How to use LINQ GroupBy Method in C#?

Question

Ravi Vishwakarma · Answer

In LINQ, theand GroupBy operator is used to grouping the list/collection items based on the specified key-value, it returns a collection of IGroupingandlt;Key, Values>. The Groupby method in LINQ is the same as the SQL group by clause.and 
Syntax
IEnumerableandlt;IGroupingandlt;key, value>> group = collection.GroupBy( condition)
Exampleand 
using System;
using System.Collections.Generic;
using System.Linq;
public class Program
{
and public static void Main()
and {
and  Listandlt;Student> students = new Listandlt;Student>(){
and  new Student() { StudentId = 1, Name = 'Ashu', Marks = 500 },
and  new Student() { StudentId = 2, Name = 'Shyam', Marks = 500 },
and  new Student() { StudentId = 3, Name = 'Shriyam', Marks = 400 },
and  new Student() { StudentId = 4, Name = 'Sunny', Marks = 550 },
and  new Student() { StudentId = 5, Name = 'Ram', Marks = 600 },
and  new Student() { StudentId = 6, Name = 'Krishna', Marks = 550 },
and  new Student() { StudentId = 7, Name = 'Anupam', Marks = 550 }
and  } ;
and  Listandlt;IGroupingandlt;int, Student>> list = students.GroupBy(stu => stu.Marks).ToList();
and  list.ForEach( evt => {
and  and Console.WriteLine('
key : ' and#43; evt.Keyand#43;' No of times : ' and#43; evt.Count() and#43; '
');
and  and Console.WriteLine('{0,-10} {1,4} {2,5}','Name','ID','Marks');
and  and foreach(Student student in evt){
and  and  Console.WriteLine('{0,-10} {1,4} {2,5}',student.Name, student.StudentId,student.Marks);
and  and }	
and  }) ;
and  Console.ReadLine();
and }
}
class Student
{
public int StudentId { get; set; }
public string Name { get; set; }
public int Marks { get; set; }
}
Output
Key : 500 No of times : 2
Name         ID Marks
Ashu          1   500
Shyam         2   500
Key : 400 No of times : 1
Name         ID Marks
Shriyam       3   400
Key : 550 No of times : 3
Name         ID Marks
Sunny         4   550
Krishna       6   550
Anupam        7   550
Key : 600 No of times : 1Name         ID MarksRam           5   600

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How to use LINQ GroupBy Method in C#?

Ethan Karla

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