Re: mutex

From:
"Victor Bazarov" <v.Abazarov@comAcast.net>
Newsgroups:
comp.lang.c++
Date:
Wed, 26 Mar 2008 14:46:01 -0400
Message-ID:
<fse5l8$2g8$1@news.datemas.de>
Ron Eggler wrote:

Hi,

I wanna use a mutex to make a class thread safe. I initialize it in
its constructor like:

GPIOcontrol::GPIOcontrol()
{//constructor
       pthread_mutex_init(GPIO_mtx, NULL);//initializing the mutex
}

But my application just terminates after issueing thiss line. I'm
using gcc
4.1.3
I have no clue what it's doing, GPIO-mtx is declared like this as a
private member of this class:
pthread_mutex_t *GPIO_mtx; // mutex declaration


It's not a mutex declaration. It's a _pointer_to_mutex_ declaration.
Where is the actual mutex? What memory does this pointer point to?

The weird thing is now, it works just fine by declaring the member
like: pthread_mutex_t GPIO_mtx; // mutex declaration
and calling the mutex_init like:
       pthread_mutex_init(&GPIO_mtx, NULL);//initializing the mutex
Why is this????
That's weirdin me out. Anyone an idea?


Learn to use pointers.

V
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