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POTo call a method that requires IntPtr, is it better to use /unsafe, or Marshal.AllocHGlobal?
 

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    <p>I have a class that will have a few instances persistent throughout the duration of the application. These objects will each need to call a dll method that appends data from an existing float[] buffer, and passes the full dataset to a DLL method that accepts an IntPtr (float array), several times per second. Is it better to do it as unmanaged code:</p> <pre><code> class PersistentThing : IDisposable { readonly IntPtr _floats = Marshal.AllocHGlobal(sizeof(float) * ArraySize); public void DoFrequentAction() { // Append data from a buffer to the memory space. var floatOffsetPtr = new IntPtr(_floats.ToInt32() + _floatsIndex * sizeof(float)); Marshal.Copy(_buffer, _bufferIndex, floatOffsetPtr, _bufferCount); // Call a DLL method with with memory pointer CallDllMethod(_floats); } // Need to dispose the unmanaged memory public void Dispose() { Marshal.FreeHGlobal(_floats); } } </code></pre> <p>or would it be better to use an unsafe tag and fixed?</p> <pre><code> class PersistentThing2 { readonly float[] _floats = new float[ArraySize]; public unsafe void DoFrequentAction() { // Append data from a buffer to the memory space. Array.Copy(_buffer, _bufferIndex, _floats, _floatsIndex, _bufferCount); // Call a DLL method with with memory pointer fixed (float* floatsPtr = _floats) { CallDllMethod((IntPtr)floatsPtr); } } } </code></pre> <p>Is there any advantage of not having to use the "unsafe" tag in the compiler? Is the Marshal class actually any "safer"? Which of these methods generally have the better performance?</p> <p>I lean toward the former, just because that way the GC doesn't have to worry about <code>_floats</code> (which could be quite large) when cleaning up the memory space. Is that a reasonable concern? Does the recommendation depend on the size of ArraySize?</p>
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