How do I search through a string and replace specific words dynamically?

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I am working on replacing words in a text before showing all text in a richtextbox. The issue I am having is that the code seems to be reiterating through the loop, instead of a bulk text replacement.

here is my code:

text file path connection string
sql connection with using select * to fill datata table(repdt)

For Each textpath As String In Files.FileNames

           RichTextBox1.Clear()

           Dim newline = String.Empty
           Dim regstr = String.Empty

           For I As Integer = 0 To repdt.Rows.Count - 1
               For Each line As String In File.ReadLines(textpath)
                   If line.Contains(repdt.Rows(I).Item("originaltext").ToString) Then
                       newline = line.Replace(repdt.Rows(I).Item("originaltext"), repdt.Rows(I).Item("replacementtext"))
                         regstr = String.Join(Environment.NewLine, line.Split(New Char() {ControlChars.Lf}, StringSplitOptions.RemoveEmptyEntries)).Replace(vbTab, "")

                       RichTextBox1.Text += newline + Environment.NewLine
                   End If
               Next
           Next

I am trying to make this into a library or text to replace.

What I have tried:

Initially, I was using this:

For Each textpath As String In Files.FileNames
           RichTextBox1.Clear()

           Dim regstr As String = String.Join(Environment.NewLine, System.IO.File.ReadAllText(textpath).Split(New Char() {ControlChars.Lf}, StringSplitOptions.RemoveEmptyEntries))

           Dim replacestr As String = regstr.Replace("text", "text").Replace("text", "text").Replace("text", "text"). 'etc

           RichTextBox1.Text = replacestr
       Next

however, this requires coding everytime I want to replace something.

Posted 9-Sep-18 12:13pm

Member 11856456

Updated 10-Sep-18 8:30am

v2

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Comments

Ralf Meier 10-Sep-18 9:51am

From where does the replace-string-parts come from ?
If you want to have a library-method - how do you want to tell it what it should do ?

Member 11856456 10-Sep-18 10:29am

it compares what I have in my datatable to the lines of the document. What I would like to do is have a way to use the database information and have it fill in the .replace method.

I just dont know how to make the code look like this:
regstr.Replace("text", "text").Replace("text", "text").Replace("text", "text"). 'etc

where it automatically will add the .Replace("text", "text") for every datatable entry that matche.

Ralf Meier 10-Sep-18 14:04pm

I understand ...
What I suggest is : you make a method (function) to which you give the source-string and also the replacements (for example as a List or an Array).
Inside your method you look for the size of the Array (it's length) and iterate through it and do your replacements item by item.
If you build up a combined command like in your code-sample (replacestr = regstr.Replace("text", "text").Replace("text", "text").Replace("text", "text")) it will also do the replacements step by step (but in this case ordered by the compiler).

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Alek Massey · Accepted Answer · 2018-09-10T08:31:00

Here's my take on it.

C#

For Each textpath As String In Files.FileNames

           RichTextBox1.Clear()

           Dim newline = String.Empty
           Dim regstr = String.Empty

           //Process each line in the file once
           For Each line As String In File.ReadLines(textpath)
              newline = line
              //apply each replacement rule to the result of the previous replacement rule
              For I As Integer = 0 To repdt.Rows.Count - 1
                  If newline.Contains(repdt.Rows(I).Item("originaltext").ToString) Then
                       newline = newline.Replace(repdt.Rows(I).Item("originaltext"), repdt.Rows(I).Item("replacementtext"))
                  
                  //hold over code?
                  //regstr = String.Join(Environment.NewLine, newline.Split(New Char() {ControlChars.Lf}, StringSplitOptions.RemoveEmptyEntries)).Replace(vbTab, "")


                   End If
               Next
               //remove linefeeds and tabs
               newline=newline.Replace(Environment.NewLine,"").Replace(vbTab, "")
               //after all rules, add final result to the textbox
               if newline.TrimEnd().Length>0 then
                   RichTextBox1.Text += newline + Environment.NewLine
               end if
           Next