1ISLOWER(P)                 POSIX Programmer's Manual                ISLOWER(P)
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NAME

6       islower - test for a lowercase letter
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SYNOPSIS

9       #include <ctype.h>
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11       int islower(int c);
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13

DESCRIPTION

15       The  islower()  function  shall  test whether c is a character of class
16       lower in the program's current locale; see the Base Definitions  volume
17       of IEEE Std 1003.1-2001, Chapter 7, Locale.
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19       The  c  argument  is  an  int, the value of which the application shall
20       ensure is a character representable as an unsigned char or equal to the
21       value of the macro EOF. If the argument has any other value, the behav‐
22       ior is undefined.
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RETURN VALUE

25       The islower() function shall return non-zero if c is a  lowercase  let‐
26       ter; otherwise, it shall return 0.
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ERRORS

29       No errors are defined.
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31       The following sections are informative.
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EXAMPLES

34   Testing for a Lowercase Letter
35       The  following  example  tests whether the value is a lowercase letter,
36       based on the locale of the user, then uses it as part of a key value.
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39              #include <ctype.h>
40              #include <stdlib.h>
41              #include <locale.h>
42              ...
43              char *keystr;
44              int elementlen, len;
45              char c;
46              ...
47              setlocale(LC_ALL, "");
48              ...
49              len = 0;
50              while (len < elementlen) {
51                  c = (char) (rand() % 256);
52              ...
53                  if (islower(c))
54                      keystr[len++] = c;
55                  }
56              ...
57

APPLICATION USAGE

59       To ensure applications  portability,  especially  across  natural  lan‐
60       guages,  only  this  function  and those listed in the SEE ALSO section
61       should be used for character classification.
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RATIONALE

64       None.
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FUTURE DIRECTIONS

67       None.
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SEE ALSO

70       isalnum() , isalpha() , iscntrl() , isdigit() , isgraph() , isprint() ,
71       ispunct() , isspace() , isupper() , isxdigit() , setlocale() , the Base
72       Definitions  volume  of  IEEE Std 1003.1-2001,   Chapter   7,   Locale,
73       <ctype.h>
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76       Portions  of  this text are reprinted and reproduced in electronic form
77       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
78       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
79       Specifications Issue 6, Copyright (C) 2001-2003  by  the  Institute  of
80       Electrical  and  Electronics  Engineers, Inc and The Open Group. In the
81       event of any discrepancy between this version and the original IEEE and
82       The  Open Group Standard, the original IEEE and The Open Group Standard
83       is the referee document. The original Standard can be  obtained  online
84       at http://www.opengroup.org/unix/online.html .
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88IEEE/The Open Group                  2003                           ISLOWER(P)
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