notes

assignment 4:
due next monday, Oct 11

assignment 5:
due wednesday, Oct 13

String data type
collection of character

4 is an integer literal
"today" is a string literal

today in the example is a string variable

Primitive types vs Reference types

A Double, Integer, Boolean are primitive types

A String is a reference type, starts with Nothing (equivalent to NULL). when assign a string value to it, it points to that value on the heap.

If it is nothing and you try to use it, you will get a NullReferenceException

"" is the empty string. it is not Nothing

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

        Dim today As String
        today = ""

        With lstOutput.Items
            .Clear()
            .Add(today.Length)
            .Add("today")
            .Add(today)
        End With

    End Sub

        If today IsNot Nothing Then

        End If

What is an exception? Why should I use it?

instead of:
step 1
check for errors and fix
step 2
check for errors and fix
step 3
check for errors and fix
step 4
check for errors and fix

        Try
            step 1
            step 2
            step 3
            step 4
        Catch ex As Exception
            attempt to fix the problem
        End Try