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From: ttobler@unislc.uucp (Trent Tobler)
Newsgroups: comp.lang.c
Subject: Re: When do you use "if ( a = b )"? (was Re: Funny mistake)
Message-ID: <1991Mar20.191103.10242@unislc.uucp>
Date: 20 Mar 91 19:11:03 GMT
Article-I.D.: unislc.1991Mar20.191103.10242
References: <65837@eerie.acsu.Buffalo.EDU>
Organization: unisys
Lines: 28

From article <65837@eerie.acsu.Buffalo.EDU>, by chu@acsu.buffalo.edu (john c chu):
> In article <775@camco.Celestial.COM> bill@camco.Celestial.COM (Bill Campbell) writes:
> [concerning "if ( a = b )"
>>Certainly it
>>is a legal construction, but 90% of the time when I do this it
>>was my mistake!
> 
> It's been my mistake everytime I've done it!! I realize that it is a
> legal construction and I know what it does, but I was wondering...
> Is there a good use for this?

Yes.  I often use it to do the following...

---------------------
if( fp = fopen( fname, "r")) {
	do_stuff_to(fp);
	fclose(fp);
}
else
	perror( fname);
----------------------

Of course, it could be written with fp = fopen ...  on a line by itself,
followed by an if(fp) ... ,  but I find the above easier to follow.


--
  Trent Tobler  - ttobler@csulx.weber.edu , ttobler@unislc!sun!uucp