Check if string consists only of valid ISO 8859-1 characters

Question

How to check if a string consists only of chars, which can be successfully encoded in ISO 8859-1? Or in other words - how to find "illegal"/"not ISO 8859-1 compatible" chars in a string?

Would [this post](http://stackoverflow.com/questions/1025332/determine-a-strings-encoding-in-c-sharp) help? — Mechanical Object, Jul 26 '13 at 09:43
@MechanicalObject: Probably not, if it is already a C# String (and not raw bytes). — Thilo, Jul 26 '13 at 09:45

ProgramFOX · Accepted Answer · 2013-07-26T10:16:04.653

15

Try this:

    private static bool IsValidISO(string input)
    {
        byte[] bytes = Encoding.GetEncoding("ISO-8859-1").GetBytes(input);
        String result = Encoding.GetEncoding("ISO-8859-1").GetString(bytes);
        return String.Equals(input, result);
    }

This answer is based on an answer of this Java question (my code is the C# equivalent): http://www.velocityreviews.com/forums/t137810-checking-whether-a-string-contains-only-iso-8859-1-chars.html

edited Jul 26 '13 at 10:16

answered Jul 26 '13 at 09:59

ProgramFOX

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1

This looks better than mine idea. Thanks for your answer! – netblognet Jul 26 '13 at 10:05
2

@netblognet You're welcome! I also looked at your code, but it looks "dangerous" because you can't be 100% sure that non-ISO chars will give a question mark. My code is also faster. – ProgramFOX Jul 26 '13 at 10:18
1

Great answer. Small suggestion even if it is a really old post. Instead of Encoding.GetEncoding("ISO-8859-1") use Encoding.Latin1 – Oliver Voutat Jul 14 '22 at 08:45

score 0 · Answer 2 · answered Jul 26 '13 at 09:42

0

You could setup an array or list of valid characters and then iterate through your string to check if each of them exists in your list of valid characters. The list can be created by adding all valid latin-1 characters to it.

answered Jul 26 '13 at 09:42

Ron Deijkers

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score 0 · Answer 3 · answered Jul 26 '13 at 10:05

I came up with this idea. Might this be possible?

    private static bool IsValidISO(string input)
    {
        foreach (char c in input)
        {
            Encoding iso = Encoding.GetEncoding("ISO-8859-1");
            Encoding utf8 = Encoding.UTF8;

            byte[] isoBytes = iso.GetBytes(c.ToString());
            byte[] utfBytes = Encoding.Convert(iso, utf8, isoBytes);

            string convertedC = utf8.GetString(utfBytes);
            if (c != '?' && convertedC == "?")
                return false;
        }
        return true;
    }

Check if string consists only of valid ISO 8859-1 characters

3 Answers3