Do..While...Loop - vb.net

Question

My study book makes the following statement about the code below:
**"The computer evaluates the loop condition in the Do...Loop statment to determine whether the loop instructions should be processed. In this case, the inputsales <> String.Empty condition compares the contenst of the input sales variable to the String.Empty value. As you know the String.Empty value represents a zero length, or empty, string if the inputsales variable is empty, the loop condition evaluates to True and the computer process the loop instructions. *If on the other hand the inputsales variable is not empty, the loop condition evaluates to false and the computer skips over the loop instructions.
Based on the code I think it is the opposite: ...that while the inputsales value is not empty it should evaluate to true and process the loop and if it is empty it should evaluate to false and skip the loop? Please see below. Thanks so much for the help!
Option Explicit On
Option Strict On
Imports System.Globalization
Public Class SalesForm
Private Sub exitButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles exitButton.Click
Me.Close()
End Sub
Private Sub calcButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles calcButton.Click
Const prompt As String = "Enter a sales amount. Click cancel to end."
Const title As String = "Sales Entry"
Dim inputsales As String
Dim sales As Decimal
Dim salesCounter As Integer
Dim salesaccumulator As Decimal
Dim salesAverage As Decimal
Dim isconverted As Boolean
inputsales = InputBox(prompt, title, "0")
**Do While inputsales <> String.Empty
isconverted = Decimal.TryParse(inputsales, NumberStyles.Currency, NumberFormatInfo.CurrentInfo, sales)
If isconverted = True Then
salesCounter = salesCounter + 1
salesaccumulator = salesaccumulator + sales
Else
MessageBox.Show("Please re-entere the sales amount.", "sales Express", MessageBoxButtons.OK, MessageBoxIcon.Information)
End If
inputsales = InputBox(prompt, title, "0")
Loop**
If salesCounter > 0 Then
salesAverage = salesaccumulator / Convert.ToDecimal(salesCounter)
averageLabel.Text = salesAverage.ToString("C2")
Label2.Text = salesCounter.ToString
Else
averageLabel.Text = "0"
End If
End Sub
End Class

Answer 1

You are definitely correct, and the book is wrong (hopefully, the author just reversed the true/false by accident; otherwise, I'd get another book). My suggested correction (with a few additions):
As you know, the String.Empty value represents a zero length, or empty, string. If the inputsales variable is not empty, the loop condition evaluates to True, and the computer processes the loop instructions (and then jumps back to the top of the loop and reevaluates the condition). If, on the other hand, the inputsales variable is empty, the loop condition evaluates to False, and the computer skips over the loop instructions (and continues with the first statement after the loop).
As #xanatos said: Congratulations on catching your first bug in someone else's text. So +1 for the question, and I'd say that this seems promising for your programming career. :-)

Answer 2

Yes, you are correct. The loop will be executed when inputsales is non-empty. The description is wrong.