ISLOWER(3) | Library Functions Manual | ISLOWER(3)

# NAME

`islower` —
lower-case character test

# LIBRARY

Standard C Library (libc, -lc)

# SYNOPSIS

`#include <ctype.h>`

int
`islower`(int c);

# DESCRIPTION

The `islower`() function tests for any lower-case letter for which none of iscntrl(3), isdigit(3), ispunct(3), or isspace(3) is true. In the ``C'' locale, `islower`() returns true only for the characters defined as lower-case letters.

# RETURN VALUES

The `islower`() function returns zero if the character tests false and returns non-zero if the character tests true.

# SEE ALSO

ctype(3), isalnum(3), isalpha(3), isascii(3), isblank(3), iscntrl(3), isdigit(3), isgraph(3), isprint(3), ispunct(3), isspace(3), isupper(3), isxdigit(3), stdio(3), toascii(3), tolower(3), toupper(3), ascii(7)

# STANDARDS

The `islower`() function conforms to ANSI X3.159-1989 (“ANSI C89”).

# CAVEATS

The argument to `islower`() must be `EOF` or representable as an unsigned char; otherwise, the behavior is undefined. See the CAVEATS section of ctype(3) for more details.

April 17, 2008 | NetBSD 9.5