markryde@gmail.com wrote:
> Hello,
>
> I am running FC6 machine (i386 based).
> I am trying the follwing:
>
>  create a thread with pthread_create().
>  in the thread function, I have:
>  printf("tid in thread_func=%d\n",(int)pthread_self());
>
>  I get negative number for the thread id, for example:
>
>  tid in thread2_func=-1218974832
>
>  Why is it so ?

Why? Because you made it so.
Remember, the "%d" printf format string tells printf to interpret the
incoming value as a *signed* integer. The data you got back from
pthread_self(), when cast to an integer value and interpreted as a
signed integer, had a value of -1218974832. Had you told printf() to
print it as "%u", you would have seen a different printed value because
you would have told printf() to interpret the number as an unsigned
integer.

>  I saw in some places usage of this method (pthread_self()),but
> it returned non negative numbers.

This usage will print non-negative values for pthread_self() values
that are smaller than INT_MAX + 1

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