What is a dynamic array, and how does it adjust its size?

A dynamic array is a data structure that can automatically adjust its size as elements are added or removed.

A dynamic array, also known as an array list, is a type of array that has a variable size, allowing for the addition or removal of elements after it has been created. Unlike a static array, which has a fixed size determined at compile time, a dynamic array expands as you add more elements. So, it's more flexible because you don't need to determine the size of the array ahead of time.

The dynamic array works by allocating memory for a larger array when the current one is filled. When an element is added to a dynamic array that is full, the array will create a new, larger array in the memory. It then copies all the elements from the old array to the new one, and finally, it adds the new element. This process is known as 'resizing' or 're-allocating'.

The size of the new array is typically a multiple of the old array's size. This is to reduce the number of resizing operations required, as these can be computationally expensive. However, this also means that a dynamic array may use more memory than a static array, as there can be unused 'slots' in the array.

When elements are removed from a dynamic array, it may also shrink in size to free up memory. However, this is less common, as reducing the size of an array is also a costly operation, and it could lead to more resizing operations if elements are added again later.

In summary, a dynamic array is a flexible data structure that can adjust its size as needed. It does this by creating a new, larger array when it's full, and potentially shrinking when elements are removed. This makes dynamic arrays a powerful tool in programming, but it's important to be aware of the potential memory and computational costs associated with resizing operations.