Question

The following code is supposed to show in a message box the index of the third a in the string checkme, but when I run the program it doesn’t give me the right answer (should be 12, instead I get 9). What am I doing wrong and how would I go about making it work?

Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click     Dim checkme As String = 'thais is a sample sentence a'     Dim indexnum As Integer     indexnum = checkme.IndexOf('a', checkme.IndexOf('a') + 3)     MessageBox.Show(CStr(indexnum)) End Sub 

Option Explicit and Strict must be On. Thanks in advance.

Answer 1

You’re only finding the second ‘a’. Try using a loop like so.

Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click     Dim checkme As String = 'thais is a sample sentence a'     Dim indexnum As Integer = -1     For i As Integer = 1 To 3         indexnum = checkme.IndexOf('a', indexnum + 1)     Next     MessageBox.Show(CStr(indexnum)) End Sub