c - Is it a good idea to put srand() in the header file? -

my program includes function uses rand(). function called more once can't put srand() @ beginning of function. now, there general rule suggests whether srand() should put in header file of function, or in beginning of main function?

my understanding both work same. difference if want reuse function in future, having srand() in header makes function more self-contained, may end multiple headers having srand().

--edit--

yes, mean like

/*header.h*/ srand(); void my_funciton(); 

so won't work?

now, there general rule suggests whether srand() should put in header file of function

if mean like

/**  * foo.h  */  srand();   void my_function_that_uses_rand(); 

that won't cause srand called whatever includes header file; treated old-style implicit int function declaration (which not work c99 or later compilers, since implicit int function declarations no longer supported), cause other problems if you've included math.h in whatever file including file.

edit

actually, it's worse that, because call srand requires seed parameter, if wanted randomize on time, header file like

/**  * foo.h  */ srand(time(null));  void my_function_that_uses_rand(); 

which compiler yak on, since srand(time(null)); not valid declaration in first place.

srand should called once before first call rand, , it's application code so. note if call srand same seed value, same sequence of values in rand calls.