Subj : Re: a thread question
To   : comp.programming.threads
From : David Schwartz
Date : Thu May 12 2005 06:46 pm


"Chris Thomasson" <_no_damn_spam_cristom@_no_damn_comcast.net_spam> wrote in 
message news:KI-dnUIImY33Lx7fRVn-ig@comcast.com...

>>> To be visible from every threads, the variable must be global.

>>    Nope. All variables are visible to all threads.

> void* thread_a( void *s )
> {
>  int a_local;
>
>  return 0;
> }
>
>
> void* thread_b( void *s )
> {
>  int b_local;
>
>  return 0;
> }
>
>
> void* thread_c( void *s )
> {
>  /*
>
>  How could this thread modify and/or read a_local and/or b_local?
>
>  */
>
>  return 0;
> }

    The same way any other thread could. How would 'thread_b' access it? 
Simple -- it finds out its address some how and dereferences that. Now it's 
easier for threads 'a' and 'b' to do it, but certainly possible for thread c 
to do it.

    You've simply set up a case where thread c *does* *not* access the 
variables. However, it easily could.

    DS

.