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Path: utzoo!utgpu!water!watnot!watmath!clyde!rutgers!brl-adm!adm!Dizio@udel.edu
From: Dizio@udel.edu
Newsgroups: comp.lang.c
Subject: assert
Message-ID: <4907@brl-adm.ARPA>
Date: Wed, 11-Mar-87 17:55:42 EST
Article-I.D.: brl-adm.4907
Posted: Wed Mar 11 17:55:42 1987
Date-Received: Fri, 13-Mar-87 01:06:37 EST
Sender: news@brl-adm.ARPA
Lines: 38



I found this macro for assert in <assert.h> under ULTRIX 1.2
under the SYSTEM_FIVE #ifdef

#define assert(EX) if (EX) ; else _assert("EX", __FILE__, __LINE__)
                                          ^culprit

It fails when given given an expression containing '"'.  
  eg. assert ((fp = fopen("filename","r")) != NULL)

My question is this.  Is this a proper implementation of this
functionality.  I'm not sure why it wants to pass the EX to
_assert except perhaps to print the expression out,  but in reality
the line number and file name is all I ever need to know.

This is especially true since assert is mainly a debugging tool
and not anything I would put into release software.  Mainly
because one generally would want more control over the action
to take, and the message printed to the user.

The non-system define is

#define _assert(ex) \
	{if (!(ex)) {\
		fprintf(stderr,"Assertion failed: file %s, line %d\n",\
			__FILE__, __LINE__);\
		exit(1);\
	}}

and of coarse if has no problem with any valid expression.

I realize this is a minor point as I could simply write my own macro,
but I just wondered if the proposed standard has specified whether
any valid expression should be able to be used inside the assert,
Or only expressions which don't contain '"'.

Dave