Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!zaphod.mps.ohio-state.edu!brutus.cs.uiuc.edu!apple!apple.com!dowdy
From: dowdy@apple.com (Tom Dowdy)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Quick ThinkC String question...
Message-ID: <6714@internal.Apple.COM>
Date: 15 Feb 90 17:35:35 GMT
Sender: usenet@Apple.COM
Distribution: usa
Organization: Apple Computer, Inc.
Lines: 37
References:<77108@tut.cis.ohio-state.edu> <20011@bellcore.bellcore.com> <1990Feb14.210352.28118@oracle.com>


[ several people give suggestions for copying strings via procedures ]

Here are some macros for doing similar things:

#define PSTRCPY(P1, P2) BlockMove(P2, P1, P2[0]+1)

and also

#define PSTRCAT(P1, P2) \
   BlockMove(&P2[1], &P1[(P1[0]+1)], P2[0]); \
   P1[0] += P2[0];

Some cautions about these, however.  First off, neither of them do any 
kind of error checking.  In the first case, this usually isn't a problem 
when you are tossing Str255s around.  In the second case, things *can* get 
more hairy, but this is the case of having strong requirements on the 
caller rather than in the called routine.  As long as one is aware of what 
is going on, this isn't a problem.  The second macro probably isn't the 
most efficient way to code this, and no doubt some C person will tell me 
as much, but I almost never use PSTRCAT except in debugging code.

However, there is one *serious* problem to watch out for.  I hope this is 
the correct reason for this.  In MPW C, the "\p" directive isn't evaulated 
until late in the code gen, so at the macro level, taking the first 
position in the array as a length results in the value '\' rather than in 
the length of the string.  The result of this is that you can't do 
PSTRCPY(myString, "\pTesting");  This can be annoying, but since all my 
strings come out of resources (as they should in final code), I work 
around it when I have to.  I don't know if this also happens in Think C, 
it may be part of the ANSI C spec.

 Tom Dowdy                 Internet:  dowdy@apple.COM
 Apple Computer MS:81EQ    UUCP:      {sun,voder,amdahl,decwrl}!apple!dowdy
 20525 Mariani Ave         AppleLink: DOWDY1
 Cupertino, CA 95014       
 "The 'Ooh-Ah' Bird is so called because it lays square eggs."