Are you using C or C++? Make sure your compiler is set for g++ and not gcc.
Looks like you're using Code Blocks judging from your other posts, so your compiler link would be in Compiler Settings -> Toolchain executables [tab] -> C++ Compiler:
Edit: If you have to use C, C99 has <stdbool.h>, which basically makes true turn into 1, and false turn into 0. Otherwise you have to define it yourself.