🚀 go-pugleaf

Daniel Wood <dwood> writes:

> The following:
>       ((char *)src)++;        /* src is an (int *) */
> when compiled using Solaris SparcWorks 3.0.1, generates:
>       "t.c", line 12: warning: a cast does not yield an lvalue
>
> I fully understand why it makes no sense to say:
>
>       (char *)src = x;
>
> but, if the compiler thinks that it is stupid to interpret:
>
>       ((char *)src)++;
> as:
>       (char *)src = (char *)src + 1;
>
> then why is it doing it, since I am intending:
>
>       src = (char *)src + 1;
 
Or to avoid a pointer mismatch warning:

        src = (int*)((char *)src + 1);
 
> A cast on an operator like "++" should only be applied to the RHS.
>
> What does the standard say?
 
"The operand of the postfix increment or decrement operator shall have qualified
or unqualified scalar type and shall be a modifiable lvalue."
 
> The following isn't pretty but is the only why to get rid of the warning message:
>
> *(char *)(src=(int *)((char *)src+1)) = *(char *)(dst=(int *)((char *)dst+1));
 
Some compilers relax the language and interpret:
 
                            (type)lval = expr;
as:
                            *(type*)&lval = expr;
 
So, you could translate your example to:
 
                            (*(char**)&src)++;
 
Morgan Herrington