问题 I am trying to compile a program which is divided into 3 modules, corresponding to 3 source files: a.c , b.c , and z.c . z.c contains the main() function, which calls functions in a.c and b.c . Furthermore, a function in a.c calls a function in b.c , and viceversa. Finally, there is a global variable count which is used by the three modules and is defined in a separate header file, global.h . The code of the source files is the following: a.c #include "global.h" #include "b.h" #include "a.h"