Tutorial by Examples: l

Types of Selectors

In jQuery you can select elements in a page using many various properties of the element, including: Type Class ID Possession of Attribute Attribute Value Indexed Selector Pseudo-state If you know CSS selectors you will notice selectors in jQuery are the same (with minor exceptions). Ta...

jQuery • Selectors

Handling InterruptedException

InterruptedException is a confusing beast - it shows up in seemingly innocuous methods like Thread.sleep(), but handling it incorrectly leads to hard-to-manage code that behaves poorly in concurrent environments. At its most basic, if an InterruptedException is caught it means someone, somewhere, c...

Java Language • Exceptions and exception handling

Showcasing all common Angular constructs

The following example shows common AngularJS constructs in one file: <!DOCTYPE html> <html ng-app="myDemoApp"> <head> <style>.started { background: gold; }</style> <script src="https://code.angularjs.org/1.5.8/angular.min.js">&lt...

AngularJS • Getting started with AngularJS

Link that runs JavaScript

Simply use the javascript: protocol to run the text as JavaScript instead of opening it as a normal link: <a href="javascript:myFunction();">Run Code</a> You can also achieve the same thing using the onclick attribute: <a href="#" onclick="myFunction(); r...

HTML • Anchors and Hyperlinks

Adding the total rows selected to every row

SELECT your_columns, COUNT(*) OVER() as Ttl_Rows FROM your_data_set idnameTtl_Rows1example52foo53bar54baz55quux5 Instead of using two queries to get a count then the line, you can use an aggregate as a window function and use the full result set as the window. This can be used as a base for fur...

SQL • Window Functions

Setting up a flag if other rows have a common property

Let's say I have this data: Table items idnametag1exampleunique_tag2foosimple42barsimple3bazhello51quuxworld I'd like to get all those lines and know if a tag is used by other lines SELECT id, name, tag, COUNT(*) OVER (PARTITION BY tag) > 1 AS flag FROM items The result will be: idnametag...

SQL • Window Functions

Getting a running total

Given this data: dateamount2016-03-122002016-03-11-502016-03-141002016-03-151002016-03-10-250 SELECT date, amount, SUM(amount) OVER (ORDER BY date ASC) AS running FROM operations ORDER BY date ASC will give you dateamountrunning2016-03-10-250-2502016-03-11-50-3002016-03-12200-1002016-03-1410...

SQL • Window Functions

List of true and false values

use feature qw( say ); # Numbers are true if they're not equal to 0. say 0 ? 'true' : 'false'; # false say 1 ? 'true' : 'false'; # true say 2 ? 'true' : 'false'; # true say -1 ? 'true' : 'false'; # true say 1-1 ? 'true' : 'false'; # fa...

Perl Language • True and false

While Loops

var line = 0 var maximum_lines = 5 while (line < maximum_lines) { line = line + 1 println("Line number: " + line) }

Scala Language • While Loops

Do-While Loops

var line = 0 var maximum_lines = 5 do { line = line + 1 println("Line number: " + line) } while (line < maximum_lines) The do/while loop is infrequently used in functional programming, but can be used to work around the lack of support for the break/continue construct, as...

Scala Language • While Loops

Installation

QML comes with newer Version of the cross-platform application framework Qt. You can find the newest Version of Qt in the Downloads section. To create a new QML Project in the Qt Creator IDE, select "File -> New ..." and under "Applications" select "Qt Quick-Application...

qml • Getting started with qml

Check if a string matches a regular expression

3.0 Check if a string consists in exactly 8 digits: $ date=20150624 $ [[ $date =~ ^[0-9]{8}$ ]] && echo "yes" || echo "no" yes $ date=hello $ [[ $date =~ ^[0-9]{8}$ ]] && echo "yes" || echo "no" no

Bash • Pattern matching and regular expressions

Exporting the versioned data (plain download)

If you want to get the versioned project's data, but you don't need any of the version control capabilities offered by Subversion, you could run svn export <URL> command. Here is an example: $ svn export https://svn.example.com/svn/MyRepo/MyProject/trunk As a result, you will get the proje...

svn • Getting started with svn

Accessing memory beyond allocated chunk

A a pointer to a piece of memory containing n elements may only be dereferenced if it is in the range memory and memory + (n - 1). Dereferencing a pointer outside of that range results in undefined behavior. As an example, consider the following code: int array[3]; int *beyond_array = array + 3; ...

C Language • Undefined behavior

Log search

git log -S"#define SAMPLES" Searches for addition or removal of specific string or the string matching provided REGEXP. In this case we're looking for addition/removal of the string #define SAMPLES. For example: +#define SAMPLES 100000 or -#define SAMPLES 100000 git log -G&q...

Git • Browsing the history

Deleting a Remote Branch

To delete a remote branch in Git: git push [remote-name] --delete [branch-name] or git push [remote-name] :[branch-name]

Git • Working with Remotes

Removing Local Copies of Deleted Remote Branches

If a remote branch has been deleted, your local repository has to be told to prune the reference to it. To prune deleted branches from a specific remote: git fetch [remote-name] --prune To prune deleted branches from all remotes: git fetch --all --prune

Git • Working with Remotes

Copying overlapping memory

A wide variety of standard library functions have among their effects copying byte sequences from one memory region to another. Most of these functions have undefined behavior when the source and destination regions overlap. For example, this ... #include <string.h> /* for memcpy() */ ch...

C Language • Undefined behavior

Installing Docker on Mac OS X

Requirements: OS X 10.8 “Mountain Lion” or newer required to run Docker. While the docker binary can run natively on Mac OS X, to build and host containers you need to run a Linux virtual machine on the box. 1.12.0 Since version 1.12 you don't need to have a separate VM to be installed, as Docker...

Docker • Getting started with Docker

Installation

Binaries Lua binaries are provided by most GNU/Linux distributions as a package. For example, on Debian, Ubuntu, and their derivatives it can be acquired by executing this: sudo apt-get install lua50 sudo apt-get install lua51 sudo apt-get install lua52 There are some semi-of...

Lua • Getting started with Lua