（字符串）句子翻转

#include <iostream>

using namespace std;

void reverse(string &str,int start,int end){
    char tmp;
    int i=start;
    int j=end;
    while(i<j){
        tmp=str[i];
        str[i]=str[j];
        str[j]=tmp;
        i++;
        j--;
    }
}

void reverse_sentence(string &str){
    int len=str.length();
    int start=0;
    int index=0;
    while(index<len){
        while(str[index]!=' ' && index<len)
            index++;
        reverse(str,start,index-1);
        while(str[index]==' ' && index<len)
            index++;
        start=index;
    }
    reverse(str,0,len-1);
}

int main()
{
    string str="I'm a student!";
//    cout<<str.length()<<endl; //15
//    cout<<sizeof(str)<<endl;  //4
    reverse_sentence(str);
    cout<<str<<endl;
    return 0;
}