Array Passing

/*
 * Demonstrate some peculiarities of array passing in C.
 *
 * Author: Tom Bennet
 */
#include <iostream>

using namespace std;

// Each version receives the same size-5 integer array from the main pgm.

// Receive it as declared in main.
void rcvA(int arr[5])
{
        cout << "A [" << sizeof arr << "]" << endl;
        for(int m = 0; m < 5; m++)
                cout << arr[m] << " ";
        cout << endl;
}

// Receive it as the system sends it -- a pointer to the first item in the
// array.
void rcvB(int *arr)
{
        cout << "B [" << sizeof arr << "]" << endl;
        for(int m = 0; m < 5; m++)
                cout << arr[m] << " ";
        cout << endl;
}

// Since it sends a pointer and ignores the array size anyway, the system
// lets you leave it out here, too. 
void rcvC(int arr[])
{
        cout << "C [" << sizeof arr << "]" << endl;
        for(int m = 0; m < 5; m++)
                cout << arr[m] << " ";
        cout << endl;
}

// In fact, so long as the system is going to ignore the size anyway, we can
// write what we want.  The 1024 doesn't make the array that large,
// however; it's however large its creator made it.  rcvD can't find out.
void rcvD(int arr[1024])
{
        cout << "D [" << sizeof arr << "]" << endl;
        for(int m = 0; m < 5; m++)
                cout << arr[m] << " ";
        cout << endl;
}

main()
{
        // Here's the array all the fuss is about.
        int arr[5];

        // Put some stuff there.
        for(int i = 0; i < 5; ++i)
                arr[i] = 2*i -3;

        // Do exactly what the functions do.
        cout << "M [" << sizeof arr << "]" << endl;
        for(int m = 0; m < 5; m++)
                cout << arr[m] << " ";
        cout << endl;

        // Now run the functions.
        rcvA(arr);
        rcvB(arr);
        rcvC(arr);
        rcvD(arr);
}