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From: ed360463@cisunx.UUCP
Newsgroups: comp.lang.c
Subject: Why pass structs? (not struct pointers)
Message-ID: <3346@cisunx.UUCP>
Date: Thu, 26-Feb-87 23:35:17 EST
Article-I.D.: cisunx.3346
Posted: Thu Feb 26 23:35:17 1987
Date-Received: Sun, 1-Mar-87 11:16:01 EST
Reply-To: ed360463@cisunx.UUCP (wartell    m)
Distribution: na
Organization: Univ. of Pittsburgh, Comp & Info Sys
Lines: 25

I have been aware of the post V7 C compilers passing and
returning structs from procedures, and I am curious as to
why.

Passing structures as a whole seems to violate my impression
of the nature of C.  I feel that a good reason for passing
arrays by reference (yes, I know that the pointer is passed by
value :-) is to save an enormous ammount of stack and CPU time.

To pass a structure by value seems to require an arbitrarily
large amount of stack; but more importantly, non-atomic
stack operations.  That is, that I can push a long, int, char
or any pointer with (hopefully) one machine-op.  To pass 
a structure would require a number of pushes, a block-copy-op,
or some looping copy code.

I imagine that the people who added this to C had good reason,
so could someone please tell me what I am missing or have
gotten wrong?

Thank you
-- 
matt wartell
university of pittsburgh
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