Array vs ArrayList in C#

In C#, an Array is a collection of items that are stored in a contiguous block of memory. It is a fixed size, meaning that you must specify the size of the array when you create it, and you cannot change the size of the array later. Arrays are also index-based, meaning that you access items in the array using an integer index. Example:

int[] numbers = new int[5];
numbers[0] = 1;
numbers[1] = 2;
numbers[2] = 3;
numbers[3] = 4;
numbers[4] = 5;

int x = numbers[0]; // x is now 1
int y = numbers[1]; // y is now 2

On the other hand, an ArrayList is a type of collection that is similar to an array, but it is dynamically sized, meaning that you can add or remove items from the list and the size of the list will automatically adjust. Like an array, an ArrayList is index-based, so you can access items in the list using an integer index. However, an ArrayList can store items of any type, whereas an array can only store items of a single, specified type. Here is an example of how to create and use an ArrayList in C#:

ArrayList list = new ArrayList();
list.Add(1);
list.Add("Hello");
list.Add(true);

int x = (int)list[0]; // x is now 1
string y = (string)list[1]; // y is now "Hello"
bool z = (bool)list[2]; // z is now true

In summary, the main differences between Array and ArrayList in C# are:

• Array is fixed size, whereas ArrayList is dynamically sized.
• Array can only store items of a single, specified type, whereas ArrayList can store items of any type.