Pointer arithmetic

Learn to do arithmetic on pointers with + and -.

Pointer arithmetic

Pointers support arithmetic with + and -. Adding +1 to a pointer moves it to the next element; it steps by the size of the type. For example, on an int* p, p + 1 moves p by one int size.

This is useful for walking arrays. An array's name is the address of its first element; you can start with int* p = arr; and reach elements with *(p + 1), *(p + 2). This is the same as writing arr[1].

Array and pointer connection

An array's name is interpreted as the address of its first element. arr and &arr[0] mean the same. So you can write int* p = arr;; p now points to the start of the array.

arr[i] is actually a shortcut for *(arr + i). So indexing is a combination of pointer arithmetic and dereference. This connection reflects the low-level nature of C++; but in everyday code, writing arr[i] is more readable.

Exercise Walk an array with a pointer

Declare int arr[] = {10, 20, 30};. Bind p to the start of the array with int* p = arr;. Print the second element using *(p + 1) with std::cout.

Show example solution

#include <iostream>

int main() {
    int arr[] = {10, 20, 30};
    int* p = arr;
    std::cout << *(p + 1) << "\n";
    return 0;
}

Test yourself

What does this code print?
```
int arr[] = {10, 20, 30};
int* p = arr;
std::cout << *(p + 1);
```
- 10
- 20
- 0
- 30
Show answer

20 — *(p + 1) gives the second element of the array, which is 20.
Match each expression to its meaning

p + 1

Next element
*(p + 1)

Second value
arr

Array name
int* p = arr

Binding

Pointer arithmetic

std::cout << *(p ____ 1);

Show answer

std::cout << *(p + 1);

Next lesson: Summary - Pointer basics

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