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    <p>I am sorry that I do not know what specific problem you are encountering, or how to resolve it [certainly checking namespace is referenced and resolving any conflicts with similarly named methods is a start], but I did notice one or two oddities.</p> <p>Consider the following sample solution,</p> <pre><code>using System.Linq; namespace Sample.Extensions { public static class ByteExtensions { public static void RemoveHeader (this byte[] buffer, byte[] header) { // take first sequence of bytes, compare to header, if header // is present, return only content // // NOTE: Take, SequenceEqual, and Skip are standard Linq extensions if (buffer.Take (header.Length).SequenceEqual (header)) { buffer = buffer.Skip (header.Length).ToArray (); } } } } </code></pre> <p>This compiles and runs in VS2010RC. To demonstrate usage,</p> <pre><code>using Sample.Extensions; namespace Sample { class Program { static void Main (string[] args) { byte[] buffer = new byte[] { 00, 01, 02 }; byte[] header = new byte[] { 00, 01 }; buffer.RemoveHeader (header); // hm, so everything compiles and runs, but buffer == { 00, 01, 02 } } } } </code></pre> <p>So we will not receive a compile or run-time <em>error</em> but clearly it will not operate as intended. This is because extensions must still comply with standard method semantics, meaning parameters are passed by value. We cannot change <code>buffer</code> to point to our new array.</p> <p>We can resolve this issue by rewriting our method to conventional function semantics, </p> <pre><code>public static byte[] RemoveHeaderFunction (this byte[] buffer, byte[] header) { byte[] stripped = null; if (stripped.Take (header.Length).SequenceEqual (header)) { stripped = stripped.Skip (header.Length).ToArray (); } else { stripped = buffer.ToArray (); } return stripped; } </code></pre> <p>Now</p> <pre><code>using Sample.Extensions; namespace Sample { class Program { static void Main (string[] args) { byte[] buffer = new byte[] { 00, 01, 02 }; byte[] header = new byte[] { 00, 01 }; // old way, buffer will still contain { 00, 01, 02 } buffer.RemoveHeader (header); // new way! as a function, we obtain new array of { 02 } byte[] stripped = buffer.RemoveHeaderFunction (header); } } } </code></pre> <p>Unfortunately, arrays are immutable value types [may be using these terms incorrectly]. The only way to modify your "array" in-place is to change the container to a mutable reference-type, like a <code>List&lt;byte&gt;</code>.</p> <p>If you are really keen on "passing by ref", in-place, side-effect semantics, then one option may be the following</p> <pre><code>using System.Linq; namespace Sample.Extensions { public static class ListExtensions { public static void RemoveHeader&lt;T&gt; (this List&lt;T&gt; list, List&lt;T&gt; header) { if (list.Take (header.Count).SequenceEqual (header)) { list.RemoveRange (0, header.Count); } } } } </code></pre> <p>As for usage,</p> <pre><code>static void Main (string[] args) { byte[] buffer = new byte[] { 00, 01, 02 }; byte[] header = new byte[] { 00, 01 }; List&lt;byte&gt; bufferList = buffer.ToList (); // in-place side-effect header removal bufferList.RemoveHeader (header.ToList ()); } </code></pre> <p>Under the hood, <code>List&lt;T&gt;</code> is maintaining an array of type <code>T</code>. At certain thresholds, it is simply manipulating the underlying array and\or instantiating new arrays for us.</p> <p>Hope this helps! :)</p>
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    1. POHaving trouble with extension methods for byte arrays
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    1. COThanks, johnny. Audie came to the same conclusion... I wish it were possible to pass the first param as a reference. For example, why can't I use 'ref' with 'this'?
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