Tutorial by Examples: e

Introduction HTML (Hypertext Markup Language) uses a markup system composed of elements which represent specific content. Markup means that with HTML you declare what is presented to a viewer, not how it is presented. Visual representations are defined by Cascading Style Sheets (CSS) and realized...

At the command line, first verify that you have Git installed: On all operating systems: git --version On UNIX-like operating systems: which git If nothing is returned, or the command is not recognized, you may have to install Git on your system by downloading and running the installer. See...

To iterate through a list you can use for: for x in ['one', 'two', 'three', 'four']: print(x) This will print out the elements of the list: one two three four The range function generates numbers which are also often used in a for loop. for x in range(1, 6): print(x) The res...

"123.50".to_i #=> 123 Integer("123.50") #=> 123 A string will take the value of any integer at its start, but will not take integers from anywhere else: "123-foo".to_i # => 123 "foo-123".to_i # => 0 However, there is a difference when ...

1/2 #=> 0 Since we are dividing two integers, the result is an integer. To solve this problem, we need to cast at least one of those to Float: 1.0 / 2 #=> 0.5 1.to_f / 2 #=> 0.5 1 / Float(2) #=> 0.5 Alternatively, fdiv may be used to return the floating point result of di...

The git clone command is used to copy an existing Git repository from a server to the local machine. For example, to clone a GitHub project: cd <path where you'd like the clone to create a directory> git clone https://github.com/username/projectname.git To clone a BitBucket project: cd ...

In its most simple form, an if condition can be used like this: var i = 0; if (i < 1) { console.log("i is smaller than 1"); } The condition i < 1 is evaluated, and if it evaluates to true the block that follows is executed. If it evaluates to false, the block is skipped....

Consider a database with the following two tables. Employees table: IdFNameLNameDeptId1JamesSmith32JohnJohnson4 Departments table: IdName1Sales2Marketing3Finance4IT Simple select statement * is the wildcard character used to select all available columns in a table. When used as a substitute f...

The JSONSerialization class is built into Apple's Foundation framework. 2.2 Read JSON The JSONObjectWithData function takes NSData, and returns AnyObject. You can use as? to convert the result to your expected type. do { guard let jsonData = "[\"Hello\", \"JSON\"]&q...

An enum provides a set of related values: enum Direction { case up case down case left case right } enum Direction { case up, down, left, right } Enum values can be used by their fully-qualified name, but you can omit the type name when it can be inferred: let dir = Dire...

Enum cases can contain one or more payloads (associated values): enum Action { case jump case kick case move(distance: Float) // The "move" case has an associated distance } The payload must be provided when instantiating the enum value: performAction(.jump) performA...

Normally, enums can't be recursive (because they would require infinite storage): enum Tree<T> { case leaf(T) case branch(Tree<T>, Tree<T>) // error: recursive enum 'Tree<T>' is not marked 'indirect' } The indirect keyword makes the enum store its payload with...

Enums without payloads can have raw values of any literal type: enum Rotation: Int { case up = 0 case left = 90 case upsideDown = 180 case right = 270 } Enums without any specific type do not expose the rawValue property enum Rotation { case up case right cas...

This example assumes Ruby and Ruby on Rails have already been installed properly. If not, you can find how to do it here. Open up a command line or terminal. To generate a new rails application, use rails new command followed by the name of your application: $ rails new my_app If you want to c...

Logical OR (||), reading left to right, will evaluate to the first truthy value. If no truthy value is found, the last value is returned. var a = 'hello' || ''; // a = 'hello' var b = '' || []; // b = [] var c = '' || undefined; // c = undefined var d = 1 |...

Standard While Loop A standard while loop will execute until the condition given is false: var i = 0; while (i < 100) { console.log(i); i++; } Expected output: 0 1 ... 99 Decremented loop var i = 100; while (i > 0) { console.log(i); i--; /* equivalent to i...

Breaking out of a while loop var i = 0; while(true) { i++; if(i === 42) { break; } } console.log(i); Expected output: 42 Breaking out of a for loop var i; for(i = 0; i < 100; i++) { if(i === 42) { break; } } console.log(i); Expected o...

Continuing a "for" Loop When you put the continue keyword in a for loop, execution jumps to the update expression (i++ in the example): for (var i = 0; i < 3; i++) { if (i === 1) { continue; } console.log(i); } Expected output: 0 2 Continuing a While...

Place the following code into a file name hello.go: package main import "fmt" func main() { fmt.Println("Hello, 世界") } Playground When Go is installed correctly this program can be compiled and run like this: go run hello.go Output: Hello, 世界 Once you are...

Using the def statement is the most common way to define a function in python. This statement is a so called single clause compound statement with the following syntax: def function_name(parameters): statement(s) function_name is known as the identifier of the function. Since a function def...