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?

Answer 1

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

Answer 2

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.

Answer 3

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;
    }