Significant differences in Array vs Array List?
arraylist, arrays, c#
Solution
An array is a low-level data structure that essentially maps to a region in memory. An `ArrayList` is a variable length list implemented as an array of `object` that is re-allocated as the list grows.
`ArrayList` therefore has some overhead related to managing the size of the internal array, and more overhead related to casting objects to the correct type when you access the list.
Also, storing everything as `object` means that value types get boxed on write and unboxed on read, which is extremely detrimental to performance. Using `List<T>`, a similar but strongly-typed variable size list avoids this issue.
In fact, `ArrayList` is practically deprecated in favor of `List<T>` since .NET 2.0.
Problem
Possible Duplicate: When to use ArrayList over array[] in c#? From the perspective of memory or processor costs, does there appear to be a significant difference between an array and an arrayList object?