Pointers and Arrays in C++

Pointers and Arrays in C++

In C++, arrays and pointers are closely related. The name of an array acts as a pointer to its first element. This allows pointers to access array elements using pointer arithmetic, making arrays and pointers interchangeable in many situations.

Key Points

• The name of an array (e.g., arr) is a pointer to its first element.
• You can use pointers to traverse arrays using arithmetic operations like +, -, ++, and --.
• Access array elements using either arr[index] or *(ptr + index).

Example: Array Traversal Using Pointer

#include <iostream>
using namespace std;

int main() {

    int arr[5] = {10, 20, 30, 40, 50};
    int *ptr = arr; // Pointer to the first element of the array

    cout << "Accessing array elements using pointer:" << endl;

    for(int i = 0; i < 5; i++) {
        cout << "Element " << i << ": " << *(ptr + i) << endl;
    }

    return 0;
}

Output

Element 0: 10
Element 1: 20
Element 2: 30
Element 3: 40
Element 4: 50

Example: Modifying Array Elements Using Pointer

#include <iostream>
using namespace std;

int main() {

    int arr[5] = {10, 20, 30, 40, 50};
    int *ptr = arr;

    // Modify elements using pointer
    for(int i = 0; i < 5; i++) {
        *(ptr + i) += 5;
    }

    cout << "Array after modification: ";
    for(int i = 0; i < 5; i++) {
        cout << arr[i] << " ";
    }
    cout << endl;

    return 0;
}

Output

Array after modification: 15 25 35 45 55

Important Notes

• Pointers and arrays can be used interchangeably for accessing and modifying elements.
• Pointer arithmetic automatically accounts for the size of the data type when incrementing or decrementing.
• Be careful not to access memory outside the bounds of the array to prevent undefined behavior.

Next Topic

Next, learn about C++ References.