functions highlights the letter F and U

These two functions highlights the letter F and U.
highlight_F()
highlight_U()

They work perfectly individually. When I run them in sequence, I get the following inconsistent results. What is wrong with my code?

$30.85 FU <-- U gets highlighted blue (correct)

| $30.80 F | $30.85 FU | $30.85 F | $30.90 F | $31.00 F | $31.00 F | $31.50 F | $31.50 F | $31.50 F | $31.50 F | $22.48 +$4.99 (27.47) | $24.19 +$4.99 (29.18) | $25.00 +$4.99 (29.99) | $25.00 +$4.99 (29.99) | $25.60 +$4.99 (30.59) | $26.00 +$4.62 (30.62) | $27.00 +$4.99 (31.99) | $28.00 +$4.99 (32.99) | $29.99 +$4.62 (34.61) | $29.99 +$4.99 (34.98)

$37.99 F <-- F gets highlighted blue (incorrect)

| $33.50 F | $30.98 +$4.99 (35.97) | $30.99 +$4.99 (35.98) | $31.99 +$4.60 (36.59) | $37.99 F | $39.99 +$4.99 (44.98) | $25.99 +$5.99 (31.98) | $28.99 +$4.57 (33.56) | $29.99 +$4.99 (34.98) | $30.00 +$4.99 (34.99) | $32.23 +$4.99 (37.22) | $34.99 +$4.99 (39.98) | $37.95 +$4.99 (42.94) | $38.00 +$4.99 (42.99) | $39.99 +$4.99 (44.98) | $40.00 +$4.99 (44.99)

Public Function highlight_F()
RichTextBox1.SelectAll()
RichTextBox1.SelectionColor = Color.Black
RichTextBox1.SelectionBackColor = Color.White
RichTextBox1.DeselectAll()

Dim FoundAtPosition As Integer
FoundAtPosition = RichTextBox1.Find("F")
RichTextBox1.SelectionColor = Color.Red
RichTextBox1.SelectionFont = New Font("Arial", 12, FontStyle.Bold)

Do Until FoundAtPosition < 0
RichTextBox1.SelectionColor = Color.Red
RichTextBox1.SelectionFont = New Font("Arial", 12, FontStyle.Bold)

If FoundAtPosition + 1 < RichTextBox1.Text.Length Then
FoundAtPosition = RichTextBox1.Find("F", FoundAtPosition + 1, RichTextBoxFinds.None)
Else
FoundAtPosition = -1
End If
Loop

End Function

Public Function highlight_U()

Dim FoundAtPosition As Integer
FoundAtPosition = RichTextBox1.Find("U")
RichTextBox1.SelectionColor = Color.Blue
RichTextBox1.SelectionFont = New Font("Arial", 14, FontStyle.Bold)

Do Until FoundAtPosition < 0
RichTextBox1.SelectionColor = Color.Blue
RichTextBox1.SelectionFont = New Font("Arial", 14, FontStyle.Bold)

If FoundAtPosition + 1 < RichTextBox1.Text.Length Then
FoundAtPosition = RichTextBox1.Find("U", FoundAtPosition + 1, RichTextBoxFinds.None)
Else
FoundAtPosition = -1
End If
Loop

End Function

When you post, could you please wrap any code in [CODE]Your code goes here[/CODE] tags or [HIGHLIGHT=VB.NET]Your code goes here[/HIGHLIGHT] tags. It makes it much easier to read and therefore more likely that someone will read it and answer your questions.

You had me confused there. I couldn't replicate your problem until I realised that the text example you supplied are four separate examples, not a single block of text from the rtb.

The problem is that the highlight methods leave the rtb's SelectionStart, SelectionLength and SelectionColor properties set to the last highlighted letter. So for $37.99 F they have the values 7, 1, Color.Red, i.e. all pointing to the F. This would not normally be a problem, as they will be cleared when you click in the rtb.

However, you immediately call the highlight_U function. The first four lines of code in that are:

Code:

---

Dim FoundAtPosition As Integer
FoundAtPosition = RichTextBox1.Find("U")
RichTextBox1.SelectionColor = Color.Blue
RichTextBox1.SelectionFont = New Font("Arial", 14, FontStyle.Bold)

---

As there is no "U", the Find method will return -1 and apparently not change the values of the SelectionStart, SelectionLength and SelectionColor properties. So your code will then set the "F"'s colour to Blue, as it is the text that the above properties are still referring to.

A simple solution is to change

Code:

---

Dim FoundAtPosition As Integer
FoundAtPosition = RichTextBox1.Find("U")
RichTextBox1.SelectionColor = Color.Blue
RichTextBox1.SelectionFont = New Font("Arial", 14, FontStyle.Bold)

---

in both methods to (using ("F") where appropriate, of course)

Code:

---

Dim FoundAtPosition As Integer
FoundAtPosition = RichTextBox1.Find("U")

---

That said, I'd recommend you change your code somewhat. You are using Functions but never return a value, so you should instead be using Subs. You also have a lot of repeated code that could be tidied up and made more versatile. I'd suggest something along the lines of:

Code:

---

Private Sub ResetTextColour()
    RichTextBox1.SelectAll()
    RichTextBox1.SelectionColor = Color.Black
    RichTextBox1.SelectionBackColor = Color.White
    RichTextBox1.DeselectAll()
End Sub

Private Sub Highlight(searchText As String, highlightFont As Font, highlightColour As Color)
    Dim foundAtPosition As Integer = -1
    Dim startAtPosition As Integer = 0

    foundAtPosition = RichTextBox1.Find(searchText, RichTextBoxFinds.None)

    Do Until startAtPosition > foundAtPosition
        RichTextBox1.SelectionColor = highlightColour
        RichTextBox1.SelectionFont = highlightFont

        startAtPosition = foundAtPosition + searchText.Length
        foundAtPosition = RichTextBox1.Find(searchText, startAtPosition, RichTextBoxFinds.None)
    Loop

End Sub

---

which you would use as:

Code:

---

ResetTextColour()
Highlight("F", New Font("Arial", 14, FontStyle.Bold), Color.Red)
Highlight("U", New Font("Arial", 14, FontStyle.Bold), Color.Blue)

---

Note I set the access levels for the methods to Private. If you actually need Public access, then don't forget to change the modifiers back to Public.