Exclude non printable characters except new line

Question

I've an issue like this: string filter: detect non-ASCII signs in C# but I should exclude all no-printable characters in a string except new line chars (\n).

Starting from Regex option:

foo = System.Text.RegularExpressions.Regex.Replace(foo, @"[^\u0020-\u007E]+", string.Empty);

I've modified it in this way:

foo = System.Text.RegularExpressions.Regex.Replace(foo, @"[\u0000-\u0009\u000B-\u000C\u000E-\u0019\u007F]+", string.Empty);

This seems to work correctly, but could you suggest a less verbose solution? Thanks in advance

Did you mean "except new line (\n) and carriage return (\r) characters"? — Andrew Morton, Oct 06 '17 at 14:36
Aren't you failing to filter out some unprintable characters, namely 0x1a to 0x1f inclusive? — Matthew Watson, Oct 06 '17 at 14:48

Mustafa R · Answer 1 · 2019-04-17T11:09:37.850

3

Regex regex = new Regex(@"\p{C}+");    
string strWithPrintableChars = string.Join('\n'.ToString(),
                    foo.Split('\n').Select(line => regex.Replace(line, "")));

Explanation:

Declare the Regex for non-printable characters C# regex to remove non - printable characters, and control characters, in a text that has a mix of many different languages, unicode letters
Split string at each line break characters which returns an IEnumerable for each line. Characters matching regex are replaced for each line Lines are concatenated again as a single string with line break character, using string.join.

edited Apr 17 '19 at 11:09

answered Apr 16 '19 at 07:23

Mustafa R

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Please add an explanation so that it's easier for posterity to understand – rdas Apr 16 '19 at 08:35
In the context of .net core and multiplatforms I would suggest to change this part: foo.Split('\n') to foo.Split(new char[] { '\n', '\r' }, StringSplitOptions.RemoveEmptyEntries) and string.Join('\n'.ToString() to string.Join(Environment.NewLine, foo...... – Sebastian Widz Oct 15 '19 at 22:45
Thanks Sebastian, actually the question was asked for '\n' explicitly and has been used in the answer to explain. However, please find my remark on your points. 1. "foo.Split('\n') to foo.Split(new char[] { '\n', '\r' }" -- this is better if we are dealing with both line feed and carriage return. 2. "string.Join(Environment.NewLine, foo......" -- this should not be used because it may induce '\r' in the result on windows which is not the objective of the question. – Mustafa R Oct 29 '19 at 06:07

Exclude non printable characters except new line

1 Answers1