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C# Querying With LINQ Functional Programming in C# LINQ Method Syntax

Posted by Erica Cleary
Erica Cleary
14,077 Points

Needing help with task 2 of Querying with LINQ

I'm not sure what I am doing wrong with this answer. Can someone please help?

The task states: 'Add a new method named ReverseNumbers that has a return type of IEnumerable<int> and uses a LINQ query to return the _numbers variable in reverse order.'

NumberAnalysis.cs 
using System.Collections.Generic;
using System.Linq;

namespace Treehouse.CodeChallenges
{
    public class NumberAnalysis
    {
        private List<int> _numbers;
        public NumberAnalysis()
        {
            _numbers = new List<int> { 2, 4, 6, 8, 10 };
        }

        public IEnumerable<int> NumbersGreaterThanFive()
        {
            return _numbers.Where(n => n > 5);
        }
         public IEnumerable<int> ReverseNumbers()
        {

              return _numbers.OrderByDescending(n => n < 10);  

        }
    }
}

3 Answers

Steven Parker
Steven Parker
231,198 Points
Steven Parker
Steven Parker
231,198 Points

The new method should return all numbers in reverse order.

There's no need to compare the number to 10 (or to anything, for that matter).

Unlike the .Where() method which uses a function returning a boolean as an argument, the .OrderByDescending() method uses a function that simply returns a key.

Sara Rena Anderson
Sara Rena Anderson
15,045 Points
Sara Rena Anderson
Sara Rena Anderson
15,045 Points 
using System.Collections.Generic;
using System.Linq;

namespace Treehouse.CodeChallenges
{
    public class NumberAnalysis
    {
        private List<int> _numbers;
        public NumberAnalysis()
        {
            _numbers = new List<int> { 2, 4, 6, 8, 10 };
        }

        public IEnumerable<int> NumbersGreaterThanFive()
        {

            return _numbers.Where(n => n > 5); 

        }
           public IEnumerable<int> ReverseNumbers()
        {

              return _numbers.OrderByDescending(n => n );  

        }
    }
}
Erica Cleary
Erica Cleary
14,077 Points
Erica Cleary
Erica Cleary
14,077 Points

Thank you, Steven! That fixed it!