一个初级DLL头文件的写法

来自《windows程序设计》：请理解每一句的意思

#ifdef _cplusplus
#define EXPORT extern "C" _declspec(dllexport)
#else
#define EXPORT _declspec(dllexport)
#endif

EXPORT BOOL CALLBACK CenterText(HDC, PRECT, PCSTR);


OK，我们可以写实现文件了：

#include <windows.h>
#include "dll.h"

int WINAPI DllMain(HINSTANCE hInstance,
                 DWORD fdwReason,
                 PVOID pvReserved) {
    return TRUE;
}

EXPORT BOOL CALLBACK CenterText(HDC hdc,
                                PRECT pRect,
                                PCSTR cStr) {
    int iLength;
    SIZE size;

    iLength = strlen(cStr);
    GetTextExtentPoint32(hdc, cStr, iLength, &size);
    TextOut(hdc, (pRect->right - pRect->left - size.cx) / 2,
        (pRect->bottom - pRect->top - size.cy) / 2,
        cStr, iLength);
}