Re: [ros-dev] gcc problem or not

[Hartmut Birr]

Thomas Weidenmueller wrote:

>   Hartmut Birr wrote:
>
> >   You are right, but I've still assumed that
> > the pointer is zero or valid.
> >  The real problem is, that gcc doesn't stop to validate an expression if
> >  the result is determined and if the expression consist of simple
> >  expressions which are combined with OR. 
>
>  i tried the following test application with various configurations of
>  gcc 4.0 and 3.4.2, but it appears to work correctly.
>
>  #include <stdio.h>
>
>  int main(int argc, char* argv[])
>  {
>    volatile int *x = NULL;
>
>    if(x == NULL || *x == 0)
>    {
>       printf("true\n");
>    }
>    else
>    {
>       printf("false\n");
>    }
>    return 0;
>  }
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>  
This means, gcc is intelligent enough to made a difference between
comparing a variable with different values and between calculating
expressions from pointers.

- Hartmut