Re: Debugging standard C library routines

Richard Heathfield posted:

achintmehta@xxxxxxxxx said:

The application/software that is being run, is messing up the memory
due to which a subsequent malloc fails.

Initialise every pointer.


I wouldn't go so far as to advise to initialise _every_ pointer.

#define POVER(arr) ((arr) + sizeof(arr)/sizeof*(arr))

int *p;

for(p=array1;POVER(array1)!=p;++p) /* Something */ ;

for(p=array2;POVER(array2)!=p;++p) /* Something */ ;


Check every malloc/calloc/realloc to ensure it succeeded before you rely
on its return value.


If malloc'ing less than a kilobyte, I wouldn't bother.


Check that every array access is within bounds (0 to n - 1, for an array
of n elements).


One should _always_ watch out for such things when looking back over one's
code.


Set indeterminate ('dangling') pointers to NULL.


In Debug Mode, maybe. It wastes valuable nanoseconds (if not microseconds)
in Release Mode. Maybe something like the following would be a compromise:

#ifdef NDEBUG
#define DMODE(statement)
#else
#define DMODE(statement) statement
#endif

int main()
{
int *p;

...

free(p); DMODE(p=0);
}

--

Frederick Gotham
.

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