in reply to Re^2: Perl program calling external .dll functions
in thread Perl program calling external .dll functions

Assuming the STL even defines the internal storage format of a String, I don't know what it is. Whatever it is, it's definitely not a uint32_t as you're telling Win32::API it is.

"P" passes a pointer to the a copy of the scalar's string buffer. Don't know if your String is compatible with what you are passing were you to use "P". But you're not using "P". You're using "L".

You've provided no useful data about the type. You didn't provide the calling convention used.

I think you'd be much better off using Inline::CPP.

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Re^4: Perl program calling external .dll functions
by BrowserUk (Patriarch) on Mar 18, 2011 at 07:02 UTC

    Given the mention of Visual Basic, I'd assume that the String type mentioned is a the VB type String. Passed by reference this would render an address, which on a 32-bit platform will usually come through successfully as a 32-bit numeric. Not a great idea, but it would mostly work.

    See kb106553 for some info.

    Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
    "Science is about questioning the status quo. Questioning authority".
    In the absence of evidence, opinion is indistinguishable from prejudice.
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      Passed by reference this would render an address, which on a 32-bit platform will usually come through successfully as a 32-bit numeric.

      I thik I've used "L" to pass pointers — specifically, for nullable pointers — but I didn't use hardcoded address 123456789 or '    '. (Is that a weird way of saying NULL?)

      I'd assume that the String type mentioned is a the VB type String.

      He said the function is written in C++, I figured it was C++'s String. He really is being unclear if he can't even communicate which language's class he's talking about.

      But even if he were to communicate which class he's using clearly, it doesn't say anything about the structure of the type, necessary knowledge for building an instance of one.

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        I didn't use hardcoded address 123456789

        That's not a hardcoded address, just a string containing numbers.

        or ' '. (Is that a weird way of saying NULL?)

        Again, just a string containing four spaces.

        He really is being unclear if he can't even communicate which language's class he's talking about.

        Agreed. Reading between the lines, I'd guess that he's not a C++ programmer, and all he has is a VB example he's attempting to interpret.

        , it doesn't say anything about the structure of the type, necessary knowledge for building an instance of one.

        I've never used VB, but looking at the linked article I guess that the VB String type is compatible with c/C++ char*.

        I can't test anything because my 32-bit perl Win32::API setup is broken. Maybe this info will help you help him.

        Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
        "Science is about questioning the status quo. Questioning authority".
        In the absence of evidence, opinion is indistinguishable from prejudice.
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