Manual Pages  — ISLOWER

islower – lower-case character test

LIBRARY SYNOPSIS DESCRIPTION RETURN VALUES COMPATIBILITY SEE ALSO STANDARDS

Standard C Library (libc, -lc)

#include <ctype.h>

int
islower(int c);

int
islower_l(int c, locale_t loc);

The islower() function tests for any lower-case letters. The value of the argument must be representable as an unsigned char or the value of EOF.

In the ASCII character set, this includes the following characters (with their numeric values shown in octal):

amp;141 ``a''	142 ``b''	143 ``c''	144 ``d''	145 ``e''
amp;146 ``f''	147 ``g''	150 ``h''	151 ``i''	152 ``j''
amp;153 ``k''	154 ``l''	155 ``m''	156 ``n''	157 ``o''
amp;160 ``p''	161 ``q''	162 ``r''	163 ``s''	164 ``t''
amp;165 ``u''	166 ``v''	167 ``w''	170 ``x''	171 ``y''
amp;172 ``z''	amp;	amp;	amp;	amp;

The islower_l() function takes an explicit locale argument, whereas the islower() function uses the current global or per-thread locale.

The islower() and islower_l() functions return zero if the character tests false and return non-zero if the character tests true.

The BSD 4.4 extension of accepting arguments outside of the range of the unsigned char type in locales with large character sets is considered obsolete and may not be supported in future releases. The iswlower() function should be used instead.

The islower() function conforms to ISO/IEC 9899:1990 ("ISO C90"). The islower_l() function conforms to IEEE Std 1003.1-2008 ("POSIX.1").