unitialized memory is all zeros...why not garbage instead?

[Dag-Erling Smørgrav]

Mike Hunter <mhunter at ack.berkeley.edu> writes:
> Is the pre-zeroing of malloc'd memory documented somewhere?  By my reading
> of the malloc manapge...

malloc() does not pre-zero memory, but it hands you memory which has
been pre-zeroed by the kernel unless you've used it before.  Your test
program makes only one malloc() call, so you get memory that has never
been used before.

> ...it seems like it's saying that malloc (as opposed to calloc) is NOT
> pre-zeroed.  Is there a different document I should be reading?

No, but nowhere in the standard does it say that memory allocated with
malloc() must contain non-zero garbage.  If that is what you want,
though, read the TUNING section in the malloc(3) man page.

DES
-- 
Dag-Erling Smørgrav - des at des.no