Re: variable sized unions

"lyrx" <vijju.singh@xxxxxxxxx> writes:
> Hello. I have some legacy code which has
>
> union x {
> struct y;
> char z[64*1024];
> }
>
> I would like to change this to a variable sized union.
>
> I tried
>
> union x {
> struct y;
> char *z;
> }
>
> allocated 2k of memory, and cast it to this union. The code does not
> work. I just wanted to know if I was doing something that is not
> supposed to work.

Arrays and pointers are two entirely different things. Given "char *z",
for z to be valid it has to point to some valid chunk of memory,
either an object or a chunk allocated with malloc().

What exactly are you trying to accomplish?

You might find section 6 of the comp.lang.c FAQ, "Arrays and
Pointers", useful.

--
Keith Thompson (The_Other_Keith) kst-u@xxxxxxx <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <*> <http://users.sdsc.edu/~kst>
We must do something. This is something. Therefore, we must do this.
.

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