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From: Thiago Adams <thiago.adams@gmail.com>
Newsgroups: comp.lang.c
Subject: =?UTF-8?Q?Re=3A_technology_discussion_=E2=86=92_does_the_world_need?=
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Date: Wed, 10 Jul 2024 11:26:58 -0300
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On 10/07/2024 10:32, Ben Bacarisse wrote:
> bart <bc@freeuk.com> writes:
> 
>> On 10/07/2024 00:35, Ben Bacarisse wrote:
>>> bart <bc@freeuk.com> writes:
>>>
>>>> On 09/07/2024 18:22, Ben Bacarisse wrote:
>>>>> bart <bc@freeuk.com> writes:
>>>>>
>>>>>> 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.
>>>>> An address value is passed by value.  C has only one parameter passing
>>>>> mechanism.  You can spin it as much as you like, but C's parameter
>>>>> passing is simple to understand, provided learner tune out voices like
>>>>> yours.
>>>>
>>>> Little about C's type system is simple.
>>> Parameter passing is relatively simple though since there is only one
>>> mechanism -- pass by value.
>>
>> Except when it comes to arrays.
> 
> The oddity is that, in C, one can't pass arrays to functions at all.
> That is one of the quirks that people learning C need to learn.  It does
> not alter the fact that there is only parameter passing mechanism -- by
> value.
> 
> Your plan, of course, is to take that one place where C is relatively
> simple and complicate by pretending that C as pass by reference as well
> as by value.
> 

GCC and clang have warnings if you use sizeof of the "array" argument.

void f(int a[])
{
   int i = sizeof(a); //
}

"sizeof on array function parameter will return size of 'int *' instead 
of 'int[]' [-Wsizeof-array-argument]"

But GCC and CLANG does not complain if we do

void f(int a[])
{
   a = 0;
}

In cake I will have warnings for both cases.