关于 DLL 的调用问题，好象难倒了一大堆... (200分)

ddev · 2001-08-23

问题：关于 DLL 的调用问题 我在 VC5 中做了一个关于 ACCESS 的处理函数。但在 Delphi 中调用时，却总出现外部调用异常。 能指导一下吗？ daoCreateDatabase()调用正常； 但daoCreateTable()就出错，问题可能出现在 DAOFIELDDEF** 的调用参数上。对于这种指向数组的 指针，不知在 Delphi 中应该处理？ 源代码如下： //****************************************************************************************// VC5 DLL //****************************************************************************************// #include <afxdao.h> typedef struct tagDaoFieldDef{ char fldName[40]; int fldType; int fldSize; bool fldRequired; bool fldAllowZeroLength; }DAOFIELDDEF; extern "C"{ __declspec(dllexport) bool __stdcall daoCreateDatabase(LPCTSTR); __declspec(dllexport) bool __stdcall daoCreateTable(LPCTSTR, LPCTSTR, DAOFIELDDEF**, int); }; //-----------------------------------------------------------------------------------------// #include "DaoAPI.h" extern "C"{ __declspec(dllexport) bool __stdcall daoCreateDatabase(LPCTSTR lpszDatabaseName) { bool bSuccess = FALSE; CDaoDatabase* lpDatabase = new CDaoDatabase(); try{ lpDatabase->Create(lpszDatabaseName); if (lpDatabase->IsOpen()) lpDatabase->Close(); bSuccess = TRUE; } catch(CDaoException& E){ bSuccess = FALSE; E.Delete(); } catch(CMemoryException & E){ bSuccess = FALSE; E.Delete(); } delete lpDatabase; lpDatabase = NULL; return bSuccess; } __declspec(dllexport) bool __stdcall daoCreateTable(LPCTSTR lpszDatabaseName, LPCTSTR lpszTableName, DAOFIELDDEF** lpFieldDefs, int nCount) { bool bSuccess = FALSE; CDaoDatabase* lpDatabase = new CDaoDatabase(); try{ lpDatabase->Open(lpszDatabaseName); CDaoTableDef* lpTableDef = new CDaoTableDef(lpDatabase); CDaoFieldInfo FieldInfo; try{ lpTableDef->Create(lpszTableName); for(int i = 0; i < nCount; i++) { DAOFIELDDEF* lpFieldDef = (DAOFIELDDEF*)(lpFieldDefs); if (lpFieldDef != NULL) { FieldInfo.m_strName = lpFieldDef->fldName; FieldInfo.m_nType = lpFieldDef->fldType; FieldInfo.m_lSize = lpFieldDef->fldSize; FieldInfo.m_bRequired = lpFieldDef->fldRequired; FieldInfo.m_bAllowZeroLength = lpFieldDef->fldAllowZeroLength; lpTableDef->CreateField(FieldInfo); } } lpTableDef->Append(); bSuccess = TRUE; } catch(CDaoException& E){ bSuccess = FALSE; E.Delete(); } catch(CMemoryException & E){ bSuccess = FALSE; E.Delete(); } lpTableDef->Close(); delete lpTableDef; lpTableDef = NULL; } catch(CDaoException& E){ bSuccess = FALSE; E.Delete(); } catch(CMemoryException & E){ bSuccess = FALSE; E.Delete(); } delete lpDatabase; lpDatabase = NULL; return bSuccess; } } //-----------------------------------------------------------------------------------------// //****************************************************************************************// Delphi Call //****************************************************************************************// unit DaoAPI; interface uses   windows; const     dbBoolean         = 1;     dbByte            = 2;     dbInteger         = 3;     dbLong            = 4;     dbCurrency        = 5;     dbSingle          = 6;     dbDouble          = 7;     dbDate            = 8;     dbBinary          = 9;     dbText            = 10;     dbLongBinary      = 11;     dbMemo            = 12;     dbGUID            = 15;     dbBigInt          = 16;     dbVarBinary       = 17;     dbChar            = 18;     dbNumeric         = 19;     dbDecimal         = 20;     dbFloat           = 21;     dbTime            = 22;     dbTimeStamp       = 23; type   PDaoFieldDef = ^TDaoFieldDef;   TDaoFieldDef = record  fldName:            string[40];  fldType:            Longint;  fldSize:            Longint;  fldRequired:        Boolean;  fldAllowZeroLength: Boolean;   end;   PDaoFieldDefArr = ^TDaoFieldDefArr;   TDaoFieldDefArr = array of PDaoFieldDef; function daoCreateDatabase(lpszDatabaseName: LPCTSTR): Boolean; stdcall; function daoCreateTable(lpszDatabaseName: LPCTSTR; lpszTableName: LPCTSTR;   lpFieldDefList: PDaoFieldDefArr; nCount: Longint): Boolean; stdcall; implementation         function daoCreateDatabase; stdcall; external 'DaoAPI.dll'; function daoCreateTable; stdcall; external 'DaoAPI.dll'; end. //-----------------------------------------------------------------------------------------// unit DemoFrm; interface uses   Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,   StdCtrls; type   TDemoForm = class(TForm)     Button1: TButton;     Edit1: TEdit;     Edit2: TEdit;     ResultEdit: TEdit;     Button2: TButton;     procedure Button1Click(Sender: TObject);     procedure Button2Click(Sender: TObject);   private     { Private declarations }   public     { Public declarations }   end; var   DemoForm: TDemoForm; implementation uses DaoAPI, db; {$R *.DFM} procedure TDemoForm.Button1Click(Sender: TObject); var   bSuccess: Boolean; begin   bSuccess := daoCreateDatabase(PChar(Edit1.Text));   if bSuccess then     ResultEdit.Text := 'Success' else     ResultEdit.Text := 'Fail!'; end; procedure TDemoForm.Button2Click(Sender: TObject); var   bSuccess: Boolean;   FieldDefs: PDaoFieldDefArr; begin   FieldDefs := New(PDaoFieldDefArr);   SetLength(FieldDefs^, 4);     FieldDefs^[0] := New(PDaoFieldDef);     FieldDefs^[0].fldName := '编号';     FieldDefs^[0].fldType := dbText;     FieldDefs^[0].fldSize := 16;     FieldDefs^[0].fldRequired := False;     FieldDefs^[0].fldAllowZeroLength := True;     FieldDefs^[1] := New(PDaoFieldDef);     FieldDefs^[1].fldName := '名称';     FieldDefs^[1].fldType := dbText;     FieldDefs^[1].fldSize := 80;     FieldDefs^[1].fldRequired := False;     FieldDefs^[1].fldAllowZeroLength := True;     FieldDefs^[2] := New(PDaoFieldDef);     FieldDefs^[2].fldName := '年龄';     FieldDefs^[2].fldType := dbLong;     FieldDefs^[2].fldSize := 0;     FieldDefs^[2].fldRequired := False;     FieldDefs^[2].fldAllowZeroLength := False;     FieldDefs^[3] := New(PDaoFieldDef);     FieldDefs^[3].fldName := '备注';     FieldDefs^[3].fldType := dbMemo;     FieldDefs^[3].fldSize := 10;     FieldDefs^[3].fldRequired := False;     FieldDefs^[3].fldAllowZeroLength := True;   bSuccess := daoCreateTable(PChar(Edit1.Text), PChar(Edit2.Text), FieldDefs, 4);   if bSuccess then     ResultEdit.Text := 'Success' else     ResultEdit.Text := 'Fail!'; end; end. //-----------------------------------------------------------------------------------------//

LLLYJ · 2001-08-24

在C/C++中的函数调用约定与Pascal中是不一样的，Pascal是顺序传递参数，而C/C++正好 相反，你试试看。

ddev · 2001-08-26

这个问题怎么会没人回答？？？？？？？ 这么难？

左轻侯 · 2001-08-27

我没有仔细看你的代码，能不能试试把   PDaoFieldDefArr = ^TDaoFieldDefArr;   TDaoFieldDefArr = array of PDaoFieldDef; 改成   PDaoFieldDefArr = ^TDaoFieldDefArr;   TDaoFieldDefArr = ^PDaoFieldDefArr; C和delphi对array的处理应该不能通用的。 如果还是不能解决，建议你参考一下一个开源的控制KADao 是一个对DAO封装得很好的控件，完全Pascal源码 你的问题应该能够找到答案 到google上搜一下，实在找不到，我寄给你

Fenix · 2001-08-27

出个什么错，讲一下。

ddev · 2001-08-27

to 左轻侯： 谢谢你的答复，可以把 KaDao 的源码发给我吗？ddev@china.com。谢谢

左轻侯 · 2001-08-28

我已经上传 http://delphi.itschem.com/dispdoc.asp?id=158

ddev · 2001-09-07

多人接受答案了。

关于 DLL 的调用问题，好象难倒了一大堆... (200分)

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