trusty (3) islower.3posix.gz

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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>

       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 .