Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!wuarchive!psuvax1!gatech!hubcap!drcook
From: drcook@hubcap.clemson.edu (david richard cook)
Newsgroups: comp.lang.c
Subject: Re: parsing the format string at compile time...
Message-ID: <6737@hubcap.clemson.edu>
Date: 11 Oct 89 11:50:53 GMT
References: <705@nixbur.UUCP>
Distribution: usa
Organization: Clemson University, Clemson, SC
Lines: 17

From article <705@nixbur.UUCP>, by jobrien@nixbur.UUCP (John O'Brien):
> printf call is a constant (which it is most of the time), the compiler
> should be able to parse the string at compile time, and turn the printf
> call into something like the series of Modula-2 calls, with a correspond-
> ing increase in efficiency.  Do C compilers do this?  Are there any prob-
> lems with doing this?
> 
> 				Enquiring Minds Want to Know!
> 

	If C did allow this, it would not be C.  The compiler knows
nothing about any functions, including I/O.  Some new compilers may be
able to this, though I do not know of any, by using the #pragma
preprocesser directive to declare certain functions as builtin.  The
use of #pragma is left up to the compiler implementation and not C.
If an ANSI C implementation does not understand what the #pragma
directive is trying to accomplish, it will simply ignore it.