I was given starter code in C# and told to write code that will make it work. This is the starter code that I was given:

namespace Sample
{
    class Program
    {
        static void Main(string[] args)
        {
            Cup coffeeCup = new Cup() { TypeOfCup = TypeOfCup.Coffee };
            coffeeCup.AddItem(new liquid().WithDescription("Coffee"));
        }
    }
}

This is what I wrote in attempts to make the starter code function:

namespace Sample
{
    class Program
    {
        static void Main(string[] args)
        {
            Cup coffeeCup = new Cup() { TypeOfCup = TypeOfCup.Coffee };
            coffeeCup.AddItem(new liquid().WithDescription("Coffee"));
        }
    }
    class Cup {
        public string TypeOfCup { get; set;}
        public int numItems;
        public Cup() {
            this.numItems = 0;
        }
        public void AddItem() {
            numItems  = 1;
        }
    }
    class liquid {
        public string description;
        public liquid() {

        }
        public void WithDescription(string description) {
            this.description = description;
        }
    }
}

I receive 2 errors:

1. The name 'TypeOfCup' does not exist in the current context
2. Operator '.' cannot be applied to operand of type 'void'

I am a beginner in C# so I apologize if this is a silly problem. Any insight or tips on how to fix these errors/code would be appreciated.

CodePudding user response：

namespace Sample
{
    enum TypeOfCup
    {
        Coffee,
    }

    class Program
    {
        static void Main(string[] args)
        {
            Cup coffeeCup = new() { TypeOfCup = TypeOfCup.Coffee };
            coffeeCup.AddItem(new liquid().WithDescription("Coffee"));
        }
    }

    class Cup
    {
        public TypeOfCup TypeOfCup { get; set; }
        public List<liquid> Liquids { get; set; } = new List<liquid>();

        public void AddItem(liquid liquid)
        {
            Liquids.Add(liquid);
        }
    }

    class liquid
    {
        public string description = "";

        public liquid()
        {

        }
        public liquid(string description)
        {
            this.description = description;
        }
        public liquid WithDescription(string description)
        {
            this.description = description;
            return this;
        }
    }
}

If you are allowed to change your code in de Main function, then you probably should replace coffeeCup.AddItem(new liquid().WithDescription("Coffee")) with coffeeCup.AddItem(new liquid("Coffee"))

CodePudding user response：

You are supposed to implement TypeOfCup as enum:

enum TypeOfCup {
    None,
    Coffee,
    Tea,
    Chocolate
}

The enum constants are always accessed through the enum name: TypeOfCup.Coffee.

While this is the most idiomatic implementation, you could also implement TypeOfCup as constants or static properties:

static class TypeOfCup
{
    public const int None = 0;
    public const int Coffee = 1;
    public const int Tea = 2;
    public const int Chocolate = 3;
}

or

static class TypeOfCup
{
    public static int None => 0;
    public static int Coffee => 1;
    public static int Tea => 2;
    public static int Chocolate => 3;
}

Another problem is

Error CS1501 No overload for method 'AddItem' takes 1 arguments

You are supposed to pass it an object of type liquid, therefore AddItem must have a corresponding parameter. This means that a Cup must contain a collection storing those liquids instead of just a counter. Something like this:

class Cup
{
    public TypeOfCup TypeOfCup { get; set; }

    public List<liquid> Liquids { get; } = new List<liquid>();

    public void AddItem(liquid liquid)
    {
        Liquids.Add(liquid);
    }
}

The error

Error CS1503 Argument 1: cannot convert from 'void' to '[...].liquid'

comes from the fact the method WithDescription does not return an instance of the liquid. It should be implemented as

class liquid
{
    public string Description { get; set; }

    public liquid WithDescription(string description)
    {
        Description = description;
        return this;
    }
}

This allows calling coffeeCup.AddItem(new liquid().WithDescription("Coffee")); where the liquid that was added a description is passed to AddItem after a call to WithDescription.

Note that returning this is a common practice that allows chaining methods like this:

coffeeCup.AddItem(
    new liquid()
        .WithDescription("Coffee")
        .WithTemperature(50)
        .WithQuantity(20.5)
);

The same instance of the liquid is passed through this call chain.

According to the usual C# naming conventions class name must be in CamelCase. Therefore the liquid class should be named Liquid; however, that's an error in the starter code given to you.

CodePudding user response：

I suppose each cup has a type and a description.

class Program
{
    static void Main(string[] args)
    {
        Cup coffeeCup = new Cup() { TypeOfCup = TypeOfCup.Coffee };
        coffeeCup.AddItem(new liquid().WithDescription("Coffee"));
    }
}

class Cup
{
    public TypeOfCup TypeOfCup { get; set; }
    private liquid Liquid { get; set; }

    public void AddItem(liquid liquid)
    {
        this.Liquid = liquid;
    }
}

class liquid
{
    private string Description { get; set; }

    public liquid WithDescription(string description)
    {
        this.Description = description;
        return this;
    }
}

enum TypeOfCup
{
    Coffee,
    Tea,
}