How to find and highlight next instance of word in richtextbox in visual basic? - vba

Question

Here is the visual basic windows application form I am currently working on.
https://i.snag.gy/EzoXr3.jpg
How can I write code for the find next button like in this video.
https://www.dropbox.com/s/u93h9jn605uhwsu/CPT341Project2Walkthrough.avi?dl=0
If I can get a syntax to store a index variable outside the private sub of findnext button, I can solve the problem. Because everytime I click the findnext button, I have to find the respective instance of that word in the filetext. Or I can apply some code to find it in the substring of remaining text after its first occurrence.
Below is my code:
Public Class Form1
'Enter your name
'Date
'Class - CPT 341 VB.NET NJIT
Private Sub openBtn_Click(sender As Object, e As EventArgs) Handles openBtn.Click
If OpenFileDialog.ShowDialog <> Windows.Forms.DialogResult.Cancel Then
fileText.Text = My.Computer.FileSystem.ReadAllText(OpenFileDialog.FileName)
End If
End Sub
Private Sub btnSearch_Click(sender As Object, e As EventArgs) Handles btnSearch.Click
'Bring the form to the inital state for a different search
Dim temp As String = fileText.Text
fileText.Text = temp
outputIndex.ForeColor = Color.Black
'MessageBox to show error for empty search textbox
If inputText.Text = "" Then
MessageBox.Show("Enter Text to Search", "CPT 341 Fall 2018 - Project 2")
Else
'Declare variables
Dim txt As String : Dim x As Integer = 0 : Dim output As String
txt = inputText.Text
If fileText.Text.IndexOf(txt) <> -1 Then
Dim idx As Integer = CStr(fileText.Text.IndexOf(txt))
outputIndex.Text = idx
'Find and highlight the first word searched in the RichTextBox
fileText.Find(txt, x, fileText.TextLength, RichTextBoxFinds.None)
fileText.SelectionBackColor = Color.Yellow
'populate the string with ANSI numbers
output = Asc(txt(0))
For x = 1 To (txt.Length - 1)
output = output & " " & Asc(txt(x))
Next x
outputANSI.Text = output
ElseIf fileText.Text = "" Then
MessageBox.Show("Please open a file to search from", "CPT 341 Fall 2018 - Project 2")
Else
outputIndex.Text = txt & " is not found"
'Bring the form to inital state
fileText.Text = temp
'Change the index textbox text color to red
outputIndex.ForeColor = Color.Red
'Empty the ANSI textbox
outputANSI.Text = ""
End If
End If
End Sub
Private Sub btnFind_Click(sender As Object, e As EventArgs) Handles btnFind.Click
Dim txt As String = inputText.Text
Dim Index As Integer = fileText.Text.IndexOf(txt) + txt.Length
'Find and highlight the word searched in the RichTextBox other than first occurrence
fileText.Find(txt, Index, fileText.TextLength, RichTextBoxFinds.None)
fileText.SelectionBackColor = Color.Yellow
Index = fileText.Text.IndexOf(txt, Index) + txt.Length + 1
End Sub
Private Sub btnWords_Click(sender As Object, e As EventArgs) Handles btnWords.Click
wordCount.Text = fileText.Text.Split(" ").Length
End Sub
Private Sub btnChars_Click(sender As Object, e As EventArgs) Handles btnChars.Click
charCount.Text = fileText.Text.Length
End Sub
End Class
Or any other suggestion would be helpful.