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    <p>The point of both these structures is to prevent the garbage collector from releasing a resource and invalidating the handle before the P/Invoke call has finished. The documentation you linked indicates that these are special types recognized by the interop marshaller.</p> <p>What I gather from the documentation is that <code>HandleRef</code> is essentially a special case of the more general <code>GCHandle</code> structure.</p> <p>The <code>HandleRef</code> structure is specifically intended for wrapping handles to unmanaged resources that are used with P/Invoke code. For example, window handles (<code>HWND</code>) or device contexts (<code>HDC</code>). It has a <code>Handle</code> property that returns a value of type <code>IntPtr</code>, which is an integer value the size of a pointer on the underlying system's architecture. You can use this to quickly &amp; easily obtain the handle it wraps.</p> <p>Whereas the <code>GCHandle</code> structure allows one to specify the type of handle it wraps using one of the members of the <code>GCHandleType</code> enumeration, the <code>HandleRef</code> structure was specifically designed to wrap handles to unmanaged resources. You'd probably use the <code>GCHandle</code> structure when you're dealing directly with unmanaged memory, rather than the special handles that the Win32 API treats as black boxes.</p> <p>It is not necessary to use either. One can simply call <code>GC.KeepAlive</code> to keep the garbage collector from prematurely releasing the resource.</p> <p>And even that is probably not necessary. I've been writing P/Invoke code for years, and I've found that when it's correctly written, there's no need for either of these structures. If a class object gets garbage collected while the API call is in the middle of executing, then that's a bug in your application. I actually <em>want</em> to be notified of the failure via an exception, not hide it.</p>
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    1. USCody Gray
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    1. COThanks for answer
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      1. USVitaliy Zaverchuk
 

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