ctype.h

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/* The <ctype.h> header file defines some macros used to identify characters.
 * It works by using a table stored in chartab.c. When a character is presented
 * to one of these macros, the character is used as an index into the table
 * (__ctype) to retrieve a byte.  The relevant bit is then extracted.
 */

#ifndef _CTYPE_H
#define _CTYPE_H

#ifndef _ANSI_H
#include <ansi.h>
#endif

extern char     __ctype[];      /* property array defined in chartab.c */

#define _U              0x01    /* this bit is for upper-case letters [A-Z] */
#define _L              0x02    /* this bit is for lower-case letters [a-z] */
#define _N              0x04    /* this bit is for numbers [0-9] */
#define _S              0x08    /* this bit is for white space \t \n \f etc */
#define _P              0x10    /* this bit is for punctuation characters */
#define _C              0x20    /* this bit is for control characters */
#define _X              0x40    /* this bit is for hex digits [a-f] and [A-F]*/

/* Function Prototypes (have to go before the macros). */
_PROTOTYPE( int isalnum, (int  _c)  );  /* alphanumeric [a-z], [A-Z], [0-9] */
_PROTOTYPE( int isalpha, (int  _c)  );  /* alphabetic */
_PROTOTYPE( int iscntrl, (int  _c)  );  /* control characters */
_PROTOTYPE( int isdigit, (int  _c)  );  /* digit [0-9] */
_PROTOTYPE( int isgraph, (int  _c)  );  /* graphic character */
_PROTOTYPE( int islower, (int  _c)  );  /* lower-case letter [a-z] */
_PROTOTYPE( int isprint, (int  _c)  );  /* printable character */
_PROTOTYPE( int ispunct, (int  _c)  );  /* punctuation mark */
_PROTOTYPE( int isspace, (int  _c)  );  /* white space sp, \f, \n, \r, \t, \v*/
_PROTOTYPE( int isupper, (int  _c)  );  /* upper-case letter [A-Z] */
_PROTOTYPE( int isxdigit,(int  _c)  );  /* hex digit [0-9], [a-f], [A-F] */
_PROTOTYPE( int tolower, (int  _c)  );  /* convert to lower-case */
_PROTOTYPE( int toupper, (int  _c)  );  /* convert to upper-case */
_PROTOTYPE( int toascii, (int  _c)  );  /* convert to 7-bit ASCII */

/* Macros for identifying character classes. */
#define isalnum(c)      ((__ctype+1)[c]&(_U|_L|_N))
#define isalpha(c)      ((__ctype+1)[c]&(_U|_L))
#define iscntrl(c)      ((__ctype+1)[c]&_C)
#define isgraph(c)      ((__ctype+1)[c]&(_P|_U|_L|_N))
#define ispunct(c)      ((__ctype+1)[c]&_P)
#define isspace(c)      ((__ctype+1)[c]&_S)
#define isxdigit(c)     ((__ctype+1)[c]&(_N|_X))

#define isdigit(c)      ((unsigned) ((c)-'0') < 10)
#define islower(c)      ((unsigned) ((c)-'a') < 26)
#define isupper(c)      ((unsigned) ((c)-'A') < 26)
#define isprint(c)      ((unsigned) ((c)-' ') < 95)
#define isascii(c)      ((unsigned) (c) < 128)

#define toascii(c)      ((c) & 0x7f)

#endif /* _CTYPE_H */

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