X3J11 Pleasanton meeting summary
Henry Spencer
henry at zoo.toronto.edu
Sat Oct 6 13:32:09 AEST 1990
In article <12672 at ogicse.ogi.edu> daniels at ogicse.ogi.edu (Scott David Daniels) writes:
>However, the preceding example is really no different. If we presume the
>fortuitous ``to-be-filled-in-later size variable,'' the return statement
>of the preceding example may load the return value register (or whatever
>convention the compiler prefers for results) from the same variable...
Not unless you're willing to work hard at fudging a number of other things.
ANSI C does insist that the result of sizeof be a compile-time number, and
so it is legitimate to use a sizeof in (e.g.) dimensioning another array.
You can postpone everything to runtime if you really work at it, as witness
the existence of C interpreters, but in a traditional compiled approach,
you really do have to evaluate sizeof at compile time to type-check things
like:
char *p = sizeof(a) - sizeof(b);
which is legal if and only if the two sizeofs have the same value!
--
Imagine life with OS/360 the standard | Henry Spencer at U of Toronto Zoology
operating system. Now think about X. | henry at zoo.toronto.edu utzoo!henry
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