Marshaling Delegates as Function Pointers

The following table shows examples of how a managed delegate can be marshaled to a function pointer in unmanaged code.

Managed delegate (C#) Unmanaged function pointer (C++)

Managed delegate (C#)	Unmanaged function pointer (C++)
`public delegate int EnumDelegate( IntPtr hwnd, int LParam);` `[DllImport("coredll.dll")] static extern int EnumWindows( EnumDelegate d, Int lParm);`	`typedef BOOL (* WNDENUMPROC) (HWND, LPARAM);` `BOOL EnumWindows( WNDENUMPROC lpEnumFunc, LPARAM lParam);`
`public delegate int EnumDelegate( IntPtr hwnd, int lParam);` `[DllImport("coredll.dll")] static extern int EnumWindows( [MarshalAs(UnmanagedType.FunctionPtr0] EnumDelegate d, Int lParam);`	`typedef BOOL (* WNDENUMPROC) (HWND, LPARAM);` `BOOL EnumWindows( WNDENUMPROC lpENumFunc, LPARAM lParam);`

public delegate int EnumDelegate(
  IntPtr hwnd, int LParam);
[DllImport("coredll.dll")]
static extern int EnumWindows(
EnumDelegate d,
Int lParm);

typedef BOOL (* WNDENUMPROC) 
  (HWND, LPARAM);
BOOL EnumWindows(
WNDENUMPROC lpEnumFunc,
LPARAM lParam);

public delegate int EnumDelegate(
  IntPtr hwnd, int lParam);
[DllImport("coredll.dll")]
static extern int EnumWindows(
[MarshalAs(UnmanagedType.FunctionPtr0]
EnumDelegate d,
Int lParam);

typedef BOOL (* WNDENUMPROC) 
  (HWND, LPARAM);
BOOL EnumWindows(
WNDENUMPROC lpENumFunc,
LPARAM lParam);

Marshaling Delegates as Function Pointers

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