4.16: Swift Examples
- Page ID
- 10652
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The temperature program main function is listed twice, once using if-then-else and once using switch, followed by the supporting functions.
If Then Else
// 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 main() {
var choice: String
choice = getChoice()
if choice == "C" || choice == "c" {
processCelsius()
}
else if choice == "F" || choice == "f" {
processFahrenheit()
}
else {
print("You must enter C to convert to Celsius or F to convert to Fahrenheit.")
}
}
main()
Switch
func main() {
var choice: String
choice = getChoice()
switch choice {
case "C", "c":
processCelsius()
case "F", "f":
processFahrenheit()
default:
print("You must enter C to convert to Celsius or F to convert to Fahrenheit.")
}
}
Supporting Functions
func getChoice() -> String {
var choice: String
print("Enter C to convert to Celsius or F to convert to Fahrenheit:")
choice = readLine(strippingNewline: true)!
return choice
}
func processCelsius() {
var temperature: Double
var result: Double
temperature = getTemperature(scale:"Fahrenheit")
result = calculateCelsius(fahrenheit:temperature)
displayResult(temperature:temperature, fromScale:"Fahrenheit", result:result, toScale:"Celsius")
}
func processFahrenheit() {
var temperature: Double
var result: Double
temperature = getTemperature(scale:"Celsius")
result = calculateFahrenheit(celsius:temperature)
displayResult(temperature:temperature, fromScale:"Celsius", result:result, toScale:"Fahrenheit")
}
func getTemperature(scale: String) -> Double {
var temperature: Double
print("Enter " + scale + " temperature:")
temperature = Double(readLine(strippingNewline: true)!)!
return temperature
}
func calculateCelsius(fahrenheit: Double) -> Double {
var celsius: Double
celsius = (fahrenheit - 32) * 5 / 9
return celsius
}
func calculateFahrenheit(celsius: Double) -> Double {
var fahrenheit: Double
fahrenheit = celsius * 9 / 5 + 32
return fahrenheit
}
func displayResult(temperature: Double, fromScale: String, result: Double, toScale: String) {
print(String(temperature) + "° " + fromScale + " is " + String(result) + "° " + toScale)
}
Output
Enter C to convert to Celsius or F to convert to Fahrenheit: c Enter Fahrenheit temperature: 100 100.0° Fahrenheit is 37.77777777777778° Celsius Enter C to convert to Celsius or F to convert to Fahrenheit: f Enter Celsius temperature: 100 100.0° Celsius is 212.0° Fahrenheit Enter C to convert to Celsius or F to convert to Fahrenheit: x You must enter C to convert to Celsius or F to convert to Fahrenheit.
References
- Wikiversity: Computer Programming