第一次仔细地看这种代码，都是从网上复制做了略微改动后的产物。代码如下：
#include "reg52.h"
unsigned char Count;
sbit Xiang=P1^2 ; //蜂鸣器响
unsigned char code SONG[] ={
0x26,0x20,0x20,0x20,0x20,0x20,0x26,0x10,0x20,0x10,0x20,0x80,0x26,0x20,0x30,0x20,
0x30,0x20,0x39,0x10,0x30,0x10,0x30,0x80,0x26,0x20,0x20,0x20,0x20,0x20,0x1c,0x20,
0x20,0x80,0x2b,0x20,0x26,0x20,0x20,0x20,0x2b,0x10,0x26,0x10,0x2b,0x80,0x26,0x20,
0x30,0x20,0x30,0x20,0x39,0x10,0x26,0x10,0x26,0x60,0x40,0x10,0x39,0x10,0x26,0x20,
0x30,0x20,0x30,0x20,0x39,0x10,0x26,0x10,0x26,0x80,0x26,0x20,0x2b,0x10,0x2b,0x10,
0x2b,0x20,0x30,0x10,0x39,0x10,0x26,0x10,0x2b,0x10,0x2b,0x20,0x2b,0x40,0x40,0x20,
0x20,0x10,0x20,0x10,0x2b,0x10,0x26,0x30,0x30,0x80,0x18,0x20,0x18,0x20,0x26,0x20,
0x20,0x20,0x20,0x40,0x26,0x20,0x2b,0x20,0x30,0x20,0x30,0x20,0x1c,0x20,0x20,0x20,
0x20,0x80,0x1c,0x20,0x1c,0x20,0x1c,0x20,0x30,0x20,0x30,0x60,0x39,0x10,0x30,0x10,
0x20,0x20,0x2b,0x10,0x26,0x10,0x2b,0x10,0x26,0x10,0x26,0x10,0x2b,0x10,0x2b,0x80,
0x18,0x20,0x18,0x20,0x26,0x20,0x20,0x20,0x20,0x60,0x26,0x10,0x2b,0x20,0x30,0x20,
0x30,0x20,0x1c,0x20,0x20,0x20,0x20,0x80,0x26,0x20,0x30,0x10,0x30,0x10,0x30,0x20,
0x39,0x20,0x26,0x10,0x2b,0x10,0x2b,0x20,0x2b,0x40,0x40,0x10,0x40,0x10,0x20,0x10,
0x20,0x10,0x2b,0x10,0x26,0x30,0x30,0x80,0x00,
0x30,0x1C,0x10,0x20,0x40,0x1C,0x10,0x18,0x10,0x20,0x10,0x1C,0x10,0x18,0x40,0x1C,
0x20,0x20,0x20,0x1C,0x20,0x18,0x20,0x20,0x80,0xFF,0x20,0x30,0x1C,0x10,0x18,0x20,
0x15,0x20,0x1C,0x20,0x20,0x20,0x26,0x40,0x20,0x20,0x2B,0x20,0x26,0x20,0x20,0x20,
0x30,0x80,0xFF,0x20,0x20,0x1C,0x10,0x18,0x10,0x20,0x20,0x26,0x20,0x2B,0x20,0x30,
0x20,0x2B,0x40,0x20,0x20,0x1C,0x10,0x18,0x10,0x20,0x20,0x26,0x20,0x2B,0x20,0x30,
0x20,0x2B,0x40,0x20,0x30,0x1C,0x10,0x18,0x20,0x15,0x20,0x1C,0x20,0x20,0x20,0x26,
0x40,0x20,0x20,0x2B,0x20,0x26,0x20,0x20,0x20,0x30,0x80,0x20,0x30,0x1C,0x10,0x20,
0x10,0x1C,0x10,0x20,0x20,0x26,0x20,0x2B,0x20,0x30,0x20,0x2B,0x40,0x20,0x15,0x1F,
0x05,0x20,0x10,0x1C,0x10,0x20,0x20,0x26,0x20,0x2B,0x20,0
由于C++编译器需要支持函数的重载，会改变函数的名称，与标准C中函数名称不同。然而dll的导出函数通常是标准C定义的，让标准C编写的dll函数定义在C和C++编译器下都能编译通过，通常会使用以下的格式：（这个格式在很多成熟的代码中很常见）
#ifdef __cplusplus extern "C"
{
#endif
// ......
