swift3.0_String（字符串）的使用

//字符串格式化，使用\(item)

let apples = 6

let oranges = 8

let applesSummary = "i have \(apples) apples"

let fruitSummary = "\(apples + oranges) fruit"

print(applesSummary,"and",fruitSummary)

//类型转换

let lable = "the width is"

let val = 66

let lableWidth = lable + String(val)//swift不支持隐式类型转换，需显式转换

//字符

let money :Character = "¥"

let face:Character = "😗"

print("\(money) \(face)")

/*字符串常量包含的特殊字符：空字符\0，反斜杠\，制表符\t，换行符\n，回车符\r，双引号\"，单引号\'*/

//字符计数

let countstr = "wo shi sha sha de "

print("count's count is \(countstr.characters.count)")//算上空格

//字符串操作//////////////////////////////////////

var str00 = "i am string"

let str01 = ""

let str02 = "我是字符串"

//判断字符串是否为空

str00.isEmpty

str01.isEmpty

//获取字符串字符数量

str01.characters.count

str00.characters.count

str02.characters.count

//检查字符串是否含有特定的前缀/后缀

str00.hasPrefix("i")

str00.hasSuffix("i")

str02.hasSuffix("串")

//大小写字母转换

str00.uppercased()

str00.lowercased()

str02.uppercased()//中文进行大小写转换不起作用

str00.capitalized

//字符串截取

(str00 as NSString).substring(to: 4)//留下字符串前4个字母

(str00 as NSString).substring(from: 4)//不要前4个字母

(str00 as NSString).substring(with: NSMakeRange(2, 2))

//去除字符串最后的字母或首字母

let index0 = str00.index(before: str00.endIndex)

let index1 = str00.index(after: str00.startIndex)

str00.remove(at:index0)

str00.remove(at: index1)

//获取某个子串在父串中的范围

str00.range(of: "am")

//字符串转为数组

let str3 = "10:20:c:d:e"

let result = str3.components(separatedBy:":")

//指定范围内的字符串替换为其他字符串,将cde替换成m,使输出结果为abmfghi

let str4 = "abcdefghi"

let startIndex = str4.index(str4.startIndex, offsetBy:2)

let endIndex = str4.index(startIndex, offsetBy:3)

let result4 = str4.replacingCharacters(in:startIndex..<endIndex,with:"m")

//Int转16进制字符串

var hexStr = String().appendingFormat("%x",16)

//Int转8进制字符串

var octStr = String().appendingFormat("%o",16)

///16进制字符串转十进制数

func strHexToInt()  { 

let str = "3E 49 52"

 let strArray = str.components(separatedBy: " ") 

 var byte:UInt32 = 0  

 for i in 0 ..< strArray.count { 

     let ok = Scanner(string: strArray[i]).scanHexInt32(&byte) 

         if ok {

         //若转十进制成功 print(byte) 

         } 

     }

 }

//string转换成为Int8

func stringToInt(str: String) -> Array{ 

 let nsStr:NSString = str as NSString 

var arr = Array<Int8>()

    for i in 0 ..< str.characters.count {

        let int8:Int8 = nsStr.utf8String![i] //result = 99

        arr.append(int8)

    }

    return arr

}