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 letters. For single C chars locales (see multibyte(3) ) the value of the argument is 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):

141 ``a''

142 ``b'' 143 ``c'' 144 ``d'' 145 ``e''

146 ``f''

147 ``g'' 150 ``h'' 151 ``i'' 152 ``j''

153 ``k''

154 ``l'' 155 ``m'' 156 ``n'' 157 ``o''

160 ``p''

161 ``q'' 162 ``r'' 163 ``s'' 164 ``t''

165 ``u''

166 ``v'' 167 ``w'' 170 ``x'' 171 ``y'' 172 ``z''

Return Values

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

Compatibility

Although islower() accepts arguments outside of the range of the unsigned char type in locales with large character sets, this is a 4.4BSD extension and the iswlower() function should be used instead for maximum portability.

See Also

ctype(3) , iswlower(3) , multibyte(3) , tolower(3) , ascii(7)

Standards

The islower() function conforms to ISO/IEC 9899:1990 (``ISO C89'').

Table of Contents

• Name
• Library
• Synopsis
• Description
• Return Values
• Compatibility
• See Also
• Standards