Difference between passing an array as formal parameter as int arr[] and int arr[N] in C/C++

Question

I got confused by the accepted answer and the comments below it that are stating opposite things in Passing Arrays to Function in C++ .

As formal parameter of a function is there any difference between passing an array as int arr[] or int arr[N] ? In other words, is there a difference between void foo(int arr[]) and void foo(int arr[N]) ?

Answer 1

Both void foo(int arr[]) and void foo(int arr[N]) are exactly equivalent. This is because an array as an argument to a function is adjusted to a pointer. So both of the above translate to:

void foo(int *arr)

This is specified in section 6.7.6.3p7 of the C standard regarding "Function declarators":

A declaration of a parameter as ''array of type'' shall be adjusted to ''qualified pointer to type'', where the type qualifiers (if any) are those specified within the [ and ] of the array type derivation. If the keyword static also appears within the [ and ] of the array type derivation, then for each call to the function, the value of the corresponding actual argument shall provide access to the first element of an array with at least as many elements as specified by the size expression.

Similar language exists in section 11.3.5p5 the C++ standard :

A single name can be used for several different functions in a single scope; this is function overloading(Clause 16). All declarations for a function shall agree exactly in both the return type and the parameter-type-list. The type of a function is determined using the following rules. The type of each parameter (including function parameter packs) is determined from its own decl-specifier-seq and declarator. After determining the type of each parameter, any parameter of type “array of T” or of function type T is adjusted to be “pointer to T”. After producing the list of parameter types, any top-leve lcv-qualifiers modifying a parameter type are deleted when forming the function type. The resulting list of transformed parameter types and the presence or absence of the ellipsis or a function parameter pack is the function's parameter-type-list.[Note:This transformation does not affect the types of the parameters.