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From: gwyn@brl-smoke.ARPA (Doug Gwyn )
Newsgroups: net.lang.c
Subject: Re: type cast in initializer
Message-ID: <792@brl-smoke.ARPA>
Date: Sun, 9-Feb-86 22:19:13 EST
Article-I.D.: brl-smok.792
Posted: Sun Feb  9 22:19:13 1986
Date-Received: Wed, 12-Feb-86 07:35:18 EST
References: <302@hsi.UUCP> <1450@bbncc5.UUCP> <305@cray.UUCP> <269@spp3.UUCP>
Reply-To: gwyn@brl.ARPA
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In article <269@spp3.UUCP> ansok@spp3.UUCP (Gary Ansok) asks:

> 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;

Type casts are also useful in expressions, to avoid introducing
a temporary variable just to accomplish a type conversion.  One
example is casting a (char) to an (unsigned char) before putting
it into an (int) variable, to prevent sign-extension.  Another
is casting a (long) to an (unsigned long) before a right-shift,
to avoid sign-propagation.  A third case is converting an (int)
to a (long) early in an integer expression, to ensure that the
operations will not overflow.

But it is true that type casts should be used sparingly, and
never to compensate for sloppiness in declaring data types.

C note of the day: 'x' is of type (int), not (char).