[comp.lang.c] Historical question about backquote

jon@jonlab.UUCP (Jon H. LaBadie) (11/11/90)

I've been wondering about this for a number of years.
About time I asked the experts.

A long time ago I stumbled across some code that had
backquotes where forward quotes were intended for character
constants.  I would have expected the error message to
be something like:

	illegal character "`": line NNN

but to my surprise I got something like:

	illegal BCD constant: line NNN

or

	illegal gcos BCD constant: line NNN

I presume, but seek clarification, that at one time the designers
of C planned to include a BCD constant type in the language and
that the backquote was reserved for introducing this data type.

Can anyone clarify the reason for this vestigal message?

BTW  The compilers in question were System V.  I do not know if
     the same type of messages appear in commercial compilers.

-- 
Jon LaBadie
{att, princeton, bcr, attmail!auxnj}!jonlab!jon

gwyn@smoke.brl.mil (Doug Gwyn) (11/12/90)

In article <874@jonlab.UUCP> jon@jonlab.UUCP (Jon H. LaBadie) writes:
>	illegal gcos BCD constant: line NNN

Yes, there was support for GCOS BCD constants in the Reiser CPP.
I think the code supporting them should be disabled in UNIX environments.

datanguay@watmath.waterloo.edu (David Adrien Tanguay) (11/13/90)

In article <874@jonlab.UUCP> jon@jonlab.UUCP (Jon H. LaBadie) writes:
#A long time ago I stumbled across some code that had
#backquotes where forward quotes were intended for character
#constants.  I would have expected the error message to
#be something like:
#
#	illegal character "`": line NNN
#
#but to my surprise I got something like:
#
#	illegal BCD constant: line NNN
#
#or
#
#	illegal gcos BCD constant: line NNN

GCOS is an operating system. Its file system (and other aspects) make
heavy use of BCD encodings. The GCOS B compiler used graves to specify
BCD constants, and this was inherited by the GCOS C compiler.
Presumably, the compiler you were using was at some point ported to GCOS
and had the BCD constant extension put in.
-- 
David Tanguay            Software Development Group, University of Waterloo