#include <iostream>
#include <regex>
using namespace std;
int main() {
    string str = "yAgfy@qq.com";
    regex x(R"((\w+)@(\w+).(\w+))");

    regex_iterator Begin(str.begin(), str.end(), x);
    regex_iterator<typename string::iterator> End;

    while (Begin != End) {
        cout << (*Begin)[0] << endl;  // 输出全串
        cout << (*Begin)[1] << endl;  // 输出第一个分割串
        cout << (*Begin)[2] << endl;  // 输出第二个分割串
        cout << (*Begin)[3] << endl;  // 输出第三个分割串    
        ++Begin;
    }
    return 0;
}