In C# if an object in a list is added to another list, does changing the object in the second list change the same object in the first list?
c#, list, object, reference-type
Solution
When you have a list of objects that are reference types and not value types, that is stored in the list is a reference for each object in the list. Hence if you add the same object to two different lists, you actually add to the second list the same reference. Hence if you make any change in the object, this would be "visible" from both lists.
Problem
Say I have a list of `Person` objects (`List<Person>`) called `persons`, like this: ``` class Person { public int PersonId { get; set; } // Unique ID for the person loaded from database public string Name { get; set; } } // In a different class public List<Person> Persons = new List<Person>(); // Person objects are subsequently added to the list ``` and then I select some of the `Person` objects from the list, sort them by a property (e.g. by each person's unique ID `PersonId`), and add these selected `Person` objects to another list called `selectedPersons`. I now need to edit the properties of a `Person` object that is in `selectedPersons`, but these changes need to be made to the original copy of this `Person` object in `persons`. I currently only know the index of this person in the `selectedPersons` list, so can I simply edit the person in the `selectedPersons` list and have the changes made to that person reflected in the original `persons` list, like this: ``` selectedPersons[selectedPersonIndex].Name = "John"; ``` or do I have to edit the original `Person` object in the `persons` list by first finding the index of the person the `persons` list using the person's ID, like this: ``` persons[FindPersonIndexById(selectedPersons[selectedPersonIndex].BookingId).Name = "John"; ``` where `FindPersonIndexById` returns the index of the person in `persons` whose ID matches the ID given. I know lists are reference types in C#, but, when objects from one list are added to another list, I wasn't sure whether changes made to objects in the second list are automatically made to the same objects in the first list.