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

On 2024-07-12, bart <bc@freeuk.com> wrote:

It's clearly not by value. It's apparently not by reference. You can't
get away with saying they are not passed, as clearly functions *can*
access array data via parameters.

Actually, you probably can get away with saying that it is "passed
by reference".

The formal term that doesn't apply is "call by reference"; that's what
C doesn't have.

"call by reference" emphasizes that the function call mechanism
provides the reference semantics for a formal parameter, not that some
arbitrary means of passage of the data has reference semantics.

The following also achieves "pass by reference":

  int *global;

  void child(void)
  {
     printf("%d\", global[13]);
  }

  void parent(void)
  {
     int array[20];
     global = array;
     child();
  }

"pass" does not mean as a formal parameter.

For instance "message passing" (e.g. from one thread to
another) doesn't use formal parameters.

ISO C uses the "refer" word and derivatives thereof in connection
with pointers:

- "If an attempt is made to refer to an object defined with a
  volatile-qualified type through use of an lvalue with
  non-volatile-qualified type, the behavior is undefined".

The type from which a pointer is derived is called the "referenced
type":

- "The construction of a pointer type from a referenced type is
  called ‘‘pointer type derivation’’ [C99]

A footnote in C99 used the word "dereferencing" to describe the
action of the unary * operator. This word is commonly used in
the C programming circles:

- "Among the invalid values for dereferencing a pointer by the
  unary * operator are a null pointer, ..."

Another footnote in C99 uses "referenced" describing the relationship
of an pointer to the target object:

- "In other words, E depends on the value of P itself rather than
  on the value of an object referenced indirectly through P.

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