How do I find the index of an item in a C# List?

C# List class provides methods and properties to create a list of objects (types). For example, the IndexOf method returns the first index of an item if found in the List.

The list is a generic class. Therefore, youore using the List<T> class, you must import the following namespace.

Using System.Collections.Generic; 

Here is an example of the IndexOf method.

using System;  
using System.Collections.Generic;  
namespace ConsoleApp1  
{  
    class Program  
    {  
        static void Main(string[] args)  
        {  
            List<string> AuthorList = new List<string>();  
            AuthorList.Add("Mahesh Chand");  
            AuthorList.Add("Praveen Kumar");  
            AuthorList.Add("Raj Kumar");  
            AuthorList.Add("Nipun Tomar");  
            AuthorList.Add("Mahesh Chand");  
            AuthorList.Add("Dinesh Beniwal");  
            foreach (var author in AuthorList)  
            {  
                Console.WriteLine(author);  
            }  
            Console.WriteLine("-------------");  
            // Contains - Check if an item is in the list    
            if (AuthorList.Contains("Mahesh Chand"))  
            {  
                Console.WriteLine("Author found!");  
            }  
  
            // Find an item and replace it with new item  
            int idx = AuthorList.IndexOf("Nipun Tomar");  
            if (idx >= 0)  
            {  
                AuthorList[idx] = "New Author";  
            }  
            Console.WriteLine("\nIndexOf ");  
            foreach (var author in AuthorList)  
            {  
                Console.WriteLine(author);  
            }  
        }  
    }  
}  

The output from the above listing is as below.

Continue Reading >> C# List Tutorial