Question

I am creating a simple hash table in VS 2008 C++.

#include <map>
std::map <string, char> grade_list;
grade_list["John"] = 'B';

I am getting the error:
error C2057: expected constant expression

What does that mean? Does boost library have something better?

Thanks!

Answer 1

#include <map>
#include <iostream>
#include <string>

int main() {
    std::map<std::string, char> grade_list;
    grade_list["John"] = 'B';
    std::cout << grade_list["John"] << std::endl;
    return 0;
}

This works great with g++.
You should specify std:: before string in your map declaration, as I did in my code.