Thread: compiler linkage warning

  1. #1
    Registered User
    Join Date
    Jul 2004

    compiler linkage warning

    I don't quite understand with respect to the documentations on linkage compatibility business as shown in the compiler message below:
    1>e:\test\installer\prninst.h(159) : warning C4190: 'ObtainPrinterDriverDirectory' has C-linkage specified, but returns UDT 'std::basic_string<_Elem,_Traits,_Ax>' which is incompatible with C
    1>        with
    1>        [
    1>            _Elem=wchar_t,
    1>            _Traits=std::char_traits<wchar_t>,
    1>            _Ax=std::allocator<wchar_t>
    1>        ]
    I found a prospective problem that's associated with this warning could be that I'm using a string object inside a user-defined struct. Is it legal in the language to declare a string inside a struct?

  2. #2
    Join Date
    Oct 2007
    Inside my computer
    The function is marked as "C", but your are using C++ code inside it. That's why it warns you.
    Quote Originally Posted by Adak View Post
    io.h certainly IS included in some modern compilers. It is no longer part of the standard for C, but it is nevertheless, included in the very latest Pelles C versions.
    Quote Originally Posted by Salem View Post
    You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.

    Outside of your DOS world, your header file is meaningless.

  3. #3
    Registered User
    Join Date
    May 2008
    Quote Originally Posted by stanlvw View Post
    Is it legal in the language to declare a string inside a struct?
    Yes, that's fine. Elysia is right; what's probably goinig on is that your header contains
    extern "C"
    yet the function is returning a C++ type.

    Computer Programming: An Introduction for the Scientifically Inclined

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