Regex: Parse a Fixed Length Text File

In the c languange you can use sscanf(), but there is no function similar to this in .NET. The equivalent function is to use Regex to map fixed length field sizes to a GROUP, then access the GROUP NAMES to get the values.

// Create the pattern using Regex.  
//  is a GROUP.  
// ".{22}" means any (.) 22 characters {22}.

// SAMPLE INPUT FIXED LEGTH TEXT FILE 
// 123456789012345678901212345671234567891234567812345678123123
// 123456789012345       12345  1234567  2010041020100411ABC001
// <----22 characters---><--7--><---9---><--8---><--8---><3><3>
StringBuilder sb = new StringBuilder();
sb.AppendFormat("{0}", @"^");
sb.AppendFormat("{0}", @"(?.{22})");
sb.AppendFormat("{0}", @"(?.{7})");
sb.AppendFormat("{0}", @"(?.{9})");
sb.AppendFormat("{0}", @"(?.{8})");
sb.AppendFormat("{0}", @"(?.{8})");
sb.AppendFormat("{0}", @"(?.{3})");
sb.AppendFormat("{0}", @"(?.{3})");

string pattern = sb.ToString();
int OrderSequence = 0;
using (StreamReader sr = new StreamReader(this.FileNamePathToProcess))
{
    Regex re = new Regex(pattern);
    while (!sr.EndOfStream)
    {
        Match ma = re.Match(sr.ReadLine());

        OrderData myOrderData = new OrderData();
        myOrderData.OrderSequence = ++OrderSequence;
        myOrderData.OrderKey = ma.Groups["ORDERKEY"].Value.TrimEnd();
        myOrderData.OrderNumber = ma.Groups["ORDERNUM"].Value.TrimEnd();
        myOrderData.PatientSocialSecurity = ma.Groups["ID"].Value.TrimEnd();

        myOrderData.D_ORD = ma.Groups["DATEORDERED"].Value.TrimEnd();
        myOrderData.D_RX = ma.Groups["DATERECIEVED"].Value.TrimEnd();
        myOrderData.OrderTechnicianInitials = ma.Groups["INITIALS"].Value.TrimEnd();
        myOrderData.OrderPriority = ma.Groups["PRIORITY"].Value.TrimEnd();

        this.PackageOrderData.Add(myOrderData);
    }
}