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From: usotsuki@buric.co (Steve Nickolas)
Subject: [TUHS] C declarations.
Date: Sun, 14 May 2017 10:58:18 -0400 (EDT)	[thread overview]
Message-ID: <alpine.BSF.2.02.1705141057160.64059@frieza.hoshinet.org> (raw)
In-Reply-To: <201705141411.v4EEBYjv021607@coolidge.cs.Dartmouth.EDU>

On Sun, 14 May 2017, Doug McIlroy wrote:

>> Are there languages that copy arrays in function calls defaultly?
>
>> Pascal is an example.
>
> Pascal's var convention, where the distinction between value
> and reference is made once and for all for each argument of
> each function, is sound. The flexibility of PL/I, where the
> distinction is made at every call (parenthesize the name to
> pass an array by value) is finicky, though utterly general.

QuickBasic uses the ( ) trick too.

>> Where is all that [memory]  going to come from if you pass a
>> large array on a memory-constrained system of specs common back in the
>> days when C was designed
>
> Amusingly, under the customary linkage method in the even earlier
> days when Fortran was designed, pass-by-reference entailed a big
> overhead that could easily dominate pass-by-value for small arrays.
>
> [In the beginning, when CPUs had only one register, subroutine
> preambles plugged the reference into every mention of that variable
> throughout the body of the subroutine. This convention persisted
> in Fortran, which was designed for a machine with three index
> registered. Since reference variables were sometimes necessary
> (think of swap(a,b) for example) they were made standard.]
>
> Doug
>

Three! O_O That's a lot, if you're used to the 6502 and its mere *two* 
index registers.

-uso.


  reply	other threads:[~2017-05-14 14:58 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-05-14 14:11 Doug McIlroy
2017-05-14 14:58 ` Steve Nickolas [this message]
  -- strict thread matches above, loose matches on Subject: below --
2017-05-15 18:47 Steve Johnson
2017-05-15 19:54 ` Bakul Shah
2017-05-16  7:25 ` George Ross
2017-05-13 23:11 Richard Tobin
2017-05-15  6:46 ` Tim Bradshaw
2017-05-12 14:04 Richard Tobin
2017-05-11 21:49 Ron Natalie
2017-05-11 22:01 ` Arthur Krewat
2017-05-11 23:44   ` Dave Horsfall
2017-05-11 22:03 ` David Arnold
2017-05-11 22:32   ` Larry McVoy
2017-05-11 22:41     ` Ron Natalie
2017-05-13  1:24       ` Larry McVoy
2017-05-13  2:45         ` Ron Natalie
2017-05-13 12:20           ` Michael Kjörling
2017-05-13 12:35             ` Tim Bradshaw
2017-05-13 12:42               ` Michael Kjörling
2017-05-13 15:36                 ` Stephen Kitt
2017-05-14  1:59                 ` Lawrence Stewart
2017-05-14  2:23                   ` Dave Horsfall
2017-05-14  4:24                   ` Bakul Shah
2017-05-14  6:12                     ` Steve Johnson
2017-05-14  6:48                       ` Bakul Shah
2017-05-14 23:06                         ` Ron Natalie
2017-05-14 23:34                           ` Arthur Krewat
2017-05-15  0:14                             ` Dan Cross
2017-05-15  0:23                               ` Ron Natalie
2017-05-15  3:43                                 ` Random832
2017-05-15  0:40                               ` Larry McVoy
2017-05-15  2:00                                 ` Nevin Liber
2017-05-15 10:21                                 ` Tony Finch
2017-05-15  4:35                     ` Dave Horsfall
2017-05-15  4:54                       ` Bakul Shah
2017-05-15  5:01                         ` Dave Horsfall
2017-05-15 12:58                       ` Michael Kjörling
2017-05-15 16:58                         ` Dave Horsfall
2017-05-13 13:46               ` Hellwig Geisse
2017-05-13 19:08               ` Random832
2017-05-13 23:21                 ` Dave Horsfall
2017-05-14 14:48                   ` Nemo
2017-05-13 19:05             ` Random832
2017-05-14 13:14               ` Derek Fawcus
2017-05-12  0:15     ` Bakul Shah
2017-05-12  2:41       ` Theo Pavlidis

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