Programs & Examples On #Preconditions

Failed to execute goal org.apache.maven.plugins:maven-surefire-plugin:2.12:test (default-test) on project.

Make sure the name of the class created in the package is something like Maven only picks the java files ending with Test notation.

I was getting the same error and resolving the names of all my classes by adding 'Test' at the end made it work.

REST response code for invalid data

400 is the best choice in both cases. If you want to further clarify the error you can either change the Reason Phrase or include a body to explain the error.

412 - Precondition failed is used for conditional requests when using last-modified date and ETags.

403 - Forbidden is used when the server wishes to prevent access to a resource.

The only other choice that is possible is 422 - Unprocessable entity.

display: inline-block extra margin

White space affects inline elements.

This should not come as a surprise. We see it every day with span, strong and other inline elements. Set the font size to zero to remove the extra margin.

.container {
  font-size: 0px;
  letter-spacing: 0px;
  word-spacing: 0px;

.container > div {
  display: inline-block;
  margin: 0px;
  padding: 0px;
  font-size: 15px;
  letter-spacing: 1em;
  word-spacing: 2em;

The example would then look like this.

<div class="container">

A jsfiddle version of this.

Declaring and initializing a string array in VB.NET

I believe you need to specify "Option Infer On" for this to work.

Option Infer allows the compiler to make a guess at what is being represented by your code, thus it will guess that {"stuff"} is an array of strings. With "Option Infer Off", {"stuff"} won't have any type assigned to it, ever, and so it will always fail, without a type specifier.

Option Infer is, I think On by default in new projects, but Off by default when you migrate from earlier frameworks up to 3.5.

Opinion incoming:

Also, you mention that you've got "Option Explicit Off". Please don't do this.

Setting "Option Explicit Off" means that you don't ever have to declare variables. This means that the following code will silently and invisibly create the variable "Y":

Dim X as Integer
Y = 3

This is horrible, mad, and wrong. It creates variables when you make typos. I keep hoping that they'll remove it from the language.

Adding delay between execution of two following lines

This line calls the selector secondMethod after 3 seconds:

[self performSelector:@selector(secondMethod) withObject:nil afterDelay:3.0 ];

Use it on your second operation with your desired delay. If you have a lot of code, place it in its own method and call that method with performSelector:. It wont block the UI like sleep

Edit: If you do not want a second method you could add a category to be able to use blocks with performSelector:

@implementation NSObject (PerformBlockAfterDelay)

- (void)performBlock:(void (^)(void))block 
    block = [block copy];
    [self performSelector:@selector(fireBlockAfterDelay:) 

- (void)fireBlockAfterDelay:(void (^)(void))block


Or perhaps even cleaner:

void RunBlockAfterDelay(NSTimeInterval delay, void (^block)(void))
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, NSEC_PER_SEC*delay),
      dispatch_get_current_queue(), block);

multiprocessing: How do I share a dict among multiple processes?

Maybe you can try pyshmht, sharing memory based hash table extension for Python.


  1. It's not fully tested, just for your reference.

  2. It currently lacks lock/sem mechanisms for multiprocessing.

CSS: auto height on containing div, 100% height on background div inside containing div

Somewhere you will need to set a fixed height, instead of using auto everywhere. You will find that if you set a fixed height on your content and/or container, then using auto for things inside it will work.

Also, your boxes will still expand height-wise with more content in, even though you have set a height for it - so don't worry about that :)

#container {

How can I make a TextArea 100% width without overflowing when padding is present in CSS?

No, you cannot do that with CSS. That is the reason Microsoft initially introduced another, and maybe more practical box model. The box model that eventually won, makes it inpractical to mix percentages and units.

I don't think it is OK with you to express padding and border widths in percentage of the parent too.

How can I divide one column of a data frame through another?

There are a plethora of ways in which this can be done. The problem is how to make R aware of the locations of the variables you wish to divide.


d <- read.table(text = "263807.0    1582
196190.5    1016
586689.0    3479
names(d) <- c("min", "count2.freq")
> d
       min count2.freq
1 263807.0        1582
2 196190.5        1016
3 586689.0        3479

My preferred way

To add the desired division as a third variable I would use transform()

> d <- transform(d, new = min / count2.freq)
> d
       min count2.freq      new
1 263807.0        1582 166.7554
2 196190.5        1016 193.1009
3 586689.0        3479 168.6373

The basic R way

If doing this in a function (i.e. you are programming) then best to avoid the sugar shown above and index. In that case any of these would do what you want

## 1. via `[` and character indexes
d[, "new"] <- d[, "min"] / d[, "count2.freq"]

## 2. via `[` with numeric indices
d[, 3] <- d[, 1] / d[, 2]

## 3. via `$`
d$new <- d$min / d$count2.freq

All of these can be used at the prompt too, but which is easier to read:

d <- transform(d, new = min / count2.freq)


d$new <- d$min / d$count2.freq ## or any of the above examples

Hopefully you think like I do and the first version is better ;-)

The reason we don't use the syntactic sugar of tranform() et al when programming is because of how they do their evaluation (look for the named variables). At the top level (at the prompt, working interactively) transform() et al work just fine. But buried in function calls or within a call to one of the apply() family of functions they can and often do break.

Likewise, be careful using numeric indices (## 2. above); if you change the ordering of your data, you will select the wrong variables.

The preferred way if you don't need replacement

If you are just wanting to do the division (rather than insert the result back into the data frame, then use with(), which allows us to isolate the simple expression you wish to evaluate

> with(d, min / count2.freq)
[1] 166.7554 193.1009 168.6373

This is again much cleaner code than the equivalent

> d$min / d$count2.freq
[1] 166.7554 193.1009 168.6373

as it explicitly states that "using d, execute the code min / count2.freq. Your preference may be different to mine, so I have shown all options.

Converting Select results into Insert script - SQL Server

I had a similar problem, but I needed to be able to create an INSERT statement from a query (with filters etc.)

So I created following procedure:

CREATE PROCEDURE dbo.ConvertQueryToInsert (@input NVARCHAR(max), @target NVARCHAR(max)) AS BEGIN

    DECLARE @fields NVARCHAR(max);
    DECLARE @select NVARCHAR(max);

    -- Get the defintion from sys.columns and assemble a string with the fields/transformations for the dynamic query
        @fields = COALESCE(@fields + ', ', '') + '[' + name +']', 
        @select = COALESCE(@select + ', ', '') + ''''''' + ISNULL(CAST([' + name + '] AS NVARCHAR(max)), ''NULL'')+'''''''
    FROM tempdb.sys.columns 
    WHERE [object_id] = OBJECT_ID(N'tempdb..'+@input);

    -- Run the a dynamic query with the fields from @select into a new temp table
    CREATE TABLE #ConvertQueryToInsertTemp (strings nvarchar(max))
    DECLARE @stmt NVARCHAR(max) = 'INSERT INTO #ConvertQueryToInsertTemp SELECT '''+ @select + ''' AS [strings] FROM '+@input
    exec sp_executesql @stmt

    -- Output the final insert statement 
    SELECT 'INSERT INTO ' + @target + ' (' + @fields + ') VALUES (' + REPLACE(strings, '''NULL''', 'NULL') +')' FROM #ConvertQueryToInsertTemp

    -- Clean up temp tables
    DROP TABLE #ConvertQueryToInsertTemp
    SET @stmt = 'DROP TABLE ' + @input
    exec sp_executesql @stmt

You can then use it by writing the output of your query into a temp table and running the procedure:

-- Example table
INSERT INTO Dummy VALUES (1 , 'Foo', GetDate()), (2, 'Bar', GetDate()), (3, 'Foo Bar', GetDate())

-- Run query and procedure
SELECT * INTO #TempTableForConvert FROM Dummy WHERE Id < 3
EXEC dbo.ConvertQueryToInsert '#TempTableForConvert', 'dbo.Dummy'

Note: This procedure only casts the values to a string which can cause the data to look a bit different. With DATETIME for example the seconds will be lost.

How can I view the contents of an ElasticSearch index?

You can view any existing index by using the below CURL. Please replace the index-name with your actual name before running and it will run as is.

View the index content

curl -H 'Content-Type: application/json' -X GET https://localhost:9200/index_name?pretty

And the output will include an index(see settings in output) and its mappings too and it will look like below output -

  "index_name": {
    "aliases": {},
    "mappings": {
      "collection_name": {
        "properties": {
          "test_field": {
            "type": "text",
            "fields": {
              "keyword": {
                "type": "keyword",
                "ignore_above": 256
    "settings": {
      "index": {
        "creation_date": "1527377274366",
        "number_of_shards": "5",
        "number_of_replicas": "1",
        "uuid": "6QfKqbbVQ0Gbsqkq7WZJ2g",
        "version": {
          "created": "6020299"
        "provided_name": "index_name"

View ALL the data under this index

curl -H 'Content-Type: application/json' -X GET https://localhost:9200/index_name/_search?pretty

Getting all types in a namespace via reflection

Quite simple

Type[] types = Assembly.Load(new AssemblyName("mynamespace.folder")).GetTypes();
foreach (var item in types)

How to remove outliers from a dataset

Try this. Feed your variable in the function and save the o/p in the variable which would contain removed outliers

    new_variable<-variable[variable>mild_low & variable<mild_high]

Remove whitespaces inside a string in javascript

You can use

"Hello World ".replace(/\s+/g, '');

trim() only removes trailing spaces on the string (first and last on the chain). In this case this regExp is faster because you can remove one or more spaces at the same time.

If you change the replacement empty string to '$', the difference becomes much clearer:

var string= '  Q  W E   R TY ';
console.log(string.replace(/\s/g, '$'));  // $$Q$$W$E$$$R$TY$
console.log(string.replace(/\s+/g, '#')); // #Q#W#E#R#TY#

Performance comparison - /\s+/g is faster. See here:

How do you completely remove the button border in wpf?

What you have to do is something like this:

<Button Name="MyFlatImageButton"
   <Image Source="MyImage.png"/>

Hope this is what you were looking for.

Edit: Sorry, forgot to mention that if you want to see the button-border when you hover over the image, all you have to do is skip the Padding="-4".

Http Post request with content type application/x-www-form-urlencoded not working in Spring

The easiest thing to do is to set the content type of your ajax request to "application/json; charset=utf-8" and then let your API method consume JSON. Like this:

var basicInfo = JSON.stringify({
    firstName: playerProfile.firstName(),
    lastName: playerProfile.lastName(),
    gender: playerProfile.gender(),
    address: playerProfile.address(),

    url: "http://localhost:8080/social/profile/update",
    type: 'POST',
    dataType: 'json',
    contentType: "application/json; charset=utf-8",
    data: basicInfo,
    success: function(data) {
        // ...

    value = "/profile/update",
    method = RequestMethod.POST,
    produces = MediaType.APPLICATION_JSON_VALUE,
    consumes = MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity<ResponseModel> UpdateUserProfile(
    @RequestBody User usersNewDetails,
    HttpServletRequest request,
    HttpServletResponse response
) {
    // ...

I guess the problem is that Spring Boot has issues submitting form data which is not JSON via ajax request.

Note: the default content type for ajax is "application/x-www-form-urlencoded".

R - " missing value where TRUE/FALSE needed "

Can you change the if condition to this:

if (![l])) print(comments[l]);

You can only check for NA values with

PHP/MySQL: How to create a comment section in your website

This is my way i do comments (I think its secure):

$i  = addslashes($_POST['a']);
$ip = addslashes($_POST['b']);
$a  = addslashes($_POST['c']);
$b  = addslashes($_POST['d']);
if(isset($i) & isset($ip) & isset($a) & isset($b))
    $r = mysql_query("SELECT COUNT(*) FROM $db.ban WHERE ip=$ip"); //Check if banned
    $r = mysql_fetch_array($r);
    if(!$r[0]) //Phew, not banned
        if(mysql_query("INSERT INTO $ VALUES ($a, $b, $ip, $i)"))
            <script type="text/javascript">
                window.location="/index.php?id=".<?php echo $i; ?>;
        else echo "Error, in mysql query";  
    else echo "Error, You are banned.";
$x = mysql_query("SELECT * FROM $ WHERE i=$i");
while($r = mysql_fetch_object($x) echo '<div class="c">'.$r->a.'<p>'.$row->b.'</p> </div>';

<h1>Leave a comment, pl0x:</h1>
<form action="<?php echo $_SERVER['PHP_SELF']; ?>" method="post">
    <input type="hidden" name="a" value="<?php $echo $_GET['id']; ?>" />
    <input type="hidden" name="b" value="<?php $echo $_SERVER['REMOTE_ADDR']; ?>" />
    <input type="text" name="c" value="Name"/></br>
    <textarea name="d">
    <input type="submit" />

This does it all in one page (This is only the comments section, some configuration is needed)

How to get Map data using JDBCTemplate.queryForMap

You can do something like this.

 List<Map<String, Object>> mapList = jdbctemplate.queryForList(query));
    return -> (Long) k.get("userid"), k -> (String) k.get("username")));


  1: "abc",
  2: "def",
  3: "ghi"

How to git ignore subfolders / subdirectories?

Seems this page still shows up on the top of Google search after so many years...

Modern versions of Git support nesting .gitignore files within a single repo. Just place a .gitignore file in the subdirectory that you want ignored. Use a single asterisk to match everything in that directory:

echo "*" > /path/to/bin/Debug/.gitignore
echo "*" > /path/to/bin/Release/.gitignore

If you've made previous commits, remember to remove previously tracked files:

git rm -rf /path/to/bin/Debug
git rm -rf /path/to/bin/Release

You can confirm it by doing git status to show you all the files removed from tracking.

Find unused code

Resharper is good for this like others have stated. Be careful though, these tools don't find you code that is used by reflection, e.g. cannot know if some code is NOT used by reflection.

XAMPP - Apache could not start - Attempting to start Apache service

I had the same issue, executing "setup_xampp.bat" in xampp folder solved my issue.

Update label from another thread

Use MethodInvoker for updating label text in other thread.

private void AggiornaContatore()
    MethodInvoker inv = delegate 
      this.lblCounter.Text = this.index.ToString(); 


You are getting the error because your UI thread is holding the label, and since you are trying to update it through another thread you are getting cross thread exception.

You may also see: Threading in Windows Forms

Trying to use fetch and pass in mode: no-cors

The simple solution: Add the following to the very top of the php file you are requesting the data from.

header("Access-Control-Allow-Origin: *");

How to set a variable to current date and date-1 in linux?

you should man date first

date +%Y-%m-%d
date +%Y-%m-%d -d yesterday

How do I compare strings in Java?

== compares object references in Java, and that is no exception for String objects.

For comparing the actual contents of objects (including String), one must use the equals method.

If a comparison of two String objects using == turns out to be true, that is because the String objects were interned, and the Java Virtual Machine is having multiple references point to the same instance of String. One should not expect that comparing one String object containing the same contents as another String object using == to evaluate as true.

Convert datetime object to a String of date only in Python

Another option:

import datetime
# ouptut --> '2016-03-09T08:18:20.860968'

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

Put it in double quotes:

echo "\t";

Single quotes do not expand escaped characters.

Use the documentation when in doubt.

How can I remove the top and right axis in matplotlib?

(This is more of an extension comment, in addition to the comprehensive answers here.)

Note that we can hide each of these three elements independently of each other:

  • To hide the border (aka "spine"): ax.set_frame_on(False) or ax.spines['top'].set_visible(False)

  • To hide the ticks: ax.tick_params(top=False)

  • To hide the labels: ax.tick_params(labeltop=False)

How to solve ' a 'type', which is not valid in the given context'? (C#)


private void Form1_Load(object sender, EventArgs e) 
        CERas.CERAS = new CERas.CERAS(); 


private void Form1_Load(object sender, EventArgs e) 
        CERas.CERAS c = new CERas.CERAS(); 

Or if you wish to use it later again

change it to

using System.Drawing; 
using System.Linq; 
using System.Text; 
using System.Windows.Forms; 

namespace WinApp_WMI2 
    public partial class Form1 : Form 
        CERas.CERAS m_CERAS;

        public Form1() 

    private void Form1_Load(object sender, EventArgs e) 
        m_CERAS = new CERas.CERAS(); 


How to draw a filled circle in Java?

public void paintComponent(Graphics g) {
   Graphics2D g2d = (Graphics2D)g;
   // Assume x, y, and diameter are instance variables.
   Ellipse2D.Double circle = new Ellipse2D.Double(x, y, diameter, diameter);

Here are some docs about paintComponent (link).

You should override that method in your JPanel and do something similar to the code snippet above.

In your ActionListener you should specify x, y, diameter and call repaint().

How to remove unique key from mysql table

To add a unique key use :

alter table your_table add UNIQUE(target_column_name);

To remove a unique key use:

alter table your_table drop INDEX target_column_name;

Passing vector by reference

void do_something(int el, std::vector<int> **arr)

should be

void do_something(int el, std::vector<int>& arr)

Pass by reference has been simplified to use the & in C++.

Converting milliseconds to a date (jQuery/JavaScript)

Try this one :

var time = new Date().toJSON();

console.log not working in Angular2 Component (Typescript)

It's not working because console.log() it's not in a "executable area" of the class "App".

A class is a structure composed by attributes and methods.

The only way to have your code executed is to place it inside a method that is going to be executed. For instance: constructor()

console.log('It works here')_x000D_
export class App {_x000D_
 s: string = "Hello2";_x000D_
  constructor() {_x000D_
    console.log(this.s)            _x000D_
  }            _x000D_

Think of class like a plain javascript object.

Would it make sense to expect this to work?

class:  {_x000D_
  s: string,_x000D_

If you still unsure, try the typescript playground where you can see your typescript code generated into plain javascript.

Android sqlite how to check if a record exists

I have tried all methods mentioned in this page, but only below method worked well for me.

Cursor c=db.rawQuery("SELECT * FROM user WHERE idno='"+txtID.getText()+"'", null);
 showMessage("Error", "Record exist");
 // Inserting record

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

Implements is used for Interfaces and extends is used to extend a class.

To make it more clearer in easier terms,an interface is like it sound - an interface - a model, that you need to apply,follow, along with your ideas to it.

Extend is used for classes,here,you are extending something that already exists by adding more functionality to it.

A few more notes:

an interface can extend another interface.

And when you need to choose between implementing an interface or extending a class for a particular scenario, go for implementing an interface. Because a class can implement multiple interfaces but extend only one class.

How to use adb command to push a file on device without sd card

run below command firstly

adb root
adb remount

Then execute what you input previously

C:\anand>adb push anand.jpg /data/local
C:\anand>adb push anand.jpg /data/opt
C:\anand>adb push anand.jpg /data/tmp

How to add an auto-incrementing primary key to an existing table, in PostgreSQL?

To use an identity column in v10,

ADD COLUMN id { int | bigint | smallint}

For an explanation of identity columns, see

For the difference between GENERATED BY DEFAULT and GENERATED ALWAYS, see

For altering the sequence, see

"Could not load type [Namespace].Global" causing me grief

  1. Right Click on Project Solution and Select Batch Build.
  2. Then select Your Project Name and Clean And Rebuild.

Works Fine For Me IN VS 2015.Now I can Use Global event. My Global.asax file has this Line

<%@ Application Language="C#" CodeBehind="~/App_Code/Global.asax.cs" Inherits="Global" %>

And I make class file Global.asax.cs that is in AppCode folder that look like

public partial class Global : HttpApplication
    public Global()
        // TODO: Add constructor logic here

I hope this will help

How to retrieve an element from a set without removing it?

How about s.copy().pop()? I haven't timed it, but it should work and it's simple. It works best for small sets however, as it copies the whole set.

How to redirect to a 404 in Rails?

  get '*unmatched_route', to: 'main#not_found'

  def not_found
    render :file => "#{Rails.root}/public/404.html", :status => 404, :layout => false

Windows Bat file optional argument parsing

Though I tend to agree with @AlekDavis' comment, there are nonetheless several ways to do this in the NT shell.

The approach I would take advantage of the SHIFT command and IF conditional branching, something like this...


SET man1=%1
SET man2=%2

IF NOT "%1"=="" (
    IF "%1"=="-username" (
        SET user=%2
    IF "%1"=="-otheroption" (
        SET other=%2
    GOTO :loop

ECHO Man1 = %man1%
ECHO Man2 = %man2%
ECHO Username = %user%
ECHO Other option = %other%

REM stuff here...


Jquery- Get the value of first td in table

In the specific case above, you could do parent/child juggling.


Transform only one axis to log10 scale with ggplot2

I had a similar problem and this scale worked for me like a charm:

breaks = 10**(1:10)
scale_y_log10(breaks = breaks, labels = comma(breaks))

as you want the intermediate levels, too (10^3.5), you need to tweak the formatting:

breaks = 10**(1:10 * 0.5)
m <- ggplot(diamonds, aes(y = price, x = color)) + geom_boxplot()
m + scale_y_log10(breaks = breaks, labels = comma(breaks, digits = 1))

After executing::

enter image description here

Adding 'serial' to existing column in Postgres


Here's a version where you don't need a human to read a value and type it out themselves.

SELECT setval('foo_a_seq', coalesce(max(a), 0) + 1, false) FROM foo;
ALTER TABLE foo ALTER COLUMN a SET DEFAULT nextval('foo_a_seq'); 

Another option would be to employ the reusable Function shared at the end of this answer.

A non-interactive solution

Just adding to the other two answers, for those of us who need to have these Sequences created by a non-interactive script, while patching a live-ish DB for instance.

That is, when you don't wanna SELECT the value manually and type it yourself into a subsequent CREATE statement.

In short, you can not do:

    START WITH ( SELECT max(a) + 1 FROM foo );

... since the START [WITH] clause in CREATE SEQUENCE expects a value, not a subquery.

Note: As a rule of thumb, that applies to all non-CRUD (i.e.: anything other than INSERT, SELECT, UPDATE, DELETE) statements in pgSQL AFAIK.

However, setval() does! Thus, the following is absolutely fine:

SELECT setval('foo_a_seq', max(a)) FROM foo;

If there's no data and you don't (want to) know about it, use coalesce() to set the default value:

SELECT setval('foo_a_seq', coalesce(max(a), 0)) FROM foo;
--                         ^      ^         ^
--                       defaults to:       0

However, having the current sequence value set to 0 is clumsy, if not illegal.
Using the three-parameter form of setval would be more appropriate:

--                                             vvv
SELECT setval('foo_a_seq', coalesce(max(a), 0) + 1, false) FROM foo;
--                                                  ^   ^
--                                                is_called

Setting the optional third parameter of setval to false will prevent the next nextval from advancing the sequence before returning a value, and thus:

the next nextval will return exactly the specified value, and sequence advancement commences with the following nextval.

— from this entry in the documentation

On an unrelated note, you also can specify the column owning the Sequence directly with CREATE, you don't have to alter it later:


In summary:

SELECT setval('foo_a_seq', coalesce(max(a), 0) + 1, false) FROM foo;
ALTER TABLE foo ALTER COLUMN a SET DEFAULT nextval('foo_a_seq'); 

Using a Function

Alternatively, if you're planning on doing this for multiple columns, you could opt for using an actual Function.

CREATE OR REPLACE FUNCTION make_into_serial(table_name TEXT, column_name TEXT) RETURNS INTEGER AS $$
    start_with INTEGER;
    sequence_name TEXT;
    sequence_name := table_name || '_' || column_name || '_seq';
    EXECUTE 'SELECT coalesce(max(' || column_name || '), 0) + 1 FROM ' || table_name
            INTO start_with;
    EXECUTE 'CREATE SEQUENCE ' || sequence_name ||
            ' START WITH ' || start_with ||
            ' OWNED BY ' || table_name || '.' || column_name;
    EXECUTE 'ALTER TABLE ' || table_name || ' ALTER COLUMN ' || column_name ||
            ' SET DEFAULT nextVal(''' || sequence_name || ''')';
    RETURN start_with;

Use it like so:

INSERT INTO foo (data) VALUES ('asdf');
-- ERROR: null value in column "a" violates not-null constraint

SELECT make_into_serial('foo', 'a');
INSERT INTO foo (data) VALUES ('asdf');
-- OK: 1 row(s) affected

Android - set TextView TextStyle programmatically?

You may try this one

            } else {

What is the difference between "expose" and "publish" in Docker?

Short answer:

  • EXPOSE is a way of documenting
  • --publish (or -p) is a way of mapping a host port to a running container port

Notice below that:

  • EXPOSE is related to Dockerfiles ( documenting )
  • --publish is related to docker run ... ( execution / run-time )

Exposing and publishing ports

In Docker networking, there are two different mechanisms that directly involve network ports: exposing and publishing ports. This applies to the default bridge network and user-defined bridge networks.

  • You expose ports using the EXPOSE keyword in the Dockerfile or the --expose flag to docker run. Exposing ports is a way of documenting which ports are used, but does not actually map or open any ports. Exposing ports is optional.

  • You publish ports using the --publish or --publish-all flag to docker run. This tells Docker which ports to open on the container’s network interface. When a port is published, it is mapped to an available high-order port (higher than 30000) on the host machine, unless you specify the port to map to on the host machine at runtime. You cannot specify the port to map to on the host machine when you build the image (in the Dockerfile), because there is no way to guarantee that the port will be available on the host machine where you run the image.

from: Docker container networking

Update October 2019: the above piece of text is no longer in the docs but an archived version is here:

Maybe the current documentation is the below:

Published ports

By default, when you create a container, it does not publish any of its ports to the outside world. To make a port available to services outside of Docker, or to Docker containers which are not connected to the container's network, use the --publish or -p flag. This creates a firewall rule which maps a container port to a port on the Docker host.

and can be found here:



...The EXPOSE instruction does not actually publish the port. It functions as a type of documentation between the person who builds the image and the person who runs the container, about which ports are intended to be published.

from: Dockerfile reference

Service access when EXPOSE / --publish are not defined:

At @Golo Roden's answer it is stated that::

"If you do not specify any of those, the service in the container will not be accessible from anywhere except from inside the container itself."

Maybe that was the case at the time the answer was being written, but now it seems that even if you do not use EXPOSE or --publish, the host and other containers of the same network will be able to access a service you may start inside that container.

How to test this:

I've used the following Dockerfile. Basically, I start with ubuntu and install a tiny web-server:

FROM ubuntu
RUN apt-get update && apt-get install -y mini-httpd

I build the image as "testexpose" and run a new container with:

docker run --rm -it testexpose bash

Inside the container, I launch a few instances of mini-httpd:

root@fb8f7dd1322d:/# mini_httpd -p 80
root@fb8f7dd1322d:/# mini_httpd -p 8080
root@fb8f7dd1322d:/# mini_httpd -p 8090

I am then able to use curl from the host or other containers to fetch the home page of mini-httpd.

Further reading

Very detailed articles on the subject by Ivan Pepelnjak:

Switch php versions on commandline ubuntu 16.04

You could use these open source PHP Switch Scripts, which were designed specifically for use in Ubuntu 16.04 LTS.

There is a script which installs all required dependencies for PHP 5.6, 7.0, 7.1 & 7.2. Once this is complete, you can just run one of the following switch scripts to change the PHP CLI and Apache 2 module version.


max(length(field)) in mysql

I suppose you could use a solution such as this one :

select name, length(name)
from users
where id = (
    select id
    from users
    order by length(name) desc
    limit 1

Might not be the optimal solution, though... But seems to work.

Writing to CSV with Python adds blank lines

The way you use the csv module changed in Python 3 in several respects (docs), at least with respect to how you need to open the file. Anyway, something like

import csv
with open('test.csv', 'w', newline='') as fp:
    a = csv.writer(fp, delimiter=',')
    data = [['Me', 'You'],
            ['293', '219'],
            ['54', '13']]

should work.

DSO missing from command line

DSO here means Dynamic Shared Object; since the error message says it's missing from the command line, I guess you have to add it to the command line.

That is, try adding -lpthread to your command line.

The project was not built since its build path is incomplete

Here is what made the error disappear for me:

Close eclipse, open up a terminal window and run:

$ mvn clean eclipse:clean eclipse:eclipse

Are you using Maven? If so,

  1. Right-click on the project, Build Path and go to Configure Build Path
  2. Click the libraries tab. If Maven dependencies are not in the list, you need to add it.
  3. Close the dialog.

To add it: Right-click on the project, Maven → Disable Maven Nature Right-click on the project, Configure → Convert to Maven Project.

And then clean

Edit 1:

If that doesn't resolve the issue try right-clicking on your project and select properties. Select Java Build Path → Library tab. Look for a JVM. If it's not there, click to add Library and add the default JVM. If VM is there, click edit and select the default JVM. Hopefully, that works.

Edit 2:

You can also try going into the folder where you have all your projects and delete the .metadata for eclipse (be aware that you'll have to re-import all the projects afterwards! Also all the environment settings you've set would also have to be redone). After it was deleted just import the project again, and hopefully, it works.

How to "flatten" a multi-dimensional array to simple one in PHP?

If you're okay with loosing array keys, you may flatten a multi-dimensional array using a recursive closure as a callback that utilizes array_values(), making sure that this callback is a parameter for array_walk(), as follows.


$array = [1,2,3,[5,6,7]];
$nu_array = null;
$callback = function ( $item ) use(&$callback, &$nu_array) {
    if (!is_array($item)) {
    $nu_array[] = $item;
    if ( is_array( $item ) ) {
     foreach( array_values($item) as $v) {
         if ( !(is_array($v))) {
             $nu_array[] = $v;
             $callback( $v );

array_walk($array, $callback);

The one drawback of the preceding example is that it involves writing far more code than the following solution which uses array_walk_recursive() along with a simplified callback:


$array = [1,2,3,[5,6,7]];

$nu_array = [];
array_walk_recursive($array, function ( $item ) use(&$nu_array )
                         $nu_array[] = $item;

See live code

This example seems preferable to the previous one, hiding the details about how values are extracted from a multidimensional array. Surely, iteration occurs, but whether it entails recursion or control structure(s), you'll only know from perusing array.c. Since functional programming focuses on input and output rather than the minutiae of obtaining a result, surely one can remain unconcerned about how behind-the-scenes iteration occurs, that is until a perspective employer poses such a question.

How can I change the font size using seaborn FacetGrid?

I've made small modifications to @paul-H code, such that you can set the font size for the x/y axes and legend independently. Hope it helps:

import numpy as np
import matplotlib.pyplot as plt
import seaborn as sns
x = np.random.normal(size=37)
y = np.random.lognormal(size=37)

# defaults                                                                                                         
fig, ax = plt.subplots()
ax.plot(x, y, marker='s', linestyle='none', label='small')
ax.legend(loc='upper left', fontsize=20,bbox_to_anchor=(0, 1.1))

This is the output:

enter image description here

PHP Get Site URL Protocol - http vs https

Extracted from CodeIgniter :

if ( ! function_exists('is_https'))
     * Is HTTPS?
     * Determines if the application is accessed via an encrypted
     * (HTTPS) connection.
     * @return  bool
    function is_https()
        if ( ! empty($_SERVER['HTTPS']) && strtolower($_SERVER['HTTPS']) !== 'off')
            return TRUE;
        elseif (isset($_SERVER['HTTP_X_FORWARDED_PROTO']) && strtolower($_SERVER['HTTP_X_FORWARDED_PROTO']) === 'https')
            return TRUE;
        elseif ( ! empty($_SERVER['HTTP_FRONT_END_HTTPS']) && strtolower($_SERVER['HTTP_FRONT_END_HTTPS']) !== 'off')
            return TRUE;

        return FALSE;

Show all tables inside a MySQL database using PHP?

Try this:

SHOW TABLES FROM nameOfDatabase;

Delete all records in a table of MYSQL in phpMyAdmin

Use this query:

DELETE FROM tableName;

Note: To delete some specific record you can give the condition in where clause in the query also.

OR you can use this query also:

truncate tableName;

Also remember that you should not have any relationship with other table. If there will be any foreign key constraint in the table then those record will not be deleted and will give the error.

How to create empty folder in java?

You can create folder using the following Java code:

File dir = new File("nameoffolder");

By executing above you will have folder 'nameoffolder' in current folder.

Can't find the 'libpq-fe.h header when trying to install pg gem

Ubuntu 20.04.1 LTS, this seemed to work for me:

sudo apt-get install ruby ruby-dev libpqxx-dev libpq-fe-dev libpq-dev 
sudo gem install pg -- --with-pg-config=/usr/include/postgresql/pg_config --with-pg-include=/usr/include/postgresql/ get file names in directory?

You will need to use the IO.Directory.GetFiles function.

Dim files() As String = IO.Directory.GetFiles("c:\")

For Each file As String In files
  ' Do work, example
  Dim text As String = IO.File.ReadAllText(file)

Adding files to a GitHub repository

You can use Git GUI on Windows, see instructions:

  1. Open the Git Gui (After installing the Git on your computer).

enter image description here

  1. Clone your repository to your local hard drive:

enter image description here

  1. After cloning, GUI opens, choose: "Rescan" for changes that you made:

enter image description here

  1. You will notice the scanned files:

enter image description here

  1. Click on "Stage Changed":

enter image description here

  1. Approve and click "Commit":

enter image description here

  1. Click on "Push":

enter image description here

  1. Click on "Push":

enter image description here

  1. Wait for the files to upload to git:

enter image description here

enter image description here

How to cast an Object to an int

Finally, the best implementation for your specification was found.

public int tellMyNumber(Object any) {
    return 42;

Passing structs to functions

Passing structs to functions by reference: simply :)

#define maxn 1000

struct solotion
    int sol[maxn];
    int arry_h[maxn];
    int cat[maxn];
    int scor[maxn];


void inser(solotion &come){

void initial(solotion &come){
    for(int i=0;i<maxn;i++)

int main()
    solotion sol1;
    solotion sol2;

Is there a replacement for unistd.h for Windows (Visual C)?

I would recommend using mingw/msys as a development environment. Especially if you are porting simple console programs. Msys implements a Unix-like shell on Windows, and mingw is a port of the GNU compiler collection (GCC) and other GNU build tools to the Windows platform. It is an open-source project, and well-suited to the task. I currently use it to build utility programs and console applications for Windows XP, and it most certainly has that unistd.h header you are looking for.

The install procedure can be a little bit tricky, but I found that the best place to start is in MSYS.

Are complex expressions possible in ng-hide / ng-show?

ng-show / ng-hide accepts only boolean values.

For complex expressions it is good to use controller and scope to avoid complications.

Below one will work (It is not very complex expression)

ng-show="User=='admin' || User=='teacher'"

Here element will be shown in UI when any of the two condition return true (OR operation).

Like this you can use any expressions.

window.location.href and () methods in JavaScript

window.location.href is not a method, it's a property that will tell you the current URL location of the browser. Changing the value of the property will redirect the page. is a method that you can pass a URL to that you want to open in a new window. For example:

window.location.href example:

window.location.href = ''; //Will take you to Google. example:''); //This will open Google in a new window.

Additional Information: can be passed additional parameters. See: tutorial

Change Bootstrap input focus blue glow

In Bootstrap 3.3.7 you can change the @input-border-focus value in the Forms section of the customizer: enter image description here

Facebook development in localhost

Don't have enough cred to comment on the top voted answer, but at least in my rails environment (running 4), rails s is at http://localhost:3000, not http://www.localhost:3000. When I changed it to http://localhost:3000, it worked just fine. No need to edit any hosts file.

Unrecognized SSL message, plaintext connection? Exception

Maybe your default cerficate has expired. to renew it through admin console go "Security >SSL certificate and key management > Key stores and certificates > NodeDefaultKeyStore > Personal certificates" select the "default" alias and click on "renew" after then restart WAS.

How to store file name in database, with other info while uploading image to server using PHP?

If you want to input more data into the form, you simply access the submitted data through $_POST.

If you have

<input type="text" name="firstname" />

you access it with

$firstname = $_POST["firstname"];

You could then update your query line to read

mysql_query("INSERT INTO dbProfiles (photo,firstname)

Note: Always filter and sanitize your data.

How do you kill a Thread in Java?

Attempts of abrupt thread termination are well-known bad programming practice and evidence of poor application design. All threads in the multithreaded application explicitly and implicitly share the same process state and forced to cooperate with each other to keep it consistent, otherwise your application will be prone to the bugs which will be really hard to diagnose. So, it is a responsibility of developer to provide an assurance of such consistency via careful and clear application design.

There are two main right solutions for the controlled threads terminations:

  • Use of the shared volatile flag
  • Use of the pair of Thread.interrupt() and Thread.interrupted() methods.

Good and detailed explanation of the issues related to the abrupt threads termination as well as examples of wrong and right solutions for the controlled threads termination can be found here:

Can't find AVD or SDK manager in Eclipse

Window -> Custom Perspective -> Command Groups Availability -> Android SDK and AVD Manager check it

What is difference between Lightsail and EC2?

Lightsail VPSs are bundles of existing AWS products, offered through a significantly simplified interface. The difference is that Lightsail offers you a limited and fixed menu of options but with much greater ease of use. Other than the narrower scope of Lightsail in order to meet the requirements for simplicity and low cost, the underlying technology is the same.

The pre-defined bundles can be described:

% aws lightsail --region us-east-1 get-bundles
    "bundles": [
            "name": "Nano",
            "power": 300,
            "price": 5.0,
            "ramSizeInGb": 0.5,
            "diskSizeInGb": 20,
            "transferPerMonthInGb": 1000,
            "cpuCount": 1,
            "instanceType": "t2.nano",
            "isActive": true,
            "bundleId": "nano_1_0"

It's worth reading through the Amazon EC2 T2 Instances documentation, particularly the CPU Credits section which describes the base and burst performance characteristics of the underlying instances.

Importantly, since your Lightsail instances run in VPC, you still have access to the full spectrum of AWS services, e.g. S3, RDS, and so on, as you would from any EC2 instance.

Observable.of is not a function

If anybody is having this problem while using Angular 6/rxjs 6 see the answers here: Could not use Observable.of in RxJs 6 and Angular 6

In short, you need to import it like this:

import { of } from 'rxjs';

And then instead of calling


just use


Can't specify the 'async' modifier on the 'Main' method of a console app

To avoid freezing when you call a function somewhere down the call stack that tries to re-join the current thread (which is stuck in a Wait), you need to do the following:

class Program
    static void Main(string[] args)
        Bootstrapper bs = new Bootstrapper();
        List<TvChannel> list = Task.Run((Func<Task<List<TvChannel>>>)bs.GetList).Result;

(the cast is only required to resolve ambiguity)

standard size for html newsletter template

Ideally the email content should be about 550px wide to fit within most email clients preview window. If you know for sure your target market can view bigger then you can design bigger. Loads of email examples over on

How do I serialize a C# anonymous type to a JSON string?

Please note this is from 2008. Today I would argue that the serializer should be built in and that you can probably use swagger + attributes to inform consumers about your endpoint and return data.

Iwould argue that you shouldn't be serializing an anonymous type. I know the temptation here; you want to quickly generate some throw-away types that are just going to be used in a loosely type environment aka Javascript in the browser. Still, I would create an actual type and decorate it as Serializable. Then you can strongly type your web methods. While this doesn't matter one iota for Javascript, it does add some self-documentation to the method. Any reasonably experienced programmer will be able to look at the function signature and say, "Oh, this is type Foo! I know how that should look in JSON."

Having said that, you might try JSON.Net to do the serialization. I have no idea if it will work

How to initialize all the elements of an array to any specific value in java

If it's a primitive type, you can use Arrays.fill():

Arrays.fill(array, -1);

[Incidentally, memset in C or C++ is only of any real use for arrays of char.]

HTTP client timeout and server timeout

There's many forms of timeout, are you after the connection timeout, request timeout or time to live (time before TCP connection stops).

The default TimeToLive on Firefox is 115s (network.http.keep-alive.timeout)

The default connection timeout on Firefox is 250s (network.http.connection-retry-timeout)

The default request timeout for Firefox is 30s (

The time it takes to do an HttpRequest depends on if a connection has been made this has to be within 250s which I'm guessing you're not after. You're probably after the request timeout which I think is 30,000ms (30s) so to conclude I'd say it's timing out with a connection time out that's why you got a response back after ~150s though I haven't really tested this.

Problem with converting int to string in Linq to entities

if you use entity framework and you want to make the only int acceptable then you can use this in linq query you can try this

var items = from c in contacts
        select new ListItem
            Value = (int)ContractId 
            Text = c.Name

it will work because using (int) will cast your value to the int so you don't need any conversion for string to int and you get the result you want.

this worked for me in my project i think it would be helpful for you

Javascript validation: Block special characters

A few of the options are deprecated as of today. So watch out for those.

If you try <input onkeypress="blockSpecialCharacters(event)" />, an IDE like WebStorm will slash out event and tell you:

Deprecated symbol used, consults docs for better alternative

Then when you get to the JavaScript, console.log(e.keyCode) will also give keyCode and say:

Deprecated symbol used, consults docs for better alternative

Anyways I did it using jQuery.

<script src=""></script>

<input id="theInput" />

    function blockSpecialCharacters(e) {
            let key = e.key;
            let keyCharCode = key.charCodeAt(0);

            // 0-9
            if(keyCharCode >= 48 && keyCharCode <= 57) {
                return key;
            // A-Z
            if(keyCharCode >= 65 && keyCharCode <= 90) {
                return key;
            // a-z
            if(keyCharCode >= 97 && keyCharCode <= 122) {
                return key;

            return false;

    $('#theInput').keypress(function(e) {

How to add constraints programmatically using Swift

the following code works for me in this scenario: an UIImageView forced landscape.

    imagePreview!.isUserInteractionEnabled = true
    imagePreview!.isExclusiveTouch = true
    imagePreview!.contentMode = UIView.ContentMode.scaleAspectFit
    // Remove all constraints
    // Add the new constraints
    let guide = view.safeAreaLayoutGuide
    imagePreview!.translatesAutoresizingMaskIntoConstraints = false
    imagePreview!.leadingAnchor.constraint(equalTo: guide.leadingAnchor).isActive = true
    imagePreview!.trailingAnchor.constraint(equalTo: guide.trailingAnchor).isActive = true
    imagePreview!.heightAnchor.constraint(equalTo: guide.heightAnchor, multiplier: 1.0).isActive = true

where removeAllConstraints is an extension

extension UIView {
    func removeAllConstraints() {
        var _superview = self.superview
        func removeAllConstraintsFromView(view: UIView) { for c in view.constraints { view.removeConstraint(c) } }
        while let superview = _superview {
            for constraint in superview.constraints {
                if let first = constraint.firstItem as? UIView, first == self {
                if let second = constraint.secondItem as? UIView, second == self {
            _superview = superview.superview
        self.translatesAutoresizingMaskIntoConstraints = true

How can I change the width and height of slides on Slick Carousel?

I initialised the slider with one of the properties as

variableWidth: true

then i could set the width of the slides to anything i wanted in CSS with:

.slick-slide {
    width: 200px;

How can I introduce multiple conditions in LIKE operator?

This might help:

select * from tbl where col like '[ABC-XYZ-PQR]%'

I've used this in SQL Server 2005 and it worked.

How exactly to use Notification.Builder

In case it helps anyone... I was having a lot of trouble with setting up notifications using the support package when testing against newer an older API's. I was able to get them to work on the newer device but would get an error testing on the old device. What finally got it working for me was to delete all the imports related to the notification functions. In particular the NotificationCompat and the TaskStackBuilder. It seems that while setting up my code in the beginning the imports where added from the newer build and not from the support package. Then when I wanted to implement these items later in eclipse, I wasn't prompted to import them again. Hope that makes sense, and that it helps someone else out :)

Change Name of Import in Java, or import two classes with the same name

There is no import aliasing mechanism in Java. You cannot import two classes with the same name and use both of them unqualified.

Import one class and use the fully qualified name for the other one, i.e.

import com.text.Formatter;

private Formatter textFormatter;
private com.json.Formatter jsonFormatter;

Change the fill color of a cell based on a selection from a Drop Down List in an adjacent cell

This works with me :
1- select the cells which shall be be affected by the drop down list .
2- home -> conditional formating -> new rule .
3- format only cells that contain .
4- in format only cells with ... select specific text , in formatting rule "= select Elementary from your drop down list"
if drop list in another sheet then when select Elementary we see "=Sheet3!$F$2" in the new rule , with your own sheet and cell number.
5- format -> fill -> select color -> ok.
6-ok .
do the same for each element in drop down list then you will see the magic !

make div's height expand with its content

Use the span tag with display:inline-block css attached to it. You can then use CSS and manipulate it like a div in lots of ways but if you don't include a width or height it expands and retracts based on its content.

Hope that helps.

Making an API call in Python with an API that requires a bearer token

The token has to be placed in an Authorization header according to the following format:

Authorization: Bearer [Token_Value]

Code below:

import urllib2
import json

def get_auth_token():
    get an auth token
    return token_string

def get_response_json_object(url, auth_token):
    returns json object with info
    req=urllib2.Request(url, None, {"Authorization": "Bearer %s" %auth_token})
    return json_obj

Return JSON for ResponseEntity<String>

This is a String, not a json structure(key, value), try:

return new ResponseEntity("{"vale" : "This is a String"}", HttpStatus.OK);

Add placeholder text inside UITextView in Swift?

There is no such property in ios to add placeholder directly in TextView rather you can add a label and show/hide on the change in textView. SWIFT 2.0 and make sure to implement the textviewdelegate

func textViewDidChange(TextView: UITextView)

 if  txtShortDescription.text == ""
        self.lblShortDescription.hidden = false
        self.lblShortDescription.hidden = true


Android Canvas.drawText

Worked this out, turns out that is not the same as Color.BLACK. Changed the code to:

Paint paint = new Paint(); 

canvas.drawText("Some Text", 10, 25, paint); 

and it all works fine now!!

Arduino COM port doesn't work

This fix / solution worked for me: Device Manager --> Ports --> right click on Arduino Uno --> Update Driver Software --> Search automatically for updated driver software

How to search images from private 1.0 registry in docker?

Modifying the answer from @mre to get the list just from one command (valid at least for Docker Registry v2).

docker exec -it <your_registry_container_id> ls -a /var/lib/registry/docker/registry/v2/repositories/

JPA: how do I persist a String into a database field, type MYSQL Text

With @Lob I always end up with a LONGTEXTin MySQL.

To get TEXT I declare it that way (JPA 2.0):

@Column(columnDefinition = "TEXT")
private String text

Find this better, because I can directly choose which Text-Type the column will have in database.

For columnDefinition it is also good to read this.

EDIT: Please pay attention to Adam Siemions comment and check the database engine you are using, before applying columnDefinition = "TEXT".

Android Relative Layout Align Center

Is this what you need?

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android=""
    android:layout_height="fill_parent" >

        android:layout_marginRight="10dp" >

            android:src="@drawable/marker" />

            android:text="Place Name"
            android:textStyle="bold" />

            android:text="320" />


@ variables in Ruby on Rails

A tutorial about What is Variable Scope? presents some details quite well, just enclose the related here.

| Name Begins With |    Variable Scope    |
| $                | A global variable    |
| @                | An instance variable |
| [a-z] or _       | A local variable     |
| [A-Z]            | A constant           |
| @@               | A class variable     |

Call parent method from child class c#

Found the solution.

In the parent I declare a new instance of the ChildClass() then bind the event handler in that class to the local method in the parent

In the child class I add a public event handler:

public EventHandler UpdateProgress;

In the parent I create a new instance of this child class then bind the local parent event to the public eventhandler in the child

ChildClass child = new ChildClass();
child.UpdateProgress += this.MyMethod;

Then in the LoadData() of the child class I can call

private LoadData() {

Where OnMyMethod is:

public void OnMyMethod()
     // has the event handler been assigned?
     if (this.UpdateProgress!= null)
         // raise the event
         this.UpdateProgress(this, new EventArgs());

This runs the event in the parent class

Operator overloading ==, !=, Equals

I think you declared the Equals method like this:

public override bool Equals(BOX obj)

Since the object.Equals method takes an object, there is no method to override with this signature. You have to override it like this:

public override bool Equals(object obj)

If you want type-safe Equals, you can implement IEquatable<BOX>.

Min/Max of dates in an array?

Same as apply, now with spread :

const maxDate = new Date(Math.max(...dates));

(could be a comment on best answer)

@import vs #import - iOS 7

It seems that since XCode 7.x a lot of warnings are coming out when enabling clang module with CLANG_ENABLE_MODULES

Take a look at Lots of warnings when building with Xcode 7 with 3rd party libraries

How to disable the resize grabber of <textarea>?

Just use resize: none

textarea {
   resize: none;

You can also decide to resize your textareas only horizontal or vertical, this way:

textarea { resize: vertical; }

textarea { resize: horizontal; }

Finally, resize: both enables the resize grabber.

Can you find all classes in a package using reflection?

If you are merely looking to load a group of related classes, then Spring can help you.

Spring can instantiate a list or map of all classes that implement a given interface in one line of code. The list or map will contain instances of all the classes that implement that interface.

That being said, as an alternative to loading the list of classes out of the file system, instead just implement the same interface in all the classes you want to load, regardless of package and use Spring to provide you instances of all of them. That way, you can load (and instantiate) all the classes you desire regardless of what package they are in.

On the other hand, if having them all in a package is what you want, then simply have all the classes in that package implement a given interface.

How do I print the elements of a C++ vector in GDB?

To view vector std::vector myVector contents, just type in GDB:

(gdb) print myVector

This will produce an output similar to:

$1 = std::vector of length 3, capacity 4 = {10, 20, 30}

To achieve above, you need to have gdb 7 (I tested it on gdb 7.01) and some python pretty-printer. Installation process of these is described on gdb wiki.

What is more, after installing above, this works well with Eclipse C++ debugger GUI (and any other IDE using GDB, as I think).

How to get a list of sub-folders and their files, ordered by folder-names

In command prompt go to the main directory you want the list for ... and type the command tree /f

align 3 images in same row with equal spaces?

This should be your answer

<div align="center">
 <img src="@Url.Content("~/images/image3.bmp")" alt="" align="right" style="float:right"/>
 <img src="@Url.Content("~/images/image1.bmp")" alt="" align="left" style="float:left" />
 <div id="content" align="center"> 
     <img src="@Url.Content("~/images/image2.bmp")" alt="" align="center" />
 </div> Validation of viewstate MAC failed

Microsoft says to never use a key generator web site.

Like everyone else here, I added this to my web.config.

    <machineKey decryptionKey="ABC123...SUPERLONGKEY...5432JFEI242" 
                validation="SHA1" />

However, I used IIS as my machineKey generator like so:

  1. Open IIS and select a website to get this screen:

enter image description here

  1. Double click the Machine Key icon to get this screen:

enter image description here

  1. Click the "Generate Keys" link on the right which I outlined in the pic above.


  • If you select the "Generate a unique key for each application" checkbox, ",IsolateApps" will be added to the end of your keys. I had to remove these to get the app to work. Obviously, they're not part of the key.
  • SHA1 was the default encryption method selected by IIS and if you change it, don't forget to change the validation property on machineKey in the web.config. However, encryption methods and algorithms evolve so please feel free to edit this post with the updated preferred Encryption method or mention it in the notes and I'll update.

How to assign a value to a TensorFlow variable?

Use Tensorflow eager execution mode which is latest.

import tensorflow as tf
my_int_variable = tf.get_variable("my_int_variable", [1, 2, 3])

What is the difference between substr and substring?

substring (MDN) takes parameters as (from, to).
substr (MDN) takes parameters as (from, length).

Update: MDN considers substr legacy.

alert("abc".substr(1,2)); // returns "bc"
alert("abc".substring(1,2)); // returns "b"

You can remember substring (with an i) takes indices, as does yet another string extraction method, slice (with an i).

When starting from 0 you can use either method.

Could not load file or assembly 'log4net, Version=, Culture=neutral, PublicKeyToken=692fbea5521e1304'

If you are building a windows app try to build as x64 instead of Any CPU. It should work fine.

Generic Property in C#

You can make a generic class like this:

public class MyProp<T>
    private T _value;

    public T Value
            // insert desired logic here
            return _value;
            // insert desired logic here
            _value = value;

    public static implicit operator T(MyProp<T> value)
        return value.Value;

    public static implicit operator MyProp<T>(T value)
        return new MyProp<T> { Value = value };

...then use it in a class like so:

class SomeClass
    public MyProp<int> SomeProperty { get; set; }

The implicit operators means that you do not need to explicitly set or get the Value property of MyProp, but can write code to access the value in a more "natural" way:

SomeClass instance = new SomeClass();
instance.SomeProperty = 32;
int someInt = instance.SomeProperty;

Removing elements from array Ruby

a = [1,1,1,2,2,3]
a.slice!(0) # remove first index
a.slice!(-1) # remove last index
# a = [1,1,2,2] as desired

set the iframe height automatically

If the sites are on separate domains, the calling page can't access the height of the iframe due to cross-browser domain restrictions. If you have access to both sites, you may be able to use the [document domain hack].1 Then anroesti's links should help.

How to create a WPF Window without a border that can be resized via a grip only?

If you set the AllowsTransparency property on the Window (even without setting any transparency values) the border disappears and you can only resize via the grip.

    Width="640" Height="480" 

    <!-- Content -->


Result looks like:

How do I get a specific range of numbers from rand()?

As others have noted, simply using a modulus will skew the probabilities for individual numbers so that smaller numbers are preferred.

A very ingenious and good solution to that problem is used in Java's java.util.Random class:

public int nextInt(int n) {
    if (n <= 0)
        throw new IllegalArgumentException("n must be positive");

    if ((n & -n) == n)  // i.e., n is a power of 2
        return (int)((n * (long)next(31)) >> 31);

    int bits, val;
    do {
        bits = next(31);
        val = bits % n;
    } while (bits - val + (n-1) < 0);
    return val;

It took me a while to understand why it works and I leave that as an exercise for the reader but it's a pretty concise solution which will ensure that numbers have equal probabilities.

The important part in that piece of code is the condition for the while loop, which rejects numbers that fall in the range of numbers which otherwise would result in an uneven distribution.

Getting Cannot read property 'offsetWidth' of undefined with bootstrap carousel script

I got same error. Because i used v4 alpha class names like carousel-control-next When i changed with v3, problem solved.

C# 30 Days From Todays Date

A bit late to this question, but I created a class with all the handy methods needed to create a fully functional time trial in C#. Rather than your application config, I write the expiry time to the Windows Application Data path, and that will also remain persistent even after the program has closed (it's also tricky to find the path for the average user).

Fully documented and simple to use, I hope someone finds it useful!

public class TimeTrialManager
    private long expiryTime=0;
    private string softwareName = "";
    private string userPath="";
    private bool useSeconds = false;

    public TimeTrialManager(string softwareName) {
        this.softwareName = softwareName;
        // Create folder in Windows Application Data folder for persistence:
        userPath = Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData).ToString() + "\\" + softwareName + "_prefs\\";
        if (!Directory.Exists(userPath)) Directory.CreateDirectory(Path.GetDirectoryName(userPath));
        userPath += "expiryinfo.txt";

    // Use this method to check if the expiry has already been created. If
    // it has, you don't need to call the setExpiryDate() method ever again.
    public bool expiryHasBeenStored(){
        return File.Exists(userPath);

    // Use this to set expiry as the number of days from the current time.
    // This should be called just once in the program's lifetime for that user.
    public void setExpiryDate(double days)  {
        DateTime time = DateTime.Now.AddDays(days);
        expiryTime = time.ToFileTimeUtc();
        storeExpiry(expiryTime.ToString() );
        useSeconds = false;

    // Like above, but set the number of seconds. This should be just used for testing
    // as no sensible time trial would allow the user seconds to test the trial out:
    public void setExpiryTime(double seconds)   {
        DateTime time = DateTime.Now.AddSeconds(seconds);
        expiryTime = time.ToFileTimeUtc();
        useSeconds = true;

    // Check for this in a background timer or whenever else you wish to check if the time has run out
    public bool trialHasExpired()   {
        if(!File.Exists(userPath)) return false;
        if (expiryTime == 0)    expiryTime = Convert.ToInt64(File.ReadAllText(userPath));
        if (DateTime.Now.ToFileTimeUtc() >= expiryTime) return true; else return false;

    // This method is optional and isn't required to use the core functionality of the class
    // Perhaps use it to tell the user how long he has left to trial the software
    public string expiryAsHumanReadableString(bool remaining=false) {
        DateTime dt = new DateTime();
        dt = DateTime.FromFileTimeUtc(expiryTime);
        if (remaining == false) return dt.ToShortDateString() + " " + dt.ToLongTimeString();
        else {
            if (useSeconds) return dt.Subtract(DateTime.Now).TotalSeconds.ToString();
            else return (dt.Subtract(DateTime.Now).TotalDays ).ToString();

    // This method is private to the class, so no need to worry about it
    private void storeExpiry(string value)  {
        try { File.WriteAllText(userPath, value); }
        catch (Exception ex) { MessageBox.Show(ex.Message); }


Here is a typical usage of the above class. Couldn't be simpler!

TimeTrialManager ttm;
private void Form1_Load(object sender, EventArgs e)
    ttm = new TimeTrialManager("TestTime");
    if (!ttm.expiryHasBeenStored()) ttm.setExpiryDate(30); // Expires in 30 days time

private void timer1_Tick(object sender, EventArgs e)
    if (ttm.trialHasExpired()) { MessageBox.Show("Trial over! :("); Environment.Exit(0); }

Lists in ConfigParser

No mention of the converters kwarg for ConfigParser() in any of these answers was rather disappointing.

According to the documentation you can pass a dictionary to ConfigParser that will add a get method for both the parser and section proxies. So for a list:


germs: a,list,of,names, and,1,2, 3,numbers

Parser example:

cp = ConfigParser(converters={'list': lambda x: [i.strip() for i in x.split(',')]})'example.ini')
cp.getlist('Germ', 'germs')
['a', 'list', 'of', 'names', 'and', '1', '2', '3', 'numbers']
['a', 'list', 'of', 'names', 'and', '1', '2', '3', 'numbers']

This is my personal favorite as no subclassing is necessary and I don't have to rely on an end user to perfectly write JSON or a list that can be interpreted by ast.literal_eval.

Get the current language in device

public class LocalUtils {

    private static final String LANGUAGE_CODE_ENGLISH = "en";

    // returns application language eg: en || fa ...
    public static String getAppLanguage() {
        return Locale.getDefault().getLanguage();

    // returns device language eg: en || fa ...
    public static String getDeviceLanguage() {
        return ConfigurationCompat.getLocales(Resources.getSystem().getConfiguration()).get(0).getLanguage();

    public static boolean isDeviceEnglish() {
        return getDeviceLanguage().equals(new Locale(LANGUAGE_CODE_ENGLISH).getLanguage());

    public static boolean isAppEnglish() {
        return getAppLanguage().equals(new Locale(LANGUAGE_CODE_ENGLISH).getLanguage());


Log.i("AppLanguage: ",     LocalUtils.getAppLanguage());
Log.i("DeviceLanguage: ",  LocalUtils.getDeviceLanguage());
Log.i("isDeviceEnglish: ", String.valueOf(LocalUtils.isDeviceEnglish()));
Log.i("isAppEnglish: ",    String.valueOf(LocalUtils.isAppEnglish()));

Android Paint: .measureText() vs .getTextBounds()

The mice answer is great... And here is the description of the real problem:

The short simple answer is that Paint.getTextBounds(String text, int start, int end, Rect bounds) returns Rect which doesn't starts at (0,0). That is, to get actual width of text that will be set by calling Canvas.drawText(String text, float x, float y, Paint paint) with the same Paint object from getTextBounds() you should add the left position of Rect. Something like that:

public int getTextWidth(String text, Paint paint) {
    Rect bounds = new Rect();
    paint.getTextBounds(text, 0, end, bounds);
    int width = bounds.left + bounds.width();
    return width;

Notice this bounds.left - this the key of the problem.

In this way you will receive the same width of text, that you would receive using Canvas.drawText().

And the same function should be for getting height of the text:

public int getTextHeight(String text, Paint paint) {
    Rect bounds = new Rect();
    paint.getTextBounds(text, 0, end, bounds);
    int height = bounds.bottom + bounds.height();
    return height;

P.s.: I didn't test this exact code, but tested the conception.

Much more detailed explanation is given in this answer.

java.util.regex - importance of Pattern.compile()?

Similar to 'Pattern.compile' there is 'RECompiler.compile' [from] where:
1. compiled code for pattern [a-z] has 'az' in it
2. compiled code for pattern [0-9] has '09' in it
3. compiled code for pattern [abc] has 'aabbcc' in it.

Thus compiled code is a great way to generalize multiple cases. Thus instead of having different code handling situation 1,2 and 3 . The problem reduces to comparing with the ascii of present and next element in the compiled code, hence the pairs. Thus
a. anything with ascii between a and z is between a and z
b. anything with ascii between 'a and a is definitely 'a'

Argument of type 'X' is not assignable to parameter of type 'X'

You miss parenthesis:

var value: string = dataObjects[i].getValue(); 
var id: number = dataObjects[i].getId();

Handling urllib2's timeout? - Python

In Python 2.7.3:

import urllib2
import socket

class MyException(Exception):

    urllib2.urlopen("", timeout = 1)
except urllib2.URLError as e:
    print type(e)    #not catch
except socket.timeout as e:
    print type(e)    #catched
    raise MyException("There was an error: %r" % e)

Python - Move and overwrite files and folders

If you also need to overwrite files with read only flag use this:

def copyDirTree(root_src_dir,root_dst_dir):
Copy directory tree. Overwrites also read only files.
:param root_src_dir: source directory
:param root_dst_dir:  destination directory
for src_dir, dirs, files in os.walk(root_src_dir):
    dst_dir = src_dir.replace(root_src_dir, root_dst_dir, 1)
    if not os.path.exists(dst_dir):
    for file_ in files:
        src_file = os.path.join(src_dir, file_)
        dst_file = os.path.join(dst_dir, file_)
        if os.path.exists(dst_file):
            except PermissionError as exc:
                os.chmod(dst_file, stat.S_IWUSR)

        shutil.copy(src_file, dst_dir)

How to display the function, procedure, triggers source code in postgresql?

For function:

you can query the pg_proc view , just as the following

select proname,prosrc from pg_proc where proname= your_function_name; 

Another way is that just execute the commont \df and \ef which can list the functions.

skytf=> \df           
                                             List of functions
 Schema |         Name         | Result data type |              Argument data types               |  Type  
 public | pg_buffercache_pages | SETOF record     |                                                | normal

skytf=> \ef  pg_buffercache_pages

It will show the source code of the function.

For triggers:

I dont't know if there is a direct way to get the source code. Just know the following way, may be it will help you!

  • step 1 : Get the table oid of the trigger:
    skytf=> select tgrelid from pg_trigger  where tgname='insert_tbl_tmp_trigger';
    (1 row)
  • step 2: Get the table name of the above oid !
    skytf=> select oid,relname  from pg_class where oid=26599;
      oid  |           relname           
     26599 | tbl_tmp
    (1 row)
  • step 3: list the table information
    skytf=> \d tbl_tmp

It will show you the details of the trigger of the table . Usually a trigger uses a function. So you can get the source code of the trigger function just as the above that I pointed out !

Could not load file or assembly 'System.Web.WebPages.Razor, Version=

Another option is to update the Microsoft.AspnNet.Mvc NuGet package. Be careful, because NuGet update does not update the Web.Config. You should update all previous version numbers to updated number. For example if you update from MVC to, then this should be replaced in the Web.Config:

    <sectionGroup name="system.web.webPages.razor" type="System.Web.WebPages.Razor.Configuration.RazorWebSectionGroup, System.Web.WebPages.Razor, Version=, Culture=neutral, PublicKeyToken=31BF3856AD364E35">
      <section name="host" type="System.Web.WebPages.Razor.Configuration.HostSection, System.Web.WebPages.Razor, Version=, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" />
      <section name="pages" type="System.Web.WebPages.Razor.Configuration.RazorPagesSection, System.Web.WebPages.Razor, Version=, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" />

 <host factoryType="System.Web.Mvc.MvcWebRazorHostFactory, System.Web.Mvc, Version=, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />

    pageParserFilterType="System.Web.Mvc.ViewTypeParserFilter, System.Web.Mvc, Version=, Culture=neutral, PublicKeyToken=31BF3856AD364E35"
    pageBaseType="System.Web.Mvc.ViewPage, System.Web.Mvc, Version=, Culture=neutral, PublicKeyToken=31BF3856AD364E35"
    userControlBaseType="System.Web.Mvc.ViewUserControl, System.Web.Mvc, Version=, Culture=neutral, PublicKeyToken=31BF3856AD364E35">
    <add assembly="System.Web.Mvc, Version=, Culture=neutral, PublicKeyToken=31BF3856AD364E35" namespace="System.Web.Mvc" tagPrefix="mvc" />

referenced before assignment error in python

I think you are using 'global' incorrectly. See Python reference. You should declare variable without global and then inside the function when you want to access global variable you declare it global yourvar.



def checkTotal():
    global total
    total = 0

See this example:

#!/usr/bin/env python

total = 0

def doA():
    # not accessing global total
    total = 10

def doB():
    global total
    total = total + 1

def checkTotal():
    # global total - not required as global is required
    # only for assignment - thanks for comment Greg
    print total

def main():

if __name__ == '__main__':

Because doA() does not modify the global total the output is 1 not 11.

How to get the IP address of the docker host from inside a docker container

In linux you can run

HOST_IP=`hostname -I | awk '{print $1}'`

In macOS your host machine is not the Docker host. Docker will install it's host OS in VirtualBox.

HOST_IP=`docker run busybox ping -c 1 docker.for.mac.localhost | awk 'FNR==2 {print $4}' | sed s'/.$//'`

force line break in html table cell

I think what you're trying to do is wrap loooooooooooooong words or URLs so they don't push the size of the table out. (I've just been trying to do the same thing!)

You can do this easily with a DIV by giving it the style word-wrap: break-word (and you may need to set its width, too).

div {
    word-wrap: break-word;         /* All browsers since IE 5.5+ */
    overflow-wrap: break-word;     /* Renamed property in CSS3 draft spec */
    width: 100%;

However, for tables, you must either wrap the content in a DIV (or other block tag) or apply: table-layout: fixed. This means the columns widths are no longer fluid, but are defined based on the widths of the columns in the first row only (or via specified widths). Read more here.

Sample code:

table {
    table-layout: fixed;
    width: 100%;

table td {
    word-wrap: break-word;         /* All browsers since IE 5.5+ */
    overflow-wrap: break-word;     /* Renamed property in CSS3 draft spec */

Hope that helps somebody.

How to convert a timezone aware string to datetime in Python without dateutil?

I'm new to Python, but found a way to convert

2017-05-27T07:20:18.000-04:00 to

2017-05-27T07:20:18 without downloading new utilities.

from datetime import datetime, timedelta

time_zone1 = int("2017-05-27T07:20:18.000-04:00"[-6:][:3])
>>returns -04

item_date = datetime.strptime("2017-05-27T07:20:18.000-04:00".replace(".000", "")[:-6], "%Y-%m-%dT%H:%M:%S") + timedelta(hours=-time_zone1)

I'm sure there are better ways to do this without slicing up the string so much, but this got the job done.

How to convert UTF8 string to byte array?

The Google Closure library has functions to convert to/from UTF-8 and byte arrays. If you don't want to use the whole library, you can copy the functions from here. For completeness, the code to convert to a string to a UTF-8 byte array is:

goog.crypt.stringToUtf8ByteArray = function(str) {
  // TODO(user): Use native implementations if/when available
  var out = [], p = 0;
  for (var i = 0; i < str.length; i++) {
    var c = str.charCodeAt(i);
    if (c < 128) {
      out[p++] = c;
    } else if (c < 2048) {
      out[p++] = (c >> 6) | 192;
      out[p++] = (c & 63) | 128;
    } else if (
        ((c & 0xFC00) == 0xD800) && (i + 1) < str.length &&
        ((str.charCodeAt(i + 1) & 0xFC00) == 0xDC00)) {
      // Surrogate Pair
      c = 0x10000 + ((c & 0x03FF) << 10) + (str.charCodeAt(++i) & 0x03FF);
      out[p++] = (c >> 18) | 240;
      out[p++] = ((c >> 12) & 63) | 128;
      out[p++] = ((c >> 6) & 63) | 128;
      out[p++] = (c & 63) | 128;
    } else {
      out[p++] = (c >> 12) | 224;
      out[p++] = ((c >> 6) & 63) | 128;
      out[p++] = (c & 63) | 128;
  return out;

How to add external JS scripts to VueJS Components

I have downloaded some HTML template that comes with custom js files and jquery. I had to attach those js to my app. and continue with Vue.

Found this plugin, it's a clean way to add external scripts both via CDN and from static files

// local files
// you have to put your scripts into the public folder. 
// that way webpack simply copy these files as it is.

// cdn

How can I kill all sessions connecting to my oracle database?


startup force;

Brutal, yet elegant.

Kotlin unresolved reference in IntelliJ

Simplest Solution:

Tools->Kotlin->Configure Kotin in Project

Upvote if found Usefull.

How to convert float to varchar in SQL Server

SELECT LTRIM(STR(float_field, 25, 0))

is the best way so you do not add .0000 and any digit at the end of the value.

How to install numpy on windows using pip install?

Frustratingly the Numpy package published to PyPI won't install on most Windows computers


  1. Download the Numpy wheel for your Python version from
  2. Install it from the command line pip install numpy-1.10.2+mkl-cp35-none-win_amd64.whl

How do I convert NSMutableArray to NSArray?

In objective-c :

NSArray *myArray = [myMutableArray copy];

In swift :

 var arr = myMutableArray as NSArray

ValueError: all the input arrays must have same number of dimensions

The reason why you get your error is because a "1 by n" matrix is different from an array of length n.

I recommend using hstack() and vstack() instead. Like this:

import numpy as np
a = np.arange(32).reshape(4,8) # 4 rows 8 columns matrix.
b = a[:,-1:]                    # last column of that matrix.

result = np.hstack((a,b))       # stack them horizontally like this:
#array([[ 0,  1,  2,  3,  4,  5,  6,  7,  7],
#       [ 8,  9, 10, 11, 12, 13, 14, 15, 15],
#       [16, 17, 18, 19, 20, 21, 22, 23, 23],
#       [24, 25, 26, 27, 28, 29, 30, 31, 31]])

Notice the repeated "7, 15, 23, 31" column. Also, notice that I used a[:,-1:] instead of a[:,-1]. My version generates a column:


Instead of a row array([7,15,23,31])

Edit: append() is much slower. Read this answer.

Clear variable in python

I used a few options mentioned above :

del self.left

or setting value to None using

self.left = None

It's important to know the differences and put a few exception handlers in place when you use set the value to None. If you're printing the value of the conditional statements using a template, say,

print("The value of the variable is {}".format(self.left))

you might see the value of the variable printing "The value of the variable is None". Thus, you'd have to put a few exception handlers there :

if self.left:
    #Then only print stuff

The above command will only print values if self.left is not None

what is the unsigned datatype?

unsigned means unsigned int. signed means signed int. Using just unsigned is a lazy way of declaring an unsigned int in C. Yes this is ANSI.

Format date to MM/dd/yyyy in JavaScript

All other answers don't quite solve the issue. They print the date formatted as mm/dd/yyyy but the question was regarding MM/dd/yyyy. Notice the subtle difference? MM indicates that a leading zero must pad the month if the month is a single digit, thus having it always be a double digit number.

i.e. whereas mm/dd would be 3/31, MM/dd would be 03/31.

I've created a simple function to achieve this. Notice that the same padding is applied not only to the month but also to the day of the month, which in fact makes this MM/DD/yyyy:

function getFormattedDate(date) {_x000D_
  var year = date.getFullYear();_x000D_
  var month = (1 + date.getMonth()).toString();_x000D_
  month = month.length > 1 ? month : '0' + month;_x000D_
  var day = date.getDate().toString();_x000D_
  day = day.length > 1 ? day : '0' + day;_x000D_
  return month + '/' + day + '/' + year;_x000D_

Update for ES2017 using String.padStart(), supported by all major browsers except IE.

function getFormattedDate(date) {_x000D_
    let year = date.getFullYear();_x000D_
    let month = (1 + date.getMonth()).toString().padStart(2, '0');_x000D_
    let day = date.getDate().toString().padStart(2, '0');_x000D_
    return month + '/' + day + '/' + year;_x000D_

Get method arguments using Spring AOP?

Your can use either of the following methods.

public void logBefore1(JoinPoint joinPoint) {


@Before("execution(*, && args(inputString)")
public void logBefore2(JoinPoint joinPoint, String inputString) {

joinpoint.getArgs() returns object array. Since, input is single string, only one object is returned.

In the second approach, the name should be same in expression and input parameter in the advice method i.e. args(inputString) and public void logBefore2(JoinPoint joinPoint, String inputString)

Here, addCustomer(String) indicates the method with one String input parameter.

PHP shorthand for isset()?

PHP 7.4+; with the null coalescing assignment operator

$var ??= '';

PHP 7.0+; with the null coalescing operator

$var = $var ?? '';

PHP 5.3+; with the ternary operator shorthand

isset($var) ?: $var = '';

Or for all/older versions with isset:

$var = isset($var) ? $var : '';


!isset($var) && $var = '';

hash function for string

First, is 40 collisions for 130 words hashed to 0..99 bad? You can't expect perfect hashing if you are not taking steps specifically for it to happen. An ordinary hash function won't have fewer collisions than a random generator most of the time.

A hash function with a good reputation is MurmurHash3.

Finally, regarding the size of the hash table, it really depends what kind of hash table you have in mind, especially, whether buckets are extensible or one-slot. If buckets are extensible, again there is a choice: you choose the average bucket length for the memory/speed constraints that you have.

Jackson - How to process (deserialize) nested JSON?

Here is a rough but more declarative solution. I haven't been able to get it down to a single annotation, but this seems to work well. Also not sure about performance on large data sets.

Given this JSON:

    "list": [
            "wrapper": {
                "name": "Jack"
            "wrapper": {
                "name": "Jane"

And these model objects:

public class RootObject {
    @JsonDeserialize(contentUsing = SkipWrapperObjectDeserializer.class)
    public InnerObject[] innerObjects;


public class InnerObject {
    public String name;

Where the Jackson voodoo is implemented like:

public @interface SkipWrapperObject {
    String value();


public class SkipWrapperObjectDeserializer extends JsonDeserializer<Object> implements
        ContextualDeserializer {
    private Class<?> wrappedType;
    private String wrapperKey;

    public JsonDeserializer<?> createContextual(DeserializationContext ctxt,
            BeanProperty property) throws JsonMappingException {
        SkipWrapperObject skipWrapperObject = property
        wrapperKey = skipWrapperObject.value();
        JavaType collectionType = property.getType();
        JavaType collectedType = collectionType.containedType(0);
        wrappedType = collectedType.getRawClass();
        return this;

    public Object deserialize(JsonParser parser, DeserializationContext ctxt)
            throws IOException, JsonProcessingException {
        ObjectMapper mapper = new ObjectMapper();
        ObjectNode objectNode = mapper.readTree(parser);
        JsonNode wrapped = objectNode.get(wrapperKey);
        Object mapped = mapIntoObject(wrapped);
        return mapped;

    private Object mapIntoObject(JsonNode node) throws IOException,
            JsonProcessingException {
        JsonParser parser = node.traverse();
        ObjectMapper mapper = new ObjectMapper();
        return mapper.readValue(parser, wrappedType);

Hope this is useful to someone!

How to know the git username and email saved during configuration?

Inside your git repository directory, run git config

Why is running this command within your git repo directory important?

If you are outside of a git repository, git config gives you the value of at global level. When you make a commit, the associated user name is read at local level.

Although unlikely, let's say is defined as foo at global level, but bar at local level. Then, when you run git config outside of the git repo directory, it gives bar. However, when you really commits something, the associated value is foo.

Git config variables can be stored in 3 different levels. Each level overrides values in the previous level.

1. System level (applied to every user on the system and all their repositories)

  • to view, git config --list --system (may need sudo)
  • to set, git config --system color.ui true
  • to edit system config file, git config --edit --system

2. Global level (values specific personally to you, the user. )

  • to view, git config --list --global
  • to set, git config --global xyz
  • to edit global config file, git config --edit --global

3. Repository level (specific to that single repository)

  • to view, git config --list --local
  • to set, git config --local core.ignorecase true (--local optional)
  • to edit repository config file, git config --edit --local (--local optional)

How to view all settings?

  • Run git config --list, showing system, global, and (if inside a repository) local configs
  • Run git config --list --show-origin, also shows the origin file of each config item

How to read one particular config?

  • Run git config to get, for example.
  • You may also specify options --system, --global, --local to read that value at a particular level.

Reference: 1.6 Getting Started - First-Time Git Setup

php_network_getaddresses: getaddrinfo failed: Name or service not known

Had such a problem (with, just reload PHP and everything start worked

for Centos 6 and 7:

service php-fpm restart 

Shell script to check if file exists

The following script will help u to go to a process if that script exist in a specified variable,

cat > waitfor.csh


    while !( -e $1 )

    sleep 10m



here -e is for working with files,

$1 is a shell variable,

sleep for 10 minutes

u can execute the script by ./waitfor.csh ./temp ; echo "the file exits"

Change auto increment starting number?

Yes, you can use the ALTER TABLE t AUTO_INCREMENT = 42 statement. However, you need to be aware that this will cause the rebuilding of your entire table, at least with InnoDB and certain MySQL versions. If you have an already existing dataset with millions of rows, it could take a very long time to complete.

In my experience, it's better to do the following:

-- You may also need to add other mandatory columns and values

In this way, even if you're rolling back the transaction, MySQL will keep the auto-increment value, and the change will be applied instantly.

You can verify this by issuing a SHOW CREATE TABLE t statement. You should see:

*************************** 1. row ***************************
       Table: t
Create Table: CREATE TABLE `t` (

Checking if a string is empty or null in Java


if(!Strings.isNullOrEmpty(String str)) {
   // Do your stuff here 

What is your favorite C programming trick?

I use X-Macros to to let the pre-compiler generate code. They are especially useful for defining error values and associated error strings in one place, but they can go far beyond that.

Detect network connection type on Android

I use this simple code:

fun getConnectionInfo(): ConnectionInfo {
    val cm = appContext.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager

    return if (cm.activeNetwork == null) {
    } else {
        if (cm.isActiveNetworkMetered) {
        } else {

Java - escape string to prevent SQL injection

(This is in answer to the OP's comment under the original question; I agree completely that PreparedStatement is the tool for this job, not regexes.)

When you say \n, do you mean the sequence \+n or an actual linefeed character? If it's \+n, the task is pretty straightforward:

s = s.replaceAll("['\"\\\\]", "\\\\$0");

To match one backslash in the input, you put four of them in the regex string. To put one backslash in the output, you put four of them in the replacement string. This is assuming you're creating the regexes and replacements in the form of Java String literals. If you create them any other way (e.g., by reading them from a file), you don't have to do all that double-escaping.

If you have a linefeed character in the input and you want to replace it with an escape sequence, you can make a second pass over the input with this:

s = s.replaceAll("\n", "\\\\n");

Or maybe you want two backslashes (I'm not too clear on that):

s = s.replaceAll("\n", "\\\\\\\\n");

How to use nanosleep() in C? What are `tim.tv_sec` and `tim.tv_nsec`?

Half a second is 500,000,000 nanoseconds, so your code should read:

tim.tv_sec  = 0;
tim.tv_nsec = 500000000L;

As things stand, you code is sleeping for 1.0000005s (1s + 500ns).

nodemon not found in npm

I had this problem and even after I have used the command npm install nodemon --save in my application, I still had problem with nodemon.

I just resolved after I installed nodemon globally, using the command:npm install nodemon -g

Java how to replace 2 or more spaces with single space in string and delete leading and trailing spaces

I know replaceAll method is much easier but I wanted to post this as well.

public static String removeExtraSpace(String input) {
    input= input.trim();
    ArrayList <String> x= new ArrayList<>(Arrays.asList(input.split("")));
    for(int i=0; i<x.size()-1;i++) {
        if(x.get(i).equals(" ") && x.get(i+1).equals(" ")) { 
    String word="";
    for(String each: x) 
    return word;

Create 3D array using Python

The right way would be

[[[0 for _ in range(n)] for _ in range(n)] for _ in range(n)]

(What you're trying to do should be written like (for NxNxN)


but that is not correct, see @Adaman comment why).

WPF ListView turn off selection

Here's the default template for ListViewItem from Blend:

Default ListViewItem Template:

        <Setter Property="Template">
                <ControlTemplate TargetType="{x:Type ListViewItem}">
                    <Border x:Name="Bd" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Padding="{TemplateBinding Padding}" SnapsToDevicePixels="true">
                        <ContentPresenter HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/>
                        <Trigger Property="IsSelected" Value="true">
                            <Setter Property="Background" TargetName="Bd" Value="{DynamicResource {x:Static SystemColors.HighlightBrushKey}}"/>
                            <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.HighlightTextBrushKey}}"/>
                                <Condition Property="IsSelected" Value="true"/>
                                <Condition Property="Selector.IsSelectionActive" Value="false"/>
                            <Setter Property="Background" TargetName="Bd" Value="{DynamicResource {x:Static SystemColors.InactiveSelectionHighlightBrushKey}}"/>
                            <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.InactiveSelectionHighlightTextBrushKey}}"/>
                        <Trigger Property="IsEnabled" Value="false">
                            <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}"/>

Just remove the IsSelected Trigger and IsSelected/IsSelectionActive MultiTrigger, by adding the below code to your Style to replace the default template, and there will be no visual change when selected.

Solution to turn off the IsSelected property's visual changes:

    <Setter Property="Template">
            <ControlTemplate TargetType="{x:Type ListViewItem}">
                <Border x:Name="Bd" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Padding="{TemplateBinding Padding}" SnapsToDevicePixels="true">
                    <ContentPresenter HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/>
                    <Trigger Property="IsEnabled" Value="false">
                        <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}"/>
    </Setter> SSL handshake aborted: Failure in SSL library, usually a protocol error


I was getting SSLHandshake exceptions on devices running versions of Android earlier than Android 5.0. In my use case I also wanted to create a TrustManager to trust my client certificate.

I implemented NoSSLv3SocketFactory and NoSSLv3Factory to remove SSLv3 from my client's list of supported protocols but I could get neither of these solutions to work.

Some things I learned:

  • On devices older than Android 5.0 TLSv1.1 and TLSv1.2 protocols are not enabled by default.
  • SSLv3 protocol is not disabled by default on devices older than Android 5.0.
  • SSLv3 is not a secure protocol and it is therefore desirable to remove it from our client's list of supported protocols before a connection is made.

What worked for me

Allow Android's security Provider to update when starting your app.

The default Provider before 5.0+ does not disable SSLv3. Provided you have access to Google Play services it is relatively straightforward to patch Android's security Provider from your app.

private void updateAndroidSecurityProvider(Activity callingActivity) {
    try {
    } catch (GooglePlayServicesRepairableException e) {
        // Thrown when Google Play Services is not installed, up-to-date, or enabled
        // Show dialog to allow users to install, update, or otherwise enable Google Play services.
        GooglePlayServicesUtil.getErrorDialog(e.getConnectionStatusCode(), callingActivity, 0);
    } catch (GooglePlayServicesNotAvailableException e) {
        Log.e("SecurityException", "Google Play Services not available.");

If you now create your OkHttpClient or HttpURLConnection TLSv1.1 and TLSv1.2 should be available as protocols and SSLv3 should be removed. If the client/connection (or more specifically it's SSLContext) was initialised before calling ProviderInstaller.installIfNeeded(...) then it will need to be recreated.

Don't forget to add the following dependency (latest version found here):

compile ''



I didn't need to explicitly set which cipher algorithms my client should use but I found a SO post recommending those considered most secure at the time of writing: Which Cipher Suites to enable for SSL Socket?

Image, saved to sdcard, doesn't appear in Android's Gallery app

A simpler solution is to use the static convenience method scanFile():

File imageFile = ...
MediaScannerConnection.scanFile(this, new String[] { imageFile.getPath() }, new String[] { "image/jpeg" }, null);

where this is your activity (or whatever context), the mime-type is only necessary if you are using non-standard file extensions and the null is for the optional callback (which we don't need for such a simple case).

How to change the port number for Asp.Net core app?

3 files have to changed appsettings.json (see the last section - kestrel ), launchsettings.json - applicationurl commented out, and a 2 lines change in Startup.cs

Add below code in appsettings.json file and port to any as you wish.


 "Kestrel": {

   "Endpoints": {

     "Http": {

       "Url": "http://localhost:5003"





Modify Startup.cs with below lines.

using Microsoft.AspNetCore.Server.Kestrel.Core;


Launch a shell command with in a python script, wait for the termination and return to the script

use spawn

import os
os.spawnlp(os.P_WAIT, 'cp', 'cp', 'index.html', '/dev/null')

How do I check if a given string is a legal/valid file name under Windows?

You can get a list of invalid characters from Path.GetInvalidPathChars and GetInvalidFileNameChars.

UPD: See Steve Cooper's suggestion on how to use these in a regular expression.

UPD2: Note that according to the Remarks section in MSDN "The array returned from this method is not guaranteed to contain the complete set of characters that are invalid in file and directory names." The answer provided by sixlettervaliables goes into more details.

Reset Entity-Framework Migrations

In EF6

  1. Delete all your files in 'migrations' folder... But not the 'initial create' or 'config'.
  2. Delete the database.
  3. Now run Add-Migration Initial.
  4. Now you can 'update-database' and all will be well.

How can I replace a regex substring match in Javascript?

var str   = 'asd-0.testing';
var regex = /(asd-)\d(\.\w+)/;
str = str.replace(regex, "$11$2");

Or if you're sure there won't be any other digits in the string:

var str   = 'asd-0.testing';
var regex = /\d/;
str = str.replace(regex, "1");

Display / print all rows of a tibble (tbl_df)

The tibble vignette has an updated way to change its default printing behavior:

You can control the default appearance with options:

options(tibble.print_max = n, tibble.print_min = m): if there are more than n rows, print only the first m rows. Use options(tibble.print_max = Inf) to always show all rows.

options(tibble.width = Inf) will always print all columns, regardless of the width of the screen.


This will always print all rows:

options(tibble.print_max = Inf)

This will not actually limit the printing to 50 lines:

options(tibble.print_max = 50)

But this will restrict printing to 50 lines:

options(tibble.print_max = 50, tibble.print_min = 50)

"This SqlTransaction has completed; it is no longer usable."... configuration error?

Also check for any long running processes executed from your .NET app against the DB. For example you may be calling a stored procedure or query which does not have enough time to finish which can show in your logs as:

  • Execution Timeout Expired. The timeout period elapsed prior to completion of the operation or the server is not responding.

    • This SqlTransaction has completed; it is no longer usable.

Check the command timeout settings Try to run a trace (profiler) and see what is happening on the DB side...

Creating an empty bitmap and drawing though canvas in Android

This is probably simpler than you're thinking:

int w = WIDTH_PX, h = HEIGHT_PX;

Bitmap.Config conf = Bitmap.Config.ARGB_8888; // see other conf types
Bitmap bmp = Bitmap.createBitmap(w, h, conf); // this creates a MUTABLE bitmap
Canvas canvas = new Canvas(bmp);

// ready to draw on that bitmap through that canvas

Here's a series of tutorials I've found on the topic: Drawing with Canvas Series

Can the Twitter Bootstrap Carousel plugin fade in and out on slide transition

Came across this issue when using Bootstrap 3. My solution was to add the carousel-fade class to the carousel main DIV and slot the following CSS in, somewhere after the Bootstrap CSS is included:

.carousel-fade .item {
  opacity: 0;
  -webkit-transition: opacity 2s ease-in-out;
  -moz-transition: opacity 2s ease-in-out;
  -ms-transition: opacity 2s ease-in-out;
  -o-transition: opacity 2s ease-in-out;
  transition: opacity 2s ease-in-out;
  left: 0 !important;

.carousel-fade .active {
  opacity: 1 !important;

.carousel-fade .left {
  opacity: 0 !important;
  -webkit-transition: opacity 0.5s ease-in-out !important;
  -moz-transition: opacity 0.5s ease-in-out !important;
  -ms-transition: opacity 0.5s ease-in-out !important;
  -o-transition: opacity 0.5s ease-in-out !important;
  transition: opacity 0.5s ease-in-out !important;

.carousel-fade .carousel-control {
  opacity: 1 !important;

The style transitions that Bootstrap applies mean that you have to have the mid-stride transitions (active left, next left) quickly, otherwise the item just ends up disappearing (hence the 1/2 second transition time).

I haven't experimented with adjusting the .item and .left transition times, but they will probably need adjusting proportionally to keep the effect looking nice.

Instagram API - How can I retrieve the list of people a user is following on Instagram

I made my own way based on Caitlin Morris's answer for fetching all folowers and followings on Instagram. Just copy this code, paste in browser console and wait for a few seconds.

You need to use browser console from tab to make it works.

let username = 'USERNAME'
let followers = [], followings = []
try {
  let res = await fetch(`${username}/?__a=1`)

  res = await res.json()
  let userId =

  let after = null, has_next = true
  while (has_next) {
    await fetch(`` + encodeURIComponent(JSON.stringify({
      id: userId,
      include_reel: true,
      fetch_mutual: true,
      first: 50,
      after: after
    }))).then(res => res.json()).then(res => {
      has_next =
      after =
      followers = followers.concat({node}) => {
        return {
          username: node.username,
          full_name: node.full_name
  console.log('Followers', followers)

  has_next = true
  after = null
  while (has_next) {
    await fetch(`` + encodeURIComponent(JSON.stringify({
      id: userId,
      include_reel: true,
      fetch_mutual: true,
      first: 50,
      after: after
    }))).then(res => res.json()).then(res => {
      has_next =
      after =
      followings = followings.concat({node}) => {
        return {
          username: node.username,
          full_name: node.full_name
  console.log('Followings', followings)
} catch (err) {
  console.log('Invalid username')

Python Request Post with param data

Set data to this:

data ={"eventType":"AAS_PORTAL_START","data":{"uid":"hfe3hf45huf33545","aid":"1","vid":"1"}}

UTF-8 encoding problem in Spring MVC

There are some similar questions: Spring MVC response encoding issue, Custom HttpMessageConverter with @ResponseBody to do Json things.

However, my simple solution:

public ModelAndView getMyList(){
  String test = "ccždš";
  ModelAndView mav = new ModelAndView("html_utf8");
  mav.addObject("responseBody", test);

and the view html_utf8.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>${responseBody}

No additional classes and configuration.
And You can also create another view (for example json_utf8) for other content type.

Difference between webdriver.get() and webdriver.navigate()

driver.get(url) and both are used to go to particular web page. The key difference is that driver.get(url): It does not maintain the browser history and cookies and wait till page fully loaded. is also used to go to particular web maintain browser history and cookies and does not wait till page fully loaded and have navigation between the pages back, forward and refresh.

How to make android listview scrollable?

Putting ListView inside a ScrollView is never inspired. But if you want your posted XML-like behavior, there're 3 options to me:

  1. Remove ScrollView: Removing your ScrollView, you may give the ListViews some specific size with respect to the total layout (either specific dp or layout_weight).

  2. Replace ListViews with LinearLayouts: You may add the list-items by iterating through the item-list and add each item-view to the respective LinearLayout by inflating the view & setting the respective data (string, image etc.)

  3. If you really need to put your ListViews inside the ScrollView, you must make your ListViews non-scrollable (Which is practically the same as the solution 2 above, but with ListView codes), otherwise the layout won't function as you expect.
    To make a ListView non-scrollable, you may read this SO post, where the precise solution to me is like the one below:

listView.setOnTouchListener(new OnTouchListener() {_x000D_
  public boolean onTouch(View v, MotionEvent event) {_x000D_
    return (event.getAction() == MotionEvent.ACTION_MOVE);_x000D_

MatPlotLib: Multiple datasets on the same scatter plot

I don't know, it works fine for me. Exact commands:

import scipy, pylab
ax = pylab.subplot(111)
ax.scatter(scipy.randn(100), scipy.randn(100), c='b')
ax.scatter(scipy.randn(100), scipy.randn(100), c='r')

What's the u prefix in a Python string?

My guess is that it indicates "Unicode", is it correct?


If so, since when is it available?

Python 2.x.

In Python 3.x the strings use Unicode by default and there's no need for the u prefix. Note: in Python 3.0-3.2, the u is a syntax error. In Python 3.3+ it's legal again to make it easier to write 2/3 compatible apps.

R - argument is of length zero in if statement

"argument is of length zero" is a very specific problem that comes from one of my least-liked elements of R. Let me demonstrate the problem:

> FALSE == "turnip"
> TRUE == "turnip"
> NA == "turnip"
[1] NA
> NULL == "turnip"

As you can see, comparisons to a NULL not only don't produce a boolean value, they don't produce a value at all - and control flows tend to expect that a check will produce some kind of output. When they produce a zero-length output... "argument is of length zero".

(I have a very long rant about why this infuriates me so much. It can wait.)

So, my question; what's the output of sum(is.null(data[[k]]))? If it's not 0, you have NULL values embedded in your dataset and will need to either remove the relevant rows, or change the check to

if(!is.null(data[[k]][[k2]]) & temp > data[[k]][[k2]]){
    #do stuff

Hopefully that helps; it's hard to tell without the entire dataset. If it doesn't help, and the problem is not a NULL value getting in somewhere, I'm afraid I have no idea.

Attach (open) mdf file database with SQL Server Management Studio

i don't know if this answer can be found on the links above, but i just run SQL management studio as Administrator and worked. Hope it helps


How to detect if a browser is Chrome using jQuery?

Although it is not Jquery , I use jquery myself but for browser detection I have used the script on this page a few times. It detects all major browsers, and then some. The work is pretty much all done for you.

Converting float to char*

char buffer[64];
int ret = snprintf(buffer, sizeof buffer, "%f", myFloat);

if (ret < 0) {
    return EXIT_FAILURE;
if (ret >= sizeof buffer) {
    /* Result was truncated - resize the buffer and retry.

That will store the string representation of myFloat in myCharPointer. Make sure that the string is large enough to hold it, though.

snprintf is a better option than sprintf as it guarantees it will never write past the size of the buffer you supply in argument 2.

get list of pandas dataframe columns based on data type

If you want a list of columns of a certain type, you can use groupby:

>>> df = pd.DataFrame([[1, 2.3456, 'c', 'd', 78]], columns=list("ABCDE"))
>>> df
   A       B  C  D   E
0  1  2.3456  c  d  78

[1 rows x 5 columns]
>>> df.dtypes
A      int64
B    float64
C     object
D     object
E      int64
dtype: object
>>> g = df.columns.to_series().groupby(df.dtypes).groups
>>> g
{dtype('int64'): ['A', 'E'], dtype('float64'): ['B'], dtype('O'): ['C', 'D']}
>>> { v for k, v in g.items()}
{'object': ['C', 'D'], 'int64': ['A', 'E'], 'float64': ['B']}

jQuery UI Dialog Box - does not open after being closed

 <button onClick="abrirOpen()">Open Dialog</button>

<script type="text/javascript">
var $dialogo = $("<div></div>").html("Aqui tu contenido(here your content)").dialog({
       title: "Dialogo de UI",
       autoOpen: false,
       close: function(ev, ui){
 function abrirOpen(){

//**Esto funciona para mi... (this works for me)**

How to force IE to reload javascript?

Add a date of modification of js file at the end of your URL. With PHP it would look something like this:

echo '<script type="text/javascript" src="js/something.js?' . filemtime('js/something.js') . '"></script>';

When your script will be reloaded every time you update it.

How do I get the application exit code from a Windows command line?

At one point I needed to accurately push log events from Cygwin to the Windows Event log. I wanted the messages in WEVL to be custom, have the correct exit code, details, priorities, message, etc. So I created a little Bash script to take care of this. Here it is on GitHub,

Some excerpts:

usage: [-h] [-p] [-i=n] [-s] <description>
example: -p error -i 501 -s "failed to run the mount command"

Here is the temporary file contents part:

LGT_TEMP_FILE="$(mktemp --suffix .cmd)"
    @echo off
    exit /b %LGT_ID%
unix2dos "$LGT_TEMP_FILE"

Here is a function to to create events in WEVL:

__create_event () {
    local cmd="eventcreate /ID $LGT_ID /L Application /SO $LGT_SOURCE /T $LGT_PRIORITY /D "
    if [[ "$1" == *';'* ]]; then
        local IFS=';'
        for i in "$1"; do
            $cmd "$i" &>/dev/null
        $cmd "$LGT_DESC" &>/dev/null

Executing the batch script and calling on __create_event:

cmd /c "$(cygpath -wa "$LGT_TEMP_FILE")"

How does String.Index work in Swift

func change(string: inout String) {

    var character: Character = .normal

    enum Character {
        case space
        case newLine
        case normal

    for i in stride(from: string.count - 1, through: 0, by: -1) {
        // first get index
        let index: String.Index?
        if i != 0 {
            index = string.index(after: string.index(string.startIndex, offsetBy: i - 1))
        } else {
            index = string.startIndex

        if string[index!] == "\n" {

            if character != .normal {

                if character == .newLine {
                    string.remove(at: index!)
                } else if character == .space {
                    let number = string.index(after: string.index(string.startIndex, offsetBy: i))
                    if string[number] == " " {
                        string.remove(at: number)
                    character = .newLine

            } else {
                character = .newLine

        } else if string[index!] == " " {

            if character != .normal {

                string.remove(at: index!)

            } else {
                character = .space

        } else {

            character = .normal



    // startIndex
    guard string.count > 0 else { return }
    if string[string.startIndex] == "\n" || string[string.startIndex] == " " {
        string.remove(at: string.startIndex)

    // endIndex - here is a little more complicated!
    guard string.count > 0 else { return }
    let index = string.index(before: string.endIndex)
    if string[index] == "\n" || string[index] == " " {
        string.remove(at: index)


Format of the initialization string does not conform to specification starting at index 0

As I Know, whenever you have more than 1 connection string in your solution(your current project, startup project,...), you may confront with this error

this link may help you click

Currency formatting in Python

Not quite sure why it's not mentioned more online (or on this thread), but the Babel package (and Django utilities) from the Edgewall guys is awesome for currency formatting (and lots of other i18n tasks). It's nice because it doesn't suffer from the need to do everything globally like the core Python locale module.

The example the OP gave would simply be:

>>> import babel.numbers
>>> import decimal
>>> babel.numbers.format_currency( decimal.Decimal( "188518982.18" ), "GBP" )

batch/bat to copy folder and content at once

For Folder Copy You can Use

robocopy C:\Source D:\Destination /E

For File Copy

copy D:\Sourcefile.txt D:\backup\Destinationfile.txt /Y 

Delete file in some folder last modify date more than some day

forfiles -p "D:\FolderPath" -s -m *.[Filetype eg-->.txt] -d -[Numberof dates] -c "cmd /c del @PATH"

And you can Shedule task in windows perform this task automatically in specific time.

cartesian product in pandas

With method chaining:

product = (
    .merge(df2.assign(key=1), on="key")
    .drop("key", axis=1)

Maven does not find JUnit tests to run

In my case we are migration multimodule application to Spring Boot. Unfortunately maven didnt execute all tests anymore in the modules. The naming of the Test Classes didnt change, we are following the naming conventions.

At the end it helped, when I added the dependency surefire-junit47 to the plugin maven-surefire-plugin. But I could not explain, why, it was trial and error:


What's the best way to build a string of delimited items in Java?

Java 8", "));

Why write <script type="text/javascript"> when the mime type is set by the server?

It allows browsers to determine if they can handle the scripting/style language before making a request for the script or stylesheet (or, in the case of embedded script/style, identify which language is being used).

This would be much more important if there had been more competition among languages in browser space, but VBScript never made it beyond IE and PerlScript never made it beyond an IE specific plugin while JSSS was pretty rubbish to begin with.

The draft of HTML5 makes the attribute optional.

Concatenate in jQuery Selector

There is nothing wrong with syntax of

$('#part' + number).html(text);

jQuery accepts a String (usually a CSS Selector) or a DOM Node as parameter to create a jQuery Object.

In your case you should pass a String to $() that is

$(<a string>)

Make sure you have access to the variables number and text.

To test do:

    alert(number + ":" + text);//or use console.log(number + ":" + text)
    $('#part' + number).html(text);

If you see you dont have access, pass them as parameters to the function, you have to include the uual parameters for $.get and pass the custom parameters after them.

What is the maximum float in Python?

If you are using numpy, you can use dtype 'float128' and get a max float of 10e+4931

>>> np.finfo(np.float128)
finfo(resolution=1e-18, min=-1.18973149536e+4932, max=1.18973149536e+4932, dtype=float128)

Vue component event after render

updated() should be what you're looking for:

Called after a data change causes the virtual DOM to be re-rendered and patched.

The component’s DOM will have been updated when this hook is called, so you can perform DOM-dependent operations here.

Integer ASCII value to character in BASH using printf

One option is to directly input the character you're interested in using hex or octal notation:

printf "\x41\n"
printf "\101\n"

How to remove a class from elements in pure JavaScript?

This might help

let allElements = Array.from(document.querySelectorAll('.widget.hover'))
for (let element of allElements) {

Maven: repository element was not specified in the POM inside distributionManagement?

I got the same message ("repository element was not specified in the POM inside distributionManagement element"). I checked /target/checkout/pom.xml and as per another answer and it really lacked <distributionManagement>.

It turned out that the problem was that <distributionManagement> was missing in pom.xml in my master branch (using git).

After cleaning up (mvn release:rollback, mvn clean, mvn release:clean, git tag -d v1.0.0) I run mvn release again and it worked.

Remove scrollbar from iframe

<div id="myInfoDiv" seamless="seamless" scrolling="no" style="width:100%; height: 100%; float: left; color: #FFF; background:#ed8719; line-height:100%; font-size:100%; font-family: sans-serif>;

Use the above div and it will not show scroll bar in any browser.

How to run SQL in shell script

You can use a heredoc. e.g. from a prompt:

$ sqlplus -s username/password@oracle_instance <<EOF
set feed off
set pages 0
select count(*) from table;

so sqlplus will consume everything up to the EOF marker as stdin.