字符串是不可变值类型，内部用指针指向 UTF-8 字节数组。 ~~~ • 默认值是空字符串 ""。 • 用索引号访问某字节，如 s[i]。 • 不能用序号获取字节元素指针，&s[i] 非法。 • 不可变类型，无法修改字节数组。 • 字节数组尾部不包含 NULL。 ~~~ 使用索引号访问字符 (byte)。 ~~~ package main func main() { s := "abc" println(s[0] == '\x61', s[1] == 'b', s[2] == 0x63) } ~~~ 输出结果: ~~~ true true true ~~~ 使用 " ` " 定义不做转义处理的原始字符串，支持跨行。 ~~~ package main func main() { s := `a b\r\n\x00 c` println(s) } ~~~ 输出结果: ~~~ a b\r\n\x00 c ~~~ 连接跨行字符串时，"+" 必须在上一行末尾，否则导致编译错误。 ~~~ package main import ( "fmt" ) func main() { s := "Hello, " + "World!" // s2 := "Hello, " // +"World!" //./main.go:11:2: invalid operation: + untyped string fmt.Println(s) } ~~~ 支持用两个索引号 ([]) 返回子串。 串依然指向原字节数组，仅修改了指针和 度属性。 ~~~ package main import ( "fmt" ) func main() { s := "Hello, World!" s1 := s[:5] // Hello s2 := s[7:] // World! s3 := s[1:5] // ello fmt.Println(s, s1, s2, s3) } ~~~ 输出结果： ~~~ Hello, World! Hello World! ello ~~~ 单引号字符常量表示 Unicode Code Point， 持 \uFFFF、\U7FFFFFFF、\xFF 格式。 对应 rune 类型，UCS-4。 ~~~ package main import ( "fmt" ) func main() { fmt.Printf("%T\n", 'a') var c1, c2 rune = '\u6211', '们' println(c1 == '我', string(c2) == "\xe4\xbb\xac") } ~~~ 输出结果: ~~~ int32 // rune 是 int32 的别名 true true ~~~ 要修改字符串，可先将其转换成 []rune 或 []byte，完成后再转换为 string。无论哪种转换，都会重新分配内存，并复制字节数组。 ~~~ package main func main() { s := "abcd" bs := []byte(s) bs[1] = 'B' println(string(bs)) u := "电脑" us := []rune(u) us[1] = '话' println(string(us)) } ~~~ 输出结果: ~~~ aBcd 电话 ~~~ for 循环遍历字符串时，也有 byte 和 rune 两种方式。 ~~~ package main import ( "fmt" ) func main() { s := "abc汉字" for i := 0; i < len(s); i++ { // byte fmt.Printf("%c,", s[i]) } fmt.Println() for _, r := range s { // rune fmt.Printf("%c,", r) } fmt.Println() } ~~~ 输出结果: ~~~ a,b,c,æ,±,‰,å,­,—, a,b,c,汉,字, ~~~ string的底层布局  字符串处理： 判断是不是以某个字符串开头 ~~~ package main import ( "fmt" "strings" ) func main() { str := "hello world" res0 := strings.HasPrefix(str, "http://") res1 := strings.HasPrefix(str, "hello") fmt.Printf("res0 is %v\n", res0) fmt.Printf("res1 is %v\n", res1) } ~~~ 输出结果： ~~~ res0 is false res1 is true ~~~ 判断是不是以某个字符串结尾 ~~~ package main import ( "fmt" "strings" ) func main() { str := "hello world" res0 := strings.HasSuffix(str, "http://") res1 := strings.HasSuffix(str, "world") fmt.Printf("res0 is %v\n", res0) fmt.Printf("res1 is %v\n", res1) } ~~~ 输出结果： ~~~ res0 is false res1 is true ~~~ 判断str在s中首次出现的位置，如果没有返回-1 ~~~ package main import ( "fmt" "strings" ) func main() { str := "hello world" res0 := strings.Index(str, "o") res1 := strings.Index(str, "i") fmt.Printf("res0 is %v\n", res0) fmt.Printf("res1 is %v\n", res1) } ~~~ 输出结果： ~~~ res0 is 4 res1 is -1 ~~~ 判断str在s中最后一次出现的位置，如果没有返回-1 ~~~ package main import ( "fmt" "strings" ) func main() { str := "hello world" res0 := strings.LastIndex(str, "o") res1 := strings.LastIndex(str, "i") fmt.Printf("res0 is %v\n", res0) fmt.Printf("res1 is %v\n", res1) } ~~~ 输出结果： ~~~ res0 is 7 res1 is -1 ~~~ 字符串替换 ~~~ package main import ( "fmt" "strings" ) func main() { str := "hello world world" res0 := strings.Replace(str, "world", "golang", 2) res1 := strings.Replace(str, "world", "golang", 1) //trings.Replace("原字符串", "被替换的内容", "替换的内容", 替换次数) fmt.Printf("res0 is %v\n", res0) fmt.Printf("res1 is %v\n", res1) } ~~~ 输出结果： ~~~ res0 is hello golang golang res1 is hello golang world ~~~ 求str含s的次数 ~~~ package main import ( "fmt" "strings" ) func main() { str := "hello world world" countTime0 := strings.Count(str, "o") countTime1 := strings.Count(str, "i") fmt.Printf("countTime0 is %v\n", countTime0) fmt.Printf("countTime1 is %v\n", countTime1) } ~~~ 输出结果： ~~~ countTime0 is 3 countTime1 is 0 ~~~ 重复 n 次 str ~~~ package main import ( "fmt" "strings" ) func main() { str := "hello world " res0 := strings.Repeat(str, 0) res1 := strings.Repeat(str, 1) res2 := strings.Repeat(str, 2) // strings.Repeat("原字符串", 重复次数) fmt.Printf("res0 is %v\n", res0) fmt.Printf("res1 is %v\n", res1) fmt.Printf("res2 is %v\n", res2) } ~~~ 输出结果： ~~~ res0 is res1 is hello world res2 is hello world hello world ~~~ str 转为大写 ~~~ package main import ( "fmt" "strings" ) func main() { str := "hello world " res := strings.ToUpper(str) fmt.Printf("res is %v\n", res) } ~~~ 输出结果： ~~~ res is HELLO WORLD ~~~ str 转为小写 ~~~ package main import ( "fmt" "strings" ) func main() { str := "HELLO WORLD " res := strings.ToLower(str) fmt.Printf("res is %v\n", res) } ~~~ 输出结果： ~~~ res is hello world ~~~ 去掉 str 首尾的空格 ~~~ package main import ( "fmt" "strings" ) func main() { str := " hello world " res := strings.TrimSpace(str) fmt.Printf("res is %v\n", res) } ~~~ 去掉字符串首尾指定的字符 ~~~ package main import ( "fmt" "strings" ) func main() { str := "hi , hello world , hi" res := strings.Trim(str, "hi") fmt.Printf("res is %v\n", res) } ~~~ 输出结果： ~~~ res is , hello world , ~~~ 去掉字符串首指定的字符 ~~~ package main import ( "fmt" "strings" ) func main() { str := "hi , hello world , hi" res := strings.TrimLeft(str, "hi") fmt.Printf("res is %v\n", res) } ~~~ 输出结果： ~~~ res is , hello world , hi ~~~ 去掉字符串尾指定的字符 ~~~ package main import ( "fmt" "strings" ) func main() { str := "hi , hello world , hi" res := strings.TrimRight(str, "hi") fmt.Printf("res is %v\n", res) } ~~~ 输出结果： ~~~ res is hi , hello world , ~~~ 返回str空格分隔的所有子串的slice, ~~~ package main import ( "fmt" "strings" ) func main() { str := "hello world ，hello golang" res := strings.Fields(str) fmt.Printf("res is %v\n", res) } ~~~ 输出结果： ~~~ res is [hello world ，hello golang] ~~~ 返回str 指定字符分隔的所有子串的slice ~~~ package main import ( "fmt" "strings" ) func main() { str := "hello world ，hello golang" res := strings.Split(str, "o") fmt.Printf("res is %v\n", res) } ~~~ 输出结果： ~~~ res is [hell w rld ，hell g lang] ~~~ 用指定字符将 string 类型的 slice 中所有元素链接成一个字符串 ~~~ package main import ( "fmt" "strings" ) func main() { str := []string{"hello", "world", "hello", "golang"} res := strings.Join(str, "++") fmt.Printf("res is %v\n", res) /* num := []int{1, 2, 3, 4, 5, 6, 7, 8, 9, 0} res1 := strings.Join(num, "++") // cannot use num (type []int) as type []string in argument to strings.Join fmt.Println(res1) */ } ~~~ 输出结果： ~~~ res is hello++world++hello++golang ~~~