string to long c 2b 2b

1//stol(string , nullptr,  base);
2
3string str = "100";
4long int num = stol(str, nullptr,  10);
5cout << num << std;//output 100
6
7//Base goes over ten with letters:
8string str = "F";
9long int num = stol(str, nullptr,  16);
10cout << num << std;//output 15