Compile and link C++ and C programms together with QT-Creator -

so have serveal c++ files , need call c function after c++ part of program done. if there way somehow magically "start c file" (i hope know mean) glad hear too. actual problem: i'm trying call c function @ end of main function in main c++ file. saw of call c function c++ code , tried correct way, header file c file looks kind of this:

 #ifndef h_file  #define h_file   #ifdef __cplusplus  extern "c" {  #endif   void foo();  void bar();   #ifdef __cplusplus  }  #endif 

i tried include header file in c++ file this:

 extern "c" {  #include "folder/file.h"  } 

i alternatively tried basic #include "folder/file.h"

but i'm getting undefined reference error when i'm trying use foo() function c file. .pro file looks kind of this:

qt       += core gui  greaterthan(qt_major_version, 4): qt += widgets  target = example template = app qmake_cxxflags += -std=c++11  sources += main.cpp\ folder/file.c \  headers  += main.h \ 

so guess have add kind of flag compiled correctly, missing? thank help!

you may missing 1 more #endif @ end of header file