How to Search for Invisible Control Characters

How to search for invisible control characters

Try the following search command:

/[^ -~<09>]

(you get the <09> by pressing the tab key). Or if you want to get rid of those nasty tabs, just:

/[^ -~]

That will find and highlight any non-ASCII or control-ASCII character.

If you still have hidden characters out there, you can try this command before the search:

:set enc=latin1

That will prevent any weird Unicode character to show up in your code.

How can I view hidden characters in Notepad++?

If you really want to get a raw look, check out the HEX-Editor Plugin (Check the Plugin Manager for it). You'll see the character codes for everything; even non-printable characters.

I use it, and have no issues on the newer versions of Notepad++.

How to find and remove the invisible characters in text file using emacs

Emacs won't hide any character by default. Press Ctrl+Meta+%, or Esc then Ctrl+% if the former is too hard on your fingers, or M-x replace-regexp RET if you prefer. Then, for the regular expression, enter

[^@-^H^K-^_^?]

However, where I wrote ^H, type Ctrl+Q then Ctrl+H, to enter a “control-H” character literally, and similarly for the others. You can press Ctrl+Q then Ctrl+Space for ^@, and usually Ctrl+Q then Backspace for ^?. Replace all occurrences of this regular expression by the empty string.

Since you have the file open in Emacs, you can change its line endings while you're at it. Press C-x RET f (Ctrl+X Return F) and enter us-ascii-unix as the new desired encoding for the file.

Stripping all but visible characters from copied text (Invisible control characters corrupting code)

Update

I'm needing to apply the below resolution enough that I made a little VSCode extension for replacing non printing (NPC) control characters:

https://github.com/appsoftwareltd/no-control

Hope it helps!

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The character according to this website is

Character: Â    
ANSI Number: 194    
Unicode Number: 194 
ANSI Hex: 0xC2  
Unicode Hex: U+00C2 
HTML 4.0 Entity: Â    
Unicode Name: Latin capital letter A with circumflex    
Unicode Range: Latin-1 Supplement

Resolution has been to replace regex matches for [^\x00-\x7f] with a white space character.

As found here:

https://weblogs.asp.net/kon/finding-those-pesky-unicode-characters-in-visual-studio

Removing hidden characters from within strings

You can remove all control characters from your input string with something like this:

string input; // this is your input string
string output = new string(input.Where(c => !char.IsControl(c)).ToArray());

Here is the documentation for the IsControl() method.

Or if you want to keep letters and digits only, you can also use the IsLetter and IsDigit function:

string output = new string(input.Where(c => char.IsLetter(c) || char.IsDigit(c)).ToArray());

Does Notepad++ show all hidden characters?

Yes, it does. The way to enable this depends on your version of Notepad++. On newer versions you can use:

Menu View → Show Symbol → *Show All Characters`

or

Menu View → Show Symbol → Show White Space and TAB

(Thanks to bers' comment and bkaid's answers below for these updated locations.)

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On older versions you can look for:

Menu View → Show all characters

or

Menu View → Show White Space and TAB

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