Re: technology discussion → does the world need a "new" C ?

On 2024-07-09, bart <bc@freeuk.com> wrote:

On 09/07/2024 23:32, Kaz Kylheku wrote:

On 2024-07-09, bart <bc@freeuk.com> wrote:

On 09/07/2024 16:58, Ben Bacarisse wrote:

bart <bc@freeuk.com> writes:
>

Arrays are passed by reference:
>
    void F(int a[20]) {}
>
    int main(void) {
      int x[20];
      F(x);
    }

>
This is the sort of thing that bad tutors say to students so that they
never learn C properly.  All parameter passing in C is by value.  All of
it.  You just have to know (a) what the syntax means and (b) what values
get passed.

>
The end result is that a parameter declared with value-array syntax is
passed using a reference rather than by value.
>
And it does so because the language says, not because the ABI requires
it. A 2-byte array is also passed by reference.

 
In C, arrays are not passed to functions, period.

>
Arrays can be passed by explicit reference:

The C term for "explicit reference" is "pointer".

C has neither "pass by pointer" nor "pass by explicit reference"; it has
pointers passed by value.

Pass by reference/pointer looks like this:

  void f(var int x)
  {
     x++:
  }

  int main(void)
  {
     int x = 42;
     f(x);
     // x is now 43
  }

That's like a var parameter in Pascal or C++ references (where our
fantasy syntax looks like void f(int &x).

Pass by reference means the callee can assign to the parameter
and the caller's object changes. (Unless it's some kind of constant
reference or something.)

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