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➤微信公众号：山青咏芝（shanqingyongzhi）
➤博客园地址：山青咏芝（https://www.cnblogs.com/strengthen/ ）
➤GitHub地址：https://github.com/strengthen/LeetCode
➤原文地址：https://www.cnblogs.com/strengthen/p/9798159.html
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Swift中没法再使用传统形式的for循环。git
1 //传统for循环形式不适用于Swift 2 for（单次表达式;条件表达式;末尾循环体）{中间循环体；}
字符串遍历方法1：使用该indices属性能够访问字符串中各个字符的全部索引。github
1 let str = "Strengthen!" 2 for index in str.indices { 3 print("\(str[index]) ", terminator: "") 4 } 5 // Prints "S t r e n g t h e n ! "
字符串遍历方法2：每一个String值都有一个关联的索引类型，String.Index它对应Character于字符串中每一个值的位置。要访问远离给定索引的索引，能够使用该index(_:offsetBy:)方法而不是屡次调用其中一种方法。您能够使用下标语法来访问Character特定String索引。数组
1 extension String { 2 //subscript函数能够检索数组中的值 3 //按照索引方式读取字符 4 subscript (_ i: Int) -> Character { 5 //读取字符 6 get {return self[index(startIndex, offsetBy: i)]} 7 } 8 } 9 10 //方式1 11 let str = "Strengthen!" 12 for num in 0..<str.count 13 { 14 let char:Character = str[str.index(str.startIndex,offsetBy: num)] 15 print("\(char) ", terminator: "") 16 } 17 //Prints "S t r e n g t h e n ! " 18 19 //方式2 20 for num in 0..<str.count 21 { 22 let char:Character = str[num] 23 print("\(char) ", terminator: "") 24 } 25 //Prints "S t r e n g t h e n ! "
字符串遍历方法3：遍历字符串的每个字符微信
1 let str = "Strengthen!" 2 for char in str.characters { 3 print("\(char) ", terminator: "") 4 } 5 //Prints "S t r e n g t h e n ! "
字符串遍历方法4：遍历字符串的每个字符对应ASCII的整数值ide
1 let str = "Strengthen" 2 var strUnicodeScalars = Array(str.utf8) 3 print(strUnicodeScalars) 4 //Prints [83, 116, 114, 101, 110, 103, 116, 104, 101, 110] 5 for charNum in strUnicodeScalars 6 { 7 print("\(charNum) ", terminator: "") 8 } 9 //Prints "83 116 114 101 110 103 116 104 101 110"
倒序遍历字符串方法1：reversed()函数
1 let str = "Strengthen!" 2 for char in str.reversed() { 3 print("\(char) ", terminator: "") 4 } 5 //Prints ! n e h t g n e r t S
倒序遍历字符串方法2：stride函数 -返回一个任意可变步长类型值的序列。可变步长类型是能够设置偏移量的一维标量。学习
1 let str = "Strengthen!" 2 //from，to，by 最后一个值是 >(或<) to的值 3 for num in stride(from: str.count-1,to: 0,by: -1) 4 { 5 let char:Character = str[str.index(str.startIndex,offsetBy: num)] 6 print("\(char) ", terminator: "") 7 } 8 //Prints "! n e h t g n e r t" 9 10 //from，through，by 最后一个值是 >=(或<=) through的值 11 for num in stride(from: str.count-1,through: 0,by: -1) 12 { 13 let char:Character = str[str.index(str.startIndex,offsetBy: num)] 14 print("\(char) ", terminator: "") 15 } 16 //Prints "! n e h t g n e r t S "
字符串转字符数组：编码
1 let str = "I am Strengthen" 2 let array = str.components(separatedBy:" ") 3 print("\(array) ", terminator: "") 4 //["I", "am", "Strengthen"]
字符数组转字符串：url
1 /*字符数组转字符串*/ 2 let arrayStr = ["s","t","r","e","n","g","t","h","e","n","!"] 3 4 //方式1 5 let str1 = arrayStr.joined(separator: "") 6 let str2 = arrayStr.joined(separator: "-") 7 print("\(str1) ", terminator: "") 8 print("\(str2) ", terminator: "") 9 //strengthen! 10 //s-t-r-e-n-g-t-h-e-n-! 11 12 //方式2：注意与方式1比较，方式2只在首位添加"-" 13 let str3 = arrayStr.reduce("", {$0 + $1}) 14 let str4 = arrayStr.reduce("-", {$0 + $1}) 15 print("\(str3) ", terminator: "") 16 print("\(str4) ", terminator: "") 17 //strengthen! 18 //-strengthen! 19 20 /*整数数组转字符串*/ 21 let arrayInt = [0,1,2,3,4,5,6,7,8,9] 22 let dataInt = arrayInt.map(String.init) 23 let strInt = dataInt.joined(separator: "-") 24 print("\(strInt) ", terminator: "") 25 //0-1-2-3-4-5-6-7-8-9
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[Swift]字符串根据索引获取指定字符，依据ASCII编码，实现字符和整数的快速转换
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