Tutorial by Examples: l

JSON (JavaScript Object Notation) syntax is based on a subset of JavaScript (see also json.org). A valid JSON expression can be one of the following data types simple data types: String, Number, Boolean, Null composite data types: Value, Object, Array Simple data types A JSON string has to ...

c++03 The Rule of Three states that if a type ever needs to have a user-defined copy constructor, copy assignment operator, or destructor, then it must have all three. The reason for the rule is that a class which needs any of the three manages some resource (file handles, dynamically allocated me...

To prompt for credentials, you should almost always use the Get-Credential cmdlet: $credential = Get-Credential Pre-filled user name: $credential = Get-Credential -UserName 'myUser' Add a custom prompt message: $credential = Get-Credential -Message 'Please enter your company email address a...

The password in a credential object is an encrypted [SecureString]. The most straightforward way is to get a [NetworkCredential] which does not store the password encrypted: $credential = Get-Credential $plainPass = $credential.GetNetworkCredential().Password The helper method (.GetNetworkCrede...

To store and retrieve encrypted credentials easily, use PowerShell's built-in XML serialization (Clixml): $credential = Get-Credential $credential | Export-CliXml -Path 'C:\My\Path\cred.xml' To re-import: $credential = Import-CliXml -Path 'C:\My\Path\cred.xml' The important thing to remem...

Tuples are useful to swap values between 2 (or more) variables without using temporary variables. Example with 2 variables Given 2 variables var a = "Marty McFly" var b = "Emmett Brown" we can easily swap the values (a, b) = (b, a) Result: print(a) // "Emmett Bro...

Check if a path is a directory or a file The is_dir function returns whether the argument is a directory, while is_file returns whether the argument is a file. Use file_exists to check if it is either. $dir = "/this/is/a/directory"; $file = "/this/is/a/file.txt"; echo is_d...

The Common Lisp Quick Reference is a document which can be printed and bound as a booklet in various layouts to have a printed quick reference for Common Lisp.

You can remove all the elements in a set using the .clear() method: mySet.clear();

You can get the number of elements inside the set using the .size property const mySet = new Set([1, 2, 2, 3]); mySet.add(4); mySet.size; // 4 This property, unlike Array.prototype.length, is read-only, which means that you can't change it by assigning something to it: mySet.size = 5; mySet....

In general, classes in Perl are just packages. They can contain data and methods, as usual packages. package Point; use strict; my $CANVAS_SIZE = [1000, 1000]; sub new { ... } sub polar_coordinates { ... } 1; It is important to note that the variables declared in a packa...

To make a class a subclass of another class, use parent pragma: package Point; use strict; ... 1; package Point2D; use strict; use parent qw(Point); ... 1; package Point3D; use strict; use parent qw(Point); ... 1; Perl allows for multiple inheritance: package Point2D; use stri...

In Perl, the difference between class (static) and object (instance) methods is not so strong as in some other languages, but it still exists. The left operand of the arrow operator -> becomes the first argument of the method to be called. It may be either a string: # the first argument of new ...

To get the previous element you can use the .prev() method. <ul> <li>Mark</li> <li class="anna">Anna</li> <li>Paul</li> </ul> If you are standing on the "Anna" element and you want to get the previous element, &q...

To filter a selection you can use the .filter() method. The method is called on a selection and returns a new selection. If the filter matches an element then it is added to the returned selection, otherwise it is ignored. If no element is matched then an empty selection is returned. The HTML Thi...

On Debian-based distributions, including Ubuntu, the most straightforward way is to use the .deb installation file. Go to the Scala website. Choose the version you want to install then scroll down and look for scala-x.x.x.deb. You can install the scala deb from command line: sudo dpkg -i scala-x.x...

base.twig.html <!DOCTYPE html> <html> <head> <title>{{ title | default('Hello World') }}</title> <link rel="stylesheet" type="text/css" href="theme.css"> {% block css %} {% endblock %} &...

article.twig.html <article> <h1>{{ article.title }}</h1> {% block content %} <p>{{ article.content }}</p> {% endblock %} </article> articles.twig.html {# use default template for article #} {% for article in articles %} {% include &...

Collections in Java only work for objects. I.e. there is no Map<int, int> in Java. Instead, primitive values need to be boxed into objects, as in Map<Integer, Integer>. Java auto-boxing will enable transparent use of these collections: Map<Integer, Integer> map = new HashMap<&g...

redis-cli is the Redis command line interface program that allows to send commands to Redis and read the replies sent by the server, directly from the terminal. Basic command line usage is below: Access to redis: $ redis-cli 127.0.0.1:6379> Access to redis with authentication: $ redis-cli ...