Doing a CompareTo is giving an error Object must be of type int32
public interface IData
{
  bool EqualsTo(IData otherData);
}

public class IntegerData : IData
{
  int _data;

  public IntegerData(int data)
  {
    _data = data;
  }

  public bool EqualsTo(IData otherData)
  {
    if(_data.CompareTo(otherData) == 0)
        return true;

    return false;
  }
}

if(_data.CompareTo(otherData) == 0)

Object must of type int32

IData FirstData = new IntegerData(5);
 IData FirstData = new SecondData(5);

 bool result = FirstData.Value.EqualsTo(SecondData.Value);

if ( <intValue>.CompareTo(<IData object>) == 0 )
{ (...) }

if ( <intValue>.CompareTo(<int value>) == 0 )
{ (...) }

public bool EqualsTo(IData otherData)
{
   if(_data.CompareTo(otherData._data) == 0)
      return true;
   return false;
}

public interface IData : IEquatable<IData> { }

public class IntegerData : IData
{
   // The value will be private for this example
   // Could be public int Value { get; private set; }
   private int Value { get; set; }

   // Constructor
   public IntegerData(int value) { Value = value; }

   // Implements Equals (from IEquatable - IData)
   public bool Equals(IData other)
   { return Value.Equals(other.Value); }
}

// An interface that is based on IEquatable for better compatibility but also
// enables you to create a diferent EqualsTo method...
public interface IData<T> : IEquatable<T>
{
   T GetData();
   int GetDataHash();
   bool EqualsTo(IData<T> other);
}

// One class (string)
public class StringData : IData<string>
{
   private string Value { get; set; }

   public StringData(string value) { Value = value; }

   public string GetData() { return Value; }
   public int GetDataHash() { return GetData().GetHashCode(); }

   // From IEquatable
   public bool Equals(string other)
   { return Value.Equals(other); }

   // From IData (customized to compare the hash from raw value)
   public bool EqualsTo(IData<string> other)
   { return GetDataHash() == other.GetDataHash(); }
}

// Another class (int)
public class IntData : IData<int>
{
   private int Value { get; set; }

   public IntData(int value) { Value = value; }

   public int GetData() { return Value; }
   public int GetDataHash() { return GetData().GetHashCode(); }

   // Again from IEquatable
   public bool Equals(int other)
   { return Value == other; }

   // Again from IData (customized to compare just the hash code)
   public bool EqualsTo(IData<int> other)
   { return GetDataHash() == other.GetDataHash(); }
}

if(_data.CompareTo(((IntegerData)otherData)._data) == 0)

public interface IData<T>
    {
        bool EqualsTo(IData<T> otherData);
    }

    public class MyData<T> : IData<T>
    {
        private T _data;

        public MyData(T data)
        {
            _data = data;
        }

        public bool EqualsTo(IData<T> otherData)
        {
            if (_data is IComparable
                && otherData is MyData<T>
                && ((IComparable)_data).CompareTo(((MyData<T>)otherData)._data) == 0)
            {
                return true;
            }
            return false;
        }
    }

    static void Main(string[] args)
    {

        MyData<int> myInts1 = new MyData<int>(5);
        MyData<int> myInts2 = new MyData<int>(5);
        MyData<int> myInts3 = new MyData<int>(10);
        MyData<string> myString1 = new MyData<string>("Hello");
        MyData<string> myString2 = new MyData<string>("Hello");
        MyData<string> myString3 = new MyData<string>("World");
        if (myInts1.EqualsTo(myInts2)) Console.WriteLine("Yay");
        if (!myInts1.EqualsTo(myInts3)) Console.WriteLine("Nay");
        if (myString1.EqualsTo(myString2)) Console.WriteLine("Yay");
        if (!myString1.EqualsTo(myString3)) Console.WriteLine("Nay");
    }

public interface IData<T>
{
  bool EqualsTo(IData otherData);
  T GetData();
}

public class IntegerData : IData<int>
{
  int _data;

  public int GetData(){
      return _data;
  }

  public IntegerData(int data)
  {
    _data = data;
  }

  public bool EqualsTo(IData otherData)
  {
    if(_data.CompareTo(otherData.GetData()) == 0)
        return true;

    return false;
  }
}