tolower

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



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
       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(3P)