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swift5笔记(一):从字符串开始

swift5笔记(一):从字符串开始

作者: Harry__Li | 来源:发表于2022-10-30 15:02 被阅读0次
    字符串的创建

    初始化字符串

    let nameStr = ""
    let nameStr1 = String()
    //推断类型
    let str = "test"
    //指定类型
    let testStr :String = "name"
    
    字符串的拼接
    //字符串拼接
    let str2 = str + testStr
    print(str2)
    let str3 = str.appending(testStr)
    print("拼接的字符串是:\(str3)")
    
    字符串其他属性
    let str6 = String(format: "学习的第一行代码是:%@", greeting)
    print(str6)
    //字符串的长度
    print(str6.count)
    //判断是否为空
    print(str6.isEmpty)
    
    //遍历字符串
    for char in str6 {
        print(char)
    }
    
    
    var deleteStr = "这是一个要删除的字符串"
    print(deleteStr[deleteStr.startIndex])
    //删除首字母
    deleteStr.removeFirst()
    //删除最后的字母
    deleteStr.removeLast()
    print(deleteStr)
    //删除定制位置的字符串  删除一个字符,从首字符开始
    deleteStr.remove(at: deleteStr.index(deleteStr.startIndex, offsetBy: 2))
    print(deleteStr)
    
    deleteStr.remove(at: deleteStr.index(deleteStr.endIndex, offsetBy: -1))
    print(deleteStr)
    
    //删除从首字母的3个字符
    var str8 = "hello world"
    str8.removeFirst(3)
    print(str8)
    
    var str9 = "jjjjdkdkfjfhslehjf"
    str9.removeLast(5)
    print(str9)
    //删除指定位置的字符
    var str10 = "dkghrjdkejfjfgsef"
    let start = str10.index(str10.startIndex, offsetBy: 4)
    let end = str10.index(str10.endIndex, offsetBy: -4)
    
    str10.removeSubrange(start...end)
    print(str10)
    
    
    插入
    var inserstr = "ABCDEFGH"
    inserstr.insert("x", at: inserstr.index(inserstr.startIndex, offsetBy: 4))
    inserstr.insert(contentsOf: "abab", at: inserstr.index(inserstr.startIndex, offsetBy: 1))
    
    //字符串替换
    var replaceStr = "世界你好啊 我是地球"
    replaceStr.replacingOccurrences(of: "你好", with: "和平")
    
    replaceStr.replaceSubrange(replaceStr.index(replaceStr.endIndex, offsetBy: -2)..<replaceStr.endIndex, with: "hello world")
    
    字符串截取
    let teststr5 = "abcdefgfhfh"
    //头部截取
    print(teststr5.prefix(4))
    //尾部截取
    print(teststr5.suffix(5))
    //range截取
    let index2 = teststr5.index(teststr5.startIndex, offsetBy: 3)
    let index3 = teststr5.index(teststr5.startIndex, offsetBy: 8)
    let sl = teststr5[index2...index3]
    print(sl)
    
    //获取指定位置字符串
    let range = teststr5.range(of: "fg")
    
    print(teststr5[teststr5.startIndex..<range!.lowerBound])
    
    print(teststr5[teststr5.startIndex..<range!.upperBound])
    

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