C语言程序怎么编译成dll文件供其他语言调用？

C程序编译成dll文件只不过是在要公开的接口函数声明前面加上几个特定的修饰符而已。
下面是个例子，用dev-cpp建了个dll的默认文档
/*dll.h文件*/
#ifndef _DLL_H_
#define _DLL_H_
#if BUILDING_DLL
# define DLLIMPORT __declspec (dllexport)
#else /* Not BUILDING_DLL */
# define DLLIMPORT __declspec (dllimport)
#endif /* Not BUILDING_DLL */

DLLIMPORT void HelloWorld (void);

#endif /* _DLL_H_ */
/*dllmain.c文件*/
/* Replace "dll.h" with the name of your header */
#include "dll.h"
#include
#include
#include
DLLIMPORT void HelloWorld ()
{
MessageBox (0, "Hello World from DLL!/n", "Hi", MB_ICONINFORMATION);
}

BOOL APIENTRY DllMain (HINSTANCE hInst /* Library instance handle. */ ,
DWORD reason /* Reason this function is being called. */ ,
LPVOID reserved /* Not used. */ )
{
switch (reason)
{
case DLL_PROCESS_ATTACH:
break;
case DLL_PROCESS_DETACH:
break;
case DLL_THREAD_ATTACH:
break;
case DLL_THREAD_DETACH:
break;
}
/* Returns TRUE on success, FALSE on failure */
return TRUE;
}

具体请参考jilei08124的CSDN博客