why p->member ?

[Chuck Karish]

In article <16734 at adm.ARPA> stanonik at nprdc.arpa (Ron Stanonik) writes:
>While explaining pointers to structures someone asked why
>the -> operator was needed; ie, why couldn't the members be
>referenced as p.member.

This is explained in p. 122 of K&R, first edition.
Briefly, if we define a structure pointer with

	struct date { int year, month, day } *pd;

then

	pd->year

is equivalent to

	(*pd).year.

The parentheses show that we're dereferencing pd, not year.
Interpretation of the sort you discuss, in which the compiler
figures out automatically that p is a pointer and decides
on its own to dereference it, would be pretty confusing, not
to mention inconsistent with the way other pointers are handled.
Anyway, it's not part of the language.

Chuck Karish	ARPA:	karish at denali.stanford.edu
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