NAME

       islower - test for a lowercase letter

SYNOPSIS

       #include <ctype.h>

       int islower(int c);

DESCRIPTION

       The islower() function shall test whether c is a character of class lower in the program's
       current locale; see the  Base  Definitions  volume  of  IEEE Std 1003.1-2001,  Chapter  7,
       Locale.

       The  c  argument is an int, the value of which the application shall ensure is a character
       representable as an unsigned char or equal to the value of the macro EOF. If the  argument
       has any other value, the behavior is undefined.

RETURN VALUE

       The  islower()  function  shall  return non-zero if c is a lowercase letter; otherwise, it
       shall return 0.

ERRORS

       No errors are defined.

       The following sections are informative.

EXAMPLES

   Testing for a Lowercase Letter
       The following example tests whether the value is a lowercase letter, based on  the  locale
       of the user, then uses it as part of a key value.

              #include <ctype.h>
              #include <stdlib.h>
              #include <locale.h>
              ...
              char *keystr;
              int elementlen, len;
              char c;
              ...
              setlocale(LC_ALL, "");
              ...
              len = 0;
              while (len < elementlen) {
                  c = (char) (rand() % 256);
              ...
                  if (islower(c))
                      keystr[len++] = c;
                  }
              ...

APPLICATION USAGE

       To  ensure  applications  portability,  especially  across  natural  languages,  only this
       function and  those  listed  in  the  SEE  ALSO  section  should  be  used  for  character
       classification.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       isalnum()  ,  isalpha()  ,  iscntrl()  ,  isdigit()  , isgraph() , isprint() , ispunct() ,
       isspace() , isupper() ,  isxdigit()  ,  setlocale()  ,  the  Base  Definitions  volume  of
       IEEE Std 1003.1-2001, Chapter 7, Locale, <ctype.h>

COPYRIGHT

       Portions  of  this  text  are  reprinted  and  reproduced in electronic form from IEEE Std
       1003.1, 2003 Edition, Standard for Information Technology  --  Portable  Operating  System
       Interface  (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by
       the Institute of Electrical and Electronics Engineers, Inc and  The  Open  Group.  In  the
       event  of  any  discrepancy  between this version and the original IEEE and The Open Group
       Standard, the original IEEE and The Open Group  Standard  is  the  referee  document.  The
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .