linq in a fast start

Linq in a Fast Start

do you want to start develop your query with linq ?
im gonna show you whats diffrent betweeb some commands in it , like first and first or default and so on .
be patient and read this lecture of notes . 🙂

c# linq

whats diffrent First and firstOrDefault in linq command ?

if you search in integers First and query result = null then you have an exception

if you serach in Integers with FirstOrDefault and query result = null then your result is 0 , because default of Integer is 0 .

whats diffrent between first or single ?

in first query will search all content To end then returns values

and in single when query find first item , break and return it 🙂 >> when we will find a uniqe object can use to single and singleordefault .

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace linq1_1
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] Numbers = { 1, 2, 20000, 3, 3, 3, 7, 9, 8, 5, 8, 5, 6, 11 };
            int[] result = (from AliasN in Numbers select AliasN).ToArray(); //select * from numbers 

            int[] result2 = (from Alias_N in Numbers
                             orderby Alias_N descending
                             select Alias_N
                             ).ToArray();
            int[] Result3 = (from Alias_N in Numbers
                             where Alias_N > 30
                             select Alias_N).ToArray();

            int[] Result4 = (from Alias_n in Numbers
                             orderby Alias_n descending
                             where Alias_n > 3 && Alias_n < 10
                             select Alias_n).ToArray();

            int[] Result5 = (from Alias_N in Numbers
                             where Alias_N > 100
                             select Alias_N).ToArray();

            int[] result6 = (from alias_n in Numbers
                             where alias_n > 10
                             select alias_n).ToArray();
            int[] result7 = (from Alias_n in Numbers
                             orderby Alias_n descending
                             where Alias_n > 0
                             select Alias_n
                              ).ToArray();

            int ResultFirst = (from Alias_n in Numbers
                               where Alias_n == 3
                               select Alias_n).First();
            //here if condition is not ture then we have an exception 

            int ResulFirstOrDefault = (from Alias_n in Numbers

                                       where Alias_n == 3
                                       select Alias_n).FirstOrDefault();
            //here if query was null then return integer default value  >> 0 

            //int ResultSingle = (from n in Numbers
            //                    where n == 3
            //                    select n).Single();


            //int ResultSuingleOrDefault = (from n in Numbers
            //                              where n == 3
            //                              select n).SingleOrDefault();

            bool ResultCheckDuplicate = (from n in Numbers
                                         where n == 2
                                         select n).Any(); //.any just check its have return or not with boolean return

            var ReturnCount = (from n in Numbers
                               where n == 2
                               select n).Count();






            List<String> Names = new List<string>();
            Names.Add("Mohammad");
            Names.Add("ghorbanI");
            Names.Add("Ghorbani.dev");
            var Result = (from n in Names
                          select n).ToList();

            var ResultFindChar = (from n in Names
                                  where n.ToLower().Contains("i")
                                  select n).ToList();
                                                        


            var ResultStrartWith = (from n in Names
                                    where n.ToLower().StartsWith("g")
                                    select n).ToList();

            var ResultEndWith = (from n in Names
                                 where n.ToLower().EndsWith("m")
                                 select n).ToList();


                                            
        }
    }
    public class Person
    {
        public string Name { get; set; }
        public string Family { get; set; }
    }
}

linq , fast strat

Tags: Linq in a Fast Start