c - How to use macro for calling function? -

i want call function according func_name string. code here below:

#define make_funcname func_name##hello  void call_func(void* (*func)(void)) {     func(); }  void *print_hello(void) {     printf("print_hello called\n"); }  int main(void) {     char func_name[30] = "print_";      call_func(make_funcname);     return 0; } 

but code doesn't work. want code work call_func(print_hello). preprocessor treated code call_func("print_hello"). how use macro in c make exception? or not possible using c?

then problem code value of func_name known @ run-time.

you can this:

#define make_funcname(funcname) funcname##hello  void call_func(void* (*func)(void)) {     func(); }  void *print_hello(void) {     printf("print_hello called\n"); }  int main(void) {     call_func(make_funcname(print_));     return 0; } 

but not possible use string value within macro parameters in code snippet.

if want call functions names using string values can use table store function pointer function names this:

struct {     const char *name;     void (*ptr)(void); }; 

you can use array of structure find out function pointer @ run-time using string value. common solution using run-time strings call functions using names.