Subj : Re: pthreads and semaphore - Beginer question
To   : comp.programming.threads
From : David Schwartz
Date : Fri Aug 05 2005 05:38 pm


<plinius@gmail.com> wrote in message 
news:1123284806.836562.142730@g44g2000cwa.googlegroups.com...

> Hi,
> I did call sem_init:
> sem_init(&lampion,NULL,0);

    Right, but you corrupted it *after* that.

>> Casting the pointer is ugly. Better to use a real 'void *' and pass its
>> address to pthread_join, you can then cast the 'void *'. The problem is
>> that
>> a 'void *' might not be the same size or same format as an 'int'.
>> Casting
>> the address doesn't give the compiler the ability to fix that.

> Yes, but I used this in other multithreaded programs, and never gave
> any problem. I found it in pthread-primers (a book).
> Do you allso happen to know what might be wrong with my semaphore? Or,
> how I should do what I described, without a semaphore (although I
> prefer to use a semaphore, since it's made for such a kind of
> things...)?

    You muck up the sempahore by modifying its value. You are only supposed 
to use the sem_* functions on the sempahore.

    DS

.