Parse a string to get a SectorId

Question

In mobile phones technologies, a SectorId is a 128-bit value broadcast by a 1xEV-DO BTS system.

That is a 16 bytes data.

I made a structure to store them:

using System;
using System.Globalization;
using System.Linq;
using System.Text;
public struct SectorId
{
 readonly byte[] id;
 SectorId(byte[] id)
 {
 this.id = new byte[16];
 Array.Copy(id, this.id, 16);
 }
 public override bool Equals(object obj)
 {
 if (obj is SectorId)
 {
 return Equals((SectorId)obj);
 }
 return false;
 }
 public bool Equals(SectorId other)
 {
 return id.SequenceEqual(other.id);
 }
 public override int GetHashCode()
 {
 int hash = 0;
 unchecked
 {
 foreach (var b in id)
 {
 hash *= 397;
 hash += b;
 }
 }
 return hash;
 }
 public static SectorId Parse(string s)
 {
 Throw.IfArgumentIsNull("s", s);
 SectorId result;
 if (TryParse(s, out result))
 {
 return result;
 }
 throw new FormatException();
 }
 public override string ToString()
 {
 var sb = new StringBuilder();
 foreach (var b in id)
 {
 sb.AppendFormat("{0:X2}", b);
 }
 return sb.ToString();
 }
 public static bool TryParse(string s, out SectorId result)
 {
 if (s == null)
 {
 goto Fail;
 }
 if (s.Length > 32)
 {
 goto Fail;
 }
 if (s.Length < 32)
 {
 s = s.PadRight(32, '0'); 
 }
 var bytes = new byte[16];
 for (var i = 0; i < 16; i++)
 {
 var substring = s.Substring(i * 2, 2);
 if (!byte.TryParse(substring, NumberStyles.HexNumber, CultureInfo.InvariantCulture, out bytes[i]))
 {
 goto Fail;
 }
 }
 result = new SectorId(bytes);
 return true;
 Fail:
 result = default(SectorId);
 return false;
 }
}

The TryParse part is the worse for me. I would like to avoid gotos.

Answer 1

Note that you can use multiple return statements in a method, so instead of using goto, you can use a return statement. I.e:

if (s == null)
{
 return false;
}

• RobH: Don't forget to initialise the out parameter first.