TOLOWER(3)                 POSIX Programmer's Manual                TOLOWER(3)



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

NAME
       tolower, tolower_l -- transliterate uppercase characters to lowercase

SYNOPSIS
       #include <ctype.h>

       int tolower(int _c);
       int tolower_l(int _c, locale_t locale);

DESCRIPTION
       For tolower(): 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.1-2017 defers to the ISO C standard.

       The tolower() and tolower___l() functions have as a domain a type int,
       the value of which is representable as an unsigned char or the value of
       EOF. If the argument has any other value, the behavior is undefined. If
       the argument of tolower() or tolower___l() represents an uppercase
       letter, and there exists a corresponding lowercase letter as defined by
       character type information in the current locale or in the locale
       represented by locale, respectively (category LC__CTYPE), the result
       shall be the corresponding lowercase letter. All other arguments in the
       domain are returned unchanged.

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

RETURN VALUE
       Upon successful completion, the tolower() and tolower___l() functions
       shall return the lowercase letter corresponding to the argument passed;
       otherwise, they shall return the argument unchanged.

ERRORS
       No errors are defined.

       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       None.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       setlocale(), uselocale()

       The Base Definitions volume of POSIX.1-2017, Chapter _7, Locale,
       <ctype.h>, <locale.h>

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 .



IEEE/The Open Group                  2017                           TOLOWER(3)
