PROLOG

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of
       this interface may differ (consult the corresponding Linux  manual  page  for  details  of
       Linux behavior), or the interface may not be implemented on Linux.

NAME

       ctype.h — character types

SYNOPSIS

       #include <ctype.h>

DESCRIPTION

       Some  of  the  functionality  described on this reference page extends the ISO C standard.
       Applications shall define the appropriate feature test macro (see  the  System  Interfaces
       volume of POSIX.1‐2017, Section 2.2, The Compilation Environment) to enable the visibility
       of these symbols in this header.

       The  <ctype.h>  header  shall  define  the  locale_t  type  as  described  in  <locale.h>,
       representing a locale object.

       The  following  shall be declared as functions and may also be defined as macros. Function
       prototypes shall be provided for use with ISO C standard compilers.

           int   isalnum(int);
           int   isalnum_l(int, locale_t);
           int   isalpha(int);
           int   isalpha_l(int, locale_t);
           int   isascii(int);
           int   isblank(int);
           int   isblank_l(int, locale_t);
           int   iscntrl(int);
           int   iscntrl_l(int, locale_t);
           int   isdigit(int);
           int   isdigit_l(int, locale_t);
           int   isgraph(int);
           int   isgraph_l(int, locale_t);
           int   islower(int);
           int   islower_l(int, locale_t);
           int   isprint(int);
           int   isprint_l(int, locale_t);
           int   ispunct(int);
           int   ispunct_l(int, locale_t);
           int   isspace(int);
           int   isspace_l(int, locale_t);
           int   isupper(int);
           int   isupper_l(int, locale_t);
           int   isxdigit(int);
           int   isxdigit_l(int, locale_t);
           int   toascii(int);
           int   tolower(int);
           int   tolower_l(int, locale_t);
           int   toupper(int);
           int   toupper_l(int, locale_t);

       The <ctype.h> header shall define the following as macros:

           int   _toupper(int);
           int   _tolower(int);

       The following sections are informative.

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       <locale.h>

       The System Interfaces volume of POSIX.1‐2017, Section 2.2,  The  Compilation  Environment,
       isalnum(),  isalpha(),  isascii(),  isblank(), iscntrl(), isdigit(), isgraph(), islower(),
       isprint(), ispunct(), isspace(), isupper(),  isxdigit(),  mblen(),  mbstowcs(),  mbtowc(),
       setlocale(), toascii(), tolower(), _tolower(), toupper(), _toupper(), wcstombs(), wctomb()

COPYRIGHT

       Portions  of  this  text  are  reprinted  and  reproduced in electronic form from IEEE Std
       1003.1-2017, Standard for Information Technology -- Portable  Operating  System  Interface
       (POSIX),  The  Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by
       the Institute of Electrical and Electronics Engineers, Inc and The  Open  Group.   In  the
       event  of  any  discrepancy  between this version and the original IEEE and The Open Group
       Standard, the original IEEE and The Open Group  Standard  is  the  referee  document.  The
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

       Any  typographical  or  formatting errors that appear in this page are most likely to have
       been introduced during the conversion of the source files to man page  format.  To  report
       such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .