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Frequently Used Extension Methods in LINQ

By Lajapathy Arun on April 15, 2012
In this article we are going to see the frequently used extension methods in LINQ with the help of Lambda expressions.
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In this article we are going to see the frequently used extension methods in LINQ with the help of Lambda expressions.

Used Namespace

using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Web;

Used collection for Demo

public static List<int> GetNumberList()
        {
            List<int> list = new List<int>();
            list.Add(11);
            list.Add(22);
            list.Add(77);
            list.Add(13);
            list.Add(17);
            list.Add(41);
            return list;
        }

ALL () LINQ Method

It is used to check whether the entire item in the list matches the specified condition. If one item fails, it returns false.

/// <summary>
       /// Just to check whether all element satisfies the given condition or not.
        /// Return just TRUE or FALSE.
        /// It applies to all the DataType like string,datetime etc and also for custom class.
        /// </summary>
        public static void LinqIntALL()
        {
            List<int> list = GetNumberList();
            //It returns bool, check whether all the item in the list greather than 13.
            bool isAll = list.All(i => i > 13)
            //Print
            HttpContext.Current.Response.Write("all greather than 13 :" + isAll + "<br/>");
             //It returns bool, check whether all the item in the list greather than 10.
           isAll = list.All(i => i > 10);
            HttpContext.Current.Response.Write("all greather than 10 :" + isAll + "<br/>");
        }

img1.jpg

ANY () LINQ Method

It is used to check whether any item satisfies the given condition. If one item satisfies then it returns true otherwise false.

  /// <summary>
        /// Just to check whether all element satisfies the given condition or not.
        /// Return just TRUE or FALSE.
        /// It applies to all the DataType like string,datetime etc and also for custom class.
        /// </summary>
        public static void LinqIntANY()
        {
            List<int> list = GetNumberList();
            //It returns bool, Just to check any element is greater than 13.
            bool isAll = list.Any(i => i > 13);
            //Print
            HttpContext.Current.Response.Write("Any greather than 13 :" + isAll + "<br/>");
            //It returns bool, Just to check any element is equal to 11.
            isAll = list.All(i => i == 10);
            HttpContext.Current.Response.Write("Any equal to 11 :" + isAll + "<br/>");
        }

img2.jpg

TAKE () LINQ Method

Used to get the Top "N" items from the list. Note it can be taken in sequence order.

/// <summary>
        /// This is used to take Top 'N' items form the list.Like "Top 5" in sql.
        /// </summary>
        public static void LinqInTake()
        {
            List<int> list = GetNumberList();
 
            //This takes only the Top two items from the list and eliminate others.
            //"2" in param indicates how much item you need.
            //ToList() helps to convert IEnumerable to List.
            list = list.Take(2).ToList();
 
            //Print
            PrintLis<int>(list, "Take Only top two item");
        }

TAKEWHILE () LINQ Method

Used to take items from a list based on the given condition. It iterates sequentially and checks each and every item, if a condition

is satisfied then it adds to a collection to the specific count.

/// <summary>
        /// This is used to take Top 'N' items based on the given condition.
        /// </summary>
        public static void LinqInTakeWhile()
        {
            List<int> list = GetNumberList();
 
            //This takes item if the element is less than 77 and eliminate others.
            //ToList() helps to convert IEnumerable to List.
            list = list.TakeWhile(i => i < 77).ToList();
            //Print
            PrintLis<int>(list, "Take items less than 77");
            //This takes item if the element is less than 22 and eliminate others.
            //ToList() helps to convert IEnumerable to List.
            list = list.TakeWhile(i => i < 22).ToList();
            //Print
            PrintLis<int>(list, "Take items less than 22");
        }

img3.jpg

SKIP () LINQ Method

Used to skip the top items based on the given count.

/// <summary>
        /// This is used to Skip Top 'N' items form the list.
        /// </summary>
        public static void LinqInSKIP()
        {
            List<int> list = GetNumberList();
             //This SKIPS the Top two items from the list and keep remaining.
            //"2" in param indicates how much item you need to skip.
            //ToList() helps to convert IEnumerable to List.
            list = list.Skip(2).ToList();
            //Print
            PrintLis<int>(list, "Skips top two item");
        }


img4.jpg

SKIPWHILE () LINQ Method

Used to skip items from the list based on the given condition.

It checks each and every item sequentially and if a condition is true then it skips the items up to where the condition turns false.

/// <summary       
///
This is used to Skip Top 'N' items form the list based on the given conditon.
       ///</summary>
        public static void LinqInSKIPWhile()
        {
            List<int> list = GetNumberList();
            //This SKIPS upo the item equals to 11.
            //Sequence check if any item not equal to 11, it return default list.
            //ToList() helps to convert IEnumerable to List.
            list = list.SkipWhile(i => i == 11).ToList();
 
            //Print
            PrintLis<int>(list, "Skips the item upto it equals to 11");
        }


img5.jpg

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