#include "stdio.h"
#include "string.h"
#include "math.h"
void reverse(char *str)
{
    int length = strlen(str);
    for (length; length > 0; length--)
    {
        printf("%c", *(str + length - 1));
    }
}
int main(void)
{
    char str[1024] = {};
    printf("请输入一行字符串：");
    //这里不用scanf()是因为scanf()一次只能读取一个连续字符串，遇到空格则会舍弃空格后的其他字符
    fgets(str, 1024, stdin);
    reverse(str);
    return 0;
}

#include <iostream>
#include <string>
#include <algorithm>
using namespace std;
void show(string::iterator _begin, string::iterator _end)
{
    if(_begin <= _end)
    {
        cout << *_end << endl;
        show(_begin, --_end);
    }
}
void reverse(string &s)
{
    show(s.begin(), --s.end());
}
int main()
{
    string s("ABCDEFG");
    reverse(s);
    return 0;
}