From mboxrd@z Thu Jan  1 00:00:00 1970
From: nw@retrocomputingtasmania.com (Nigel Williams)
Date: Fri, 29 Dec 2017 21:58:28 +1100
Subject: [TUHS] origin of C header files
In-Reply-To: <CACNPpeYw3maUqXr8NxotW9FZMjhJmm-K9kEv2ma6SytiQB=1cg@mail.gmail.com>
References: <CACNPpeYw3maUqXr8NxotW9FZMjhJmm-K9kEv2ma6SytiQB=1cg@mail.gmail.com>
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On Fri, Dec 29, 2017 at 7:26 PM, Wesley Parish <wobblygong at gmail.com> wrote:
> Which raised the question: when did header files come into use? Who
> was the first to use header files to store common system-wide or
> application-wide data definitions? Was it used in any languages prior
> to C?

COBOL 60 (April 1960) had INCLUDE (page V-27):

http://bitsavers.trailing-edge.com/pdf/codasyl/COBOL_Report_Apr60.pdf

FUNCTION: To save the programmer effort by automatically incorporating
          library subroutines into the source program.

It even had a literal substitution mechanism to rewrite the included text.