2.字符串翻转

思路很重要：

获取字符串长度，两头交换相应字符。

核心代码：

void swap(char &x,char &y)
{
    x = x^y;
    y = x^y;
    x = x^y;
}
void reverse(char *s)
{
    int i = 0;
    int len = strlen(s);
    for(i = 0;i < len/2; ++i)
        swap(s[i],s[len-i-1]);
}

示例代码：

#include <cstring>
#include <iostream>
using namespace std;
void swap(char &x,char &y)
{
    x = x^y;
    y = x^y;
    x = x^y;
}
void reverse(char *s)
{
    int i = 0;
    int len = strlen(s);
    for(i = 0;i < len/2; ++i)
        swap(s[i],s[len-i-1]);
}
int main()
{
    char str[20] = "hello,world";
    reverse(str);
    cout<<str<<endl;
}