LINQ/LAMBDA Query Example

How to get the Value of attribute from XML using XDocument class

string inputXml = @"<?xml version='1.0' encoding='UTF-8'?>

            <Countries>

             <State Name = 'Karnataka'>

                 <City Name='Bangalore' /> 

                 <City Name= 'Guledgudda' />

                 <City Name= 'Hubli' /> 

                 <City Name= 'Tumkur' />

             </State>

            </Countries>";

        XDocument countrySource = XDocument.Parse(inputXml);

            //The query

 countrySource.Descendants("State").SelectMany(i => i.Elements())

 .ToList().ForEach(i => Console.WriteLine((string)i.Attribute("Name")

 ));

Output will be

Bangalore

Guledgudda

Hubli

Tumkur

How to perform group by in LINQ/LAMBDA

var input = new string[] { "Apple", "Banana", "Mango", "Apple",

"Orange", "Mango", "Strawberry", "Apple" };

Console.WriteLine("=========Using LINQ===========");

            (from a in input group a by a into g

             select new

             {

                 Key = g.Key,

                 Count = g.Count()

             })

.ToList().ForEach(i => Console.WriteLine("Number of {0} is {1}",

       i.Key, i.Count));

     Console.WriteLine("\n=========Using LAMDA===========");

input.GroupBy(g => g).Select(i => new { Key = i.Key, Count = i.Count() })

.ToList()

.ForEach(i => Console.WriteLine("Number of {0} is {1}", i.Key, i.Count));

Output will be

How to assign a computed value to the same array back

var input = new string[] { "Apple", "Banana", "Mango", "Apple", "Orange",

"Mango", "Strawberry", "Apple" };

input = (from a in input group a by a into g where g.Count() >= 2

            select g.Key + " ( " + g.Count() + " )").ToArray();

            for (int i = 0; i < input.Length; i++)

            {

                Console.WriteLine(input[i]);

            }

Output will be

Apple (3)

Mango (2)

Write a code snippet for Left outer join using LINQ

    class Employee

    {

        public string EmpName { get; set; }

        public int EmpAge { get; set; }

        public string EmpDeptID { get; set; }

    }

    class Department

    {

        public string DeptID { get; set; }

        public string DeptName { get; set; }

    }

Employee objEmp1 = new Employee { EmpName = "Naga", EmpAge = 29, EmpDeptID = "1" };

Employee objEmp2 = new Employee { EmpName = "Sundar", EmpAge = 30, EmpDeptID = "2" };

Employee objEmp3 = new Employee { EmpName = "Siva", EmpAge = 28, EmpDeptID = "3" };

Employee objEmp4 = new Employee { EmpName = "Shankar", EmpAge = 31, EmpDeptID = "4" };

         Department objDept1 = new Department { DeptID = "1", DeptName = "IT" };

         Department objDept2 = new Department { DeptID = "2", DeptName = "Admin" };

         Department objDept3 = new Department { DeptID = "3", DeptName = "Testing" };

         Department objDept4 = new Department { DeptID = "4", DeptName = "HR" };

         Department objDept5 = new Department { DeptID = "5", DeptName = "Sales" };

       //Creating List of Objects

List<Employee> employees = new List<Employee> { objEmp1, objEmp2, objEmp3, objEmp4 };

List<Department> depts = new List<Department> { objDept1, objDept2, objDept3, objDept4, objDept5 };

   //Left Side Department Right side Employee

   var DeptEmpCollection = from dept in depts

        join emp in employees on dept.DeptID equals emp.EmpDeptID into de

            from Employees in de.DefaultIfEmpty()

        select new { dept.DeptName, EmployeesName = (Employees == null ?

            "--No Employee--" : Employees.EmpName) };

       foreach (var EmpDept in DeptEmpCollection)

       {

        Console.WriteLine("Dept {0}, EmpName {1}", EmpDept.DeptName,

        EmpDept.EmployeesName);

       }

    Console.Read();

Output will be

Given an array of numbers, find if ALL numbers are a multiple of a provided number [5]

int[] numbers = { 30, 25, 15, 90, 99, 42, 75 };

bool isMultiple = MultipleTester(numbers, 5);

Console.WriteLine("isMultiple= " + isMultiple);

Console.ReadLine();

private static bool MultipleTester(int[] numbers, int divisor)

{

bool isMultiple = numbers.All(number => number % divisor == 0);

//Note:- if you want to check any number is divisible by 5 then

//use numbers.any()

return isMultiple;

}

Output will be

isMultiple= False