C# Enumerable Where(IEnumerable, Func)

Description

Filters a sequence of values based on a predicate. Each element's index is used in the logic of the predicate function.

Syntax

public static IEnumerable<TSource> Where<TSource>(
  this IEnumerable<TSource> source,
  Func<TSource, int, bool> predicate
)

Parameters

• TSource - The type of the elements of source.
• source - An IEnumerable to filter.
• predicate - A function to test each source element for a condition; the second parameter of the function represents the index of the source element.

Example

The following code example demonstrates how to use Where to filter a sequence based on a predicate that involves the index of each element.

/*w  ww  .  j  a  v a2s.  c o  m*/
using System;
using System.Linq;
using System.Collections.Generic;
public class MainClass{
  public static void Main(String[] argv){  
    int[] numbers = {15, 90, 85, 0, 30, 20,  40, 75 };

    IEnumerable<int> query =
        numbers.Where((number, index) => number <= index * 10);

    foreach (int number in query)
    {
        Console.WriteLine(number);
    }

  }
}
    

The code above generates the following result.