Changing values elsewhere

suggest change

public static void Main(string[] args)
{
  var studentList = new List<Student>();
  studentList.Add(new Student("Scott", "Nuke"));
  studentList.Add(new Student("Vincent", "King"));
  studentList.Add(new Student("Craig", "Bertt"));

  // make a separate list to print out later
  var printingList = studentList; // this is a new list object, but holding the same student objects inside it

  // oops, we've noticed typos in the names, so we fix those
  studentList[0].LastName = "Duke";
  studentList[1].LastName = "Kong";
  studentList[2].LastName = "Brett";

  // okay, we now print the list
  PrintPrintingList(printingList);
}

private static void PrintPrintingList(List<Student> students)
{
  foreach (Student student in students)
  {
      Console.WriteLine(string.Format("{0} {1}", student.FirstName, student.LastName));
  }
}

You’ll notice that even though the printingList list was made before the corrections to student names after the typos, the PrintPrintingList method still prints out the corrected names:

Scott Duke
Vincent Kong
Craig Brett

This is because both lists hold a list of references to the same students. SO changing the underlying student object propogates to usages by either list.

Here’s what the student class would look like.

public class Student
{
    public string FirstName { get; set; }
    public string LastName { get; set; }

    public Student(string firstName, string lastName)
    {
        this.FirstName = firstName;
        this.LastName = lastName;
    }
}

Found a mistake? Have a question or improvement idea? Let me know.

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