Tutorial by Examples: g

package main import ( "fmt" "io/ioutil" ) func main() { files, err := ioutil.ReadDir(".") if err != nil { panic(err) } fmt.Println("Files and folders in the current directory:") for _, fileInfo := range fi...

To access member variables and member functions of an object of a class, the . operator is used: struct SomeStruct { int a; int b; void foo() {} }; SomeStruct var; // Accessing member variable a in var. std::cout << var.a << std::endl; // Assigning member variable b in v...

To create a pure JSON table you need to provide a single field with the type JSONB: CREATE TABLE mytable (data JSONB NOT NULL); You should also create a basic index: CREATE INDEX mytable_idx ON mytable USING gin (data jsonb_path_ops); At this point you can insert data in to the table and que...

Taking a complex JSON document in a table: CREATE TABLE mytable (data JSONB NOT NULL); CREATE INDEX mytable_idx ON mytable USING gin (data jsonb_path_ops); INSERT INTO mytable VALUES($$ { "name": "Alice", "emails": [ "[email protected]", ...

Ruby can inject an array of values into a string by replacing any placeholders with the values from the supplied array. "Hello %s, my name is %s!" % ['World', 'br3nt'] # => Hello World, my name is br3nt! The place holders are represented by two %s and the values are supplied by the...

Problem: Create a String containing n repetitions of a String s. The trivial approach would be repeatedly concatenating the String final int n = ... final String s = ... String result = ""; for (int i = 0; i < n; i++) { result += s; } This creates n new string instances ...

Every case class defines an extractor that can be used to capture the members of the case class when pattern matching: case class Student(name: String, email: String) def matchStudent1(student: Student): String = student match { case Student(name, email) => s"$name has the following...

Strings in JavaScript can be enclosed in Single quotes 'hello', Double quotes "Hello" and (from ES2015, ES6) in Template Literals (backticks) `hello`. var hello = "Hello"; var world = 'world'; var helloW = `Hello World`; // ES2015 / ES6 Strings can be created...

If your string is enclosed (i.e.) in single quotes you need to escape the inner literal quote with backslash \ var text = 'L\'albero means tree in Italian'; console.log( text ); \\ "L'albero means tree in Italian" Same goes for double quotes: var text = "I feel \"high\&quot...

You can require a generic type to extend multiple upper bounds. Example: we want to sort a list of numbers but Number doesn't implement Comparable. public <T extends Number & Comparable<T>> void sortNumbers( List<T> n ) { Collections.sort( n ); } In this example T must...

Swift textView.text = "Hello, world!" Objective-C: textView.text = @"Hello, world!";

Swift textView.textAlignment = .left Objective-C textView.textAlignment = NSTextAlignmentLeft;

Responding to Editing Notifications textViewShouldBeginEditing(_:) textViewDidBeginEditing(_:) textViewShouldEndEditing(_:) textViewDidEndEditing(_:) Responding to Text Changes textView(_:shouldChangeTextIn:replacementText:) textViewDidChange(_:) Responding to URL textView(_: UITe...

Swift //System Font textView.font = UIFont.systemFont(ofSize: 12) //Font of your choosing textView.font = UIFont(name: "Font Name", size: 12) Objective-C //System Font textView.font = [UIFont systemFontOfSize:12]; //Font of your choosing textView.font = [UIFont fontWithName:...

Swift textView.textColor = UIColor.red Objective-C textView.textColor = [UIColor redColor];

To keep a container running in the background, supply the -d command line option during container startup: docker run -d busybox top The option -d runs the container in detached mode. It is also equivalent to -d=true. A container in detached mode cannot be removed automatically when it stops, t...

A Docker volume is a file or directory which persists beyond the lifetime of the container. It is possible to mount a host file or directory into a container as a volume (bypassing the UnionFS). Add a volume with the -v command line option: docker run -d -v "/data" awesome/app bootstrap....

Lets assume we have some Film model: public class Film { public string Title { get; set; } public string Category { get; set; } public int Year { get; set; } } Group by Category property: foreach (var grp in films.GroupBy(f => f.Category)) { var groupCategory = grp.Key; ...

You have started an interactive rebase. In the editor where you pick your commits, you decide that something is going wrong (for example a commit is missing, or you chose the wrong rebase destination), and you want to abort the rebase. To do this, simply delete all commits and actions (i.e. all lin...

Definition In software development, a breakpoint is an intentional stopping or pausing place in a program, put in place for debugging purposes. More generally, a breakpoint is a means of acquiring knowledge about a program during its execution. During the interruption, the programmer inspects th...