This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface

       None.

       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 .

IEEE/The Open Group                                   2017                                       ctype.h(7POSIX)

       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, Section2.2,
       TheCompilationEnvironment) 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);

       Thefollowingsectionsareinformative.

       None.

       ctype.h — character types

       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.

       None.

<locale.h>

       The System Interfaces volume of  POSIX.1‐2017,  Section2.2,  TheCompilationEnvironment,  isalnum(),
       isalpha(),  isascii(),  isblank(),  iscntrl(),  isdigit(),  isgraph(),  islower(),  isprint(), ispunct(),
       isspace(), isupper(), isxdigit(),  mblen(),  mbstowcs(),  mbtowc(),  setlocale(),  toascii(),  tolower(),
       _tolower(), toupper(), _toupper(), wcstombs(), wctomb()

       #include <ctype.h>