ex20c.cpp

不好意思

// Ex20c.cpp : Defines the initialization routines for the DLL.
//

#include "stdafx.h"
#include "Ex20c.h"
#include "math.h"

#ifdef _DEBUG
#define new DEBUG_NEW
#endif

//
//	Note!
//
//		If this DLL is dynamically linked against the MFC
//		DLLs, any functions exported from this DLL which
//		call into MFC must have the AFX_MANAGE_STATE macro
//		added at the very beginning of the function.
//
//		For example:
//
//		extern "C" BOOL PASCAL EXPORT ExportedFunction()
//		{
//			AFX_MANAGE_STATE(AfxGetStaticModuleState());
//			// normal function body here
//		}
//
//		It is very important that this macro appear in each
//		function, prior to any calls into MFC.  This means that
//		it must appear as the first statement within the 
//		function, even before any object variable declarations
//		as their constructors may generate calls into the MFC
//		DLL.
//
//		Please see MFC Technical Notes 33 and 58 for additional
//		details.
//

// CEx20cApp

BEGIN_MESSAGE_MAP(CEx20cApp, CWinApp)
END_MESSAGE_MAP()


// CEx20cApp construction

CEx20cApp::CEx20cApp()
{
	// TODO: add construction code here,
	// Place all significant initialization in InitInstance
}


// The one and only CEx20cApp object

CEx20cApp theApp;


// CEx20cApp initialization

BOOL CEx20cApp::InitInstance()
{
	CWinApp::InitInstance();

	return TRUE;
}

extern "C" __declspec(dllexport) double Ex20cSquareRoot(double d)
{
    AFX_MANAGE_STATE(AfxGetStaticModuleState());
    TRACE("Entering Ex20cSquareRoot\n");
    if (d >= 0.0) {
        return sqrt(d);
    }
    AfxMessageBox("Can抰 take square root of a negative number.");
    return 0.0;
}