Question

I have an application written in .NETMF that requires that I be able to parse an RFC822-Datetime.

Normally, this would be easy, but NETMF does not have a DateTime.parse() method, nor does it have some sort of a pattern matching implementation, so I’m pretty much stuck.

Any ideas?

EDIT: “Intelligent” solutions are probably needed. Part of the reason this is difficult is that the datetime in question has a tendency to have extra spaces in it (but only sometimes). A simple substring solution might work one day, but fail the next when the datetime has an extra space somewhere between the parts. I do not have control over the datetime, it is from the NOAA.

Answer 1

Good ol’ string manipulation:

Sun, 06 Jun 2010 20:07:44 +0000
          1         2         3
0123456789012345678901234567890

string x = Sanitize("  Sun,  06 \t Jun 2010 \r\n 20:07:44 +0000  ");

int day    = int.Parse(x.Substring(5, 2));
int month  = Array.IndexOf(months, x.Substring(8, 3)) + 1;
int year   = int.Parse(x.Substring(12, 4));

int hour   = int.Parse(x.Substring(17, 2));
int minute = int.Parse(x.Substring(20, 2));
int second = int.Parse(x.Substring(23, 2));

int offsetSgn    = (x[26] == "-") ? -1 : 1;
int offsetHour   = int.Parse(x.Substring(27, 2));
int offsetMinute = int.Parse(x.Substring(29, 2));

DateTime result = new DateTime(year, month, day, hour, minute, second, 0);
TimeSpan offset = new TimeSpan(offsetHour, offsetMinute, 0);

// TODO: add offset...

with

string[] months = new string[12];
months[0] = "Jan";
months[1] = "Feb";
months[2] = "Mar";
months[3] = "Apr";
months[4] = "May";
months[5] = "Jun";
months[6] = "Jul";
months[7] = "Aug";
months[8] = "Sep";
months[9] = "Oct";
months[10] = "Nov";
months[11] = "Dec";

and

string Sanitize(string s)
{
    if (s == null)
    {
        return null;
    }

    char[] buffer = new char[s.Length];
    int pos = 0;
    bool inSpace = true;

    for (int i = 0; i < s.Length; i++)
    {
        if (s[i] == ' ' || s[i] == '\t' || s[i] == '\r' || s[i] == '\n')
        {
            if (!inSpace)
            {
                buffer[pos] = ' ';
                pos++;
                inSpace = true;
            }
        }
        else
        {
            buffer[pos] = s[i];
            pos++;
            inSpace = false;
        }
    }

    return new string(buffer, 0, pos);
}