Is there a way to get the object located in the coordinates retrieved from a 2d array to compare it?

Question

I am trying to print the coordinates if my object is found in the 2D array. Am using .Equals but it seems to be ignoring it.

    private void PrintCarInfo(Car car, object[,] matrix)
    {
        int xCoordinate = 0;
        int yCoordinate = 0;

        int w = matrix.GetLength(0);
        int h = matrix.GetLength(1);

        for (int x = 0; x < w; ++x)
        {
            for (int y = 0; y < h; ++y)
            {
                if (matrix[x, y].Equals(car))
                {
                    xCoordinate = x;
                    yCoordinate = y;
                }
            }
        }
    }

This is the Car class:

public class Car
{
    public int Index { get; set; }

    public string Name { get; set; }

    public bool Manual { get; set; }

    public bool Diesel { get; set; }

    public Car()
    {

    }

    public Car(Car car)
    {
        Index = car.Index;
        Name = car.Name;
        Manual = car.Manual;
        Diesel = car.Diesel;
    }
}

This is what I get when debug from the 2D array:

[1,1] {Toyota (15)}

If you don't override `Equals` then an object won't be equal unless it is the actual same instance, even if all the properties are equal. — Jodrell, Jan 21 '19 at 14:05
As an aside, I'd prefer a [jagged array to a multi-dimensional array](https://stackoverflow.com/questions/4648914/why-we-have-both-jagged-array-and-multidimensional-array). — Jodrell, Jan 21 '19 at 14:08
@Jodrell - jagged (array-of-array) is a little faster but unless there is a direct need for a non-rectangular shape I would prefer multi dim. Keep it simple. — bommelding, Jan 21 '19 at 14:12

bommelding · Answer 1 · 2019-01-21T14:10:49.683

2

Am using .Equals but it seems to be ignoring it.

Yes,

 if (matrix[x, y].Equals(car))

will only work

When car is a reference to an instance in the matrix, or
When you override Car.Equals

The default comparison for classes is Reference Equality. That will only work when the search element car is the exact same object as is in the matrix.

When you want to compare to a different object but with the same property values, you will have to implement Equality by yourself.

edited Jan 21 '19 at 14:10

answered Jan 21 '19 at 14:03

bommelding

2,969
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14

3. use of value type / struct – fubo Jan 21 '19 at 14:04
1

@fubo - `Car` is a `class`. And I wouldn't encourage making it a struct. – bommelding Jan 21 '19 at 14:06
my fault - it seemed to me that you wanted to numerate all possible ways how `Equals()` would work and I just wanted to add another option – fubo Jan 21 '19 at 14:08
Is it possible to retrieve and compare using just one attribute from the whole object? meaning if the index is the same, true – marrs Jan 21 '19 at 14:16
Sure, `if (matrix[x, y].Index == car.Index)` – bommelding Jan 21 '19 at 14:18
it won't let me because object[,] is being passed not Car[,] – marrs Jan 21 '19 at 14:33
No mention of `obj[,]` in the question. Rethink your entire setup and dataflow. – bommelding Jan 21 '19 at 14:36
It becomes `if (((Car)matrix[x, y]).Index == car.Index)` – bommelding Jan 21 '19 at 14:46

Is there a way to get the object located in the coordinates retrieved from a 2d array to compare it?

1 Answers1