Thread: How do they do it???

This is the code from Turbo C 2.01's DIR.H file.

Code:

#if __STDC__
#define _Cdecl
#else
#define _Cdecl	cdecl
#endif

#if     !defined(__DIR_DEF_)
#define __DIR_DEF_

struct	ffblk	{
	char		ff_reserved[21];
	char		ff_attrib;
	unsigned	ff_ftime;
	unsigned	ff_fdate;
	long		ff_fsize;
	char		ff_name[13];
};

#define WILDCARDS 0x01
#define EXTENSION 0x02
#define FILENAME  0x04
#define DIRECTORY 0x08
#define DRIVE	  0x10

#define MAXPATH   80
#define MAXDRIVE  3
#define MAXDIR	  66
#define MAXFILE   9
#define MAXEXT	  5

int	 _Cdecl chdir		(const char *path);
int	 _Cdecl findfirst	(const char *path, struct ffblk *ffblk, 
				 int attrib);
int	 _Cdecl findnext	(struct ffblk *ffblk);
void	 _Cdecl fnmerge		(char *path,const char *drive,const char *dir,
				 const char *name, const char *ext);
int	 _Cdecl fnsplit		(const char *path, char *drive, char *dir, 
				 char *name, char *ext);
int	 _Cdecl getcurdir	(int drive, char *directory);
char	*_Cdecl getcwd		(char *buf, int buflen);
int	 _Cdecl getdisk		(void);
int	 _Cdecl mkdir		(const char *path);
char	*_Cdecl mktemp		(char *template);
int	 _Cdecl rmdir		(const char *path);
char	*_Cdecl searchpath	(const char *file);
int	 _Cdecl setdisk		(int drive);

#endif

How do they make all of the functions work Is there some secret that I don't know about?

then where does it tell the OS to make those calls? All that I see are definitions of dirves, etc. and definitions of funtions.

DLLs are in Windows, not DOS.