Mapping a byte array to a structure in C#

August 21, 2006 · 1 min read

Some of the C# code I've been writing recently communicates via TCP/IP with legacy C++ applications. These applications use a raw packet format where C/C++ structures are passed back and forth.

Here is a simplified example of what the legacy code could look like:

The problem I was faced with was how to receive and handle this kind of message in a C# application. One method is to use BitConverter and Encoding.ASCII to grab the data field by field. This is tedious, prone to errors and easy to break of modifications are made in the future.

A better method is to marshal the byte array to a C# structure. Here is an example of how to do that marshaling:

The GCHandle.Alloc call pins the byte[] in memory so the garbage collector doesn't mess with it. The AddrOfPinnedObject call returns an IntPtr pointing to the start of the array and the Marshal.PtrToStructure does the work of marshaling the byte[] to the structure.

If the actual structure data didn't start at the beginning of the byte array you would use the following assuming the structure data starts at position 10 of the array:

This article is part of the GWB Archives. Original Author: Richard Taylor

New on Geeks with Blogs

  • We Won The One Award I Actually Care About

    Full Scale made the Inc. 5000 for the fifth year straight, the 12th listing across my three companies. Here is why the one award you cannot buy is worth stopping for.

  • Your Customers Build the Features Now

    I let a tool I liked sit dead for a year rather than build the features I wanted. An MCP server meant I never had to, and your customers can do the same to your product.

  • Get the Size of a Directory in Linux the Easy Way

    du -sh for the quick answer, ncdu for the cleanup, df for the disk itself: every command for checking directory size in Linux, plus why du and df never agree.

  • Vim Search and Replace: The Ultimate Guide

    One :%s command replaces every match in a file before a find dialog would even open. The Vim substitute patterns worth the muscle memory: flags, ranges, capture groups, and multi-file edits.