islower
—
lower-case character test
Standard C Library (libc, -lc)
#include <ctype.h>
int
islower
(int
c);
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.
The islower
() function returns zero if the character
tests false and returns non-zero if the character tests true.
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)
The islower
() function conforms to ANSI
X3.159-1989 (“ANSI C89”).
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.