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From: ansok@spp3.UUCP (Gary Ansok)
Newsgroups: net.lang.c
Subject: Re: type cast in initializer
Message-ID: <269@spp3.UUCP>
Date: Fri, 7-Feb-86 18:15:55 EST
Article-I.D.: spp3.269
Posted: Fri Feb  7 18:15:55 1986
Date-Received: Tue, 11-Feb-86 04:27:22 EST
References: <302@hsi.UUCP> <1450@bbncc5.UUCP> <305@cray.UUCP>
Organization: TRW, Redondo Beach  CA
Lines: 23

>	int	x = 0;
>	char	*ptr = (char *) &x;

Even if the pointers (int *) and (char *) have different formats,
the assignment should take care of the conversion, so the cast should
be unnecessary.  A cast in an assignment var_1 = (type) var_2 is never
strictly necessary, except for readability (a good reason!), to keep
lint happy, or to work around bad compilers.  (The cast *should* be
acceptable to the compiler, though).  As I understand it, a cast has
the effect of an assignment to a temporary unnamed variable;
sqrt((double) i) is equivalent to (tmp_double = i, sqrt(tmp_double)).

Are there any other cases where casts are NEEDED besides:

	function calls:  doub_var = sqrt((double) int_var);
	pointer punning: long_var = *(long *) char_ptr;

Note: that last example is NONportable and downright dangerous
on machines with alignment requirements.  Still, it gets used
by a lot of programmers (including me, on occasion...sigh).

			Gary Ansok
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