Question

I have a std::map called ‘prompts’ which is declared like this:

std::map<const int, wstring, std::less<int>, std::allocator<std::pair<const int, std::wstring> >> prompts;

and it stores int ‘key’ and wstring ‘value’ pairs. If I do this:

wcout << prompts[interpreter->get_state()];

The compiler (vc10) complains

error C2679: binary '<<' : no operator found which takes a right-hand operand of type 'std::basic_string<_Elem,_Traits,_Ax>' (or there is no acceptable conversion)

What do I have to do to get the wstring value returned from the map to print with wcout? Some sort of cast? Or…?

Answer 1

In the first line, you are missing an std::

std::map<const int,std::wstring, std::less<int>, std::allocator<std::pair<const int, std::wstring> >> prompts;

You should write std::wcout instead of wcout.

I just tried this code and it compiles.

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

int main()
{
    std::map<const int, std::wstring, std::less<int>, std::allocator<std::pair<const int, std::wstring> >> prompts;
    std::wcout << prompts[1];
    return 0;
}