go简要 - string字符串函数

常用字符串操作函数

类型转换

比较对比

搜索 查找 统计

替换

删除过滤

大小写转换

前缀后缀

字符串分割

拼接

中拼接字符串方式对比

package main
 
import (
    "bytes"
    "fmt"
    "strconv"
    "strings"
    "time"
)
 
func main() {
    fmt.Println("字符串测试")
 
    fmt.Println("字符串转化")
    //获取程序运行的操作系统平台下 int 类型所占的位数，如：strconv.IntSize。
    //strconv.IntSize
 
    fmt.Println("将字符串转换为 int 型。")
    var trastr01 string = "100"
    traint01, err_tra := strconv.Atoi(trastr01)
    if err_tra != nil {
        fmt.Println(err_tra)
    } else {
        fmt.Println(traint01)
    }
    fmt.Println("将字符串转换为 float64 型")
    var trastr02 string = "100.55"
    trafloat01, err_float := strconv.ParseFloat(trastr02, 10)
    if err_float != nil {
        fmt.Println(err_float)
    } else {
        fmt.Println(trafloat01)
    }
    trastr03 := strconv.Itoa(99)
    fmt.Println("int 转字符安 " + trastr03)
 
    var str01 string = "hello,world"
    str02 := "你好,世界"
    fmt.Println(str01)
    fmt.Println(str02)
 
 
    //字符串比较
    com01 := strings.Compare(str01, str02)
    if com01 == 0 {
        fmt.Println("相等")
    } else {
        fmt.Println("不相等 " + string(com01))
    }
    fmt.Println(com01)
 
    //查找 包含
    var isCon bool = strings.Contains(str01, "hello")
    fmt.Println(isCon) //true
 
    //查找位置
    var theIndex int = strings.Index(str01, ",")
    fmt.Println(theIndex)                     //5
    fmt.Println(strings.Index(str01, "haha")) //不存在返回-1
 
    lastIndex := strings.LastIndex(str01, "o")
    fmt.Println("在字符串中最后出现位置的索引 " + strconv.Itoa(lastIndex)) //7
    //-1 表示字符串 s 不包含字符串
 
    //统计给定子串sep的出现次数, sep为空时, 返回1 + 字符串的长度
    fmt.Println(strings.Count("cheeseeee", "ee")) // 3
    fmt.Println(strings.Count("five", ""))        // 5
 
    // 重复s字符串count次, 最后返回新生成的重复的字符串
    fmt.Println("hello " + strings.Repeat("world ", 10))
 
    fmt.Println("替换")
    // 在s字符串中, 把old字符串替换为new字符串，n表示替换的次数，小于0表示全部替换
    var str03 string = "/Users//Documents/GOPatch/src/MyGO/config/TestString/"
    str04 := strings.Replace(str03, "/", "**", -1)
    str05 := strings.Replace(str03, "/", "**", 4)
 
    fmt.Println(str04) //**Users****Documents**GOPatch**src**MyGO**config**TestString**
    fmt.Println(str05) //**Users****Documents**GOPatch/src/MyGO/config/TestString/
 
    fmt.Println("删除字符串的开头和尾部")
    fmt.Println("删除两头的/ = " + strings.Trim(str03, "/"))      
 
    //Users//Documents/GOPatch/src/MyGO/config/TestString
    fmt.Println("删除左边的/ =  " + strings.TrimLeft(str03, "/")) 
 
    //Users//Documents/GOPatch/src/MyGO/config/TestString/
    //还有 TrimRight
 
    str06 := strings.TrimSpace(" hello hao hao hao ")
    fmt.Println("删除开头末尾的空格 =" + str06) //'hello hao hao hao'
 
    fmt.Println("大小写")
    str07 := "hello hao hao hao"
    fmt.Println(strings.Title(str07))                  //Hello Hao Hao Hao
    fmt.Println(strings.ToLower(" Hello Hao Hao Hao")) // hello hao hao hao
    fmt.Println(strings.ToUpper(str07))                //HELLO HAO HAO HAO
 
    //前缀 后缀
    fmt.Println(strings.HasPrefix("Gopher", "Go")) // true
    fmt.Println(strings.HasSuffix("Amigo", "go"))  // true
 
    fmt.Println("字符串分割")
    fieldsStr := "  hello   it's  a  nice day today    "
    //根据空白符分割,不限定中间间隔几个空白符
    fieldsSlece := strings.Fields(fieldsStr)
    fmt.Println(fieldsSlece) //[hello it's a nice day today]
 
    for i, v := range fieldsSlece {
        fmt.Printf("下标 %d 对应值 = %s \n", i, v)
    }
    for i := 0; i < len(fieldsSlece); i++ {
        fmt.Println(fieldsSlece[i])
    }
 
    //根据特定字符分割
    slice01 := strings.Split("q,w,e,r,t,y,", ",")
    fmt.Println(slice01)      //[q w e r t y ]
    fmt.Println(cap(slice01)) //7  最后多个空""
    for i, v := range slice01 {
        fmt.Printf("下标 %d 对应值 = %s \n", i, v)
    }
 
    //拼接
    //Join 用于将元素类型为 string 的 slice, 使用分割符号来拼接组成一个字符串：
    var str08 string = strings.Join(fieldsSlece, ",")
    fmt.Println("Join拼接结果=" + str08) //hello,it's,a,nice,day,today
 
    fmt.Println("------------对比字符串拼接效率----------------")
    var buffer bytes.Buffer
 
    start := time.Now()
    for i := 0; i < 100000; i++ {
        buffer.WriteString("test is here\n")
    }
    buffer.String() // 拼接结果
    end := time.Now()
    fmt.Println("Buffer time is ", end.Sub(start).Seconds())
 
    start = time.Now()
    str := ""
    for i := 0; i < 100000; i++ {
        str += "test is here\n"
    }
    end = time.Now()
    fmt.Println("+= time is ", end.Sub(start).Seconds())
 
    start = time.Now()
    var sl []string
    for i := 0; i < 100000; i++ {
        sl = append(sl, "test is here\n")
    }
    strings.Join(sl, "")
    end = time.Now()
    fmt.Println("Join time is", end.Sub(start).Seconds())
    /*
       Buffer time is  0.00388283
       += time is  11.730007558
       Join time is 0.016644653
    */
}