CODEWITHSUNDEEP
c#
Confused
Confused

Reputation: 53

Cant Figure out this c# reference

I was using the "this" keyword in my default constructor, below is the code in the class movie

namespace Movie_List
{ enum GenreType { Action, War, Drama, Thriller }; 
 class Movie 
 { 
    //Data Members 
    private String _title; 
    private int _rating; 
    private GenreType _type;

    //Properties


    public GenreType GenType
    {
        get { return _type; }
        set { _type = value; }
    }
    public String Title
    {
        get { return _title; }
        set { _title = value; }
    }


    public int Rating
    {
        get { return _rating; }
        set { _rating = value; }
    }




    public Movie()
        : this("Jaws", GenreType.Action, 4) { } 

    public Movie(String title, GenreType type, int rating ) //working ctor
    {
        Title = title;
        GenType = type;
        Rating = rating;

    }

    public override string ToString()
    {           
        return String.Format(" {0} Genre : {1},  Rating: {2:d} Stars. ", Title, GenType, Rating);
    }

}

I wanted to read in from a text file so i used this code in the MainWindow.xaml.cs

private void btnLoad_Click(object sender, RoutedEventArgs e)
{

    string lineIn = "";
    string[] filmarray;
    using (StreamReader file = new StreamReader("filmlist.txt"))
    {
        while ((lineIn = file.ReadLine()) != null)
        {
            filmarray = lineIn.Split(new char[] { ',' });
            moviecollection.Add(new Movie()

            {
                Title = filmarray[0],
                GenType = (GenreType)Enum.Parse(typeof(GenreType), filmarray[1]),
                Rating = Convert.ToInt32(filmarray[2]),
            });
            lstFilms.ItemsSource = moviecollection;
        }


    }
}

I dont need this bit of code now

: this("Jaws", GenreType.Action, 4)

But when i deleted it, the genre action and rating 0 stars still prints.

Why is this Happening does anyone know?

Upvotes: 0

Views: 76

Answers (2)

John Woo
John Woo

Reputation: 263723

When you have this initialization:

Movie movie = new Movie();

the empty constructor 

public Movie() : this("Jaws", GenreType.Action, 4) { }

calls the overloaded constructor which have several parameters:

public Movie(String title, GenreType type, int rating) { ... }

When you delete this line: this("Jaws", GenreType.Action, 4) { }, what is happening now is that you are only calling the empty constructor which does nothing at all.

So when you call

int ratingValue = movie.Rating;

the default value of integer which is zero is returned because you did set anything on it.

UPDATE

a simple if (maybe, if I understand what you mean)

Assuming Rating should be greater than zero.

public override string ToString()
{     
    if (Rating == 0)
    {
        return String.Format("{0}", Title);
    }
    else
    {
        return String.Format(" {0} Genre : {1},  Rating: {2:d} Stars. ", Title, GenType, Rating);
    }
}

Upvotes: 1

nikib3ro
nikib3ro

Reputation: 20606

It's because enum and int are always initialized with default value of 0.

It's not like string - if you don't initialize it will equal null. If you want to emulate this behavior for int, you can always try using int? type.

To get more details on this subject take a look at Default Values Table (C#).

Upvotes: 0

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