Home>Network programming tutorial>Delphi tutorial

Dynamic link libraries call each other between VC and Delphi

Author：Eve Cole Update Time：2025-02-05 22:48:01

    Delphi calls VC's DLL

  1. DLL declaration format in VC:

    Extern “C” void __declspec(dllexport) __stdcall ShowMess(HWND hwnd, char* mess);

    The output format is: _ShowMess@8, "8" is the number of bytes of function parameters

    In order to avoid name splitting, the following methods can be used to solve the problem:

    1. Do not add __stdcall in the statement and use the VC default format __cdecl. However, in Delphi, you must indicate that the calling format is cdecl.

    2. Add def file in VC project, such as:

    LIBRARY

    EXPORTS

    ShowMess@1

    Then the output function name in the DLL is not split.

  2. Calling format in Delphi:

    PRocedure ShowMess (h:HWND; mess:PChar); Stdcall;{Cdecl;} external LibName;

    If there is no Stdcall or Cdecl statement, Delphi defaults to the Register(FastCall) calling format.

  3. Note that the alignment formats of Delphi and VC are different. When defining the structure in VC, use the following format:

    #pragma pack(4)

    //structure definition

    #pragma pack()

  4. Commonly used tools:

TDump.exe - provided by Delphi 4 and C++ Builder 3

Impdef.exe and Implib.exe - provided by C++ Builder 3

DumpBin.exe-provided by VC5.0

Lib.exe-provided by VC5.0

VC calls Delphi's DLL

    1. Statement format in Delphi:

      Function ShowDialog( hMainWnd:THandle; Msg:PChar ):integer; stdcall;

      Names are not split when outputting to a Dll file.

    2. Calling format in VC:

    extern "C" __declspec(dllimport) int __stdcall ShowDialog( HWND hwnd,char* Msg );

    ． If __stdcall is included, the corresponding function name in the Lib file is required to be split. The following steps can be used to generate the Lib file:

    ． Use Impdef.exe to generate a def file in the format: Impdef def file name dll file name

    ． Manually adjust def file parameters, such as changing ShowDialog to ShowDialog@8

    ． Use Lib.exe to generate lib files in the format: Lib /def:def file name

    ． If there is no __stdcall in the statement, the default calling format is still stdcall, but name splitting is not required. Use the following batch file MkLib.bat to generate a Lib file:

    @echo off

    if %1.==. goto error

    impdef %1.def %1.dll

    lib /def:%1.def

    goto end

    :error

    echo Usage: MkLib DllName

    echo Note: Don't add extension ".dll" to parameter "DllName"

    :end

    Related Articles