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From: holloway@drivax.UUCP (Bruce Holloway)
Newsgroups: net.lang.c
Subject: Re: a basic like gosub in C
Message-ID: <300@drivax.UUCP>
Date: Wed, 26-Feb-86 13:05:32 EST
Article-I.D.: drivax.300
Posted: Wed Feb 26 13:05:32 1986
Date-Received: Fri, 28-Feb-86 21:55:11 EST
References: <202@crunch.uucp>
Reply-To: holloway@drivax.UUCP (Bruce Holloway)
Organization: Digital Research, Monterey, CA
Lines: 43

In article <202@crunch.uucp> josh@crunch.uucp (Josh Siegel) writes:
>In basic there is a GOSUB routine that will push the current
> position onto the stack and jump to another line.  Then, upon
> hitting a return will return to that place.  I wish to write
> something like that in C that will be movable between compilers.

(Sorry I'm not sending MAIL... but it doesn't seem to work from "rn" under
the C shell....)

You should use the setjmp() and longjmp() routines.

Call setjmp with a implementation specific environment buffer. When a
longjmp is called with the same buffer, it returns from the setjmp with
a return code. setjmp returns zero in a normal routine, or the longjmp 
parameter if that's wwhere it came from. Hmmm.

	jmp_buf env;

	func(){
	    :
	    :
	    if(setjmp(env)){

/* Code executed when returning from LONGJMP */

		}
	    :
	    :
	    longjmp(env,ret_code);
	    }


-- 

+----------------------------------------------------------------------------+
|Whatever I write are not the opinions or policies of Digital Research, Inc.,|
|and probably won't be in the foreseeable future.                            |
+----------------------------------------------------------------------------+

Bruce Holloway

....!ucbvax!hplabs!amdahl!drivax!holloway
(I'm not THAT Bruce Holloway, I'm the other one.)