Message from discussion __FUNCTION__ ????

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From: f...@genesis.demon.co.uk (Lawrence Kirby)
Newsgroups: comp.lang.c
Subject: Re: __FUNCTION__ ????
Date: Fri, 19 Oct 2001 12:44:14 GMT
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Message-ID: <1003495454snz@genesis.demon.co.uk>
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In article <47295485.0110190255.7f389...@posting.google.com>
           sob...@eudoramail.com "Sobhan Vezzu" writes:

>Hello All,
>
>         I understood that __FUNCTION__ is a preprocessor macro, which
>will substitute a file name. Similar to __FILE__ and __LINE__.

The C language doesn't define anything called __FUNCTION__ although it does
define __FILE__ and __LINE__

>         1) I have written a small code, only for __FUNCTION__ it
>prints as unknown why?

Perhaps because it isn't defined?

>What is the difference between __FILE__ and
>__FUNCTION__. When I comment #ifndef __FUNCTION block it prints the
>file name.

You compiler may provide __FUNCTION__ as an extension. Most likely it
will expand to the name of the function containing it. If it isn't
in a function then it won't be able to expand to anything. The new
C standard C99 does introduce something like this but it is called
__func__ and it is *not* a macro, it acts like the name of a static
variable within that function.

>         2) Where do I get a list of all the preprocessor macros.

Any good tutorial book on C should give one.

>#include <stdio.h>
>#include <errno.h>
>
>#ifndef __LINE__
>#define __LINE__ 0
>#endif
>
>#ifndef __FILE__
>#define __FILE__ "Unknown"
>#endif
>
>
>#ifndef __FUNCTION__
>#define __FUNCTION__ "Unknown"
>#endif
>
>int assert(int bool, int line, char *file, char *fun)

There is a standard defined macro named assert(), this is an unwise name
to define in your code.

-- 
-----------------------------------------
Lawrence Kirby | f...@genesis.demon.co.uk
Wilts, England | 70734....@compuserve.com
-----------------------------------------