Call native C++ function from C# : <p>I have C++ legacy code with functions in the form:</p>

<pre><code>double func(double)
</code></pre>

<p><strong>I have this as a source file</strong> -  it isnt in the form of a DLL although it could be turned into one if necessary</p>

<p>How can I call <code>func</code> in my C# code (maybe over managed C++)? I heard of Marshalling and <code>DllImport</code> but I did not find MSDN very helpful.</p>
