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?

What does Notepad++ do? – Mathias R. Jessen Nov 10 '22 at 13:00 — Mathias R. Jessen, Nov 10 '22 at 13:00
Control characters are usually characters below 0x20. – jdweng Nov 10 '22 at 13:08 — jdweng, Nov 10 '22 at 13:08

phuclv · Accepted Answer · 2022-11-10T13:27:51.640

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

Hilariously ... Notepad++ doesn't have a renderer for those characters :D thye just show up as squares :D — Brondahl, Nov 10 '22 at 13:52
@Brondahl that's a font problem and has nothing to do with Notepad++. Choose a different font with those characters. Notepad++ doesn't have very good font substitution/font replacement like many other editors — phuclv, Nov 10 '22 at 14:19

score 1 · Answer 2 · answered Nov 10 '22 at 13:12

1

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

 return stringBuilder.ToString();

answered Nov 10 '22 at 13:12

Lucian

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this prints the code point of the control character, but it's not *what Notepad++ does* – phuclv Nov 10 '22 at 13:13

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

2 Answers2