Name
DllImportAttribute
Synopsis
This attribute (and, in C#, the keyword “extern”) specifies that a method definition is implemented externally (usually in a DLL). Apply this attribute to a method that has been declared (but not defined) to specify the DLL name and entry point in which the method can be found.
The attribute can be customized in a number of different ways to help
control the binding against the external method. The
CallingConvention
value dictates how the
parameters to the call (and return value coming back) should be sent
to the function. CallingConvention.StdCall
(used
for calling into _stdcall
-declared functions,
which is most of the Win32 API set) and
CallingConvention.Cdecl
(used for calling
functions declared directly from C or C++) are the two most common
values. The CharSet
value indicates which
character set parameters to the call are expected to be, either
two-byte Unicode or one-byte ANSI. EntryPoint
indicates the name of the exported function from the DLL to bind to
(normally this is guessed from the name of the .NET-declared method),
and ExactSpelling
indicates whether the .NET
compiler should attempt to “best
match” a declared DllImport
method against a possible set of exported functions. The
PreserveSig
value indicates how .NET should treat
[out]
-declared and
[retval]
-declared parameters. By default, the .NET
compilers ignore the HRESULT return value on IDL-declared methods and
use the [retval]
-declared parameter as the return
value; setting PreserveSig ...
Get C# in a Nutshell, Second Edition now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.