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RTF text font/color changing [duplicate]

I want to create a simple editor like Notepad++ with simple functionality... I need to color a specific word in the rich text box area. How can I do that?
For example: when the user write these word, I want to color them to the blue color. These words are: for, while, if, try, etc.
How can I make the richtextbox to select a specific word and then color them?
And, if I want to make a comment and color everything after the //, how is that done in the richtextbox?
How do I number the line in the text box, so I can now the line number when I'm coding in my editor?

Here's some code you can build on in order to achieve the functionality you want.
private void ColourRrbText(RichTextBox rtb)
{
Regex regExp = new Regex("\b(For|Next|If|Then)\b");
foreach (Match match in regExp.Matches(rtb.Text))
{
rtb.Select(match.Index, match.Length);
rtb.SelectionColor = Color.Blue;
}
}
The CodeProject article Enabling syntax highlighting in a RichTextBox shows how to use RegEx in a RichTextBox to perform syntax highlighting. Specifically, look at the SyntaxRichtTextBox.cs for the implementation.

In general, you have to work on the selection in RichTextBox. You can manipulate the current selection using the Find method or using SelectionStart and SelectionLength properties. Then you can change properties of selected text using SelectionXXX properties. For example, SelectionColor would set the color of current selection, etc. So you have to parse text in richtextbox and then select part of texts and change their properties as per your requirements.
Writing a good text editor using RichTextBox can be quite cumbersome. You should use some library such as Scintilla for that. Have a look at ScintillaNet, a .NET wrapper over Scintilla.

Did you know that Notepad++ uses Scintilla?
You actually do not have to reinvent the wheel by going through all the trouble as there is a .NET port of Scintilla named ScintillaNET which you can freely embed in your application as the source code editor :)
But to answer your question, there are few parts that you need to understand
Finding what to color
When to color
How to color
For the first part, there may be different approaches, but I think using regular expressions would be a good choice. I am sorry, but I don't know regular expressions much so I cannot help you in that case.
When to color is very crucial and if you do it wrong, your application will suffer a heavy performance penalty. I suggest you refer to XPath Visualizer which was done by our own Stack Overflow member, Cheeso. Take a look at the source on how the coloring of the syntax was done. But if you ScintillaNET, everything would be taken care of. Anyway, I really can't seem to find this documentation where he clearly showed how the coloring of the text was done. I would most definitely post it here if I find it.
The third question I think is covered by VinayC. But basically you use SelectionColor along with SelectionStart.

here is a good link on c-sharpcorner.com website on basic richtextbox syntax highlighting. I assume that you and any one visiting this page for similar problem want to do it for learning purpose. But if any one wants to do it for some making some comercial level IDE then it must use scintilla or some similar.
An other approach for this is to directly change the RTF of the richtextbox. Look in codeproject.com there are lot of articles similar to this problem.

I had some problems with that and here is my solution, beats me why it has to be done like this, but it works:
// position on end of control...
richTextBox.UpdateLayout();
richTextBox.ScrollToEnd();
richTextBox.UpdateLayout();
// ...then select text and it will be position on top of control.
richTextBox.Focus();
richTextBox.Selection.Select(foundRange.Start, foundRange.End);
richTextBox.BringIntoView();

Vb.net implementation
Imports System.Text.RegularExpressions
Private Sub formatString()
Dim rg =New Regex("\b(for|while|if|try)\b")
Dim m As Match
For Each m In rg.Matches(RichTextBox1.Text)
RichTextBox1.Select(m.Index,m.Length)
RichTextBox1.SelectionColor=Color.Green
Next
End Sub

Get the correct character/string from the ones formatted in a wrong font?

I don't really know what kind of this task to call. For some characters/string, if you display them in a TextBox with some font (I call it Font 1), it displays them correctly. But if you change the font of TextBox to another one (I call it Font 2), the character/strings may be displayed wrong (wrong font). What I want is how to convert those characters/string (as displayed in Font 2) to some corresponding characters/string/values (as displayed in Font 1). I have to do this because in my language, there are not any character like the ones displayed in Font 2.
To make it clearer, for example:
I've encountered a case in which the correct character was 'ă', however there was another 'expression' like '¨' which will be displayed exactly as 'ă' in Font 1, however in Font 2, it's displayed as '¨'. '¨' is not a character/letter in my language alphabet. It looks like that this is related to Font issue. This is like a problem with Input and Output:
Input: The weird/wrong character (like as '¨') and the Font in which that weird/wrong character displays correctly (like as 'ă'). That Font is Font 1 as I called above.
Output: The correct character (like 'ă'). I'm sure this character should be displayed correctly in almost Unicode Font. So the specified Font to display the output correctly is not necessary to mentioned here, and if it is a condition for the output (choose some specified Fonts for displaying the output correctly), I think it'll be OK because I intend to display the output characters in some fixed Font.
One of the 'converter' (calling it converter is not exact, maybe a translator) I have already is any TextBox. This should be called translator because it can help you translate the weird/wrong character to the correct one (you can see the output), however it's not a converter because you can't grasp the output, for example, select and copy it to Clipboard and paste to another textbox (such as Google search box). The TextBox operates like a translator, it receives the input (the weird/wrong character is assigned for the Text property and the Font is assigned for the Font property) and gives out the output (the correct character but as I said, you can only see it, not grasp/get it or at least get the corresponding character which is displayed correctly in another Font).
If this can't be done, I'm afraid that I have to add a column called 'FontName' or 'FontFamily' to my table so that every time I query the text from my table, I have also to query the corresponding Fonts to display the texts correctly on my forms/grids. This is one of the most annoying things I've ever known.
I hope you understand my problem. As I said, I even don't know what kind of task it is, but you may know. Please help me out.
Thanks!
UPDATE
I want to give an example of the converter, see it as a function/method like this:
public char GetCorrectChar(char c){
switch(c){
case '¨':
return 'ă';
case 'Ç'
return 'ầ';
....
}
}
This function is possible to implement, however it requires me to collect all the possible pairs (of the input chars and output chars) and I'm not sure if it's efficient. Thanks!

Windows-Store-App RichEditBox Markdown Highlighting

at the moment I'm trying to get into Windows Store App Development and I'm stuck at some point.
I want to implement sort of a "markdown language" like the one on stackoverflow to highlight certain parts of text input.
Besides that I want to give the user the ability to use different font colors on his text.
The RichEditBox seems to be the ideal control for this task, but I don't know how to detect markup entering on the fly.
For example when the user enters **Test** the text should be transformed to Test immediately.
I have tried to approach this by listening to the "TextChanged" event and looking if the user enters **. If this is the case and if he entered the sequence ** already one time before, then I'm setting the character format of the text range from the end of the first annotation sequence (start marker) to the beginning of the second (close marker) annotation to bold.
But this solutions seems to be very quick and dirty.
My second thought was to use the WebView control to render the text after preprocessing it with "Markdown Sharp".
But then the user won't be able to edit text.
So I need to get some advice or tip on approaching this problem. I also looked into writing a custom RichEditBox control, but I have no experience in custom control development and there aren't that many resources on the web for Windows 8 development for now.
Thanks in advance.

As I see it, your problem is that you want to edit the "source" based on Markdown syntax AND show the formatted result in the same place. How would you revert Test to regular, as long as the asterisks are gone? If the answer is "using a button" then why not use the button to make it bold in first place?
However, you could do a hybrid thing: apply formatting in the source text, while maintaining the Markdown markup (not sure if this is entirely doable for all Markdown tricks, though). That is, **Test** would look in the source like **Test**. For the final, formatted result you would use a separate view, such as RichTextBlock.
In order to do the hybrid formatting, an option would be to have a background thread matching regularly the whole text against regular expressions specific to the Markdown syntax. For each match the corresponding text range would then be formatted accordingly.

Using superscript in C# resource file

I have some superscript text that I need to define in a C# UI project resource file that will eventually be put in a XAML datatable.
For instance the 2 in this example needs to be superscript: (kg/m2)
Is there any way to define this right in the Value field of the Resource string...perhaps via a Unicode or HTML tag that a standard Xaml control bound to this value could parse?
I'm not opposed to using a XAML converter, but short of putting some sort of hacky string in the resource (e.g.(kg/mSQUARED)) and using the XAML to look for it, I can't think of an elegant way to that either.
Thanks!

Based on your comment above, it sounds like "squared" is the only one you need. So, to amplify my comment:
There's already a Unicode code point for "squared" aka "SUPERSCRIPT TWO". It's called U+00B2, if you want to Google more information about it.
Here it is:
²
Highlight that character in your Web browser, copy it to the clipboard, and paste it into your resource file.

Use US International keyboard layout, Press Alt-Gr + 2, that will show
Alt-Gr + 3 = ³

How to select text from the RichTextBox and then color it?

I want to create a simple editor like Notepad++ with simple functionality... I need to color a specific word in the rich text box area. How can I do that?
For example: when the user write these word, I want to color them to the blue color. These words are: for, while, if, try, etc.
How can I make the richtextbox to select a specific word and then color them?
And, if I want to make a comment and color everything after the //, how is that done in the richtextbox?
How do I number the line in the text box, so I can now the line number when I'm coding in my editor?

Here's some code you can build on in order to achieve the functionality you want.
private void ColourRrbText(RichTextBox rtb)
{
Regex regExp = new Regex("\b(For|Next|If|Then)\b");
foreach (Match match in regExp.Matches(rtb.Text))
{
rtb.Select(match.Index, match.Length);
rtb.SelectionColor = Color.Blue;
}
}
The CodeProject article Enabling syntax highlighting in a RichTextBox shows how to use RegEx in a RichTextBox to perform syntax highlighting. Specifically, look at the SyntaxRichtTextBox.cs for the implementation.

In general, you have to work on the selection in RichTextBox. You can manipulate the current selection using the Find method or using SelectionStart and SelectionLength properties. Then you can change properties of selected text using SelectionXXX properties. For example, SelectionColor would set the color of current selection, etc. So you have to parse text in richtextbox and then select part of texts and change their properties as per your requirements.
Writing a good text editor using RichTextBox can be quite cumbersome. You should use some library such as Scintilla for that. Have a look at ScintillaNet, a .NET wrapper over Scintilla.

Did you know that Notepad++ uses Scintilla?
You actually do not have to reinvent the wheel by going through all the trouble as there is a .NET port of Scintilla named ScintillaNET which you can freely embed in your application as the source code editor :)
But to answer your question, there are few parts that you need to understand
Finding what to color
When to color
How to color
For the first part, there may be different approaches, but I think using regular expressions would be a good choice. I am sorry, but I don't know regular expressions much so I cannot help you in that case.
When to color is very crucial and if you do it wrong, your application will suffer a heavy performance penalty. I suggest you refer to XPath Visualizer which was done by our own Stack Overflow member, Cheeso. Take a look at the source on how the coloring of the syntax was done. But if you ScintillaNET, everything would be taken care of. Anyway, I really can't seem to find this documentation where he clearly showed how the coloring of the text was done. I would most definitely post it here if I find it.
The third question I think is covered by VinayC. But basically you use SelectionColor along with SelectionStart.

here is a good link on c-sharpcorner.com website on basic richtextbox syntax highlighting. I assume that you and any one visiting this page for similar problem want to do it for learning purpose. But if any one wants to do it for some making some comercial level IDE then it must use scintilla or some similar.
An other approach for this is to directly change the RTF of the richtextbox. Look in codeproject.com there are lot of articles similar to this problem.

I had some problems with that and here is my solution, beats me why it has to be done like this, but it works:
// position on end of control...
richTextBox.UpdateLayout();
richTextBox.ScrollToEnd();
richTextBox.UpdateLayout();
// ...then select text and it will be position on top of control.
richTextBox.Focus();
richTextBox.Selection.Select(foundRange.Start, foundRange.End);
richTextBox.BringIntoView();

Vb.net implementation
Imports System.Text.RegularExpressions
Private Sub formatString()
Dim rg =New Regex("\b(for|while|if|try)\b")
Dim m As Match
For Each m In rg.Matches(RichTextBox1.Text)
RichTextBox1.Select(m.Index,m.Length)
RichTextBox1.SelectionColor=Color.Green
Next
End Sub