Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!purdue!haven!mimsy!chris
From: chris@mimsy.UUCP (Chris Torek)
Newsgroups: comp.lang.c
Subject: Re: malloc() and sizeof
Message-ID: <16687@mimsy.UUCP>
Date: 3 Apr 89 14:11:42 GMT
References: <510@lakesys.UUCP>
Distribution: usa
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 21

In article <510@lakesys.UUCP> chad@lakesys.UUCP (Chad Gibbons) writes:
>	I have seen a somewhat strange style of coding a malloc() call on
>some systems.  Usually, given struct foo, you would execute the call such
>as this:
>
>	struct foo tmp = (struct foo *)malloc(sizeof(struct foo));

No: rather, `struct foo *tmp = <as above>'

>The style I have seen used recently around here has been this:
>
>	struct foo tmp = (struct foo *)malloc(sizeof *tmp);

Perfectly legal (given `struct foo *tmp' rather than `struct foo
tmp').  The argument to sizeof is examined only to find its type; any
compiler that actually tries to find `*tmp' during program execution
has a severe bug (one on the order of computing 1|2 as -1 instead of 3,
or 1||2 as -1 instead of 1).
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163)
Domain:	chris@mimsy.umd.edu	Path:	uunet!mimsy!chris