C# Enumerable TakeWhile(IEnumerable, Func)

Description

Returns elements from a sequence as long as a specified condition is true. The element's index is used in the logic of the predicate function.

Syntax

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

Parameters

• TSource - The type of the elements of source.
• source - The sequence to return elements from.
• 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 TakeWhile to return elements from the start of a sequence as long as a condition that uses the element's index is true.

/*from   www .  ja  va 2  s . c om*/
using System;
using System.Linq;
using System.Collections.Generic;
public class MainClass{
  public static void Main(String[] argv){  
 
    string[] fruits = { "apple", "orange", "blueberry", "grape", "strawberry" };
 
    IEnumerable<string> query =
        fruits.TakeWhile((fruit, index) => fruit.Length >= index);
 
    foreach (string fruit in query)
    {
        Console.WriteLine(fruit);
    }
 

  }
}
 

The code above generates the following result.