# Programming Fundamentals/Functions/Swift

## functions.swift

```// This program asks the user for a Fahrenheit temperature,
// converts the given temperature to Celsius,
// and displays the results.
//
// References:
//     https://www.mathsisfun.com/temperature-conversion.html
//     https://developer.apple.com/library/content/documentation/Swift/Conceptual/Swift_Programming_Language/TheBasics.html

func getFahrenheit() -> Double
{
var fahrenheit: Double

print("Enter Fahrenheit temperature:")
fahrenheit = Double(readLine(strippingNewline: true)!)!

return fahrenheit
}

func calculateCelsius(fahrenheit: Double) -> Double
{
var celsius: Double

celsius = (fahrenheit - 32) * 5 / 9

return celsius
}

func displayResult(fahrenheit: Double, celsius: Double)
{
print(String(fahrenheit) + "° Fahrenheit is " + String(celsius) + "° Celsius")
}

func main()
{
var fahrenheit: Double
var celsius: Double

fahrenheit = getFahrenheit()
celsius = calculateCelsius(fahrenheit:fahrenheit)
displayResult(fahrenheit:fahrenheit, celsius:celsius)
}

main()
```

## Try It

Copy and paste the code above into one of the following free online development environments or use your own Swift compiler / interpreter / IDE.