Home/ Questions/Q 6133375
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-23T17:13:12+00:00

I’d like to do Marshal.AllocHGlobal in managed code, fill it with data, and pass

  • 0

I’d like to do Marshal.AllocHGlobal in managed code, fill it with data, and pass that memory block to unmanaged (C++) code that will then be responsible for freeing it.

Under the hood, Marshal.AllocHGlobal calls LocalAlloc (and, I’m guessing, LocalLock). But in order for the unmanaged code to call LocalFree, it needs the HLOCAL returned by LocalAlloc, which Marshal.AllocHGlobal doesn’t provide.

I’m not necessarily restricted to using AllocHGlobal; the high level goal is to let the managed code allocate memory that the unmanaged code and then read and free.

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    This is not a handle, not since Windows version 3. Calling LocalFree() on the pointer is fine, as the Windows SDK article shows in its example. Marshal.AllocCoTaskMem and CoTaskMemFree() are the better mouse trap here.

    • 0