Tutorial by Examples: ce

C and C++ are well known as high-performance languages - largely due to the heavy amount of code customization, allowing a user to specify performance by choice of structure. When optimizing it is important to benchmark relevant code and completely understand how the code will be used. Common opti...

As stated in the basic examples, you can have variable bound arguments and the variable argument list (...). You can use this fact to recursively pull apart a list as you would in other languages (like Haskell). Below is an implementation of foldr() that takes advantage of that. Each recursive call ...

Use a mutex to synchronise access to a variable which is accessed from multiple threads: counter = 0 counter_mutex = Mutex.new # Start three parallel threads and increment counter 3.times.map do |index| Thread.new do counter_mutex.synchronize { counter += 1 } end end.each(&:joi...

Sometimes it is desirable to prevent Prolog from backtracking into alternative solutions. The basic tool available to the programmer to stop prolog from continuing futher in its backtrack is the cut operator. consider the following. % (percent signs mean comments) % a is the parent of b, c, and d....

As Rebar3 is free, open source and written in Erlang, it's possible to simply clone and build it from the source code. $ git clone https://github.com/erlang/rebar3.git $ cd rebar3 $ ./bootstrap This will create the rebar3 script, which you can put on your PATH or link to /usr/local/bin as expl...

The variable command ensures that a given namespace variable is created. Until a value is assigned to it, the variable's value is undefined: namespace eval mynamespace { variable alpha set alpha 0 } The variable can be accessed from outside the namespace (from anywhere, in fact) by at...

String#at Returns a substring of a string object. Same interface as String#[]. str = "hello" str.at(0) # => "h" str.at(1..3) # => "ell" str.at(-2) # => "l" str.at(-2..-1) # => "lo" str.at(5) # => nil str.at(5..-...

Most of the time you need to import namespaces in your XAML file. How this is done is different for the different XAML variants. For Windows Phone, Silverlight, WPF use the clr-namespace syntax: <Window ... xmlns:internal="clr-namespace:rootnamespace.namespace" xmlns:exte...

Open Android Device Monitor ( ie C:<ANDROID_SDK_LOCATION>\tools\monitor.bat) Select your device Click on Screen Capture Button

This is an example of a package-info.java file that binds an XML namespace to a serializable Java class. This should be placed in the same package as the Java classes that should be serialized using the namespace. /** * A package containing serializable classes. */ @XmlSchema ( xmlns = ...

This is a step-by-step guide to installing OpenCV 3 on a Debian-based Linux system from source. The steps should stay the same for other distros, just replace the relevant package manager commands when installing packages for the build. Note: If you don't feel like wasting time building stuff or di...

Store data in SEQUENCEFILE if the data needs to be compressed. You can import text files compressed with Gzip or Bzip2 directly into a table stored as TextFile. The compression will be detected automatically and the file will be decompressed on-the-fly during query execution. CREATE TABLE raw_seque...

Round a decimal number to an integer value For exact numeric values (e.g. DECIMAL): If the first decimal place of a number is 5 or higher, this function will round a number to the next integer away from zero. If that decimal place is 4 or lower, this function will round to the next integer value cl...

5.1 This Example demonstrates how to automatically assign a value to each entry in an enum list. This will prevent two enums from having the same value by mistake. NOTE: Object.freeze browser support var testEnum = function() { // Initializes the enumerations var enumList = [ &q...

SpriteKit functionality can be implemented in a subclass of SKScene. For example, a game may implement the main game functionality within an SKScene subclass called GameScene. In Swift: import SpriteKit class GameScene: SKScene { override func didMoveToView(view: SKView) { /* Co...

A simple use case it to create an SKScene that exactly fills the SKView. This avoids the need to consider scaling the view to fit or setting a camera to show a part of the scene. The following code assumes an SKView called skView already exists (e.g. as defined in Create a Full Screen SKView using ...

An SKScene has a scaleMode parameter that defines how it will change its size to fit within the SKView it is presented into the SKView if it is not the same size and/or shape. There are four options for scaleMode: AspectFit: the scene is scaled (but not stretched) until it fits within the view. ...

You can place an SKCameraNode into an SKScene to define which part of the scene is shown in the SKView. Think of the SKScene as a 2D world with a camera floating above it: the SKView will show what the camera 'sees'. E.g. the camera could be attached to the main character's sprite to follow the act...

This program demonstrates how to run another process using fork() and wait its termination using waitpid(): fork() creates an identical copy of the current process. The original process is the parent process, while the newly created one is the child process. Both processes continue exactly afte...

The complete sample code for this application (Android + Node server) is available in the PayPal Developer Github repository. From step 2, an async request has been made to our server at the /fpstore endpoint, passing along the auth code and metadata ID. We now need to exchange those for a token in...