How to correctly P/Invoke this function?
How to correctly P/Invoke this function?
co开发者_如何学JAVAnst char * GetReplyTo(const char * pszInText, char * pszOutText, int len)
I've tried to do it this way and got access violation exception:
[DllImport("SmartBot.dll", EntryPoint = "GetReplyTo")]
public static extern IntPtr GetReplyTo([In] [MarshalAs(UnmanagedType.LPStr)] string pszInText, IntPtr pszOutText, int len);
// somewhere below:
IntPtr pbuf = GCHandle.Alloc(new byte[1000], GCHandleType.Pinned).AddrOfPinnedObject();
GetReplyTo("hi", pbuf, 2);
UPDATE Here is pascal header for this file:
{***************************************************************************
* SmartBot Engine - Boltun source code,
* SmartBot Engine Dynamic Link Library
*
* Copyright (c) 2003 ProVirus,
* Created Alexander Kiselev Voronezh, Russia
***************************************************************************
SmartBot.pas : Header Pascal for SmartBot Engine.
}
unit SmartBot;
interface
{
function GetReplyTo(const InText: PChar; OutText: PChar; Len: integer): PChar;stdcall;export;
function LoadMind(MindFile: PChar): integer;stdcall;export;
function SaveMind(MindFile: PChar): integer;stdcall;export;
}
function GetReplyTo(const InText: PChar; OutText: PChar; Len: integer): PChar;stdcall;external 'smartbot.dll' name 'GetReplyTo';
function LoadMind(MindFile: PChar): integer;stdcall;external 'smartbot.dll' name 'LoadMind';
function SaveMind(MindFile: PChar): integer;stdcall;external 'smartbot.dll' name 'SaveMind';
implementation
end.
UPDATE 2 It works. Looks like I messed up with initialization function. It returns 1 on success and 0 on fail. Weird.
You probably don't want an IntPtr
here. You're making way too much work for yourself. For an output string parameter, you should use StringBuilder
. You'll probably need to specify CharSet
on your P/Invoke declaration, since the function appears to use one byte per character.
[DllImport("SmartBot.dll", CharSet = CharSet.Ansi)]
public static extern string GetReplyTo(string pszInText,
StringBuilder pszOutText, int len);
var stringBuilder = new StringBuilder(1000);
GetReplyTo("hi", stringBuilder, stringBuilder.Capacity);
Also make sure you're specifying the right calling convention (the CallingConvention
property on the DllImport
attribute).
you should use a StringBuilder for the second parameter that you initialize to size len
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