C / C++ / MFC

////////////////////////////////////
// cFunctions.h
 
#ifdef __cplusplus
extern "C" {
#endif
 
// Functions declared here can be used both
// in C and C++ code
 
int c_func_in_c_file(int someParm);
int c_func_in_c_file2();
 
#ifdef __cplusplus
}
#endif
 
 
////////////////////////////////////
// cFunctions.c
 
#include "cFunctions.h"
#include "cppFunctions.h"
 
int c_func_in_c_file(int someParm)
{
   return someParm + c_func_in_cpp_file();
}
 
int c_func_in_c_file2()
{
   return 42;
}
 
 
/////////////////////////////////////
// cppFunctions.h
 
#ifdef __cplusplus
extern "C"
{
#endif
 
// Functions declared here can be used both
// in C and C++ code
 
int c_func_in_cpp_file();
 
#ifdef __cplusplus
}
 
// Functions declared here can only be used
// in C++ code
 
int cpp_func_in_cpp_file();
 
#endif
 
 
/////////////////////////////////////
// cppFunctions.cpp
 
#include "cppFunctions.h"
#include "cFunctions.h"
 
extern "C" int c_func_in_cpp_file()
{
   return cpp_func_in_cpp_file() + c_func_in_c_file2();
}
 
int cpp_func_in_cpp_file()
{
   return c_func_in_c_file2();
}

int nNumbers[9][9] = {0}; // initialize all to unoccupied
...
while (1)
{
    int nRow = rand() % 9;
    int nCol = rand() % 9;
    if (0 == nNumbers[nRow][nCol])
    {
        nNumbers[nRow][nCol] = 1; // mark as occupied
        break;
    }
}

"Ideas are a dime a dozen. People who put them into action are priceless." - Unknown

"Ideas are a dime a dozen. People who put them into action are priceless." - Unknown