Is it safe to disable buffering with stdout and stderr?

Question

Sometimes we put some debug prints in our code this way

printf(\"successfully reached at debug-point 1\\n\"); 

some code is here

printf(\"successfully reached          


        

Answer 1

A possible way might be to have a bool dodebug global flag and define a macro like e.g.

#ifdef NDEBUG
#define debugprintf(Fmt,...) do{} while(0)
#else
#define debugprintf(Fmt,...) do {if (dodebug) {                 \
   printf("%s:%d " Fmt "\n", __FILE__, __LINE__, ##__VA_ARGS__); \
   fflush(stdout); }} while(0)
#endif

Then inside your code, have some

debugprintf("here i=%d", i);

Of course, you could, in the macro above, do fprintf instead... Notice the fflush and the appended newline to the format.

Disabling buffering should probably be avoided for performance reasons.