344.Reverse String

question:

Write a function that takes a string as input and returns the string reversed.

Example:
Given s = "hello", return "olleh".

answer：

交换字符串中的元素

class Solution {
public:
    string reverseString(string s) {
        int l = s.length();
        int i;
        char tem;
        for(i=0;i<l/2;i++){
            tem = s[i];
            s[i] = s[l-1-i];
            s[l-1-i] = tem;
            
        }
        return s;
    }
};