Programming Fundamentals/Variable Examples Swift

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

References

• Wikiversity: Computer Programming

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