LINQ-Group BY, C# - rextester

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//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace Rextester
{
    public class Program
    {
        public static void Main(string[] args)
        {
            Account[] accounts = {
                                    new Account("Tom", "Smith", "132CK", 100.23),
                                    new Account("Tom", "Krammer", "132CD", 10000.00),
                                    new Account("Ralph", "Smith", "436CD", 1923.85),
                                    new Account("Ralph", "Jones", "454MM", 987.132),
                                    new Account("Ted", "Krammer", "897CD", 3223.19),
                                    new Account("Ralph", "Jones", "434CK", -123.32),
                                    new Account("Sara", "Smith", "543MM", 5017.40),
                                    new Account("Sara", "Krammer", "547CD", 34955.79),
                                    new Account("Sara", "Jones", "843CK", 345.00),
                                    new Account("Albert", "Smith", "445CK", 213.67),
                                    new Account("Betty", "Krammer","968MM",5146.67),
                                    new Account("Carl", "Smith", "078CD", 15345.99),
                                    new Account("Jenny", "Jones", "108CK", 10.98)
                                 };
            var accInfo = from acc in accounts
                           orderby acc.firstName
                           group acc by acc.firstName;
            
            foreach(var grpAcc in accInfo){
                Console.WriteLine("Grouped by firstName: "+grpAcc.Key);
                foreach(var acc in grpAcc){
                    Console.WriteLine("        "+acc.firstName+" "+acc.lastName+" --> "+acc.balance);
                }
                Console.WriteLine();
            }
        }
    }
    
    public class Account{
        public string firstName{get;private set;}
        public string lastName{get;private set;}
        public string accNum{get;private set;}
        public double balance{get;private set;}
        
        public Account(string firstName, string lastName, string accNum, double balance){
            this.firstName = firstName;
            this.lastName = lastName;
            this.accNum = accNum;
            this.balance = balance;
        }
    }
}

Show compiler warnings [ + ] Show input
Compilation time: 0,19 sec, absolute running time: 0,11 sec, cpu time: 0,11 sec, average memory usage: 14 Mb, average nr of threads: 3, absolute service time: 0,34 sec