[Regex] 7-9 determines whether the E-mail address is valid (20 minutes)

Enter a string, determine whether it is legitimate mail (to the correct format, regardless of whether there really) input only letters, numbers, underscores, and @. Five, at around @ only letters or numbers, and. after only com, is output YES, otherwise output NO.

Input formats:

A string of characters.

Output formats:

For each input, output YES or NO.

Sample input:

[email protected]

Sample output:

YES

 1 #include<iostream>
 2 #include<string>
 3 #include<regex>
 4 using namespace std;
 5 int main()
 6 {
 7     string s;
 8     cin >> s;
 9     regex r("[a-zA-Z0-9\_]+@[a-zA-Z0-9]+(\.(com))");
10     if (regex_match(s, r))
11         cout << "YES";
12     else
13         cout << "NO";
14     return 0;
15 }