C#

    using (System.IO.MemoryStream saveStream = new System.IO.MemoryStream())
    {
/*Ex*/  System.Xml.Serialization.XmlSerializer saveSerializer = new System.Xml.Serialization.XmlSerializer(typeof(MyFineCollection));
        saveSerializer.Serialize(saveStream, _manyObjects);
    }

using System;
using System.Collections.Generic;
using System.Text;
using System.Collections;

namespace Test_Xml
{
    public class MyFantasticBaseClass
    {
        private int _id = 0;

        public MyFantasticBaseClass(int id)
        {
            this._id = id;
        }

        public int Id
        {
            get { return (_id); }
        }
    }


    public class FirstDerivedClass : MyFantasticBaseClass
    {
        private bool _isReallyUseful = true;

        public bool IsReallyUseful
        {
            get { return (_isReallyUseful); }
            set { _isReallyUseful = value; }
        }
    }


    public class SecondDerivedClass : MyFantasticBaseClass
    {
        private double _zoom = 1.0;
        private MyFantasticBaseClass _linkedElement = null;

        public double Zoom
        {
            get { return (_zoom); }
            set { _zoom = value; }
        }

        public MyFantasticBaseClass LinkedElement
        {
            get { return (_linkedElement); }
            set { _linkedElement = value; }
        }
    }


    public class MyFineCollection:ICollection<MyFantasticBaseClass>
    {
        List<MyFantasticBaseClass> _innerList = new List<MyFantasticBaseClass>();

        // ICollection implementation details
    }
}

Class A
{
void CallingFunction()
{
    string data = "";
    DataTable dttemp = new DataTable();
    bool isValid = false;
    checkValue(ref data,ref isValid, ref dttemp);

    //perform some operation on data, dttemp
}

private void checkValue(ref string msg, ref bool valid, ref DataTable dttemp)
{
     msg += "Hello";
     valid = false;

     DataRow dr = dttemp.NewRow();
     dr["cID"] = "2";
     dttemp.Rows.Add(dr);
 }
}

Class A
{

DataTable dttemp;
string data = "";
bool isValid = false;

void CallingFunction()
{    
    dttemp = new DataTable();    
    checkValue();

    //perform some operation

    //reset them
    data = "";isValid = false; dttemp.Dispose();
}

private void checkValue()
{
     data += "Some data";
     isValid = true;

     DataRow dr = dttemp.NewRow();
     dr["cID"] = "2";
     dttemp.Rows.Add(dr);
 }
}

class __declspec(dllexport) MyClass
{
public:
 MyClass(void);
~MyClass(void);
 void GetName()
 {
   .......
 }
};

_declspec(dllexport) void MyFun()
{

}

public partial class Form1 : Form
 {
     [DllImport("CPPDLL.dll", EntryPoint="MyFun")]
     static extern void MyFun();

     [DllImport("CPPDLL.dll", EntryPoint="MyClass")]
     static class MyClass;

     public Form1()
     {
         InitializeComponent();

     }
 }