Copy Object

Question

I have List-control of objects.

I want find a certain object and save it away for later use.

To do this, I used a foreach-loop and tried to copy the object I found into a new object-variable.

Something like:

Book temporary = null; //Reference to Book-object

foreach (Book B in BookList)
if (txtBox1.Text.Equals(B.ID.ToString()))
temporary = B;

But that doesn´t seem to work.

How can I do this?

Vulpes · Answer

OK but if temporary is still null then that can only mean that this condition is never satisfied: if (txtBox1.Text.Equals(B.ID.ToString())) Notice that for the Equals() method to work txtBox1.Text and B.ID.ToString() must be identical. In particular capitalization should be the same and so should spacing.

Lars Persson · Answer

You were right Vulpes. Was so sure that the condition was met. It clearly wasn´t. Without the condition it works. Thanks!

Lars Persson · Answer

Well this is how it was done in an old project in Java and I was trying to do the same thing in C#. I create a Book-object which points to null; I then go through the List to find the book that corresponds to what ever I write in txtBox1. When I found the right object I want to save it (or rather the referens to it I suppose) so I can use it. When I do this it seems like temporary still points to null. So I guess that getting the reference to the right Book-object is what I want. Not make a clone of it. What I'm trying to do is find a Book-object in the BookList find a Customer-object in the CustomerList and then register the loan.

Sam Hobbs · Answer

What do you mean by doesn´t seem to work?

Vulpes · Answer

Well what you're doing just now is saving a reference to the same Book object that's in the List to the 'temporary' variable. So if you were to change the properties of this object via the temporary variable it would also change the properties of the Book in the List as they're the same object. If you want to create an independent copy of the object (i.e. clone it) then you need to write code to do that in the Book class itself.