On Thu, 2008-04-03 at 06:30 +1000, Michael D. Setzer II wrote:
On 2 Apr 2008 at 18:09, Matthew Saltzman wrote:
On Wed, 2008-04-02 at 09:48 -0700, Les wrote:
On my punch cards they did. Every card had a number sequential to the sequence. The punch we used inserted them automatically. Well, the programming card did. The reference number used for calls may have been different, but I don't remember it.
Those weren't line numbers per se (in the sense that BASIC had line numbers, for example). In FORTRAN, an 80-column card was divided into fields:
Column 1: 'C' indicated a comment line, ' ' a code line.
Columnt 1-5: is for line numbers and on many compilers they had to be right aligned.
OK, but these are the statement labels described below, not line numbers per se.
Column 2-6: Statement label numbers. These were arbitrary numbers used as targets for FORMAT, GOTO and "computed GOTO" (now *that* was a flow control concept!), and DO statements. These did not have to obey any ordering rules. There was no concept of an if-else block or a while loop with a logical test, so flow control was handled by GOTOs of some variety. Targeted statements were usually CONTINUE statements (no-ops), because there was some ambiguity regarding when the targeted statement was actually executed, and because it made reorganizing the flow a bit easier (especially with punchcards[1]).
Column 6: Was used for continuing information from the previous card. Generally putting a 1 in column 6 for the first continuation line, and 2, and so on, but most didn't care. COBOL uses Column 7 for this, and uses a hyphen if splitting a word or quoted text.
Damn, forgot the continuation character.
Column 7-72: Code.
Column 73-80: Ignored. Intended to be used for sequence numbers so you could sort the cards down in order if somebody dropped the deck. The numbers could be anything really, for example a three-letter alpha code identifying the deck and a four-digit sequence number.
(Somebody is bound to correct me on the actual column numbers, now...)
Thanks for the corrections. I wasn't near my FORTRAN Coloring Book (Roger Kaufman, Cambridge, Massachusetts and London England, The MIT Press, 1978. 285 pp., paperback ISBN 0 262 61026 4, http://www.seas.gwu.edu/~kaufman1/FortranColoringBook/ColoringBkCover.html) when I wrote that.