Dynamic Array

/daɪˈnæmɪk əˈreɪ/

noun … “Resizable contiguous memory collection.”

Dynamic Array is a data structure similar to an array but with the ability to grow or shrink at runtime. Unlike fixed-size arrays, dynamic arrays allocate memory on the heap and can expand when more elements are added, typically by allocating a larger block and copying existing elements. They balance the efficiency of indexed access with flexible memory usage.

Key characteristics of Dynamic Array include:

• Resizable: automatically increases capacity when the current block is full.
• Indexed access: supports constant-time access to elements by index.
• Amortized allocation: resizing occurs infrequently, so average insertion cost remains low.
• Memory trade-offs: larger capacity may be preallocated to reduce frequent reallocations.
• Integration with pointers: in languages like C++, dynamic arrays are managed via pointers and memory management functions.

Workflow example: Adding elements to a dynamic array in pseudocode:

function append(dynamic_array, value) {
    if dynamic_array.size >= dynamic_array.capacity:
        new_block = allocate(2 * dynamic_array.capacity)
        copy(dynamic_array.block, new_block)
        free(dynamic_array.block)
        dynamic_array.block = new_block
        dynamic_array.capacity *= 2
    dynamic_array.block[dynamic_array.size] = value
    dynamic_array.size += 1
}

Here, when the array reaches capacity, a larger memory block is allocated, existing elements are copied, and the old block is freed, allowing continued insertion without overflow.

Conceptually, Dynamic Array is like a backpack that can magically expand to hold more items as you acquire them, maintaining order and direct access to each item.

See Array, Heap, Pointer, Memory Management, Vector.