Programming and Graphics

5.2 Pointers to vectors and strings 135

Note that it isnotpermissible to state:

double * memad1 = &A;

A vector name is a pointer

The perfectly valid statement:

double * memad1 = A;

reveals that avector name is a pointer.The statement:

cout << *A << endl;

will print the first element of the vector (in our case 1.1), and the statement

cout << *(A+1) << endl;

will print the second element of the vector (in our case 1.2). Thus, the expression
A[0]is identical toA, the expressionA[1]is identical to(A+1), and the
expression

A[n]

is identical to

*(A+n)

wherenis an integer. In fact, the compiler blindly substitutes*(A+n), for every
instance ofA[n].

Vector layout

The following code contained in the filepointervector1.ccfurther illus-
trates the layout of a vector in a contiguous memory block:

#include <iostream>

using namespace std;

int main()

{

double A[3]={1.1, 1.2, 1.3};

double * memad1 = A;

double * memad2 = memad1+1;

double * memad3 = memad2+1;