ISLOWER(3P)						     POSIX Programmer's Manual						       ISLOWER(3P)

PROLOG

       This  manual page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (consult the correspond-
       ing Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

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 Defi-
       nitions 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 Technol-
       ogy -- 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 .

IEEE
/The Open Group						       2003							       ISLOWER(3P)