TOLOWER(3) BSD Library Functions Manual TOLOWER(3)NAME
tolower -- upper case to lower case letter conversion
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <ctype.h>
int
tolower(int c);
DESCRIPTION
The tolower() function converts an upper-case letter to the corresponding lower-case letter.
RETURN VALUES
If the argument is an upper-case letter, the tolower() function returns the corresponding lower-case letter if there is one; otherwise the
argument is returned unchanged.
SEE ALSO ctype(3), isalnum(3), isalpha(3), isascii(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), ascii(7)STANDARDS
The tolower() function conforms to ANSI X3.159-1989 (``ANSI C89'').
CAVEATS
The argument to tolower() must be EOF or representable as an unsigned char; otherwise, the behavior is undefined. See the CAVEATS section of
ctype(3) for more details.
BSD April 17, 2008 BSD
Check Out this Related Man Page
ISALPHA(3) Linux Programmer's Manual ISALPHA(3)NAME
isalnum, isalpha, isascii, isblank, iscntrl, isdigit, isgraph, islower, isprint, ispunct, isspace, isupper, isxdigit - character classifi-
cation routines
SYNOPSIS
#include <ctype.h>
int isalnum(int c);
int isalpha(int c);
int isascii(int c);
int isblank(int c);
int iscntrl(int c);
int isdigit(int c);
int isgraph(int c);
int islower(int c);
int isprint(int c);
int ispunct(int c);
int isspace(int c);
int isupper(int c);
int isxdigit(int c);
DESCRIPTION
These functions check whether c, which must have the value of an unsigned char or EOF, falls into a certain character class according to
the current locale.
isalnum()
checks for an alphanumeric character; it is equivalent to (isalpha(c) || isdigit(c)).
isalpha()
checks for an alphabetic character; in the standard "C" locale, it is equivalent to (isupper(c) || islower(c)). In some locales,
there may be additional characters for which isalpha() is true--letters which are neither upper case nor lower case.
isascii()
checks whether c is a 7-bit unsigned char value that fits into the ASCII character set. This function is a BSD extension and is
also an SVID extension.
isblank()
checks for a blank character; that is, a space or a tab. This function is a GNU extension.
iscntrl()
checks for a control character.
isdigit()
checks for a digit (0 through 9).
isgraph()
checks for any printable character except space.
islower()
checks for a lower-case character.
isprint()
checks for any printable character including space.
ispunct()
checks for any printable character which is not a space or an alphanumeric character.
isspace()
checks for white-space characters. In the "C" and "POSIX" locales, these are: space, form-feed ('f'), newline ('
'), carriage
return ('
'), horizontal tab (' '), and vertical tab ('v').
isupper()
checks for an uppercase letter.
isxdigit()
checks for a hexadecimal digits, i.e. one of 0 1 2 3 4 5 6 7 8 9 a b c d e f A B C D E F.
RETURN VALUE
The values returned are nonzero if the character c falls into the tested class, and a zero value if not.
CONFORMING TO
ANSI - C, BSD 4.3. isascii() is a BSD extension and is also an SVID extension. isblank() is a GNU extension.
NOTE
The details of what characters belong into which class depend on the current locale. For example, isupper() will not recognize an A -
umlaut as an uppercase letter in the default C locale.
SEE ALSO tolower(3), toupper(3), setlocale(3), ascii(7), locale(7)GNU 1995-09-02 ISALPHA(3)