it gave me an error message: Can't call method "Call" on an undefined value at (eval 4) line 2.

From the error message, it seems likely that it either: failed to load the dll; or locate the function. If you added an error check, it might tell you which, and why. Eg: 

Win32::API->Import(
    $S{DLL_path}, 
    'int RegisterClient2(int *pnClientId, char *pszIPAddress)'
) or die $^E;

[download]
use Inline C => Config => MYEXTLIB => 'd:\path\to\CrappyLibrary.dll',

That should point to the CrappyLibrary.lib, not the .dll. You do have the .lib file?

Do you have the utility: dumpbin.exe on your system?

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.
RIP an inspiration; A true Folk's Guy

In reply to Re: Calling a function form an external DLL with Inline::C on windows by BrowserUk
in thread Calling a function form an external DLL with Inline::C on windows by Anonymous Monk

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