Removing control characters from a UTF-8 string

Question

I found this question but it removes all valid utf-8 characters also (returns me a blank string, while there are valid utf-8 characters plus control characters). As I read about utf-8, there's not a specific range for control characters and each character set has its own control characters.

How can I modify above solution to only remove control characters ?

Answer 1

I think the following code will work for you:

public static string RemoveControlCharacters(string inString)
{
    if (inString == null) return null;
    StringBuilder newString = new StringBuilder();
    char ch;
    for (int i = 0; i < inString.Length; i++)
    {
        ch = inString[i];
        if (!char.IsControl(ch))
        {
            newString.Append(ch);
        }
    }
    return newString.ToString();
}

Answer 2

This is how I roll:

Regex.Replace(evilWeirdoText, @"[\u0000-\u001F]", string.Empty)

This strips out all the first 31 control characters. The next hex value up from \u001F is \u0020 AKA the space. Everything before space is all the line feed and null nonsense.

To believe me on the characters: http://donsnotes.com/tech/charsets/ascii.html

Answer 3

If you plan to use the string as a query string, you should consider using the Uri.EscapeUriString() or Uri.EscapeDataString() before sending it out. Note: You might still need to pull out anything from char.IsControl() first?