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Frequently Used Extension Methods in LINQ

Posted by Lajapathy Arun Articles | LINQ 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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