Difference between C++ dlls and Delphi dlls

Is there a real difference between C++ dlls and Delphi dlls? A application loads only C++ dlls. Changing calling convention to cdecl is of no use Is there a way to find whether a dll is a C++ dll? What is the advantage of that dll? I mean a Delphi dll can have parameters and/or return type of Del开发者_StackOverflow社区phi. Like that C++ dll may have some exclusive data type/

Thanks for any hint

C++ dlls can, of course, use or expose C++-specific items (C++ classes, template functions, etc.), and a Delphi DLL could expose Delphi-specific items (sets, strings, etc.). But if both are written properly, and only use things other languages can use too, there should be no difference.

Fact is that not all C++ or Delphi DLLs are written properly. Also the default calling convention in Delphi is register (__fastcall in C++Builder), while C and C++ by default use cdecl. But generally both languages should use stdcall.

The only way to use a DLL is to either get a header file (.h) for it, or a Delphi import unit. The .h file can be translated into an import unit. If you only have a DLL but none of these, it doesn't make much sense to try to guess the parameters of functions.

If you look at the DLL with TDUMP.exe or Dependency Walker, you might get a hint, as was said in another answer. Dependency on e.g. msvcrtXX.dll might be a good hint it is a C++ DLL.

You might also try to get a .tlb from the DLL. You can do this in the IDE (From memory: "Component menu" - "import component" or some such).

If you want to know the calling convention, read this, especially the part about finding out the calling convention.

Addition

Some C++ programmers forget to wrap their declarations in extern "C" blocks, so the exported functions are mangled. This could tell you which parameters are required, but you get ugly names. For this, Dependency Walker is a great help, as it can translate them (for VC++ generated or compatible DLLs at least). It makes using those functions from a different C++ compiler or a C compiler pretty hard, though.

You can use Dependency Walker to examine the functions in DLLs:

http://dependencywalker.com/