4. Pointer to a C++ variable

Solution:

int main( )
{
    int x = 5;
    double d = 0.1;

    // Variable sizes:
    int x_bytes = sizeof( x );
    int d_bytes = sizeof( d );

    // We need pointers to store addresses:
    int* x_ptr = &x;
    double* d_ptr = &d;

    return 0;
}

Simply taking an address of a variable would be meaningless!

In addition to address, we must recognize the object type.

Therefore, we need a special variable to accommodate both type and address.

Declaration statement

    int* x_ptr = &x;

instantiates a pointer variable named x_ptr, initialized by the address of variable x.