Question

I have this homework, I have only 1 problem, and I don’t know the solution. We have this class, and we musn’t create another variables or methods…

I have a beers dictionary with < Beer object, int income >. But the method has got only the Beer object’s name (prop), not the object.

And I don’t have another idea, how can I get the Beer object’s name from a Dictionary

I have only 2 idea, but these don’t work.

The first is I tried use a ContainsKey() method. The second is an foreach iteration

using System;
using System.Collections.Generic;

namespace PubBeer
{
    public class Beer
    {
        string name;
        int price; 
        double alcohol;


        public string Name{ get { return name; } }

        public int Price{ get; set; }

        public double Alcohol{ get { return alcohol;} }

        public Sör(string name, int price, double alcohol)
        {
            this.name= name;
            this.price= price;
            this.alcohol= alcohol;
        }


        public override bool Equals(object obj)
        {
            if (obj is Beer)
            {
                Beer other = (Beer)obj;
                return this.name== other.name;
            }
            return false;
        }
    }

    public class Pub
    {

        int income;

        IDictionary<Beer, int> beers= new Dictionary<Beer, int>();


        public int Income{ get; set; }


        public int Sold(string beerName, int mug)
        {
           // Here the problem

            beers; // Here I want to like this: beers.Contains(beerName)
                  //  beers.ContainsKey(Object.Name==beerName) or someone like this 

           // foreach (var item in beers)
           // {
           //     item.Key.Name== beerName;
           //  }


        }
...

Answer 1

Use LINQ to query over the collection of Keys.

//Throws an error if none or more than one object has the same name.
var beer = beers.Keys.Single(b => b.Name == beerName);

beers[beer] = ...;

// -or -

//Selects the first of many objects that have the same name.
//Exception if there aren't any matches.
var beer = beers.Keys.First(b => b.Name == beerName);

beers[beer] = ...;

// -or -

//Selects the first or default of many objects.
var beer = beers.Keys.FirstOrDefault(b => b.Name == beerName);

//You'll need to null check
if (beer != null)
{
    beers[beer] = ...;
}

// etc...

---

Update: NON-LINQ Alternative

Beer myBeer;

foreach (var beer in beers.Keys)
{
    if (beer.Name == beerName)
    {
        myBeer = beer;
        break;
    }
}

if (myBeer != null)
{
    beers[myBeer] = ...;
}