How would you get an array of Unicode code points from a .NET String?

Question

I have a list of character range restrictions that I need to check a string against, but the char type in .NET is UTF-16 and therefore some characters become wa

Answer 1

You are asking about code points. In UTF-16 (C#'s char) there are only two possibilities:

1. The character is from the Basic Multilingual Plane, and is encoded by a single code unit.
2. The character is outside the BMP, and encoded using a surrogare high-low pair of code units

Therefore, assuming the string is valid, this returns an array of code points for a given string:

public static int[] ToCodePoints(string str)
{
    if (str == null)
        throw new ArgumentNullException("str");

    var codePoints = new List(str.Length);
    for (int i = 0; i < str.Length; i++)
    {
        codePoints.Add(Char.ConvertToUtf32(str, i));
        if (Char.IsHighSurrogate(str[i]))
            i += 1;
    }

    return codePoints.ToArray();
}

An example with a surrogate pair