Arraylist in C#

In c#, Arraylist is used to store an elements of different data types and the size of arraylist can grow or shrink dynamically based on the need of our application like adding or removing an elements from arraylist.

In c#, arraylists are same as an arrays but only difference is arrays are used to store a fixed number of same data type elements.

C# Arraylist Declaration

In c#, arraylist is a non-generic type of collection and it is provided by System.Collections namespace.

As discussed, collection is a class so to define an arraylist, we must need to declare an instance of the arraylist class before we perform any operations like add, delete, etc. like as shown below.

If you observe above arraylist declaration, we created a new arraylist (arrList) with an instance of arraylist class without specifying any size.

C# Arraylist Properties

Following are the some of commonly used properties of an arraylist in c# programming language.

C# Arraylist Methods

Following are the some of commonly used methods of an arraylist to add, search, insert, delete or sort an elements of arraylist in c# programming language.

C# Arraylist Example

Following is the example of using an arraylist in c# programming language.

If you observe above example, we are able to define a new arraylist (arrlist) collection by using System.Collections namespace. Here, we are binding a different data type values to newly created arraylist (arrlist) by using Add method and with Count & Capacity properties we are able to access number of elements in an arraylist.

When we execute above c# program, we will get the result like as shown below.

This is how we can use arraylist in c# to hold a group of different data type objects based on our requirements.

Following are the some of useful examples to work with arraylist in c# programming language.

C# Add Elements to ArrayList

In c#, by using Add or AddRange method, we can add a different data type elements to an arraylist. 

Following is the example of adding an elements to arraylist using Add or AddRange methods in c#.

If you observe above example, we created a multiple arraylists (arrlist, arrlist2) and adding an elements to the arraylists in different ways.

When we execute above c# program, we will get the result like as shown below.

C# Access ArrayList Elements

In c#, we have a different ways to access arraylist elements i.e. either by using index positions or by iterating through an arraylist using for / foreach loops.

Following is the example of accessing an arraylist elements in different ways.

If you observe above example, we are accessing arraylist elements in different ways by using index positions, for and foreach loops based on our requirements.

When we execute above c# program, we will get the result like as shown below.

C# Insert Elements into ArrayList

In c#, we can insert an elements into arraylist either by using Insert() or InsertRange() methods.

Following is the example of inserting an elements into arraylist by using Insert and InsertRange methods in c#.

If you observe above example, we inserted an elements into arraylist at different index positions (0, 1) by using Insert() method. Same way, by using InsertRange() method we are inserting all the element of newly created arraylist (arrlist2) into arrlist at index position 2.

When we execute above c# program, we will get the result like as shown below.

C# Remove Elements from ArrayList

In c#, we have a different methods to remove an elements from arraylist i.e. either by using Remove() or RemoveAt() or RemoveRange() methods.

Following is the example of deleting an elements from arraylist in c# programming language.

If you observe above example, we used a Remove() method to delete particular value of element from arraylist and used a RemoveAt() method to delete an element at specified index position.

Same way, we used RemoveRange() method to delete specified number of elements from arraylist starting from the specified index position.

When we execute above c# program, we will get the result like as shown below.

In case, if you want to remove all the elements from arraylist, then use Clear() method.

Same way, we can use different methods like Sort() method to sort an elements of arraylist and Reverse() method to reverse the order of arraylist elements.

C# ArrayList Check If Item Exists

 By using Contains() method, we can check whether the specified element exists in arraylist or not. In case, if it exists it will return true otherwise false.

Following is the example of using Contains() method to check for an item exists in arraylist or not in c#.

If you observe above example, we used a Contains() method to check for an item (100) exists in arraylist (arrlist) or not.

When we execute above c# program, we will get the result like as shown below.

C# ArrayList Overview

Following are important points which needs to remember about arraylist in c#.

• Arraylist is used to store an elements of different data types and the size of arraylist can grow or shrink dynamically by adding or removing an elements.
• Arraylist is a non-generic type of collection and available with System.Collections namespace.
• We can access arraylist elements either by using loops (for and foreach) or with particular index position.
• We need to cast arraylist items to appropriate data type before we use it in our application.
• Arraylist provided a different methods to perform a multiple operations like add, insert, delete, sort, reverse, etc. on elements of arraylist.

C# Difference between Array and ArrayList

Following are the main difference between array and arraylist in c# programming language.

• Array is a strongly typed which means it can store only the elements of same data type but in arraylist we can store an elements of different data types.
• The size of array is fixed whereas the size of arraylist will vary dynamically based on requirements.
• Arraylist provided a different methods to perform an operations like add, insert, remove, etc. on multiple elements but in array, we can get or set the value of only one element at a time.
• In c#, an array can have multiple dimensions but an arraylist will have only one dimension.
• To use an arraylist items, we need to cast it to appropriate data type but in array we don’t need to cast an elements because it’s a strongly type.