TOLOWER
Section: POSIX Programmer's Manual (3P)
Updated: 2017
Page Index
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This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
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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 .