Highlight text in a richtextbox in windows forms - vb.net

Question

How to make when i type in a RichTextBox a certain word it gets highlited?
how do i find words in the text to use SelectionColor or SelectionFont
For example: i want that all times that the word "hello" appear in the RichTextBox it turn to bold or turn into a color...
Then if i open my program and type "hello, how are you?" the word hello turns into bold... any idea? (my idea is to make a text editor with syntax highlight that ill specify the words)
(sorry if there is another question like that, i tried to search but i didn't find a answer that helped me)
its windows forms, visual basic

Answer 1

This code should do the work:
Dim searchstring As String = "hello"
' The word you're looking for
Dim count As New List(Of Integer)()
For i As Integer = 0 To richTextBox1.Text.Length - 1
If richTextBox1.Text.IndexOf(searchstring, i) <> -1 Then
'If the word is found
'Add the index to the list
count.Add(richTextBox1.Text.IndexOf(searchstring, i))
End If
Next
Try
For i As Integer = 0 To count.Count - 1
richTextBox1.[Select](count(i), searchstring.Length)
richTextBox1.SelectionFont = New Font(richTextBox1.Font, FontStyle.Bold)
count.RemoveAt(i)
Next
Catch
End Try
richTextBox1.[Select](richTextBox1.Text.Length, 0)
richTextBox1.SelectionFont = New Font(richTextBox1.Font, FontStyle.Regula
For each index select the text and make it bold.
Now add this code to the TextChanged-Event to check any time the text changed for your word.

Answer 2

I got it in a different way:
While Not RichTextBox1.Text.IndexOf("hello", startIndex) = -1
selectedIndex= RichTextBox1.SelectionStart
Try
RichTextBox1.Select(RichTextBox1.Text.IndexOf("test", startIndex) - 1, 1)
Catch
End Try
If RichTextBox1.SelectedText = " " Or RichTextBox1.SelectedText = Nothing Then
RichTextBox1.Select(RichTextBox1.Text.IndexOf("hello", startIndex) + "test".Length, 1)
If RichTextBox1.SelectedText = " " Or RichTextBox1.SelectedText = Nothing Then
RichTextBox1.Select(RichTextBox1.Text.IndexOf("hello", startIndex), "test".Length)
RichTextBox1.SelectionColor = Color.Blue
End If
End If
startIndex = RichTextBox1.Text.IndexOf("hello", startIndex) + "hello".Length
RichTextBox1.SelectionStart = selectedIndex
RichTextBox1.SelectionLength = 0
RichTextBox1.SelectionColor = Color.Black
End While
I don't know if it is the best way, but works.

Answer 3

That is a code for highlighting selected text at yellow (can be replaced by any other color), after finding it:
'find the text that need to be highlighted.
foundIndex = RichTextBox1.Find("hello", foundIndex + 1, -1, selectedFinds)
RichTextBox1.Focus()
If foundIndex = -1 Then
MessageBox.Show("This document don't contains the text you typed, or any of the text you typed as a whole word or mach case.", "Find Text Error", MessageBoxButtons.OK, MessageBoxIcon.Asterisk)
else
'now the text will be highlighted.
RichTextBox1.SelectionBackColor = Color.Yellow
Richtextbox1.focus
End If
I hope that code will help.

Answer 4

Private Sub RichTextBox1_DragOver(sender As Object, e As DragEventArgs) Handles RichTextBox1.DragOver
Dim p As Point
p.X = e.X
p.Y = e.Y
Dim num As Integer
Dim rightTXT As String
Dim leftTXT As String
Dim textpart As String
Dim TSelect As Boolean
Dim curpos As Integer = RichTextBox1.GetCharIndexFromPosition(RichTextBox1.PointToClient(p))
Dim PosStart As Integer
TSelect = False
If e.Data.GetDataPresent(DataFormats.StringFormat) Then
e.Effect = DragDropEffects.All
Try
leftTXT = Microsoft.VisualBasic.Left(RichTextBox1.Text, curpos)
If InStr(leftTXT, "%", CompareMethod.Text) Then
rightTXT = Microsoft.VisualBasic.Right(RichTextBox1.Text, Len(RichTextBox1.Text) - curpos)
If InStr(rightTXT, "%", CompareMethod.Text) Then
PosStart = curpos - InStr(StrReverse(leftTXT), "%") + 1
num = curpos + InStr(rightTXT, "%") - PosStart - 1
textpart = (RichTextBox1.Text.Substring(PosStart, num).TrimEnd)
Label3.Text = "mouse drag over:" + textpart
Label5.Text = num.ToString()
If ListBox1.Items.Contains(textpart) Then
TSelect = True
End If
End If
End If
Catch ex As Exception
Label4.Text = ex.ToString()
End Try
End If
If TSelect Then
Me.RichTextBox1.Select(PosStart - 1, num + 2)
wordSearch = RichTextBox1.SelectedText
Label4.Text = "word drag state: true"
match = True
Else
Label3.Text = "mouse drag over:"
Label4.Text = "word drag state: false"
Me.RichTextBox1.Select(0, 0)
End If
End Sub

Answer 5

I find the above codes to be too lengthy/complicated for a simple task...
Dim c As Integer = 0
Dim o As Integer = 0
Dim s As Integer = 0
Dim txt As String = RTB.Text
RTB.BackColor = Color.Black
Dim starts As Integer = 0
Do While txt.Contains(key) ' this avoids unnecessary loops
s = txt.IndexOf(key)
starts = s + o
RTB.Select(starts, key.Length)
RTB.SelectionBackColor = Color.Yellow
RTB.SelectionColor = Color.Blue
txt = txt.Substring(s + key.Length)
o += (s + key.Length)
c += 1
Loop
Me.Status.Text = c.ToString() & " found" ' and the number found