Dynamic memory allocation allows you to allocate memory at runtime on the Heap. Unlike stack memory, heap memory must be manually managed by the programmer using new and delete.

Use dynamic memory when the amount of data is not known at compile-time, or when you need data to persist beyond the scope of a single function.

• Allocation (new): $O(1)$ average (depends on allocator).
• Deallocation (delete): $O(1)$.

cpp Standard
// Single variable
int *ptr = new int(5);
delete ptr;

// Array on heap
int *arr = new int[10];
delete[] arr; // Use delete[] for arrays!

• Memory Leaks: Forgetting to call delete.
• Double Free: Calling delete on the same pointer twice (causes crash).
• Using delete instead of delete[] for arrays.
• Accessing memory after it has been deleted.