System.Net.HttpDateParse.ParseCookieDate C# (CSharp) Method

        ParseCookieDate(string dateString, out DateTime dtOut) {
            //
            // The format variants
            //
            // 1) .NET HttpCookie   = "dd-MMM-yyyy HH:mm:ss GMT'"
            // 2) Version0          = "dd-MMM-yy HH:mm:ss GMT"
            // 3) Some funky form   = "dd MMM yyyy HH:mm:ss GMT"
            //
            // In all above cases we also accept single digit dd,hh,mm,ss
            // That's said what IE does.

            dtOut = DateTime.MinValue;
            char[] buffer = dateString.ToCharArray();
            char ch;

            if (buffer.Length < 18) { //cover all before "ss" in the longest case
                return false;
            }

            int idx = 0;
            // Take the date
            int  day=0;
            if (!Char.IsDigit(ch = buffer[idx++]))  {return false;}
            else                                    {day = ch-'0';}
            if (!Char.IsDigit(ch = buffer[idx++]))  {--idx;}                //one digit was used for a date
            else                                    {day = day*10 +(ch-'0');}
            
            
            if (day > 31)  {return false;}

            ++idx;  //ignore delimiter and position on Month

            // Take the Month
            int month = MapDayMonthToDword(buffer, idx);
            if (month == DATE_TOKEN_ERROR)                   {return false;}

            idx+=4; //position after Month and ignore delimiter

            // Take the year
            int year=0;
            int i;
            for (i=0; i < 4; ++i) {
                if (!Char.IsDigit(ch = buffer[i+idx])) {
                    // YY case
                    if (i != 2)             {return false;}
                    else                    {break;}
                }
                year = year*10 + (ch-'0');
            }

            //check for two digits
            if (i == 2) {
                year += ((year < 80) ? 2000 : 1900);
            }

            i += idx;       //from now on 'i' is used as an index
            if (buffer[i++] != ' ')             {return false;}

            //Take the hour
            int  hour=0;
            if (!Char.IsDigit(ch = buffer[i++])) {return false;}
            else                                 {hour = ch-'0';}
            if (!Char.IsDigit(ch = buffer[i++])) {--i;}                     //accept single digit
            else                                 {hour = hour*10 +(ch-'0');}

            if (hour > 24 || buffer[i++] != ':') {return false;}

            //Take the min
            int  min=0;
            if (!Char.IsDigit(ch = buffer[i++])) {return false;}
            else                                 {min = ch-'0';}
            if (!Char.IsDigit(ch = buffer[i++])) {--i;}                     //accept single digit
            else                                 {min = min*10 +(ch-'0');}

            if (min > 60 || buffer[i++] != ':')  {return false;}

            //Check that the rest will fit the buffer size "[s]s GMT"
            if ((buffer.Length - i) < 5)       {return false;}

            //Take the sec
            int  sec=0;
            if (!Char.IsDigit(ch = buffer[i++])) {return false;}
            else                                 {sec = ch-'0';}
            if (!Char.IsDigit(ch = buffer[i++])) {--i;}                     //accept single digit
            else                                 {sec = sec*10 +(ch-'0');}

            if (sec > 60 || buffer[i++] != ' ')  {return false;}

            //Test GMT
            if((buffer.Length - i) < 3 || buffer[i++] != 'G' || buffer[i++] != 'M' || buffer[i++] != 'T') {
                return false;
            }

            dtOut = new DateTime (year, month, day, hour, min, sec, 0).ToLocalTime();
            return true;
        }
    }