How to write a class, where one of its attributes is an Array?

nstk

Hi there, I am willing to declare a class, where one of its attributes has to be an Array of integers. 1st question: How should I write the set and get methods, cause the following is not working.

class Testclass
{
........

    private int\[\] \_number;
    public int number
    {
        get { return \_number\[\]; }
        set { \_number\[\] = value; }
    }
    
    ........
 }

2nd question: Not knowing how to deal with the above methods ani in order to advance into coding I declared the attribute as public public int[] number; Although I declare a new Object in the Form class (it should be a windows App) Testclass Myclass = new Testclass(); the programme crashes Myclass.number[i] = i + 2; saying that System.NullReferenceException was unhandled and asking me to create a new object instance for Myclass.number[i] A bit confusing for me...

Pete OHanlon

There are a few things here. First of all, the return type from number would be int[] not int - the two are not comparable. Secondly, you don't return _number[], you return _number. Finally, why use an array at all? Arrays have the nasty habit of becoming complicated to manage - why not look into a generic List? So this becomes:

class TestClass
{
public TestClass()
{
Number = new List<int>();
}
public List<int> Number { get; set; }
}

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David1987

class Testclass
{
private int[] _number;
public int[] number
{
get { return _number; }
set { _number = value; }
}
}

number will be null unless you initialize it somehow.

realJSOP

This is all you need:

public class TestClass
{
public int[] Numbers { get; set; }
}

However, I would probably use a List in the following form:

public class NumbersList : List<int>
{
// You don't have to put anything in the class if you don't want/need
// to. It's just to clean up the allocation and type references because
// typing "private NumbersList numbers; is cleaner than typing
// "private List<int> numbers;" (at least, that's the way I see it).
}

...which would allow you then to do this:

public class TestClass
{
public NumbersList Numbers { get; set; }
}

...as well as being much more flexible than a mere array.

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Lost User

Ditto what others have said regarding arrays. Personally I'd only use an int[] if it is being initialised once, and then will not have elements added or removed. That could be useful for certain specific applications. For example...

public class Simple
{
    private int\[\] \_int = { 1, 2, 3, 4, 5 };
    public int\[\] MyInt { get { return \_int; } }
}



    private static void TestSimple()
    {
        Simple s = new Simple();
        s.MyInt\[0\] += 1;
    }

...is fine. But as others have said if the size of the array is to be dynamic (items being added) I'd use say a List<int> probably.

nstk

Thank you all for your help. This is a great forum indeed! I will definately use a List, as there will be numbers of unknown quantity and value in the beginning of the programme.

nstk

Is this a different list than an ArrayList? http://msdn.microsoft.com/en-us/library/system.collections.arraylist(v=VS.100).aspx