Swift - Repeating Code Using Loops(while loop, String(multiplication operator), print the triangle)

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) 15.をSwiftで考えてみる。

9.10(Exercises) 15.

コード(Xcode)

main.swift

//
//  main.swift
//  sample15
//
//  Created by kamimura on 9/20/14.
//  Copyright (c) 2014 kamimura. All rights reserved.
//

import Foundation

println("13.")

var i:Int = 1
while i <= 7 {
    println("T" * i)
    i += 1
}

println("14.")

i = 6
while i >= 0 {
    println(" " * i + "T" * (7 - i))
    i -= 1
}

string.swift

//
//  string.swift
//  string
//
//  Created by kamimura on 8/10/14.
//  Copyright (c) 2014 kamimura. All rights reserved.
//

import Foundation

extension String {
    var swapcaseString:String {
    var result: String = ""
        for ch in self {
            let s = String(ch)
            result += s.uppercaseString == s ? s.lowercaseString : s.uppercaseString
        }
        return result
    }
    var isUpper:Bool { return self.uppercaseString == self }
    var isLower:Bool { return self.lowercaseString == self }
    var length:Int { return (self as NSString).length }
    var strip:String { return self.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet())}
    var floatValue:Float { return (self as NSString).floatValue }
    var doubleValue:Double { return (self as NSString).doubleValue }
    func count(sub:String) -> Int {
        var result:Int = 0
        var s = self
        let index:String.Index = "a".endIndex
        while s != "" {
            if s.hasPrefix(sub) {
                result += 1
                s = s.substringFromIndex(sub.endIndex)
            } else {
                s = s.substringFromIndex(index)
            }
            
        }
        return result
    }
    func find(sub:String, start:Int = 0, end:Int? = nil) -> Int {
        var s = self as NSString
        var s_temp = s.substringFromIndex(start)
        let end_temp:Int = end != nil ? end! : s.length
        for i in start..<end_temp {
            if (s_temp.hasPrefix(sub)) {
                return i
            }
            s_temp = s.substringFromIndex(i + 1) as NSString
        }
        return -1
    }
    func indexAt(i:Int) -> String {
        if i >= 0 {
            return (self as NSString).substringWithRange(NSRange(location: i, length: 1))
        }
        let new_i = self.length + i
        return (self as NSString).substringWithRange(NSRange(location: new_i, length: 1))
    }
    func replace(old_str:String, new_str:String) -> String {
        return self.stringByReplacingOccurrencesOfString(old_str, withString: new_str)
    }
    func slice(start:Int=0, end:Int?=nil) -> String {
        let s = self as NSString
        var new_end:Int
        if (end != nil) {
            new_end = end!
        } else {
            new_end = s.length
        }
        return  s.substringWithRange(NSRange(location: start, length:new_end - start))
    }
    func split(sep:String = "") -> [String] {
        var result:[String] = []
        if (sep == "") {
            for ch in self {
                result.append(String(ch))
            }
            return result
        }
        var s:String = self
        var len = sep.length
        var temp:String = ""
        while s != "" {
            if s.hasPrefix(sep) {
                if temp != "" {
                    result.append(temp)
                    temp = ""
                }
                s = s.slice(start: len)
            } else {
                temp += s.slice(start: 0, end: 1)
                s = s.slice(start: 1)
            }
        }
        if temp != "" {
            result.append(temp)
        }
        return result
    }
    var reversed:String { return "".join(self.split().reverse()) }
    func repeat(n:Int) -> String {
        var result:String = ""
        for i in 0..<n {
            result += self
        }
        return result
    }
}

func * (left:String, right:Int) -> String{
    return left.repeat(right)
}

func * (left:Int, right:String) -> String{
    return right.repeat(left)
}

入出力結果(Console Output)

13.
T
TT
TTT
TTTT
TTTTT
TTTTTT
TTTTTTT
14.
      T
     TT
    TTT
   TTTT
  TTTTT
 TTTTTT
TTTTTTT
Program ended with exit code: 0