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Engineering LibreTexts

2.22: Swift Examples

  • Page ID
    10619
  • Overview

    The following examples demonstrate data types, arithmetic operations, and input in Swift.

    Data Types

    // This program demonstrates variables, literal constants, and data types.
    
    var i: Int
    var d: Double
    var s: String
    var b: Bool
    
    i = 1234567890
    d = 1.23456789012345
    s = "string"
    b = true
    
    print("Integer i =", i)
    print("Double d =", d)
    print("String s =", s)
    print("Boolean b =", b)

    Output

    Integer i = 1234567890
    Double d = 1.23456789012345
    String s = string
    Boolean b = true

    Discussion

    Each code element represents:

    • // begins a comment
    • var i: Int defines an integer variable named i
    • var d: Double defines a double floating-point variable named d
    • var s: String defines a string variable named s
    • var b: Bool defines a Boolean variable named b
    • i = , d = , s =, b = assign literal values to the corresponding variables
    • print() calls the print function

    Arithmetic

    // This program demonstrates arithmetic operations.
    
    var a: Int
    var b: Int
    
    a = 3
    b = 2
    
    print("a =", a)
    print("b =", b)
    print("a + b =", (a + b))
    print("a - b =", (a - b))
    print("a * b =", a * b)
    print("a / b =", a / b)
    print("a % b =", (a % b))
    

    Output

    a = 3
    b = 2
    a + b = 5
    a - b = 1
    a * b = 6
    a / b = 1
    a % b = 1
    

    Discussion

    Each new code element represents:

    • +, -, *, /, and % represent addition, subtraction, multiplication, division, and modulus, respectively.

    Temperature

    // This program converts a Fahrenheit temperature to Celsius.
    //
    // References:
    //     https://www.mathsisfun.com/temperature-conversion.html
    //     https://developer.apple.com/library/content/documentation/Swift/Conceptual/Swift_Programming_Language/TheBasics.html
    
    var fahrenheit: Double
    var celsius: Double
    
    print("Enter Fahrenheit temperature:")
    fahrenheit = Double(readLine()!)!
    
    celsius = (fahrenheit - 32) * 5 / 9
    
    print(String(fahrenheit) + "° Fahrenheit is " + String(celsius) + "° Celsius")

    Output

    Enter Fahrenheit temperature:
     100
    100.0° Fahrenheit is 37.7777777777778° Celsius

    Discussion

    Each new code element represents:

    • readline()! reads the next line from standard input
    • Double()! converts the input to a double floating-point value
    • String() converts the output numeric value to a string