220127_pointer_reference_2.cpp

// Inspired by "Expert C Programming" Chapter 4
// Pointer vs. Reference

#include <cstdio>

int some_array[3];

int main()
{
    // In chapter 4 of "Expert C Programming", the book explains why the following declaration is ill-formed:
    //extern int *some_array;
    // The compiler detects above statement as error with message: "conflicting declaration".
    // Correct way is:
    extern int some_array[3];

    // I think I'm understanding more and more on references.

    int a[3] = { 239, 241, 251 };   // a is a name of an array, the array starts from memory address "rbp - 20"
                                    //   [rbp - 20] = 239, [rbp - 16] = 241, [rbp - 12] = 251
    int *p = a;                     // address of p is "rbp - 32", [rbp - 32] = rbp - 20
    int (&r)[3] = a;                // address of r is "rbp - 8" , [rbp - 8 ] = rbp - 20

    std::printf("*a: %i\n", *a);    // mov eax,  [rbp - 20]
    std::printf("*p: %i\n", *p);    // mov eax, [[rbp - 32]]
    std::printf("*r: %i\n", *r);    // mov eax, [[rbp - 8 ]]
    std::printf("\n");

    std::printf(" a: %x\n", a);     // lea eax, [rbp - 20]
    std::printf(" p: %x\n", p);     // mov eax, [rbp - 32]
    std::printf(" r: %x\n", r);     // mov eax, [rbp - 8 ]
    std::printf("\n");

    std::printf("&a: %x\n", &a);    // lea eax, [rbp - 20] (address of a is also "rbp - 20"!!)
    std::printf("&p: %x\n", &p);    // lea eax, [rbp - 32]
    std::printf("&r: %x\n", &r);    // mov eax, [rbp - 8 ]
    std::printf("\n");

    /*
    prints:

    239
    239
    239

    some value A
    some value A
    some value A

    some value A
    some value B (not A)
    some value A
    */
}