passing structures

[Dale Cook]

In article <241 at motto.UUCP>, andrew at motto.UUCP (Andrew Walduck) writes:
|> okay folks here goes...
|> 
|> In the new ANSI standard, we can now pass (and return) a structure by
|> value. Like so...(fragment follows)
|> 
|> -----------------------------------------------------------------------
|> #include <stdio.h>
|> 
|> typedef struct complex {
|>                          int real;
|>         		 int imag; 
|>                        } complex;
|> 
|> complex add(complex, complex); /* function prototype for complex add */
|> 
|> int main(void)
|> {
|>   complex result, a, b;
|> 
|>   a.real = 5; a.imag = 6; /* 5+6i */
|>   b.real = 8; b.imag = 3; /* 8+3i */
|> 
|>   result = add(a,b); /* should be 13+9i */
|> 
|>   printf("result : %i+%ii\n", result.real, result.imag);
|> }
|> 
|> complex add(complex a, complex b)
|> {
|>   complex result;
|> 
|>   result.real = a.real + b.real;
|>   result.imag = a.imag + b.imag;
|>   
|>   return result;
|> }
|> ----------------------------------------------------------------------- 
|> Now, that should work right?!!
|> 
|> Now, here's the problem...what if I wanted to pass a constant structure
|> to add! For example I wanted to add 5+8i to a:
|> 
|> The call to add would look like this??
|> 
|> result = add(a,{5,8});
|> 
|> But this isn't supported by ANSII! There's no way to pass a structure
|> as a parameter! It should be do-able, the prototype exists, so the 
|> types can be punned appropriately...any idea why it wasn't? No prior-art?
|> 
|> Any idea how I can suggest this to the committee?
|> 
|> Thanx
|> Andrew Walduck
|>  ______________________________________________________________________
|> |andrew at motto.UUCP | I wasn't aware that Ada was useful - Henry Spencer|

Forgive me for being dense, but why would one want to do this at all?
First of all, it's bad form to bury hard numbers in code.
Second, passing structures by value might be ok for small structures, but 
as the size increases, your stack requirements do as well.  Especially
if you're using recursive routines...

--- Dale Cook

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