Hi i want to cast the Parent object to Child object in C#
public class Parent
{
public string FirstName {get; set;}
public string LastName {get; set;
You may use reflection as well, but this is simpler for your case.
foreach(var obj in lstParent)
{
Child child = new Child(){ FirstName = obj.FirstName, LastName=obj.LastName, City = obj.City};
child.MobileNumber = "some mobile number";
child.PhoneNumber = "some phone number";
lstChild.Add((Child)obj);
}