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int a; std::cout << a; // Undefined behavior! This results in undefined behavior, because a is uninitialised. It is often, incorrectly, claimed that this is because the value is "indeterminate", or "whatever value was in that memory location before". However, it is th...

In order to record audio from a user's microphone, we must first gain permission from the user to access the device: navigator.mediaDevices.getUserMedia({ audio: true }) .then(successCallback) .catch(failureCallback); On success, our successCallback will be called with a MediaStream ob...

Download and extract the OSGi starter kit for your platform from Equinox download page for Neon release. Start the framework from the rt/plugins folder with the following command (or your platform's rt executable from the rt folder): rt/plugins$ java -jar org.eclipse.equinox.launcher_1.3.200.v2016...

Optionals (also known as Maybe types) are used to represent a type whose contents may or may not be present. They are implemented in C++17 as the std::optional class. For example, an object of type std::optional<int> may contain some value of type int, or it may contain no value. Optionals ar...

One of the most elementary DCG nonterminals is ... //0, which can be read as "anything at all": ... --> [] | [_], ... . It can be used to describe a list Ls that contains the element E via: phrase(( ..., [E], ... ), Ls)

DCGs can be used for parsing. Best of all, the same DCG can often be used to both parse and generate lists that are being described. For example: sentence --> article, subject, verb, object. article --> [the]. subject --> [woman] | [man]. verb --> [likes] | [enjoys]. object ...

The C-API is the most powerful way to access PostgreSQL and it is surprisingly comfortable. Compilation and linking During compilation, you have to add the PostgreSQL include directory, which can be found with pg_config --includedir, to the include path. You must link with the PostgreSQL client s...

Prerequisites In order to run Elasticsearch, a Java Runtime Environment (JRE) is required on the machine. Elasticsearch requires Java 7 or higher and recommends Oracle JDK version 1.8.0_73. Install Oracle Java 8 sudo add-apt-repository -y ppa:webupd8team/java sudo apt-get update echo "or...

The Locals window provides easy access to the current value of variables and objects within the scope of the function or subroutine you are running. It is an essential tool to debugging your code and stepping through changes in order to find issues. It also allows you to explore properties you might...

Although people often say Sass as the name of this CSS-preprocessor, they often mean the SCSS-syntax. Sass uses the .sass file extension, while SCSS-Sass uses the .scss extension. They are both referred to as "Sass". Speaking generally, the SCSS-syntax is more commonly used. SCSS looks li...

Sass tends to be the more "lazy" syntax. Nothing illustrates this nicer than how you define and include mixins. Defining a mixin = is how you define a mixin in Sass, @mixin in SCSS. // SCSS @mixin size($x: 10rem, $y: 20rem) { width: $x; height: $y; } // Sass =size($x: 10...

Use charAt() to get a character at the specified index in the string. var string = "Hello, World!"; console.log( string.charAt(4) ); // "o" Alternatively, because strings can be treated like arrays, use the index via bracket notation. var string = "Hello, World!";...

OrientDB is available in two editions: Community Edition is released as an open source project under the Apache 2 license. This license allows unrestricted free usage for both open source and commercial projects. Enterprise Edition is commercial software built on top of the Community Edit...

In ASP.NET Web API, a controller is a class that handles HTTP requests. The public methods of the controller are called action methods or simply actions. When the Web API framework receives a request, it routes the request to an action. To determine which action to invoke, the framework uses a rou...

To load a bundled image: package com.example; public class ExampleApplication { private Image getIcon() throws IOException { URL imageURL = ExampleApplication.class.getResource("icon.png"); return ImageIO.read(imageURL); } }

Cross join does a Cartesian product of the two members, A Cartesian product means each row of one table is combined with each row of the second table in the join. For example, if TABLEA has 20 rows and TABLEB has 20 rows, the result would be 20*20 = 400 output rows. Using example database SELECT d...

A template autorun may be used to (re)subscribe to a publication. It establishes a reactive context which is re-executed whenever any reactive data it depends on changes. In addition, an autorun always runs once (the first time it is executed). Template autoruns are normally put in an onCreated met...

Everything to the right of // in the same line is commented. int i = 0; // Commented out text

Sometimes a term is defined in multiple sections of the manual. By default, man will only display the first page it finds, which can be annoying for programmers because C functions are documented in a later section than commands and system calls. Use the following to display all pages that match a...

You can use the Substring method to get any number of characters from a string at any given location. However, if you only want a single character, you can use the string indexer to get a single character at any given index like you do with an array: string s = "hello"; char c = s[1]; //...