Newsgroups: comp.lang.c
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: typedef vs #define
Message-ID: <1990Feb24.234433.14252@utzoo.uucp>
Organization: U of Toronto Zoology
References: <8430@cbnewsh.ATT.COM>
Date: Sat, 24 Feb 90 23:44:33 GMT

In article <8430@cbnewsh.ATT.COM> em@cbnewsh.ATT.COM (edward.man) writes:
>	typedef short	FLAGS
>	#define FLAGS	short
>
>If I had two identical pieces of code, one used the "typedef" and
>ther other "#define" as defined above, would there be any difference
>in the compiled code? Does the C compiler handle the two differently?

The #define is handled by the preprocessor, while the typedef is handled
by the compiler proper.  (Actually, a less implementation-dependent way
of stating this is that the #define is handled in ANSI C translation
phase 4 while typedef is handled in phase 7.)  In this particular case,
it will make little difference.  However, consider:

	typedef int (*intfp)();
	intfp ptrarray[10];

You can't do that with #define.
-- 
"The N in NFS stands for Not, |     Henry Spencer at U of Toronto Zoology
or Need, or perhaps Nightmare"| uunet!attcan!utzoo!henry henry@zoo.toronto.edu