Pointers & Arrays

Overview

In C++, an array's name acts as a constant pointer to its first element. Pointers and arrays are deeply intertwined.

Syntax

cpp

int arr[3] = {10, 20, 30};

// arr is implicitly converted to &arr[0]
int* ptr = arr; 

cout << ptr[0]; // 10
cout << ptr[1]; // 20

Common Pitfalls

You cannot reassign an array name like a pointer (e.g., `arr = &anotherVar` is illegal because `arr` is a constant pointer).

Interview Tips

Explain array decay: when passing an array to a function `void func(int arr[])`, it 'decays' into a pointer `void func(int* arr)`. The function loses the size information of the array.

Real-World Example

Iterating an array using a pointer.

example

cpp

#include <iostream>
using namespace std;

int main() {
    int arr[] = {1, 2, 3, 4, 5};
    int* ptr = arr;
    
    for (int i = 0; i < 5; i++) {
        cout << ptr[i] << " ";
    }
    return 0;
}

Take C++ Quiz