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POSafeArrayPutElement method throws System.AccessViolationException
 

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  1. POSafeArrayPutElement method throws System.AccessViolationException
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    <p>I am trying to pass an array of ints from C# to C++/CLI. Here's my code:</p> <pre><code>// SafeArrayTesting_PlusPlus.cpp #include "stdafx.h" #include &lt;comdef.h&gt; using namespace System; namespace SafeArrayTesting_PlusPlus { public ref class MyCppClass { public: MyCppClass(); ~MyCppClass(); void SetMyInts(array&lt;int&gt;^ myInts); }; MyCppClass::MyCppClass(){} MyCppClass::~MyCppClass(){} void MyCppClass::SetMyInts(array&lt;int&gt;^ myInts) { // Create safearray SAFEARRAY *safeArrayPointer; SAFEARRAYBOUND arrayDim[1]; // one dimensional array arrayDim[0].lLbound= 0; arrayDim[0].cElements= myInts-&gt;Length; safeArrayPointer = SafeArrayCreate(VT_UNKNOWN,1,arrayDim); // copy ints to safearray for (long lo= 0; lo &lt; myInts-&gt;Length; lo++) { cli::pin_ptr&lt;int&gt; pinnedIntPointer = &amp;(myInts[lo]); SafeArrayPutElement( safeArrayPointer, &amp;lo, static_cast&lt;void*&gt; (pinnedIntPointer)); // line XX } // do something with the safearray here } } // SafeArrayTesting_Main.cs using SafeArrayTesting_PlusPlus; namespace SafeArrayTesting_Main { class SafeArrayTesting_Main { static void Main() { var myCppClass = new MyCppClass(); myCppClass.SetMyInts(new[]{42}); } } } </code></pre> <p>When I run this, line XX throws the following exception:</p> <blockquote> <p>System.AccessViolationException: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.</p> </blockquote> <p>I have a feeling that I'm doing something basically wrong with the <code>SafeArrayPutElement</code> method. Can you spot the error?</p> <p>(By the way, I have asked a more complex variation of this question at <a href="https://stackoverflow.com/questions/3464901/">Passing an array of interfaces from C# to C++/CLI</a> . I think the difference is big enough to warrant two separate questions.)</p>
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    1. COThis isn't your core problem, but it's extremely wasteful to recreate the `pin_ptr` inside the loop. Pinning is in fact totally unnecessary for what you are doing. Copy each value to a local variable, and pass its address to `SafeArrayPutElement`.
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