Programming Fundamentals/Files/Swift
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strings.swift
[edit | edit source]// This program creates a file, adds data to the file, displays the file,
// appends more data to the file, displays the file, and then deletes the file.
// It will not run if the file already exists.
//
// References:
// https://www.mathsisfun.com/temperature-conversion.html
// https://developer.apple.com/library/content/documentation/Swift/Conceptual/Swift_Programming_Language/TheBasics.html
import Foundation
func fileExists(filename:String) -> Bool {
let fileManager = FileManager.default
return fileManager.fileExists(atPath:filename)
}
func calculateFahrenheit(celsius:Double) -> Double {
var fahrenheit: Double
fahrenheit = celsius * 9 / 5 + 32
return fahrenheit
}
func createFile(filename:String) {
var text: String
var fahrenheit: Double
text = "C,F\n"
for celsius in stride(from: 0.0, through: 50.0, by: 1.0) {
fahrenheit = calculateFahrenheit(celsius:celsius)
text += String(celsius) + "," + String(fahrenheit) + "\n"
}
do {
try text.write(toFile: filename, atomically: true, encoding: .utf8)
} catch {
print("Error creating ", filename)
print(error.localizedDescription)
}
}
func readFile(filename:String) {
var text = ""
do {
text = try String(contentsOfFile: filename, encoding: .utf8)
let lines = text.components(separatedBy:"\n")
for line in lines {
print(line)
}
} catch {
print("Error reading " + filename)
print(error.localizedDescription)
}
}
func appendFile(filename:String) {
var text: String
var fahrenheit: Double
do {
text = try String(contentsOfFile: filename, encoding: .utf8)
for celsius in stride(from: 51.0, through: 100.0, by: 1.0) {
fahrenheit = calculateFahrenheit(celsius:celsius)
text += String(celsius) + "," + String(fahrenheit) + "\n"
}
try text.write(toFile: filename, atomically: true, encoding: .utf8)
} catch {
print("Error appending to ", filename)
print(error.localizedDescription)
}
}
func deleteFile(filename:String) {
do {
let fileManager = FileManager.default
try fileManager.removeItem(atPath:filename)
} catch {
print("Error deleting", filename)
print(error.localizedDescription)
}
}
func main() {
let filename:String = "~file.txt"
if (fileExists(filename:filename)) {
print("File already exists.")
}
else {
createFile(filename:filename)
readFile(filename:filename)
appendFile(filename:filename)
readFile(filename:filename)
deleteFile(filename:filename)
}
}
main()
Try It
[edit | edit source]Copy and paste the code above into one of the following free online development environments or use your own Swift compiler / interpreter / IDE.