c++ - visual studio gives undeclared identifier error -

my project working fine , when change in header file got error:

error c2065 'map': undeclared identifier

although did #include <map>

part of game.h:

#include <map>  class game{      game();  } 

the line gives me error in game.cpp:

_results.insert(map<std::string, int>::value_type(_players[i]->getusername(), 0)); 

this code line worked fine ! until point

my guess @ 1 point, either had class named map in global namespace, provided interface similar std::map, or more likely, relying on using namespace std; directive has since been removed (whether unintentionally or not; perhaps else had 1 in header using, removed when realised bad idea). either put using-directive std or using-declaration std::map in code block containing line, or explicitly use std::map whenever want use c++ standard library map class; latter recommended, because makes code clearer , cleaner.

if using custom map class before, check header still #included, , doesn't run same namespace issue.