Does C# have built-in methods to convert string control characters to "normal characters"?

Question

There is a Char.IsControl() method to identify such characters, but I want a way to convert them to "normal" characters. i.e. some way to visualise a string that contains such characters. Probably similar to what Notepad++ does.

Obviously such a visualisation will be imperfect, and ambiguous ... but does it exist as a built in method?

Answer 1

Notepad++ is converting the control characters to the control pictures U+240x and you'll also have to do that yourself. To convert controlChar to its visualization just use controlChar + 0x2400 or controlChar + '\u2400'

Console.Write((char)(i + 0x2400));

Demo on dotnetfiddle. Output:

␀ ␁ ␂ ␃ ␄ ␅ ␆ ␇ ␈ ␉ ␊ ␋ ␌ ␍ ␎ ␏ ␐ ␑ ␒ ␓ ␔ ␕ ␖ ␗ ␘ ␙ ␚ ␛ ␜ ␝ ␞ ␟

You can also do like this

Console.Write(char.ConvertFromUtf32(i + '\u2400'));

Of course this only works for the first 32 control characters (and space), to convert the remaining ones you have to use a Dictionary or something similar because the code points aren't contiguous. For example 0x7F will need to be converted to ␡ (U+2421). There aren't any control pictures for the C1 control codes so you're out of luck for those. There are many other control codes above U+0080 and most of them don't have a control picture either

Answer 2

var stringBuilder = new StringBuilder();
foreach (var character in input)
  {
   if (character.IsControl())
     stringBuilder.Append(Convert.ToInt32(character).ToString("X4"));
  }

 return stringBuilder.ToString();