Re: [9fans] the declaration of main()

[forsyth@caldo.demon.co.uk]

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>>Note that Forsyth's example is from 6th edition Unix, not 7th edition.
>>(The "s4/" in the source file name is a dead giveaway.)

i'm afraid not.

>>C didn't really become widely used until after the 7th edition, and
>>v7 C is really the ancestral root of most other implementations.  It is

the C compilers knew nothing of main, and if 7th edition really was the ancestral
root of most other implementations (which isn't so, because there were
some before 7th edition), they wouldn't have needed the invention
of EXIT_FAILURE and EXIT_SUCCESS.


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From: Mike Haertel <mike@ducky.net>
To: 9fans@cse.psu.edu
Subject: Re: [9fans] the declaration of main()
Date: Thu, 26 Apr 2001 12:17:47 -0700 (PDT)
Message-ID: <200104261917.f3QJHlG03409@ducky.net>

Forsyth wrote:

>cpu% cat s4/crt0.s
>/ C runtime startoff

Note that Forsyth's example is from 6th edition Unix, not 7th edition.
(The "s4/" in the source file name is a dead giveaway.)

Here's the corresponding code fragment from 7th edition
/usr/src/libc/csu/crt0.s:

1:
	mov	r0,4(sp)
	mov	r0,_environ
	jsr	pc,_main
	cmp	(sp)+,(sp)+
	mov	r0,(sp)
	jsr	pc,*$_exit
	sys	exit

Here the int return value from main does indeed become the exit status.

C didn't really become widely used until after the 7th edition, and
v7 C is really the ancestral root of most other implementations.  It is
also the version of the language that most nearly coincided with the
publication of the 1st edition of "The C Programming Language".