c# find index of item in list code example

Example 1: c# find index element array

int[] arr = { 3, 6, 4, 1, 6, 8 };

// returns 1
Array.IndexOf(arr, 6);

Example 2: c# get index of item in list

Array.IndexOf(arrName, searchingFor)

Example 3: find index of string in a list C#

using System;
using System.Collections.Generic;
public class Program {
   public static void Main() {
      List < string > myList = new List < string > () {
         "Football",
         "Soccer",
         "Tennis",
      };

      // finding index
      int index = myList.FindIndex(a => a.Contains("Tennis"));

      // displaying index
      Console.WriteLine("List Item Tennis Found at index: " + index);
   }
}

Example 4: c# list any retun indec

public class Item {
	public int Id { get; set; }
	public Item() {}
	public Item(int id) { Id = id; }
}
List<Item> idList = { new Item(1), new Item(2), new Item(3) };
Item[] idLArr = [ new Item(1), new Item(2), new Item(3) ];

Item newItem = new Item(1);

// Using a lambda expression we can do the following query
int index = idList.FindIndex(item => item.Id == newItem.Id);
int arrIndex = Array.IndexOf(idLArr, newItem.Id);

//Then use it like so:
if (index != -1)
{
	// The item exists at index 0!
}

Example 5: Get Index position of an element in a list in c#

int index = myList.FindIndex(a => a.Prop == oProp);