How to use the IndexOf(,) method of array class in C#?

The IndexOf() method of array class in C# searches for the specified object and returns the index of the first occurrence within the entire one-dimensional Array.

We have set the array.

int[] arr = new int[10];
arr[0] = 100;
arr[1] = 200;
arr[2] = 300;
arr[3] = 400;
arr[4] = 500;
arr[5] = 600;
arr[6] = 700;
arr[7] = 800;
arr[8] = 900;
arr[9] = 1000;

Now use the IndexOf() method and set the element for which you want the index, for example, I have set it for element 800.

int a = Array.IndexOf(arr, 800);

The following is the example showing the usage of IndexOf(,) method in C#.

Example

 Live Demo

using System;
class Program {
   static void Main() {
      int[] arr = new int[10];
      arr[0] = 100;
      arr[1] = 200;
      arr[2] = 300;
      arr[3] = 400;
      arr[4] = 500;
      arr[5] = 600;
      arr[6] = 700;
      arr[7] = 800;
      arr[8] = 900;
      arr[9] = 1000;
      int a = Array.IndexOf(arr, 800);
      Console.WriteLine(a);
   }
}

Output

7