throw error msgs when two appointments are at the same time

Hello experts,

                     I need to create an application in VB .Net where the user will enter the reason to their appointment in a textbox and the time from a combo box. Upon entering the info and selecting a time, they enter these information through a button click event. I have two listbox where the first one stores the reason for the appointment and the second one stores the time. Now, I don't want them to enter two appointments at the same time. If they do so, I want to throw an error message saying "The appointment at this time already exists. Any help??

This is what I tried so far:

Under button1_Click event
{
     lstAppointment.Items.Add(txtAppointment.Text)
     lsttime.Items.Add(cboTimeInput.SelectedValue)
}

But i don't know know how would I check to throw an error message if they have two appointments at the same time.
siddhuoopsAsked:
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Babycorn-StarfishCommented:
Hi there,

you can try searching the Items property of the listbox by using the contains method. In this case if it contains the item you don't want it to be added and a message appears:

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
       'see if the item is already listed
        If TimeList.Items.Contains(TimesCombo.SelectedItem) Then
            MessageBox.Show("Some kind of error message")            
        Else
            TimeList.Items.Add(TimesCombo.SelectedItem)
            'other stuff added
        End If

hope this helps
    End Sub
0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Visual Basic.NET

From novice to tech pro — start learning today.