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       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

       isupper, isupper_l — test for an uppercase letter

SYNOPSIS

       #include <ctype.h>

       int isupper(int c);
       int isupper_l(int c, locale_t locale);

DESCRIPTION

       For  isupper():  The  functionality  described  on this reference page is aligned with the
       ISO C standard. Any conflict  between  the  requirements  described  here  and  the  ISO C
       standard is unintentional. This volume of POSIX.1‐2008 defers to the ISO C standard.

       The isupper() and isupper_l() functions shall test whether c is a character of class upper
       in the current locale, or in the locale represented by locale, respectively; see the  Base
       Definitions volume of POSIX.1‐2008, Chapter 7, Locale.

       The  c  argument is an int, the value of which the application shall ensure is a character
       representable as an unsigned char or equal to the value of the macro EOF. If the  argument
       has any other value, the behavior is undefined.

       The  behavior  is  undefined  if  the locale argument to isupper_l() is the special locale
       object LC_GLOBAL_LOCALE or is not a valid locale object handle.

RETURN VALUE

       The isupper() and isupper_l() functions shall return non-zero if c is an uppercase letter;
       otherwise, they shall return 0.

ERRORS

       No errors are defined.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       To  ensure  applications  portability,  especially  across  natural  languages, only these
       functions and the functions in the reference pages listed in the SEE ALSO  section  should
       be used for character classification.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       isalnum(),  isalpha(),  isblank(),  iscntrl(), isdigit(), isgraph(), islower(), isprint(),
       ispunct(), isspace(), isxdigit(), setlocale(), uselocale()

       The Base Definitions volume of POSIX.1‐2008, Chapter 7, Locale, <ctype.h>, <locale.h>

COPYRIGHT

       Portions of this text are reprinted and  reproduced  in  electronic  form  from  IEEE  Std
       1003.1,  2013  Edition,  Standard  for Information Technology -- Portable Operating System
       Interface (POSIX), The Open Group Base Specifications Issue 7, Copyright (C) 2013  by  the
       Institute  of  Electrical  and  Electronics  Engineers,  Inc and The Open Group.  (This is
       POSIX.1-2008 with the  2013  Technical  Corrigendum  1  applied.)  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.unix.org/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 .