Using lists rather than an array to create objects in a class

Question

I have just started to learn about OOP and I am wondering if it is possible to create objects using a list rather than an array. The list seems to have oodles of methods that are really useful and can be of an indeterminate length So, this is what I have

Class STUDENT
    'establish properties / members
    Public firstname As String
    Public surname As String
    Public DOB As Date
End Class

'declare a variable of the data type above to put aside memory
Dim students As List(Of STUDENT)

Sub Main()
    Dim selection As Char
    While selection <> "C"
        Console.WriteLine("Welcome to student database")
        Console.WriteLine("Number of students: " & students.Count)
        Console.WriteLine(" (A) Add a student")
        Console.WriteLine(" (B) View a student")
        Console.WriteLine(" (C) Quit")

        selection = Console.ReadLine.ToUpper

        If selection = "A" Then
            Console.Write("Please enter a firstname: ")
            students.firstname.add= Console.ReadLine
...etc
END While

This line is causing a problem

students.firstname.add= Console.ReadLine

I don't think this is how you would add an object using the list I set up. So how is it done?? Will the syntax need adjusting to add more than one item?

**[Five Minute Intro to Classes and Lists](http://stackoverflow.com/a/34164458/1070452)** may be helpful. I'd use properties not fields in the class: `Public Property firstname As String`. Fields dont work the same as properties when it comes to binding — Ňɏssa Pøngjǣrdenlarp, Jun 28 '16 at 14:15
Strictly speaking, a list is not of *indeterminate* length: you can determine the number of elements with [`list.Count()`](https://msdn.microsoft.com/en-us/library/27b47ht3(v=vs.110).aspx). A list has an automatically adjusted size. — Andrew Morton, Jun 28 '16 at 17:14

score 3 · Accepted Answer · answered Jun 28 '16 at 14:24

There are multiple issues with this line: students.firstname.add= Console.ReadLine

Breaking it down we have:

students.firstname.add and add = Console.ReadLine

You need a student object first. students.firstname doesn't exist.

Dim tempStudent = New STUDENT()
tempStudent.firstname = Console.ReadLine()
' Other property assignments, etc

Once you have fully created your student object, you then add it to the list. Add is a method so we use parentheses:

students.Add(tempStudent)

Besides that there are a few casing errors which you should address.

Ah, I see. Thanks. Feel like I have the tools to really experiment now — MissDizy, Jun 28 '16 at 17:12

Using lists rather than an array to create objects in a class

1 Answers1