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From: Joe Pfeiffer <pfeiffer@cs.nmsu.edu>
Newsgroups: comp.lang.c
Subject: Re: relearning C: why does an in-place change to a char* segfault?
Date: Sat, 03 Aug 2024 08:32:00 -0600
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Richard Damon <richard@damon-family.org> writes:

> On 8/2/24 9:31 PM, Lawrence D'Oliveiro wrote:
>> On Fri, 2 Aug 2024 14:19:49 -0400, James Kuyper wrote:
>> 
>>> I've heard that in some other
>>> languages, if you call foo(3), and foo() changes the value of it's
>>> argument to 2, then subsequent calls to bar(3) will pass a value of 2 to
>>> bar(). That sounds like such a ridiculous mis-feature that I hesitate to
>>> identify which languages I had heard accused of having that feature ...
>> I heard that, too. I think it was on some early FORTRAN compilers,
>> on
>> early machine architectures, without stacks or reentrancy. And with the
>> weird FORTRAN argument-passing conventions.
>
> I remember it too, and was based on the fact that all arguments were
> pass by reference (so they could be either in or out parameters), and
> constants were passed as pointers to the location of memory where that
> constant was stored, and perhaps used elsewhere too. Why waste
> precious memory to setup a temporary to hold be initialized and hold
> the value, when you could just pass the address of a location that you
> knew had the right value.

I actually had a bug once in my FORTRAN code on a CDC6400 where I changed the
value of an argument in a function, and then passed in a constant.  That
"constant" had the new value for the rest of the program.  Finding that
one was a challenge, particularly since I was a very inexperienced
undergrad at the time.