Passing single dimensional arrays via functions

[ChosenTorture]

We pass a single dimensional array like this :

void func() // some function
      {
         int ARR[20];
         .....
         func1(ARR); // Passing the address of the first element of the array
         .....
      }

I am also aware that there are three ways to receive arrays

void func1(int *A) //Receive the address via a pointer variable
or
void func1(int A[]) //Receive the address with an unsized array
or
void func1(int A[20]) //Receive the address with an array of a size

My question is that what is the difference between the three allowed types of array receiving ? I think that changes made via a pointer variable are permanent while in the case of others it's not but I'm not sure about this. Is it true or not ? Thanks ! ^_^

[Peter87]

All three are completely equivalent. The type of A in func1 is int*.

[ChosenTorture]

I'm aware that all the three are equivalent for receiving arrays.

Assume that the value of ARR[5] was 5 in the function func(). After that i passed the array to func1(). But if i try to access the array by doing *(A+5)=10 this will it affect the original array ARR[20] ? If yes then will the change also happen when i use A[] or A[20] ?

[Peter87]

The the original array will be affected because A is just a pointer to the first element in the array.

[Zephilinox]

Yeah, their all the same... why couldn't you test it yourself? it took me 3 minutes and you already had your editor open.

#include <iostream>

void func1(int *Array)
{
    for (int i = 0; i < 5; i++)
    {
        std::cout << Array[i] << std::endl;
        Array[i] = i*2;
    }
}

void func2(int Array[])
{
    for (int i = 0; i < 5; i++)
    {
        std::cout << Array[i] << std::endl;
        Array[i] = i*3;
    }
}

void func3(int Array[5])
{
    for (int i = 0; i < 5; i++)
    {
        std::cout << Array[i] << std::endl;
        Array[i] = i*4;
    }
}

int main()
{
    int Array[5] = {0, 1, 2, 3, 4};
    func1(Array); //replace func1 with func2 or func3
    
    for (int i = 0; i < 5; i++)
        std::cout << Array[i] << std::endl;
}

[ChosenTorture]

@Zephilinox: Thanks for that code and yeah I'm sorry. I'm just starting to learn and sought for advice before starting my project. I saw that in all the cases the original array is modified. I didn't think it would happen in the case of func2() and func()3 though. Thanks again !! :)

[Zephilinox]

no problem, good luck