TakeWhile

In this chapter you will learn:

How to use TakeWhile operator
TakeWhile with filter delegate
Filter string array
SkipWhile then TakeWhile
TakeWhile by index

Get to know TakeWhile operator

TakeWhile enumerates the input sequence, emitting each item, until the given predicate is false.

It then ignores the remaining elements:

using System;//from   j a v a2 s.  co  m
using System.Collections;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static void Main()
    {
        int[] numbers = { 3, 5, 2, 7, 4, 1 };
        var takeWhileSmall = numbers.TakeWhile(n => n < 5);
        foreach(int s in takeWhileSmall){
           Console.WriteLine(s);
        }
    }
}

The output:

TakeWhile with filter delegate

using System;//from  jav  a2 s .  co  m
using System.Collections;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static void Main()
    {

        string[] names = { "Java", "C#", "Javascript", "SQL", 
              "Oracle", "Python", "C++", "C", "HTML", "CSS" };

        IEnumerable<string> query = names.TakeWhile(n => n.Length < 5);
        foreach(String s in query){
           Console.WriteLine(s);
        }
    }
}

The output:

Filter string array

using System;//from  j  a v  a 2s  .co m
using System.Linq;
using System.Collections;
using System.Collections.Generic;
public class MainClass {
    public static void Main() {

        string[] presidents = {"ant", "Hard", "Harrison", "Hayes", "Hoover", "Jack"};

        IEnumerable<string> items = presidents
         .TakeWhile((s, i) => s.Length < 10 && i < 5);

        foreach (string item in items)
            Console.WriteLine(item);

    }
}

SkipWhile then TakeWhile

using System;/*from   java2  s  .c om*/
using System.Collections.Generic;
using System.Data;
using System.Linq;
using System.Text;


public class MainClass{

   public static void Main(string[] args){   
         String[] TestData = {"One", "Two", "Three", "Four",
                              "Five", "Six", "Seven", "Eight", 
                              "Nine", "Ten"};

         var ThisQuery = 
            TestData.SkipWhile(ThisElement => ThisElement != "Four").
            TakeWhile(ThisElement => ThisElement != "Nine");

         foreach (var ThisElement in ThisQuery)
            Console.WriteLine(ThisElement);


   }
}

TakeWhile by index

using System;// j av a2s  .  c  o m
using System.Collections;
using System.Collections.Generic;
using System.Text;
using System.Linq;

public class MainClass{
   public static void Main(){
       int[] numbers = { 1, 3, 5, 4};
       var query = numbers.TakeWhile(( n, index) => n >= index);

       var query2 = numbers.SkipWhile(( n, index) => n >= index);
    }
}

Next chapter...

What you will learn in the next chapter: