Swift - Repeating Code Using Loops(while loop, counter, increment, decrement))

The Swift Programming Language
Apple Inc.

開発環境

• OS X Mavericks - Apple(OS)
• Xcode 6.0 Beta 6
• 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 9(Repeating Code Using Loops)、9.10(Exercises) 16.をSwiftで考えてみる。

9.10(Exercises) 16.

コード(Xcode)

main.swift

//
//  main.swift
//  sample16
//
//  Created by kamimura on 9/21/14.
//  Copyright (c) 2014 kamimura. All rights reserved.
//

import Foundation

var rat_1_weight:Double = 1
var rat_2_weight:Double = 1
let rat_1_rate:Int = 4

println("a.")
var weeks:Int = 0
var temp:Double = rat_1_weight
let rat_1_inc:Double = 1.0 + Double(rat_1_rate) / 100
while temp < rat_1_weight * 1.25 {
    temp *= rat_1_inc
    weeks += 1
}
println(weeks)

println("b.")
let rat_2_rate:Int = rat_1_rate - 1
let rat_2_inc:Double = 1 + Double(rat_2_rate) / 100
weeks = 0
while rat_1_weight < rat_2_weight * 1.1 {
    rat_1_weight *= rat_1_inc
    rat_2_weight *= rat_2_inc
    weeks += 1
}
println("rat_1_weight:\(rat_1_weight), rat_2_weight:\(rat_2_weight), weeks:\(weeks)")

入出力結果(Console Output)

a.
6
b.
rat_1_weight:1.48024428491834, rat_2_weight:1.34391637934412, weeks:10
Program ended with exit code: 0