Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!cornell!uw-beaver!uw-entropy!dataio!bright
From: bright@Data-IO.COM (Walter Bright)
Newsgroups: comp.lang.c
Subject: Re: Casting malloc() in ANSI C?
Message-ID: <2243@dataio.Data-IO.COM>
Date: 13 Dec 89 21:41:20 GMT
References: <24969@cup.portal.com>
Reply-To: bright@dataio.Data-IO.COM (Walter Bright)
Distribution: usa
Organization: Data I/O Corporation; Redmond, WA
Lines: 24

In article <24969@cup.portal.com> Kevin_P_McCarty@cup.portal.com writes:
<In ANSI C, assigning a void pointer to any pointer variable is
<legal, so casting the value returned by malloc() to the
<appropriate pointer type is no longer necessary.  As a matter of
<recommended style, should the redundant cast be retained?

Yes. In C++, implicit casts of (void *) to (any *) is not allowed.
The 'redundant' cast is required in C++ code. Since C++ is the way
C is moving, leave the cast in.

<- When the appropriate header is ommitted, a cast will suppress a
<helpful diagnostic, and at worst can result in the return value
<from malloc() being silently munged beyond use.

C++ solves this problem by *requiring* functions to be prototyped before
use. This eliminates the nasty problems caused by forgetting to declare
malloc.

<- Some ANSI-aware compilers will complain upon encountering a
<function call for which no prototype has been seen.  This is a
<Good Thing, to be encouraged, but is a quality of implementation
<issue and can't be relied on.

It's required in C++, and can be relied on.