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))
```

```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:")

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