C data types define in library files

Apart from this primary data type c library provides many very useful data types. Those data types are very necessary to write some program in c. Those data types with header files are:

(1) FILE (stdio.h)

(2) size_t (stdio.h)

(3) fpost_t (stdio.h)

(4) complex (math.h)

(5) ptrdiff_t

(6) wchar_t (stddef.h)

(7) time (dos.h)

(8) dostime_t (dos.h)

(9) date (dos.h)

(10)dosdate_t (dos.h)

(11)COUNTRY (dos.h)

(12) BYTEREGS (dos.h)

(13) WORDREGS (dos.h)

(14) REGS  (dos.h)

(15) time_t (time.h)

(16) clock_t (time.h) etc.

    In c there are three typed of user defined data type. They are structure, union and enum. A enum data type is generally used for defining or creating constants. Above all data types are mainly either structure or union or combination of both. As we known with the help of typedef keyword we can gives a meaningful name of a data type.

What is FILE data type?

    FILE data type has been defined in the header file stdio.h as:

typedef struct {

  short          level;

  unsigned       flags;

  char           fd;

  unsigned char  hold;

  short          bsize;

  unsigned char *buffer, *curp;

  unsigned       istemp;

  short          token;

} FILE;

Hence we can say FILE data type in c special type structure.

Declaration of other data type in c:

(1) complex:

struct complex {

  double  x, y;

};

(2)time:

struct time {

  unsigned char  ti_min;   /* minutes */

  unsigned char  ti_hour;  /* hours */

  unsigned char  ti_hund;  /* hundredths of seconds */

  unsigned char  ti_sec;   /* seconds */

};

(3) BYTEREGS:

struct BYTEREGS  {

  unsigned char  al, ah, bl, bh;

  unsigned char  cl, ch, dl, dh;

};

(4) WORDREGS

struct WORDREGS  {

  unsigned int  ax, bx, cx, dx;

  unsigned int  si, di, cflag, flags;

};

(5) REGS

 union REGS {

  struct  WORDREGS  x;

  struct  BYTEREGS  h;

};