Thanks for your help. This is work for me. Final solution as like these;

public class myObject
{
    public List<ChildObject> subObject = new List<ChildObject> { };

    public string ObjectName { get; set; }

    public class ChildObject
    {
        public string ChildObjectName { get; set; }
        public MemoryStream ChildStream { get; set; }

        public ChildObject()
        {
            ChildStream = new MemoryStream();
        }
        ~ChildObject()
        {
            ChildStream.Dispose();
        }
    }
}

Impressive ;) Is it possible to auto create this MemoryStream in my subClass's constructor? When I Create following...

MyObj.subObject.Add(new myObject.ChildObject());

I want to use this MemoryStream directly. Thanks

I've object and it has a lot of objects :-\ When I access Childobjects everything is ok but not MemoryStreams;

public class myObject
{
public List<ChildObject> subObject = new List<ChildObject> { };

    public string ObjectName { get; set; }

    public class ChildObject
    {
        public string ChildObjectName { get; set; }
        public MemoryStream ChildStream { get; set; }
    }
}

When I use this object I am using following code;

// This is OK
MemoryStream myMS = new MemoryStream();
myMS.Position = 0;
// End of This is OK
//
myObject MyObj = new myObject();
MyObj.ObjectName = "My First Object";
MyObj.subObject.Add(new myObject.ChildObject());
MyObj.subObject[0].ChildObjectName = "My First Sub Object";
MyObj.subObject[0].ChildStream.Position = 0; // :mad:ERROR LINE

Thanks for your reply. :rolleyes:

I am the new about class and objects in c#. I just want to define an object for this issue after than I will save and restore from a file this ExamFile.

ExamFile.Title = "Test Exam File";
ExamFile.FileName = "my First Exam.mfe";

ExamFile.Exam[0].ExamName = "This is my First Exam";
ExamFile.Exam[1].ExamName = "This is my Second Exam";

ExamFile.Exam[0].Question[0].Remark = "First Exam's first Q";
ExamFile.Exam[0].Question[0].Type = "Multiple";
ExamFile.Exam[0].Question[1].Remark = "First Exam's Second Q"
ExamFile.Exam[0].Question[1].Type = "Single";

ExamFile.Exam[1].Question[0].Remark = "Second Exam's First Q";
ExamFile.Exam[1].Question[0].Type = "Multiple";

Thanks