D_
      browserName = navigator.appName;_x000D_
    // trim the fullVersion string at semicolon/space if present_x000D_
    if ((ix=fullVersion.indexOf(";"))!=-1)_x000D_
    if ((ix=fullVersion.indexOf(" "))!=-1)_x000D_
    majorVersion = parseInt(''+fullVersion,10);_x000D_
    if (isNaN(majorVersion)) {_x000D_
     fullVersion  = ''+parseFloat(navigator.appVersion); _x000D_
     majorVersion = parseInt(navigator.appVersion,10);_x000D_
     +'Browser name  = '+browserName+'<br>'_x000D_
     +'Full version  = '+fullVersion+'<br>'_x000D_
     +'Major version = '+majorVersion+'<br>'_x000D_
     +'navigator.appName = '+navigator.appName+'<br>'_x000D_
     +'navigator.userAgent = '+navigator.userAgent+'<br>'_x000D_
    // This script sets OSName variable as follows:_x000D_
    // "Windows"    for all versions of Windows_x000D_
    // "MacOS"      for all versions of Macintosh OS_x000D_
    // "Linux"      for all versions of Linux_x000D_
    // "UNIX"       for all other UNIX flavors _x000D_
    // "Unknown OS" indicates failure to detect the OS_x000D_
    var OSName="Unknown OS";_x000D_
    if (navigator.appVersion.indexOf("Win")!=-1) OSName="Windows";_x000D_
    if (navigator.appVersion.indexOf("Mac")!=-1) OSName="MacOS";_x000D_
    if (navigator.appVersion.indexOf("X11")!=-1) OSName="UNIX";_x000D_
    if (navigator.appVersion.indexOf("Linux")!=-1) OSName="Linux";_x000D_
    document.write('Your OS: '+OSName);

Unable to create a constant value of type Only primitive types or enumeration types are supported in this context

It's worth adding, since the OP's code sample doesn't provide enough context to prove otherwise, but I received this error as well on the following code:

public RetailSale GetByRefersToRetailSaleId(Int32 refersToRetailSaleId)
    return GetQueryable()
        .FirstOrDefault(x => x.RefersToRetailSaleId.Equals(refersToRetailSaleId));

Apparently, I cannot use Int32.Equals in this context to compare an Int32 with a primitive int; I had to (safely) change to this:

public RetailSale GetByRefersToRetailSaleId(Int32 refersToRetailSaleId)
    return GetQueryable()
      .FirstOrDefault(x => x.RefersToRetailSaleId == refersToRetailSaleId);

Retrieve a Fragment from a ViewPager

The easiest and the most concise way. If all your fragments in ViewPager are of different classes you may retrieve and distinguish them as following:

public class MyActivity extends Activity

    public void onAttachFragment(Fragment fragment) {
        if (fragment.getClass() == MyFragment.class) {
            mMyFragment = (MyFragment) fragment;


How to make the window full screen with Javascript (stretching all over the screen)

The new html5 technology – fullscreen API gives us an easy way to present a web page content in full-screen mode. We are about to give you detailed information about the fullscreen mode. Just try to imagine about all possible advantages which you can get using this technology – full-screen photo albums, videos, and even games.

But before we describe this new technology, I have to note that this technology is experimental, and supported by all major Browsers.

You can find the full tutorial here :

Here is working Demo :

How to do an update + join in PostgreSQL?

For those wanting to do a JOIN that updates ONLY the rows your join returns use:

SET price = b_alias.unit_price
FROM      a AS a_alias
LEFT JOIN b AS b_alias ON a_alias.b_fk =
WHERE a_alias.unit_name LIKE 'some_value' 
--the below line is critical for updating ONLY joined rows
AND a.pk_id = a_alias.pk_id;

This was mentioned above but only through a comment..Since it's critical to getting the correct result posting NEW answer that Works

Assembly code vs Machine code vs Object code?

8B 5D 32 is machine code

mov ebx, [ebp+32h] is assembly containing 8B 5D 32 is object code

Reading/parsing Excel (xls) files with Python

For xlsx I like the solution posted earlier as I uses modules from the standard library only.

def xlsx(fname):
    import zipfile
    from xml.etree.ElementTree import iterparse
    z = zipfile.ZipFile(fname)
    strings = [el.text for e, el in iterparse('xl/sharedStrings.xml')) if el.tag.endswith('}t')]
    rows = []
    row = {}
    value = ''
    for e, el in iterparse('xl/worksheets/sheet1.xml')):
        if el.tag.endswith('}v'):  # Example: <v>84</v>                            
            value = el.text
        if el.tag.endswith('}c'):  # Example: <c r="A3" t="s"><v>84</v></c>                                 
            if el.attrib.get('t') == 's':
                value = strings[int(value)]
            letter = el.attrib['r']  # Example: AZ22                         
            while letter[-1].isdigit():
                letter = letter[:-1]
            row[letter] = value
            value = ''
        if el.tag.endswith('}row'):
            row = {}
    return rows

Improvements added are fetching content by sheet name, using re to get the column and checking if sharedstrings are used.

def xlsx(fname,sheet):
    import zipfile
    from xml.etree.ElementTree import iterparse
    import re
    z = zipfile.ZipFile(fname)
    if 'xl/sharedStrings.xml' in z.namelist():
        # Get shared strings
        strings = [element.text for event, element
                   in iterparse('xl/sharedStrings.xml')) 
                   if element.tag.endswith('}t')]
    sheetdict = { element.attrib['name']:element.attrib['sheetId'] for event,element in iterparse('xl/workbook.xml'))
                                      if element.tag.endswith('}sheet') }
    rows = []
    row = {}
    value = ''

    if sheet in sheets:
    sheetfile = 'xl/worksheets/sheet'+sheets[sheet]+'.xml'
    for event, element in iterparse(
        # get value or index to shared strings
        if element.tag.endswith('}v') or element.tag.endswith('}t'):
            value = element.text
        # If value is a shared string, use value as an index
        if element.tag.endswith('}c'):
            if element.attrib.get('t') == 's':
                value = strings[int(value)]
            # split the row/col information so that the row leter(s) can be separate
            letter = re.sub('\d','',element.attrib['r'])
            row[letter] = value
            value = ''
        if element.tag.endswith('}row'):
            row = {}

    return rows

String or binary data would be truncated. The statement has been terminated

SQL Server 2016 SP2 CU6 and SQL Server 2017 CU12 introduced trace flag 460 in order to return the details of truncation warnings. You can enable it at the query level or at the server level.

Query level

INSERT INTO dbo.TEST (ColumnTest)
VALUES (‘Test truncation warnings’)

Server Level

DBCC TRACEON(460, -1);

From SQL Server 2019 you can enable it at database level:


The old output message is:

Msg 8152, Level 16, State 30, Line 13
String or binary data would be truncated.
The statement has been terminated.

The new output message is:

Msg 2628, Level 16, State 1, Line 30
String or binary data would be truncated in table 'DbTest.dbo.TEST', column 'ColumnTest'. Truncated value: ‘Test truncation warnings‘'.

In a future SQL Server 2019 release, message 2628 will replace message 8152 by default.

Use 'class' or 'typename' for template parameters?

According to Scott Myers, Effective C++ (3rd ed.) item 42 (which must, of course, be the ultimate answer) - the difference is "nothing".

Advice is to use "class" if it is expected T will always be a class, with "typename" if other types (int, char* whatever) may be expected. Consider it a usage hint.

Rounding a variable to two decimal places C#

You can round the result and use string.Format to set the precision like this:

decimal pay = 200.5555m;
pay = Math.Round(pay + bonus, 2);
string payAsString = string.Format("{0:0.00}", pay);

How do I get a list of installed CPAN modules?

$ for M in `perldoc -t perllocal|grep Module |sed -e 's/^.*" //'`; do V=`perldoc -t perllocal|awk "/$M/{y=1;next}y" |grep VERSION |head -n 1`; printf "%30s %s\n" "$M" "$V"; done |sort
              Class::Inspector     *   "VERSION: 1.28"
                    Crypt::CBC     *   "VERSION: 2.33"
               Crypt::Rijndael     *   "VERSION: 1.11"
                    Data::Dump     *   "VERSION: 1.22"
                   DBD::Oracle     *   "VERSION: 1.68"
                           DBI     *   "VERSION: 1.630"
                   Digest::SHA     *   "VERSION: 5.92"
           ExtUtils::MakeMaker     *   "VERSION: 6.84"
                       install     *   "VERSION: 6.84"
               IO::SessionData     *   "VERSION: 1.03"
               IO::Socket::SSL     *   "VERSION: 2.016"
                          JSON     *   "VERSION: 2.90"
                  MIME::Base64     *   "VERSION: 3.14"
                  MIME::Base64     *   "VERSION: 3.14"
                   Mozilla::CA     *   "VERSION: 20141217"
                   Net::SSLeay     *   "VERSION: 1.68"
                        parent     *   "VERSION: 0.228"
                  REST::Client     *   "VERSION: 271"
                    SOAP::Lite     *   "VERSION: 1.08"
                  Task::Weaken     *   "VERSION: 1.04"
                 Term::ReadKey     *   "VERSION: 2.31"
                Test::Manifest     *   "VERSION: 1.23"
                  Test::Simple     *   "VERSION: 1.001002"
                  Text::CSV_XS     *   "VERSION: 1.16"
                     Try::Tiny     *   "VERSION: 0.22"
                   XML::LibXML     *   "VERSION: 2.0108"
         XML::NamespaceSupport     *   "VERSION: 1.11"
                XML::SAX::Base     *   "VERSION: 1.08"

Java: Casting Object to Array type

What you've got (according to the debug image) is an object array containing a string array. So you need something like:

Object[] objects = (Object[]) values;
String[] strings = (String[]) objects[0];

You haven't shown the type of values - if this is already Object[] then you could just use (String[])values[0].

Of course even with the cast to Object[] you could still do it in one statement, but it's ugly:

String[] strings = (String[]) ((Object[])values)[0];

How to get the first item from an associative PHP array?

another easy and simple way to do it use array_values


Copying one structure to another

Since C90, you can simply use:

dest_struct = source_struct;

as long as the string is memorized inside an array:

struct xxx {
    char theString[100];

Otherwise, if it's a pointer, you'll need to copy it by hand.

struct xxx {
    char* theString;

dest_struct = source_struct;
dest_struct.theString = malloc(strlen(source_struct.theString) + 1);
strcpy(dest_struct.theString, source_struct.theString);

Reliable way for a Bash script to get the full path to itself

Considering this issue again: there is a very popular solution that is referenced within this thread that has its origin here:

DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"

I have stayed away from this solution because of the use of dirname - it can present cross-platform difficulties, particularly if a script needs to be locked down for security reasons. But as a pure Bash alternative, how about using:

DIR="$( cd "$( echo "${BASH_SOURCE[0]%/*}" )" && pwd )"

Would this be an option?

Fatal error: Call to a member function query() on null

put this line in parent construct : $this->load->database();

function  __construct() {

this way.. it should work..

Objects inside objects in javascript

You may have as many levels of Object hierarchy as you want, as long you declare an Object as being a property of another parent Object. Pay attention to the commas on each level, that's the tricky part. Don't use commas after the last element on each level:

{el1, el2, {el31, el32, el33}, {el41, el42}}

var MainObj = {_x000D_
  prop1: "prop1MainObj",_x000D_
  Obj1: {_x000D_
    prop1: "prop1Obj1",_x000D_
    prop2: "prop2Obj1",    _x000D_
    Obj2: {_x000D_
      prop1: "hey you",_x000D_
      prop2: "prop2Obj2"_x000D_
  Obj3: {_x000D_
    prop1: "prop1Obj3",_x000D_
    prop2: "prop2Obj3"_x000D_
  Obj4: {_x000D_
    prop1: true,_x000D_
    prop2: 3_x000D_
  }  _x000D_

Pycharm: run only part of my Python file

You can select a code snippet and use right click menu to choose the action "Execute Selection in console".

How do you sign a Certificate Signing Request with your Certification Authority?

In addition to answer of @jww, I would like to say that the configuration in openssl-ca.cnf,

default_days     = 1000         # How long to certify for

defines the default number of days the certificate signed by this root-ca will be valid. To set the validity of root-ca itself you should use '-days n' option in:

openssl req -x509 -days 3000 -config openssl-ca.cnf -newkey rsa:4096 -sha256 -nodes -out cacert.pem -outform PEM

Failing to do so, your root-ca will be valid for only the default one month and any certificate signed by this root CA will also have validity of one month.

Apply jQuery datepicker to multiple instances

When adding datepicker at runtime generated input textboxes you have to check if it already contains datepicker then first remove class hasDatepicker then apply datePicker to it.

function convertTxtToDate() {
        $('.dateTxt').each(function () {
            if ($(this).hasClass('hasDatepicker')) {

How can I see an the output of my C programs using Dev-C++?

i think you should link your project in console mode

just press Ctrl+h and in General tab select console.

How to get element by classname or id

If you want to find the button only by its class name and using jQLite only, you can do like below:

var myListButton = $document.find('button').filter(function() {
    return angular.element(this).hasClass('multi-files');

Hope this helps. :)

Bash script plugin for Eclipse?

Debugger for Bash version 3(Bourne again shell).
Plugin for Eclipse. Will only work with shell script editor ShellEd. basheclipse

Python: Best way to add to sys.path relative to the current running script

If you don't want to change the script content in any ways, prepend the current working directory . to $PYTHONPATH (see example below)

PYTHONPATH=.:$PYTHONPATH alembic revision --autogenerate -m "First revision"

And call it a day!

Python functions call by reference

Consider that the variable is a box and the value it points to is the "thing" inside the box:

1. Pass by reference : function shares the same box and thereby the thing inside also.

2. Pass by value : function creates a new box, a replica of the old one, including a copy of whatever thing is inside it. Eg. Java - functions create a copy of the box and the thing inside it which can be: a primitive / a reference to an object. (note that the copied reference in the new box and the original both still point to the same object, here the reference IS the thing inside the box, not the object it is pointing to)

3. Pass by object-reference: the function creates a box, but it encloses the same thing the initial box was enclosing. So in Python:

a) if the thing inside said box is mutable, changes made will reflect back in the original box (eg. lists)

b) if the thing is immutable (like python strings and numeric types), then the box inside the function will hold the same thing UNTIL you try to change its value. Once changed, the thing in the function's box is a totally new thing compared to the original one. Hence id() for that box will now give the identity of the new thing it encloses.

Error:Execution failed for task ':app:transformClassesWithJarMergingForDebug'

I resolve this is by changing the version no of recyleview to recyclerview-v7:24.2.1. Please check your dependencies and use the proper version number.

How can I make visible an invisible control with jquery? (hide and show not work)

Here's some code I use to deal with this.

First we show the element, which will typically set the display type to "block" via .show() function, and then set the CSS rule to "visible":

jQuery( '.element' ).show().css( 'visibility', 'visible' );

Or, assuming that the class that is hiding the element is called hidden, such as in Twitter Bootstrap, toggleClass() can be useful:

jQuery( '.element' ).toggleClass( 'hidden' );

Lastly, if you want to chain functions, perhaps with fancy with a fading effect, you can do it like so:

jQuery( '.element' ).css( 'visibility', 'visible' ).fadeIn( 5000 );

jQuery or Javascript - how to disable window scroll without overflow:hidden;

CSS 'fixed' solution (like Facebook does):

body_temp = $("<div class='body_temp' />")
    .css('position', 'fixed')
    .css('top', "-" + scrolltop + 'px')

to toggle to normal state:

var scrolltop = Math.abs($('.body_temp').position().top);

Jenkins Slave port number for firewall

A slave isn't a server, it's a client type application. Network clients (almost) never use a specific port. Instead, they ask the OS for a random free port. This works much better since you usually run clients on many machines where the current configuration isn't known in advance. This prevents thousands of "client wouldn't start because port is already in use" bug reports every day.

You need to tell the security department that the slave isn't a server but a client which connects to the server and you absolutely need to have a rule which says client:ANY -> server:FIXED. The client port number should be >= 1024 (ports 1 to 1023 need special permissions) but I'm not sure if you actually gain anything by adding a rule for this - if an attacker can open privileged ports, they basically already own the machine.

If they argue, then ask them why they don't require the same rule for all the web browsers which people use in your company.

Cell spacing in UICollectionView

I have a horizontal UICollectionView and subclassed UICollectionViewFlowLayout. The collection view has large cells, and only shows one row of them at a time, and the collection view fits the width of the screen.

I tried iago849's answer and it worked, but then I found out I didn't even need his answer. For some reason, setting the minimumInterItemSpacing does nothing. The spacing between my items/cells can be entirely controlled by minimumLineSpacing.

Not sure why it works this way, but it works.

Call asynchronous method in constructor?

The best solution is to acknowledge the asynchronous nature of the download and design for it.

In other words, decide what your application should look like while the data is downloading. Have the page constructor set up that view, and start the download. When the download completes update the page to display the data.

I have a blog post on asynchronous constructors that you may find useful. Also, some MSDN articles; one on asynchronous data-binding (if you're using MVVM) and another on asynchronous best practices (i.e., you should avoid async void).

How to make HTTP Post request with JSON body in Swift

a combination of several answers found in my attempt to not use 3rd party frameworks like Alamofire.

    let body: [String: Any] = ["provider": "Google", "email": "[email protected]"]
    let api_url = ""
    let url = URL(string: api_url)!
    var request = URLRequest(url: url)

    do {
        let jsonData = try body, options: .prettyPrinted)
        request.httpBody = jsonData
    } catch let e {

    request.httpMethod =
    request.addValue("application/json", forHTTPHeaderField: "Content-Type")

    let task = URLSession.shared.dataTask(with: request) { data, response, error in
        guard let data = data, error == nil else {
            print(error?.localizedDescription ?? "No data")
        let responseJSON = try? JSONSerialization.jsonObject(with: data, options: [])
        if let responseJSON = responseJSON as? [String: Any] {


Does HTTP use UDP?

Typically, no.

Streaming is seldom used over HTTP itself, and HTTP is seldom run over UDP. See, however, RTP.

For something as your example (in the comment), you're not showing a protocol for the resource. If that protocol were to be HTTP, then I wouldn't call the access "streaming"; even if it in some sense of the word is since it's sending a (possibly large) resource serially over a network. Typically, the resource will be saved to local disk before being played back, so the network transfer is not what's usually meant by "streaming".

As commenters have pointed out, though, it's certainly possible to really stream over HTTP, and that's done by some.

Open a PDF using VBA in Excel

WOW... In appreciation, I add a bit of code that I use to find the path to ADOBE

Private Declare Function FindExecutable Lib "shell32.dll" Alias "FindExecutableA" _
    (ByVal lpFile As String, _
     ByVal lpDirectory As String, _
     ByVal lpResult As String) As Long

and call this to find the applicable program name

Public Function GetFileAssociation(ByVal sFilepath As String) As String
Dim i               As Long
Dim E               As String
    GetFileAssociation = "File not found!"
    If Dir(sFilepath) = vbNullString Or sFilepath = vbNullString Then Exit Function
    GetFileAssociation = "No association found!"
    E = String(260, Chr(0))
    i = FindExecutable(sFilepath, vbNullString, E)
    If i > 32 Then GetFileAssociation = Left(E, InStr(E, Chr(0)) - 1)
End Function

Thank you for your code, which isn't EXACTLY what I wanted, but can be adapted for me.

What is the hamburger menu icon called and the three vertical dots icon called?

Cannot say about the "official nomenclature" - infact I wonder whose word will be "official" anyway - but here's how they can be called:

Angular + Material - How to refresh a data source (mat-table)

You can just use the datasource connect function


like so. 'data' being the new values for the datatable

html select only one checkbox in a group

<script src=""></script>_x000D_
<!DOCTYPE html>_x000D_
  <script src=""></script>_x000D_
    angular.module('app', []).controller('appc', ['$scope',_x000D_
      function($scope) {_x000D_
        $scope.selected = 'male';_x000D_
<body ng-app="app" ng-controller="appc">_x000D_
  <label>SELECTED: {{selected}}</label>_x000D_
    <input type="checkbox" ng-checked="selected=='male'" ng-true-value="'male'" ng-model="selected">Male_x000D_
    <input type="checkbox" ng-checked="selected=='female'" ng-true-value="'female'" ng-model="selected">Female_x000D_
    <input type="checkbox" ng-checked="selected=='other'" ng-true-value="'other'" ng-model="selected">Other_x000D_

How to create a simple proxy in C#?

Proxy can work in the following way.

Step1, configure client to use proxyHost:proxyPort.

Proxy is a TCP server that is listening on proxyHost:proxyPort. Browser opens connection with Proxy and sends Http request. Proxy parses this request and tries to detect "Host" header. This header will tell Proxy where to open connection.

Step 2: Proxy opens connection to the address specified in the "Host" header. Then it sends HTTP request to that remote server. Reads response.

Step 3: After response is read from remote HTTP server, Proxy sends the response through an earlier opened TCP connection with browser.

Schematically it will look like this:

Browser                            Proxy                     HTTP server
  Open TCP connection  
  Send HTTP request  ----------->                       
                                 Read HTTP header
                                 detect Host header
                                 Send request to HTTP ----------->
                                 Read response and send
                   <-----------  it back to the browser
Render content

How do I make case-insensitive queries on Mongodb?

You'd need to use a case-insensitive regular expression for this one, e.g.

db.collection.find( { "name" : { $regex : /Andrew/i } } );

To use the regex pattern from your thename variable, construct a new RegExp object:

var thename = "Andrew";
db.collection.find( { "name" : { $regex : new RegExp(thename, "i") } } );

Update: For exact match, you should use the regex "name": /^Andrew$/i. Thanks to Yannick L.

Bootstrap Dropdown with Hover

For CSS it goes crazy when you also click on it. This is the code that I'm using, it also don't change anything for mobile view.

    if(!$('.navbar-toggle').is(':visible')) { // disable for mobile view
        if(!$(this).hasClass('open')) { // Keeps it open when hover it again
            $('.dropdown-toggle', this).trigger('click');

Java get String CompareTo as a comparator object

Ok this is a few years later but with java 8 you can use Comparator.naturalOrder():

From javadoc:

static <T extends Comparable<? super T>> Comparator<T> naturalOrder()

Returns a comparator that compares Comparable objects in natural order. The returned comparator is serializable and throws NullPointerException when comparing null.

HAX kernel module is not installed

If you are running a modern Intel processor make sure HAXM (Intel® Hardware Accelerated Execution Manager) is installed:

  1. In Android SDK Manager, ensure the option is ticked (and then installed)

  2. Run the HAXM installer via the path below:


This video shows all the required steps which may help you to solve the problem.

For AMD CPUs (or older Intel CPUs without VT-x technology), you will not be able to install this and the best option is to emulate your apps using Genymotion. See: Intel's HAXM equivalent for AMD on Windows OS

JUnit tests pass in Eclipse but fail in Maven Surefire

I suddenly experienced this error, and the solution for me was to disable to run tests in parallel.

Your milage may vary, since I could lower number of failing tests by configuring surefire to run parallel tests by ´classes´.:


As I wrote first, this was not enough for my test suite, so I completely disabled parallel by removing the <configuration> section.

How to iterate (keys, values) in JavaScript?

I think the fast and easy way is

Object.entries(event).forEach(k => {
    console.log("properties ... ", k[0], k[1]); });

just check the documentation

Does C# support multiple inheritance?

C# does not support multiple inheritance built in.

For adding multiple inheritance to languages that does not support it, You can use twin design pattern

How to install pip for Python 3.6 on Ubuntu 16.10?

This website contains a much cleaner solution, it leaves pip intact as-well and one can easily switch between 3.5 and 3.6 and then whenever 3.7 is released.

A short summary:

sudo apt-get install python python-pip python3 python3-pip
sudo add-apt-repository ppa:jonathonf/python-3.6
sudo apt-get update
sudo apt-get install python3.6
sudo update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.5 1
sudo update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.6 2


$ pip -V
pip 8.1.1 from /usr/lib/python2.7/dist-packages (python 2.7)
$ pip3 -V
pip 8.1.1 from /usr/local/lib/python3.5/dist-packages (python 3.5)

Then to select python 3.6 run

sudo update-alternatives --config python3

and select '2'. Then

$ pip3 -V
pip 8.1.1 from /usr/local/lib/python3.6/dist-packages (python 3.6)

To update pip select the desired version and

pip3 install --upgrade pip

$ pip3 -V
pip 9.0.1 from /usr/local/lib/python3.6/dist-packages (python 3.6)

Tested on Ubuntu 16.04.

How to add item to the beginning of List<T>?

Since .NET 4.7.1, you can use the side-effect free Prepend() and Append(). The output is going to be an IEnumerable.

// Creating an array of numbers
var ti = new List<int> { 1, 2, 3 };

// Prepend and Append any value of the same type
var results = ti.Prepend(0).Append(4);

// output is 0, 1, 2, 3, 4
Console.WriteLine(string.Join(", ", results ));

Timestamp Difference In Hours for PostgreSQL

extract(hour from age(now(),links.created)) gives you a floor-rounded count of the hour difference.

iPhone 5 CSS media query

None of the response works for me targeting a phonegapp App.

As the following link points, the solution below works.

@media screen and (device-height: 568px) and (orientation: portrait) and (-webkit-min-device-pixel-ratio: 2) {
    // css here

how I can show the sum of in a datagridview column?

int sum = 0;
for (int i = 0; i < dataGridView1.Rows.Count; ++i)
    sum += Convert.ToInt32(dataGridView1.Rows[i].Cells[1].Value);
label1.Text = sum.ToString();

gridview data export to excel in

Your sheet is blank because your string writer in null. Here is what may help

System.Web.UI.HtmlTextWriter htmlWrite =
    new HtmlTextWriter(stringWrite);


Here is the full code

protected void Button1_Click(object sender, EventArgs e)

    Response.AddHeader("content-disposition", "attachment;

    Response.ContentType = "application/vnd.xls";

    System.IO.StringWriter stringWrite = new System.IO.StringWriter();

    System.Web.UI.HtmlTextWriter htmlWrite =
    new HtmlTextWriter(stringWrite);





Get the data received in a Flask request

To get request.form as a normal dictionary , use request.form.to_dict(flat=False).

To return JSON data for an API, pass it to jsonify.

This example returns form data as JSON data.

@app.route('/form_to_json', methods=['POST'])
def form_to_json():
    data = request.form.to_dict(flat=False)
    return jsonify(data)

Here's an example of POST form data with curl, returning as JSON:

$ curl -d "name=ivanleoncz&role=Software Developer"
  "name": "ivanleoncz", 
  "role": "Software Developer"

convert nan value to zero

A code example for drake's answer to use nan_to_num:

>>> import numpy as np
>>> A = np.array([[1, 2, 3], [0, 3, np.NaN]])
>>> A = np.nan_to_num(A)
>>> A
array([[ 1.,  2.,  3.],
       [ 0.,  3.,  0.]])

How can I get list of values from dict?

Yes it's the exact same thing in Python 2:


In Python 3 (where dict.values returns a view of the dictionary’s values instead):


Custom Card Shape Flutter SDK

You can use it this way

enter image description here

  shape: RoundedRectangleBorder(
    borderRadius: BorderRadius.circular(15.0),
  child: Text(
    'Card with circular border',
    textScaleFactor: 1.2,
  shape: BeveledRectangleBorder(
    borderRadius: BorderRadius.circular(10.0),
  child: Text(
    'Card with Beveled border',
    textScaleFactor: 1.2,
  shape: StadiumBorder(
  side: BorderSide(
    width: 2.0,
  child: Text(
    'Card with Beveled border',
    textScaleFactor: 1.2,

How to change navbar/container width? Bootstrap 3

If you are dealing with more dynamic screen resolution/sizes, instead of hardcoding the size in pixels you can change the width to a percentage of the media width as such

@media (min-width: 1200px) {
        max-width: 70%;

How to parse a CSV file in Bash?

From the man page:

-d delim The first character of delim is used to terminate the input line, rather than newline.

You are using -d, which will terminate the input line on the comma. It will not read the rest of the line. That's why $y is empty.

How to convert a time string to seconds?

Inspired by sverrir-sigmundarson's comment:

def time_to_sec(time_str):
    return sum(x * int(t) for x, t in zip([1, 60, 3600], reversed(time_str.split(":"))))

SQL Server 2000: How to exit a stored procedure?

Unless you specify a severity of 20 or higher, raiserror will not stop execution. See the MSDN documentation.

The normal workaround is to include a return after every raiserror:

if @whoops = 1
    raiserror('Whoops!', 18, 1)
    return -1

How to do a SUM() inside a case statement in SQL server

The error you posted can happen when you're using a clause in the GROUP BY statement without including it in the select.


This one works!

     SELECT t.device,
            SUM(case when transits.direction = 1 then 1 else 0 end) ,
            SUM(case when transits.direction = 0 then 1 else 0 end) from t1 t 
            where t.device in ('A','B') group by t.device

This one not (omitted t.device from the select)

            SUM(case when transits.direction = 1 then 1 else 0 end) ,
            SUM(case when transits.direction = 0 then 1 else 0 end) from t1 t 
            where t.device in ('A','B') group by t.device

This will produce your error complaining that I'm grouping for something that is not included in the select

Please, provide all the query to get more support.

AngularJS sorting rows by table header

You can use this code without arrows.....i.e by clicking on header it automatically shows ascending and descending order of elements

    <!DOCTYPE html>
<html xmlns="">
    <script src="scripts/angular.min.js"></script>
    <script src="Scripts/Script.js"></script>
        table {
            border-collapse: collapse;
            font-family: Arial;

        td {
            border: 1px solid black;
            padding: 5px;

        th {
            border: 1px solid black;
            padding: 5px;
            text-align: left;
<body ng-app="myModule">
    <div ng-controller="myController">

        <br /><br />
                        <a href="#" ng-click="orderByField='name'; reverseSort = !reverseSort">
                        <a href="#" ng-click="orderByField='dateOfBirth'; reverseSort = !reverseSort">
                            Date Of Birth
                        <a href="#" ng-click="orderByField='gender'; reverseSort = !reverseSort">
                        <a href="#" ng-click="orderByField='salary'; reverseSort = !reverseSort">
                <tr ng-repeat="employee in employees | orderBy:orderByField:reverseSort">
                        {{ }}
                        {{ employee.dateOfBirth | date:"dd/MM/yyyy" }}
                        {{ employee.gender }}
                        {{ employee.salary  }}
        var app = angular
        .module("myModule", [])
        .controller("myController", function ($scope) {

            var employees = [
                    name: "Ben", dateOfBirth: new Date("November 23, 1980"),
                    gender: "Male", salary: 55000
                    name: "Sara", dateOfBirth: new Date("May 05, 1970"),
                    gender: "Female", salary: 68000
                    name: "Mark", dateOfBirth: new Date("August 15, 1974"),
                    gender: "Male", salary: 57000
                    name: "Pam", dateOfBirth: new Date("October 27, 1979"),
                    gender: "Female", salary: 53000
                    name: "Todd", dateOfBirth: new Date("December 30, 1983"),
                    gender: "Male", salary: 60000

            $scope.employees = employees;
            $scope.orderByField = 'name';
            $scope.reverseSort = false;


MySQl Error #1064

maybe you forgot to add ";" after this line of code:

`quantity` INT NOT NULL)


Use SELECT COUNT(*) FROM t WHERE a = current_a AND c = 'const' ) as d.

Git pull till a particular commit

You can also pull the latest commit and just undo until the commit you desire:

git pull origin master
git reset --hard HEAD~1

Replace master with your desired branch.

Use git log to see to which commit you would like to revert:

git log

Personally, this has worked for me better.

Basically, what this does is pulls the latest commit, and you manually revert commits one by one. Use git log in order to see commit history.

Good points: Works as advertised. You don't have to use commit hash or pull unneeded branches.

Bad points: You need to revert commits on by one.

WARNING: Commit/stash all your local changes, because with --hard you are going to lose them. Use at your own risk!

LabelEncoder: TypeError: '>' not supported between instances of 'float' and 'str'

This is due to the series df[cat] containing elements that have varying data types e.g.(strings and/or floats). This could be due to the way the data is read, i.e. numbers are read as float and text as strings or the datatype was float and changed after the fillna operation.

In other words

pandas data type 'Object' indicates mixed types rather than str type

so using the following line:

df[cat] = le.fit_transform(df[cat].astype(str))

should help

jQuery toggle CSS?

I would use the toggleClass function in jQuery and define the CSS to the class e.g.

/* start of css */ {
    border-bottom-right-radius: 5px;
    border-bottom-left-radius: 5px;
    -webkit-border-bottom-right-radius: 5px; /* user-agent specific */
    -webkit-border-bottom-left-radius: 5px;
    -moz-border-radius-bottomright: 5px;
    -moz-border-radius-bottomleft: 5px; /* etc... */
/* start of js */
$('#user_button').click(function() {
    return false;

How can I alter a primary key constraint using SQL syntax?

In my case, I want to add a column to a Primary key (column4). I used this script to add column4


    [column1] ASC,
    [column2] ASC, 
    [column3] ASC,
    [column4] ASC

What's the difference between Invoke() and BeginInvoke()

The difference between Control.Invoke() and Control.BeginInvoke() is,

  • BeginInvoke() will schedule the asynchronous action on the GUI thread. When the asynchronous action is scheduled, your code continues. Some time later (you don't know exactly when) your asynchronous action will be executed
  • Invoke() will execute your asynchronous action (on the GUI thread) and wait until your action has completed.

A logical conclusion is that a delegate you pass to Invoke() can have out-parameters or a return-value, while a delegate you pass to BeginInvoke() cannot (you have to use EndInvoke to retrieve the results).

Pretty printing JSON from Jackson 2.2's ObjectMapper

the IDENT_OUTPUT did not do anything for me, and to give a complete answer that works with my jackson 2.2.3 jars:

public static void main(String[] args) throws IOException {

byte[] jsonBytes = Files.readAllBytes(Paths.get("C:\\data\\testfiles\\single-line.json"));

ObjectMapper objectMapper = new ObjectMapper();

Object json = objectMapper.readValue( jsonBytes, Object.class );

System.out.println( objectMapper.writerWithDefaultPrettyPrinter().writeValueAsString( json ) );

Error in installation a R package

I had the same problem with e1071 package. Just close any other R sessions running parallelly and you will be good to go.

How can I easily view the contents of a datatable or dataview in the immediate window

Give Xml Visualizer a try. Haven't tried the latest version yet, but I can't work without the previous one in Visual Studio 2003.

on top of displaying DataSet hierarchically, there are also a lot of other handy features such as filtering and selecting the RowState which you want to view.

$(document).ready not Working

I had copy pasted my inline js from some other .php project, inside that block of code there was some php code outputting some value, now since the variable wasn't defined in my new file, it was producing the typical php undefined warning/error, and because of that the js code was being messed up, and wasn't responding to any event, even alert("xyz"); would fail silently!! Although the erronous line was way near the end of the file, still the js would just die that too,

without any errors!!! >:(

Now one thing confusing is that debugger console/output gave no hint/error/warning whatsoever, the js was dying silently.

So try checking if you have php inline coded with the js, and see if it is outputting any error. Once removed/sorted your js should work fine.

Fastest way to remove non-numeric characters from a VARCHAR in SQL Server

I saw this solution with T-SQL code and PATINDEX. I like it :-)

CREATE Function [fnRemoveNonNumericCharacters](@strText VARCHAR(1000))
    WHILE PATINDEX('%[^0-9]%', @strText) > 0
        SET @strText = STUFF(@strText, PATINDEX('%[^0-9]%', @strText), 1, '')
    RETURN @strText

C#: How do you edit items and subitems in a listview?

If you're looking for "in-place" editing of a ListView's contents (specifically the subitems of a ListView in details view mode), you'll need to implement this yourself, or use a third-party control.

By default, the best you can achieve with a "standard" ListView is to set it's LabelEdit property to true to allow the user to edit the text of the first column of the ListView (assuming you want to allow a free-format text edit).

Some examples (including full source-code) of customized ListView's that allow "in-place" editing of sub-items are:

C# Editable ListView
In-place editing of ListView subitems

Getting "cannot find Symbol" in Java project in Intellij

For me - I tried these steps(Invalidate Cache & Restart, Maven Reimport)) but they didn't work. So I deleted the .idea, .settings, and .project folder and tried - it worked.

npm ERR cb() never called

Run the following command which solved my issue

npm install --no-package-lock

*ngIf else if in template

<ion-row *ngIf="cat === 1;else second"></ion-row>_x000D_
<ng-template #second>_x000D_
    <ion-row *ngIf="cat === 2;else third"></ion-row>_x000D_
<ng-template #third>_x000D_

Angular is already using ng-template under the hood in many of the structural directives that we use all the time: ngIf, ngFor and ngSwitch.

> What is ng-template in Angular

Xampp localhost/dashboard

Here's what's actually happening localhost means that you want to open htdocs. First it will search for any file named index.php or index.html. If one of those exist it will open the file. If neither of those exist then it will open all folder/file inside htdocs directory which is what you want.

So, the simplest solution is to rename index.php or index.html to index2.php etc.

How to rename a file using Python

#src and dst should be inside Folder2