private static boolean isPunct(char c) {
        return ( c >= 0x21 && c <= 0x2F ) ||
        ( c >= 0x3a && c <= 0x40 ) ||
        ( c >= 0x5B && c <= 0x60 ) ||
        ( c >= 0x7B && c <= 0x7E );
    }
Only works with non-negative numbers
main/src/main/java/cgeo/geocaching/wherigo/kahlua/stdlib/StringLib.java