Storing different types inside a list?

Question

Related: A list of multiple data types?

I want to know how to store different array types (including system types) inside an array.

The above question covered ho

Answer 1

You should create a class

public class MyClass
{
    public string x {get;set;}
    public double y{get;set;}
}

Then just create an array of that class. This class can have whatever types you want, that's the beauty of having objects in an object oriented language.

public MyClass[] someList=new MyClass[insert_number_of_elements];

Answer 2

I know that I'm a little late to the party, but I do this all the time. Especially when I'm initializing new classes. I like to do the heavy lifting outside of my main method, so I use object arrays to handle it. Object[] lets you put whatever you want into the array. then, when you return the array, you cast the array value to whatever you want. for example:

int NewInt = (int)InitArray[0];
string NewString = (String)InitArray[1];
double NewDouble = (Double)InitArray[2];

That might not be the most elegant solution in all cases, but for the work I do, it certainly handles the single output problem nicely.

Answer 3

You also can use the ? option, make a list of the following type:

public class MyClass
{
    public string? x {get;set;}
    public double? y {get;set;}
}

This way you can select if none, one or both can have a value.

Or if you don't like the HasValue/Value functions:

public class MyClass
{
    public enum EType { String, Double };

    EType TypeFilled {get; private set }

    string _x;
    public string X { get { return _x; }; set { _x = value; TypeFilled = EType.String; }
    double y;
    public double y { get { return _y; }; set { _y = value; TypeFilled = EType.Double; }
}

This way the typeFilled property decides what is filled. You could add validation to prevent being set twice etc.

Answer 4

You can create a custom collection in which you implement Add() method which only accepts doubles and string, something like:

void Add(object toAdd)
{
     if (toAdd is string)
         // add into inner collection ... 
      ... (same for double)
}

But, to be honest, I really can't think of any way that you would need a collection that accepts only these two types. You can probably solve the problem some other way...

Answer 5

You can specify not only custom types. List<int>, List<double>, List<string> will works as well. If you need to store mixed types - you need to specify closest base class for all types. In List<object> can be stored instance of any type.

Answer 6

If you are willing to give away type safety you can use an ArrayList, which was the only way to use a list of stuff pre generics.

You can put some wrapper code around it to only accept doubles and strings.