Swift中字符串的简单用法

//

//  main.swift

//  Swift

//

//  Created by 空想家 on 16/7/1.

//  Copyright © 2016年 kongxiangjia. All rights reserved.

//

import Foundation

print("Hello, World!")

let someString = "Some string leteral value"

var emptyString = ""

var anotherEmptyString = String()

if emptyString.isEmpty {

print("emptyString isEmpty")

}

// 字符串可变性

var variableString = "variable"

variableString += "String"

print(variableString)

// 操作字符

for character in "There".characters{

//    print(character)

print(character)

}

//  String值可以通过传入 Character值的字符串作为实际参数到它的初始化器来构造：

let catCharacters:[Character] = ["C","a","t"]

let catString = String(catCharacters)

print(catString)

// 连接字符串和字符

let string1 = "Hello"

let string2 = " look"

var hw = string1 + string2

print(string2 + string1)

var h = " there"

hw += h

print(hw)

let exclmaionMark:Character = "!"

hw.append(exclmaionMark)

hw.append(exclmaionMark)

print(hw)

// 字符串插值

let multiplier = "3"

/*

2.2 语法

let message = "\(multiplier) times 2.5 is \(Double(multiplier) * 2.5)"

*/

// 3.0语法

let message = "\(multiplier) times 2.5 is \(Double(multiplier)! * 2.5)"

print(message)

// 扩展字形集群

let eAcute: Character = "\u{E9}" // é

let combinedEAcute:Character = "\u{65}\u{301}" // e followed by ́

print(eAcute,combinedEAcute)

// 字符串统计

let unusualMenagerie = "Koala 🐨, Snail 🐌, Penguin 🐧, Dromedary 🐪"

print("unusualMenagerie has \(unusualMenagerie.characters.count) characters")

let kaola = "🐨"

print("🐨 has\(kaola.characters.count)")

// 访问和修改字符串

// 字符串索引

let greeting = "Guten Tag!"

let firstWordOfGreeting = greeting[greeting.startIndex]

print(firstWordOfGreeting)

let lastWordOfGreeting = greeting[greeting.index(before: greeting.endIndex)]

print(lastWordOfGreeting)

let index = greeting.index(greeting.startIndex, offsetBy: 2)

print(greeting[index])

for index in greeting.characters.indices {

//    print("\(greeting[index])",index)

print(index)

// terminator 终结

//    print("\(greeting[index]) ", terminator: "")

}

var str = "Hello"

for (index, string) in str.characters.enumerated() {

print("index = \(index), string = \(string)")

}

// 插入删除字符串

var welcome = "hello"

// 插入单个字符

welcome.insert("!", at: welcome.endIndex)

// 插入字符串

welcome.insert(contentsOf:"插入字符串".characters, at: welcome.startIndex)

print(welcome)

// 删除某个字符

welcome.remove(at: welcome.index(before: welcome.endIndex))

print(welcome)

// 删除某段字符串

let range = welcome.index(welcome.startIndex, offsetBy: 4)..