Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!lll-winken!ames!pacbell!pbhya!dbsuther
From: dbsuther@PacBell.COM (Daniel B. Suthers)
Newsgroups: comp.bugs.misc
Subject: Re: Need help with C bug.
Keywords: pcc2 char array code generation
Message-ID: <24971@pbhya.PacBell.COM>
Date: 1 Apr 89 00:27:59 GMT
References: <349@iconsys.UUCP>
Reply-To: dbsuther@PacBell.COM (Daniel B. Suthers)
Distribution: usa
Organization: Pacific * Bell, San Ramon, CA
Lines: 32


>Has anyone isolated the following pcc2 bug?  (I assume it is a bug.)
>We have a Mot SVR2 based compiler.
>	char	p[50];
>	main()
>	{
>		printf("p = 0x%08X\n", p);
>		if (p)
>			printf("ok\n");
>		else
>			printf("bad berries\n");
>	}
>When run, this it says:
>	p = 0x00002F84
>	bad berries
>Any pointers?

It seems that your interpretation of what "p" is changes from statement to 
statement.  In the printf(), p is interpreted as a hexadecimal number, and
you are actually printing the address of p. (see "The C Programming Language",
Chapter 4.3: "when an array name appears as an argument to a function, the
location of the beginning of the array is passed")


At a guess:
In the if() test you are looking at (probably) the hi order byte represented
by the address of p[0];   this appears to be 0x0000.  

Do you really want to check to ensure that there is a value stored at &p[0]?
( if(p[0])  ) or do you want to ensure you have an array ( if(p != NULL) )

Dan Suthers, Systems Analyst;