1ISDIGIT(3P)                POSIX Programmer's Manual               ISDIGIT(3P)
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PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
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NAME

12       isdigit - test for a decimal digit
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SYNOPSIS

15       #include <ctype.h>
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17       int isdigit(int c);
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DESCRIPTION

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

31       The  isdigit()  function shall return non-zero if c is a decimal digit;
32       otherwise, it shall return 0.
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ERRORS

35       No errors are defined.
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37       The following sections are informative.
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EXAMPLES

40       None.
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APPLICATION USAGE

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

48       None.
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FUTURE DIRECTIONS

51       None.
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SEE ALSO

54       isalnum(),  isalpha(),  iscntrl(),  isgraph(),  islower(),   isprint(),
55       ispunct(),  isspace(), isupper(), isxdigit(), the Base Definitions vol‐
56       ume of IEEE Std 1003.1-2001, Chapter 7, Locale, <ctype.h>
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59       Portions of this text are reprinted and reproduced in  electronic  form
60       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
61       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
62       Specifications  Issue  6,  Copyright  (C) 2001-2003 by the Institute of
63       Electrical and Electronics Engineers, Inc and The Open  Group.  In  the
64       event of any discrepancy between this version and the original IEEE and
65       The Open Group Standard, the original IEEE and The Open Group  Standard
66       is  the  referee document. The original Standard can be obtained online
67       at http://www.opengroup.org/unix/online.html .
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71IEEE/The Open Group                  2003                          ISDIGIT(3P)
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