Difference b/w array and arraylist in c#

Extracted from here :
http://stackoverflow.com/questions/128636/net-data-structures-arraylist-list-hashtable-dictionary-sortedlist-sorted[^]



Array - represents an old-school memory array - kind of like a alias for a normal type[] array. Can enumerate. Can't grow automatically. I would assume very fast insertion and retriv. speed.

ArrayList - automatically growing array. Adds more overhead. Can enum., probably slower than a normal array but still pretty fast. These are used a lot in .NET

List - one of my favs - can be used with generics, so you can have a strongly typed array, e.g. List<string>. Other than that, acts very much like ArrayList.

Hashtable - plain old hashtable. O(1) to O(n) worst case. Can enumerate the value and keys properties, and do key/val pairs.

Dictionary - same as above only strongly typed via generics, such as Dictionary<string,>

SortedList - a sorted generic list. Slowed on insertion since it has to figure out where to put things. Can enum., probably the same on retrieval since it doesn't have to resort, but deletion will be slower than a plain old list.

-Array is of fixed size but Arraylist is a datastructure which can dynamically grow and shrink.

-Array is created in stack memory where Arraylist is created and stored in heap area.

http://social.msdn.microsoft.com/Forums/en-US/csharplanguage/thread/bfc6cf96-1ef2-4383-8dda-eca0d99ac15f/[^]

Try the following link :

An Extensive Examination of Data Structures

Read This : http://social.msdn.microsoft.com/Forums/en-US/csharplanguage/thread/bfc6cf96-1ef2-4383-8dda-eca0d99ac15f/[^]

class Program
{
static void Main()
{
//
// Create an ArrayList and add three elements.
//
ArrayList list = new ArrayList();
list.Add("One");
list.Add("Two");
list.Add("Three");
}
}
class program
{
static void Main(string[] args)
{
List<string> lstString = new List<string>();

lstString.Add("ABCD");

lstString.Add(new Program()); //Compiler error

lstString.Add(4); // Compiler Error





foreach (object o in lstString)

{

Console.WriteLine(o.ToString());

}
}
}