Tutorial by Examples: e

Throwing exception in a lock statement

Following code will release the lock. There will be no problem. Behind the scenes lock statement works as try finally lock(locker) { throw new Exception(); } More can be seen in the C# 5.0 Specification: A lock statement of the form lock (x) ... where x is an expression of a referenc...

C# Language • Lock Statement

Converting string to upper case

The function toupper will convert a string to upper case (capital letters). For example: BEGIN { greeting = "hello" loud_greeting = toupper(greeting) print loud_greeting } This code will output "HELLO" when run.

awk • String manipulation functions

Simple "Hello World" Project

Given a C++ source file main.cpp defining a main() function, an accompanying CMakeLists.txt file (with the following content) will instruct CMake to generate the appropriate build instructions for the current system and default C++ compiler. main.cpp (C++ Hello World Example) #include <iostream...

cmake • Getting started with cmake

Creating Processes

We create a new concurrent process by calling the spawn function. The spawn function will get as parameter a function Fun that the process will evaluate. The return value of the spawn function is the created process identifier (pid). 1> Fun = fun() -> 2+2 end. #Fun<erl_eval.20.52032458&gt...

Erlang Language • Processes

Functions and Properties in enums

Enum classes can also declare members (i.e. properties and functions). A semicolon (;) must be placed between the last enum object and the first member declaration. If a member is abstract, the enum objects must implement it. enum class Color { RED { override val rgb: Int = 0xFF0000 ...

Kotlin • Enum

Simple enum

enum class Color { RED, GREEN, BLUE } Each enum constant is an object. Enum constants are separated with commas.

Kotlin • Enum

Hello World

File: test.cfm Tag Implementation <cfoutput>Hello World!</cfoutput> CFScript Implementation <cfscript> writeOutput("Hello World!"); </cfscript>

coldfusion • Getting started with coldfusion

Printing to a browser's debugging console

A browser's debugging console can be used in order to print simple messages. This debugging or web console can be directly opened in the browser (F12 key in most browsers – see Remarks below for further information) and the log method of the console Javascript object can be invoked by typing the fol...

JavaScript • Console

Hello World

Begin by including highcharts.js in your index.html <html> <head> <script src="http://code.highcharts.com/highcharts.js"></script> </head> Add a <div> to contain your chart <body> <div id="chart"> <!...

highcharts • Getting started with highcharts

Saving a read-only file edited in Vim

Sometimes, we may open a file which we do not have permission to write in Vim without using sudo. Use this command to save a read-only file edited in Vim. :w !sudo tee > /dev/null % Which you could map to :w!! in your .vimrc: cmap w!! w !sudo tee > /dev/null % You will be presented a ...

vim • Getting started with vim

Canvas size and resolution

The size of a canvas is the area it occupies on the page and is defined by the CSS width and height properties. canvas { width : 1000px; height : 1000px; } The canvas resolution defines the number of pixels it contains. The resolution is set by setting the canvas element width and heigh...

html5-canvas • Getting started with html5-canvas

Creating a responsive full page canvas

Starter code to create and remove a full page canvas that responds to resize events via javascript. var canvas; // Global canvas reference var ctx; // Global 2D context reference // Creates a canvas function createCanvas () { const canvas = document.createElement(&q...

html5-canvas • Responsive Design

Off screen canvas

Many times when working with the canvas you will need to have a canvas to hold some intrum pixel data. It is easy to create an offscreen canvas, obtain a 2D context. An offscreen canvas will also use the available graphics hardware to render. The following code simply creates a canvas and fills it ...

html5-canvas • Getting started with html5-canvas

Simple animation with 2D context and requestAnimationFrame

This example will show you how to create a simple animation using the canvas and the 2D context. It is assumed you know how to create and add a canvas to the DOM and obtain the context // this example assumes ctx and canvas have been created const textToDisplay = "This is an example that uses...

html5-canvas • Animation

Drawing many translated, scaled, and rotated images quickly

There are many situation where you want to draw an image that is rotated, scaled, and translated. The rotation should occur around the center of the image. This is the quickest way to do so on the 2D canvas. These functions a well suited to 2D games where the expectation is to render a few hundred e...

html5-canvas • Transformations

Installation and Setup

Pyinstaller is a normal python package. It can be installed using pip: pip install pyinstaller Installation in Windows For Windows, pywin32 or pypiwin32 is a prerequisite. The latter is installed automatically when pyinstaller is installed using pip. Installation in Mac OS X PyInstaller works...

Python Language • PyInstaller - Distributing Python Code

Using Pyinstaller

In the simplest use-case, just navigate to the directory your file is in, and type: pyinstaller myfile.py Pyinstaller analyzes the file and creates: A myfile.spec file in the same directory as myfile.py A build folder in the same directory as myfile.py A dist folder in the same directory as m...

Python Language • PyInstaller - Distributing Python Code

Backing up one database

pg_dump -Fc -f DATABASE.pgsql DATABASE The -Fc selects the "custom backup format" which gives you more power than raw SQL; see pg_restore for more details. If you want a vanilla SQL file, you can do this instead: pg_dump -f DATABASE.sql DATABASE or even pg_dump DATABASE > DATABA...

postgresql • Backup and Restore

Restoring backups

psql < backup.sql A safer alternative uses -1 to wrap the restore in a transaction. The -f specifies the filename rather than using shell redirection. psql -1f backup.sql Custom format files must be restored using pg_restore with the -d option to specify the database: pg_restore -d DATABA...

postgresql • Backup and Restore

Backing up the whole cluster

$ pg_dumpall -f backup.sql This works behind the scenes by making multiple connections to the server once for each database and executing pg_dump on it. Sometimes, you might be tempted to set this up as a cron job, so you want to see the date the backup was taken as part of the filename: $ post...

postgresql • Backup and Restore