Swift - Making Choices(if statements, while loop, break)

The Swift Programming Language
Apple Inc.

開発環境

• OS X Mavericks - Apple(OS)
• Xcode 6.0 Beta
• Swift (プログラミング言語)

Practical Programming: An Introduction to Computer Science Using Python 3 (Pragmatic Programmers) (Paul Gries (著)、Jennifer Campbell (著)、Jason Montojo (著)、Lynn Beighley (編集)、Pragmatic Bookshelf)のChapter 5(Making Choices)、5.6(Exercises) 10.をSwiftで考えてみる。

5.6(Exercises) 10.

コード(Xcode)

main.swift

//
//  main.swift
//  ample9
//
//  Created by kamimura on 8/4/14.
//  Copyright (c) 2014 kamimura. All rights reserved.
//

import Foundation

func input(msg:String = "") -> String {
    print(msg)
    var in_fh = NSFileHandle.fileHandleWithStandardInput()
    var data = in_fh.availableData
    var s = NSString(data: data, encoding: NSUTF8StringEncoding)
    s = s.substringToIndex(s.length - 1)
    return s;
}

while true {
    let s = input(msg: "phを入力: ")
    if s == "" {
        break
    }
    let ph = Float(s.toInt()!)
    if ph < 7.0 {
        println("It's acidic!")
    }
    if ph < 4.0 {
        println("It's a strong acid!")
    }
}

入出力結果(Console Output)

phを入力: 0
It's acidic!
It's a strong acid!
phを入力: 1
It's acidic!
It's a strong acid!
phを入力: 2
It's acidic!
It's a strong acid!
phを入力: 3
It's acidic!
It's a strong acid!
phを入力: 4
It's acidic!
phを入力: 5
It's acidic!
phを入力: 6
It's acidic!
phを入力: 7
phを入力: 8
phを入力: 9
phを入力: 10
phを入力: 
Program ended with exit code: 0