Swift Language Getting started with Swift Language Your first Swift program
Example
Write your code in a file named hello.swift:
print("Hello, world!")
- To compile and run a script in one step, use
swiftfrom the terminal (in a directory where this file is located):
To launch a terminal, press CTRL+ALT+T on Linux, or find it in Launchpad on macOS. To change directory, enter
cddirectory_name(orcd ..to go back)
$ swift hello.swift Hello, world!
A compiler is a computer program (or a set of programs) that transforms source code written in a programming language (the source language) into another computer language (the target language), with the latter often having a binary form known as object code. (Wikipedia)
- To compile and run separately, use
swiftc:
$ swiftc hello.swift
This will compile your code into hello file. To run it, enter ./, followed by a filename.
$ ./hello Hello, world!
- Or use the swift REPL (Read-Eval-Print-Loop), by typing
swiftfrom the command line, then entering your code in the interpreter:
Code:
func greet(name: String, surname: String) {
print("Greetings \(name) \(surname)")
}
let myName = "Homer"
let mySurname = "Simpson"
greet(name: myName, surname: mySurname)
Let's break this large code into pieces:
func greet(name: String, surname: String) { // function body }- create a function that takes anameand asurname.
print("Greetings \(name) \(surname)")- This prints out to the console "Greetings ", thenname, thensurname. Basically\(variable_name)prints out that variable's value.
let myName = "Homer"andlet mySurname = "Simpson"- create constants (variables which value you can't change) usingletwith names:myName,mySurnameand values:"Homer","Simpson"respectively.
greet(name: myName, surname: mySurname)- calls a function that we created earlier supplying the values of constantsmyName,mySurname.
Running it using REPL:
$ swift
Welcome to Apple Swift. Type :help for assistance.
1> func greet(name: String, surname: String) {
2. print("Greetings \(name) \(surname)")
3. }
4>
5> let myName = "Homer"
myName: String = "Homer"
6> let mySurname = "Simpson"
mySurname: String = "Simpson"
7> greet(name: myName, surname: mySurname)
Greetings Homer Simpson
8> ^D
Press CTRL+D to quit from REPL.
