Delphi调用C++ DLL多输出参数传递

Delphi调用C++ DLL多输出参数传递

开发环境

1. VS2015
2. Dephi 6

C++编写DLL

使用VS2015创建生成DLL的空的工程TestDLL，添加一个test.cpp文件，编写代码如下：

extern "C" int __declspec(dllexport) __stdcall Add(int x, int y)
{
	return x + y;
}

extern "C" int __declspec(dllexport) __stdcall Generate(unsigned char* result, unsigned char* width, unsigned char* height, int * size)
{
	result[0] = 5;
	result[1] = 6;
	result[2] = 7;

	*width = 10;
	*height = 20;

	*size = 3;

	return 0;
}

添加一个模块定义文件Source.def，编写内容如下：

LIBRARY TestDLL
EXPORTS
Add
Generate

选择Release和x86模式，点击生成TestDLL，即可生成TestDLL.dll文件。

Delphi编写代码

创建一个工程，代码如下：

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    btnAdd: TButton;
    edtResult: TEdit;
    lbl1: TLabel;
    edtWidth: TEdit;
    lblHeight: TLabel;
    edtHeight: TEdit;
    lbl2: TLabel;
    edtSize: TEdit;
    lbl3: TLabel;
    edtValue: TEdit;
    lbl4: TLabel;
    procedure btnAddClick(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

  function Add(a:Integer; b:Integer):Integer;stdcall;external 'TestDLL.dll';

  function Generate(result:PByte; width: PByte; height: PByte; size: PInteger):Integer;stdcall;external 'TestDLL.dll';

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.btnAddClick(Sender: TObject);
var
  res: Integer;
  retData: array[0..10] of Byte;
  width: Byte;
  height: Byte;
  size: Integer;
  resultStr: string;
  i:Integer;
begin
  res := Generate(@retData, @width, @height, @size);
  edtWidth.Text := IntToStr(width);
  edtHeight.Text := IntToStr(height);
  edtSize.Text := IntToStr(size);
  i := 0;
  for i := 0 to size-1 do
    resultStr := resultStr + ' ' + IntToStr(retData[i]);
  edtValue.Text := resultStr;
  edtResult.Text := IntToStr(res);
end;

end.

执行程序，得到如下结果：

可以看到，C++的DLL可以向Delphi中传出数组和整数等。