How can you strip non-ASCII characters from a string? (in C#)

Question

How can you strip non-ASCII characters from a string? (in C#)

Answer 1

string s = "søme string";
s = Regex.Replace(s, @"[^\u0000-\u007F]+", string.Empty);

Answer 2

Here is a pure .NET solution that doesn't use regular expressions:

string inputString = "Räksmörgås";
string asAscii = Encoding.ASCII.GetString(
    Encoding.Convert(
        Encoding.UTF8,
        Encoding.GetEncoding(
            Encoding.ASCII.EncodingName,
            new EncoderReplacementFallback(string.Empty),
            new DecoderExceptionFallback()
            ),
        Encoding.UTF8.GetBytes(inputString)
    )
);

It may look cumbersome, but it should be intuitive. It uses the .NET ASCII encoding to convert a string. UTF8 is used during the conversion because it can represent any of the original characters. It uses an EncoderReplacementFallback to to convert any non-ASCII character to an empty string.

Answer 3

I believe MonsCamus meant:

parsememo = Regex.Replace(parsememo, @"[^\u0020-\u007E]", string.Empty);

Answer 4

If you want not to strip, but to actually convert latin accented to non-accented characters, take a look at this question: How do I translate 8bit characters into 7bit characters? (i.e. Ü to U)

Answer 5

Inspired by philcruz's Regular Expression solution, I've made a pure LINQ solution

public static string PureAscii(this string source, char nil = ' ')
{
    var min = '\u0000';
    var max = '\u007F';
    return source.Select(c => c < min ? nil : c > max ? nil : c).ToText();
}

public static string ToText(this IEnumerable<char> source)
{
    var buffer = new StringBuilder();
    foreach (var c in source)
        buffer.Append(c);
    return buffer.ToString();
}

This is untested code.

Answer 6

no need for regex. just use encoding...

sOutput = System.Text.Encoding.ASCII.GetString(System.Text.Encoding.ASCII.GetBytes(sInput));

Answer 7

I found the following slightly altered range useful for parsing comment blocks out of a database, this means that you won't have to contend with tab and escape characters which would cause a CSV field to become upset.

parsememo = Regex.Replace(parsememo, @"[^\u001F-\u007F]", string.Empty);

If you want to avoid other special characters or particular punctuation check the ascii table

Answer 8

I came here looking for a solution for extended ascii characters, but couldnt find it. The closest I found is bzlm's solution. But that works only for ASCII Code upto 127(obviously you can replace the encoding type in his code, but i think it was a bit complex to understand. Hence, sharing this version). Here's a solution that works for extended ASCII codes i.e. upto 255 which is the ISO 8859-1

It finds and strips out non-ascii characters(greater than 255)

Dim str1 as String= "â, ??î or ôu🕧� n☁i✑💴++$-💯♓!🇪🚑🌚‼⁉4⃣od;/⏬'®;😁☕😁:☝)😁😁///😍1!@#"

Dim extendedAscii As Encoding = Encoding.GetEncoding("ISO-8859-1", 
                                                New EncoderReplacementFallback(String.empty),
                                                New DecoderReplacementFallback())

Dim extendedAsciiBytes() As Byte = extendedAscii.GetBytes(str1)

Dim str2 As String = extendedAscii.GetString(extendedAsciiBytes)

console.WriteLine(str2)
'Output : â, ??î or ôu ni++$-!‼⁉4od;/';:)///1!@#$%^yz:

Here's a working fiddle for the code

Replace the encoding as per the requirement, rest should remain the same.

Answer 9

This is not optimal performance-wise, but a pretty straight-forward Linq approach:

string strippedString = new string(
    yourString.Where(c => c <= sbyte.MaxValue).ToArray()
    );

The downside is that all the "surviving" characters are first put into an array of type char[] which is then thrown away after the string constructor no longer uses it.

Answer 10

I used this regex expression:

    string s = "søme string";
    Regex regex = new Regex(@"[^a-zA-Z0-9\s]", (RegexOptions)0);
    return regex.Replace(s, "");

Answer 11

I use this regular expression to filter out bad characters in a filename.

Regex.Replace(directory, "[^a-zA-Z0-9\\:_\- ]", "")

That should be all the characters allowed for filenames.