Question

我有一个用C ++编写的DLL。我想从Delphi 7中调用一个函数。

我只有一个用VB.NET编写的示例。

在发布到这里之前，我已经尝试过自己转换代码。

问题是当我调用函数时，它给我二进制输出错误，这显然意味着我对输入做错了。

这是VB.NET中的原始代码：

Private Shared Declare Unicode Function Read_Write Lib "Subway.dll" (obej As IntPtr, Data_in As Byte(), in_siz As Integer, <Out()> ByRef Data_out As IntPtr, ByRef out_siz As Integer) As Integer

Dim obej As IntPtr = IntPtr.Zero
Dim Data_out As IntPtr = 0
Dim out_siz As Integer = 0
Dim Res As Integer = -1

Res = Read_Write(obej, Encoding.[Default].GetBytes(Mystr), Mystr.Length, Data_out, out_siz)

我在Delphi中转换后的代码：

function Read_Write(obej: Pointer; Data_in: TByteDynArray; in_siz:Cardinal; var Data_out: TByteDynArray; var out_siz: Cardinal): Integer; stdcall; external 'Subway.dll';

var
  tx, rx: TByteDynArray;
  obej: pointer;
  s:string;
  Res: Integer;
  out_siz: Integer;

SetLength(tx, Length(s));
Move(s[1], tx[0], Length(s));
Res := Read_Write(obej, tx, length(s), rx, out_siz);

普通电话（C语言）：

int __stdcall Read_Write(void *u_arg, const unsigned char  *p_data_in, unsigned int  data_in_len, unsigned char  **pp_data_out, unsigned int  *p_data_out_len);

Answer 1

您的Read_Write()的Delphi声明与VB.NET声明不匹配。您没有考虑.NET如何将参数编组为非托管语言。另外，TByteDynArray是特定于Delphi的类型，您不能原样传递给其他语言，尤其是在输出参数中。

请尝试以下类似操作：

function Read_Write(obej: Pointer; Data_in: PByte; in_siz: Integer, var Data_out: Pointer; var out_siz: Integer): Integer; stdcall; external 'Subway.dll';

var
  obej: Pointer;
  Data_out: Pointer;
  out_siz: Integer;
  Res: Integer;
  MyStr: AnsiString;
  buf: TByteDynArray;
begin
  ...

  obej := nil;
  Data_out := nil;
  out_siz := 0;

  MyStr := ...;
  SetLength(buf, Length(MyStr));
  Move(PAnsiChar(MyStr)^, PByte(buf)^, Length(MyStr));

  Res := Read_Write(obej, PByte(buf), Length(buf), Data_out, out_siz);
  // use Data_out up to out_siz bytes as needed...
  // free Data_out as needed...

  ...
end;

或者，您可以省略TByteDynArray并直接跳过AnsiString数据：

Res := Read_Write(obej, PByte(PAnsiChar(MyStr)), Length(MyStr), Data_out, out_siz);

在Delphi 7中调用C ++ DLL函数

1 个答案: