C# Language Value type vs Reference type Changing values elsewhere
Example
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;
}
}
