给出两个字符串，求出两个字符串的最长公共子串

#include<iostream>
#include<string>
using namespace std;
int main()
{string a, b;while (cin >> a >> b){if (a.size() > b.size())swap(a, b);string str_m;//存储最长公共子串for (int i = 0; i < a.size(); i++){for (int j = i; j < a.size(); j++){string temp = a.substr(i, j - i + 1);if (int(b.find(temp))<0)break;else if (str_m.size() < temp.size())str_m = temp;}}cout << str_m << endl;}return 0;
}

basic_string substr(size_type _Off = 0,size_type _Count = npos) const;
_Off，所需字符串的起始位置
_Count，所需字符个数
返回值：一个子字符串，从其指定位置开始