Basic question about malloc

Valdis.Kletnieks at Valdis.Kletnieks at
Wed Apr 22 23:03:45 EDT 2015

On Thu, 23 Apr 2015 09:52:56 +0800, 慕冬亮 said:

>      I'm looking for that whether the object allocated by malloc is the
> multiple of certain bytes!
>      Or how does the malloc allocate dynamic memory ??
>      I does an experiment in my computer!

1) malloc() is a userspace function, not kernel.

2) There are multiple malloc() implementations out there - the one you're
using is *probably* glibc's, but there are others (including debugging
memory allocators that return strictly the number of bytes allocated, with
canaries on either end to trap misuse of memory).

> But the result has no feature about a ,b ,c!

What do you mean by "no feature", and what were you expecting? When I run it, I

% ./a.out
a = f35010
b = f35040
c = f35070

which tells me that malloc() returned 3 pointers that are 48 bytes
apart (which is *not* the same thing as "there are 48 bytes safe to use").
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