#include <iostream>
using namespace std;
#include <string>

string father, son;

int main()
{
    cout << "请输入主串" << endl;
    cin >> father;
    cout << "请输入子串" << endl;
    cin >> son;
    int f_size = father.size();
    int s_size = son.size();
    cout << father << endl;
    cout << son << endl;
    int i = 0, j = 0;    //两个串的要比对元素的下标
    while (i < f_size && j < s_size)    //条件为i、j均不超界
    {
        if (father[i] == son[j])
        {
            i++;
            j++;
        }
        else
        {
            i = i - j + 1;
            j = 0;
        }
    }
    if (j < s_size)     
    {
        cout << "没有找到子串" << endl;
    }
    else
    {
        cout << "子串在第：" << i - s_size << "个位置" << endl;
    }

    return 0;
}