![]() For starters, Borland and Microsoft disagree on file formats for OBJs and import library files (Visual C++ uses the COFF library format while Borland uses OMF). Unfortunately, Borland and Microsoft disagree on several points. In an ideal world, calling a DLL created with Visual C++ would be no more difficult than calling a DLL built with C++Builder. Void _fastcall TForm1::Button3Click(TObject *Sender) Void _fastcall TForm1::Button2Click(TObject *Sender) Void _fastcall TForm1::Button1Click(TObject *Sender) _fastcall TForm1::TForm1(TComponent* Owner) ![]() ![]() Listing C: MAINFORM.CPP - DLLTest program Listing C shows code that calls each the DLL functions from Listing A and B. Finally, add code that calls the DLL functions. Next, add a #include statement in the main unit that includes DLL.H. Select the Project | Add To Project menu option and add the LIB file to the project. Copy the DLL, the import library, and the DLL.H header file from DLL project to this new project. Create a new project in C++Builder and save it to your hard drive. Now we need a C++Builder project that will try to call the DLL functions. LIB extension.Īt this point, you have the three ingredients needed to call a DLL from a C++Builder project: the DLL itself, a header file for function prototypes, and an import library to link with. C++Builder generates both a DLL and an import library with a. Next, compile the project and take a look at the files produced. Make sure that the #define for _BUILD_DLL_ is placed above the include statement for DLL.H. Then copy the code from Listing B and insert it into DLL.CPP. Cut and paste the text from Listing A and insert it into the header file DLL.H. That file will contain a DLL entry point function and some include statements. C++Builder responds by creating a new project with a single source file. Select the DLL icon and click the OK button. To create a test DLL from Listing A and Listing B, open up C++Builder and bring up the Object Repository by selecting the File | New menu option. -įUNCTION int _stdcall StdCallFunction(int Value) įUNCTION int _cdecl CdeclFunction (int Value) įUNCTION int _stdcall StdCallFunction(int Value)įUNCTION int _cdecl CdeclFunction(int Value) This unknown function will act as a measuring stick for DLL functions that don't list their calling convention. Also notice that one function does not explicitly list the calling convention that it uses. When you try to call a DLL that was compiled with Visual C++, most of your headaches will result from disagreements due to calling conventions. Notice that the test code implements two different calling conventions (_stdcall and _cdecl). Listings A and B contain source code for a DLL that can serve as a test DLL. ![]() The last step is to add the code that calls the DLL function. Next, insert a #include statement for the DLL header file in the C++ source file that needs to call one of the DLL functions. To call a DLL function, add the import library to your C++Builder project by selecting the Project | Add To Project menu option in C++Builder. You need to gather three ingredients in order to call a DLL function from your C++Builder program: the DLL itself, a header file with function prototypes, and an import library (you could load the library at runtime instead of using an import library, but we will stick to the import library method for simplicity). A DLL that was created with C++Builder presents fewer roadblocks than one that was made by Visual C++. Before we attempt to tackle DLLs generated by Visual C++, it may be beneficial to review how you call a DLL that was created with C++Builder. * Step 4: Add the import library to your projectĬalling DLL functions from a C++Builder projectĬalling a DLL that was created with Visual C++ presents C++Builder programmers with some unique challenges. * Step 3: Generate an import library for the Visual C++ DLL * Step 2: Examine the linker names in the DLL * Step 1: Identify calling conventions used by the Visual C++ DLL * Calling DLL functions from a C++Builder project Given a DLL and a header file, this article shows you how to call the DLL from your C++Builder project. Often times, the original DLL source code won't be available to you, either because the DLL comes from a third party vendor, or because the 22 year old intern just deleted the \DLL\SRC directory from the network. It is likely that one day your boss will ask you if you can create a GUI with C++Builder that interfaces to an existing 32 bit DLL compiled with Microsoft Visual C++. Using Visual C++ DLLs in a C++Builder Project
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