golang 支持中文字符串截取, 支持end 负数截取

import (
    "bytes"
)

//支持中文截取, 支持end 负数截取
func SubStr(source interface{}, start int, end int) string {
    str := source.(string)
    var r = []rune(str)
    length := len(r)
    subLen := end - start
    
    for {
        if start < 0 {
            break
        }
        if start == 0 && subLen == length {
            break
        }
        if end > length {
            subLen = length - start
        }
        if end < 0 {
            subLen = length - start + end
        }
        var substring bytes.Buffer
        if end > 0 {
            subLen = subLen + 1
        }
        for i := start; i < subLen; i++ {
            substring.WriteString(string(r[i]))
        }
        str = substring.String()
        
        break
    }
    
    return str
}

调用

func main() {
    a := tools.SubStr("a我a爱b你中国，打的-1", 1,-1)
    fmt.Println(a)
}

输出

我a爱b你中国，打的