Re: pid_t data type
- From: Falcon Kirtaran <falconnews@xxxxxxxxxxxxxxxx>
- Date: Tue, 08 Apr 2008 16:10:42 -0600
On Mar 16, 12:34 pm, Rainer Weikusat <rweiku...@xxxxxxxxxxx> wrote:Logan Shaw <lshaw-use...@xxxxxxxxxxxxx> writes:Sanchit wrote:A 'typedef-name' is just an alias for an existing type. This meansSo if i will use long.. and i am not concerned with memoryIf you use pid_t, it will be fine in every case. If you use
management.. will it be fine in every case..
long, there are no guarantees. If you use pid_t, you will be
using what the producers of the system have tested. If you
use long, you will be using something that is unsupported and
that if an implementation had a
typedef long pid_t
the only difference between the two would be that usage looked
different in source code. One of the nice properties of C is that
'types' stick to objects and not to values: A value originally
returned be fork can be stored into anything large enough to represent
it without being "damaged" and a compiler is required to not introduce
artificial differences between identically valued numbers coming from
Are you sure pid_t is typedef of long.. I really dont know. As on
mymachine sizeof(pid_t)= sizeof(int)
And I think my question is misunderstood. I just want you to tell me
if there are cases where long will fail to take place of pid_t. I dont
care if pid_t is an int or short or long!
Your question is nonsensical. The answer is definitionally "yes" because pid_t in POSIX does not have an upper limit on its size, and the size of long is also implementation-defined in C.
In order to get around the problem of the length of PIDs and integer types being largely implementation-defined, we invented things like size_t and pid_t. Use them.
If you don't, your code is definitionally not portable (and might not even work on your own implementation, depending on the specifics of the implementation).
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