C# Querying With LINQ Now You're Querying Selecting, Projecting and Anonymous Types

Carel Du Plessis
PRO
Carel Du Plessis
Pro Student 16,356 Points

I don't quite understand why my code doesn't display values.

I initialized a List with the bird object as the data type so that I can go through it and display the values by using the foreach loop.

the code that doesn't work I have commented out.

// Program.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Ex_LINQ
{
    class Program
    {
        static void Main(string[] args)
        {

            // This doesn't work

            //List<Bird> birds = new List<Bird>();

            //foreach (Bird bird in birds)
            //{
                 //Console.WriteLine(bird.Sightings);
            // }



             //This  works??? 

            List<Bird> birds = BirdRepository.LoadBirds();

            foreach (Bird bird in birds){
                Console.WriteLine();
                Console.WriteLine("Bird Name: " + bird.Name);
                Console.WriteLine("Bird Color: " + bird.Color);
                Console.WriteLine("Bird Sightings: " + bird.Sightings);
            }

            Console.ReadKey();
        }
    }
}


// Bird.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Ex_LINQ
{
    public class Bird
    {
        public string Name { get; set; }
        public string Color { get; set; }
        public int Sightings { get; set; }
    }
}



// BirdRepository.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Ex_LINQ
{
    public static class BirdRepository
    {
        public static List<Bird> LoadBirds()
        {
            //Refactor the LoadBirds method by using object initialization to add the pelican to the birds variable.

            List<Bird> birds = new List<Bird>{
                new Bird {Name = "Pelican", Color = "White", Sightings = 3}
            };
            return birds;
        }
    }
}

2 Answers

For the commented code, you have a list of birds that you have initialized but have no value. So Console.WriteLine has nothing to write since the bird.Sightings property is empty. look more at your BirdRepository class

Kiron Roy
Kiron Roy
3,209 Points

I took elements of the code an came up with this is works. It can be also be checkout here

using System;
using System.Collections.Generic;
using System.Linq;


namespace LINQStuff
{
    class Program
    {

        static void Main()
        {

            var birds = new List<Bird>
            {
                new Bird { Name = "Cardinal", Color = "Red", Sightings = 3 },
                new Bird { Name = "Dove", Color = "White", Sightings = 2 } ,
                new Bird { Name = "Robin", Color = "Red", Sightings = 5 } ,
                new Bird { Name = "Blue Jay", Color = "Blue", Sightings = 1 } ,
            };

            var canary = new Bird { Name = "Canary", Color = "Yellow", Sightings = 0 };
            birds.Add(canary);


            foreach (Bird bird in birds)
            {

                Console.WriteLine();
                Console.WriteLine($" Bird Name: {bird.Name} \n " +
                    $"Bird Color: {bird.Color} \n " +
                    $"Bird Sightings: {bird.Sightings} " );
            }


            Console.ReadLine(); // this takes out the line "press any key to continue"

        }
    }
}