CODEWITHSUNDEEP
c#methodssubclass
Liam George
Liam George

Reputation: 27

Having trouble with classes derived from a List<List<string>>

I'm new to defining classes. I want to define a class dubbed 'dataplane' (as it's a 2-dimensional set of data used to store csv files, and therefore might be represented as a plane in space) that inherits all methods of the class List<List<string>> (if that is a class).

So far I've managed to declare the class and create a method to return a 'column' of data, but I can't invoke that method. I earlier had trouble with getting the class to inherit methods from the List<List<string>> class, but got there after some research.

For some reason when I try to translate tutorials to build a method returning the column of data in a List<string>, it doesn't let me invoke the method.

Could someone give me a clear example and Layman's terms explanation of how to declare a class that inherits from another, and write a method for it that uses the class's value?

Alternatively, could someone describe how I could use extended methods for this?

Also, in case someone has insight, here's what I have so far:

public class dataplanematrix : List<List<string>>
{
    List<List<string>> dataplane;

    private List<string> getColumn (int value)
    {
            List<string> columnValue = new List<string>();
            foreach (List<string> line in dataplane)
            {
                columnValue.Add(line[value].ToString());
            }
            return columnValue;
    }
}

The above code's issue is that I can't call the getColumn method.

Thanks in advance for your help.

Upvotes: 1

Views: 58

Answers (2)

Enigmativity
Enigmativity

Reputation: 117047

The superficial problem is that you have declared your method private when it should be public.

However, your class definition is wrong. There's no need to have a field.

Just do this:

public class DataPlaneMatrix : List<List<string>>
{
    public List<string> GetColumn(int value)
    {
        List<string> columnValue = new List<string>();
        foreach (List<string> line in this)
        {
            columnValue.Add(line[value]);
        }
        return columnValue;
    }
}

There's also no need to do line[value].ToString() as line[value] will do just fine.

You could also define your class like so:

public class DataPlaneMatrix : List<List<string>>
{
    public List<string> GetColumn(int value)
    {
        return this.Select(line => line[value]).ToList();
    }
}

Or, if you're using C# 6.0, like this:

public class DataPlaneMatrix : List<List<string>>
{
    public List<string> GetColumn(int value) => this.Select(line => line[value]).ToList();
}

Upvotes: 3

Matti Virkkunen
Matti Virkkunen

Reputation: 65126

Make your method public instead of private.

Upvotes: 2

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