NAME
tolower,
tolower_l, _tolower —
upper case to lower case letter
conversion
SYNOPSIS
#include
<ctype.h>
int
tolower(int
c);
int
tolower_l(int
c, locale_t
locale);
int
_tolower(int
c);
DESCRIPTION
The
tolower()
and
tolower_l()
functions convert an upper-case letter to the corresponding lower-case
letter. The
_tolower()
function is identical to tolower() except that
c must be an upper-case letter.
OpenBSD always uses the C locale for these functions, ignoring the global locale, the thread-specific locale, and the locale argument.
RETURN VALUES
If the argument to the tolower() or
tolower_l() function is an upper-case letter, the
corresponding lower-case letter is returned if there is one; otherwise the
argument is returned unchanged. If the argument to the
_tolower() function is an upper-case letter, the
corresponding lower-case letter is returned; otherwise the output is
undefined.
ENVIRONMENT
On systems supporting non-ASCII single-byte character encodings,
the results of tolower() and
_tolower() may depend on the
LC_CTYPE
locale(1).
SEE ALSO
isalnum(3), isalpha(3), isascii(3), isblank(3), iscntrl(3), isdigit(3), isgraph(3), islower(3), isprint(3), ispunct(3), isspace(3), isupper(3), isxdigit(3), stdio(3), toascii(3), toupper(3), towlower(3), ascii(7)
STANDARDS
The tolower() and
_tolower() functions conform to
ANSI X3.159-1989 (“ANSI C89”),
and tolower_l() to IEEE Std
1003.1-2008 (“POSIX.1”).
HISTORY
The tolower() function first appeared in
Version 7 AT&T UNIX and acquired the
current semantics in AT&T System III
UNIX, where _tolower() first appeared.
The tolower_l() function has been
available since OpenBSD 6.2.
CAVEATS
The argument c must be
EOF or representable as an unsigned
char; otherwise, the result is undefined.