package  main

import (
	"fmt"
	"regexp"
)

func main() {
	oldstr := "I                have   a dream"
	fmt.Println(oldstr)
	newstr := DeleteExtraSpace(oldstr)
	fmt.Println(newstr)
}

//删除字符串中的多余空格,有多个空格时,仅保留一个空格
func DeleteExtraSpace(s string) string {
	regstr := "\\s{2,}"
	reg, _ := regexp.Compile(regstr)
	tmpstr := make([]byte, len(s))
	copy(tmpstr, s)
	spc_index := reg.FindStringIndex(string(tmpstr))
	for len(spc_index) > 0 {
		tmpstr = append(tmpstr[:spc_index[0]+1], tmpstr[spc_index[1]:]...)
		spc_index = reg.FindStringIndex(string(tmpstr))
	}
	return string(tmpstr)
}