How can I create a dynamic array of integers in C++?

General Discussions
1

I want to create a C++ dynamic array of integers using the new keyword. What is the correct syntax to allocate, use, and eventually free a dynamic integer array in C++?

2

I’ve done this many times :sweat_smile:. In C++, you can allocate a dynamic array like this:

#include <iostream>

int main() {
    int n = 5;

    // Allocate dynamic array
    int* arr = new int[n];

    // Use the array
    for (int i = 0; i < n; ++i) {
        arr[i] = i * 10;
        std::cout << arr[i] << " ";
    }
    std::cout << std::endl;

    // Free memory
    delete[] arr;

    return 0;
}

Always pair new[] with delete[] to avoid memory leaks.

I use this when I need manual control over array size at runtime.

3

Honestly, I almost always prefer std::vector now:

#include <iostream>
#include <vector>

int main() {
    int n = 5;
    std::vector<int> arr(n);  // dynamic size

    for (int i = 0; i < n; ++i) {
        arr[i] = i * 10;
        std::cout << arr[i] << " ";
    }
    std::cout << std::endl;

    // No need to manually delete—vector cleans up automatically
    return 0;
}

std::vector handles memory management automatically.

You can resize it anytime with arr.push_back(value), much safer and more flexible than raw pointers.

4

For modern C++ (C++11+), you can use std::unique_ptr for automatic cleanup:


#include <iostream>
#include <memory>

int main() {
    int n = 5;
    std::unique_ptr<int[]> arr(new int[n]);

    for (int i = 0; i < n; ++i) {
        arr[i] = i * 10;
        std::cout << arr[i] << " ";
    }
    std::cout << std::endl;

    // Memory is automatically freed when arr goes out of scope
    return 0;
}

I use this when I need raw-style arrays but want automatic memory management.

Combines safety of vector with familiar array syntax.