1ISALPHA(3P)                POSIX Programmer's Manual               ISALPHA(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       isalpha, isalpha_l — test for an alphabetic character
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SYNOPSIS

15       #include <ctype.h>
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17       int isalpha(int c);
18       int isalpha_l(int c, locale_t locale);
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DESCRIPTION

21       For isalpha(): The functionality described on this  reference  page  is
22       aligned  with the ISO C standard. Any conflict between the requirements
23       described here and the ISO C standard is unintentional. This volume  of
24       POSIX.1‐2017 defers to the ISO C standard.
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26       The isalpha() and isalpha_l() functions shall test whether c is a char‐
27       acter of class alpha in the current locale, or  in  the  locale  repre‐
28       sented  by  locale,  respectively;  see  the Base Definitions volume of
29       POSIX.1‐2017, Chapter 7, Locale.
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31       The c argument is an int, the value  of  which  the  application  shall
32       ensure  is  representable  as an unsigned char or equal to the value of
33       the macro EOF. If the argument has any other  value,  the  behavior  is
34       undefined.
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36       The  behavior is undefined if the locale argument to isalpha_l() is the
37       special locale object LC_GLOBAL_LOCALE or is not a valid locale  object
38       handle.
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RETURN VALUE

41       The  isalpha()  and isalpha_l() functions shall return non-zero if c is
42       an alphabetic character; otherwise, they shall return 0.
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ERRORS

45       No errors are defined.
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47       The following sections are informative.
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EXAMPLES

50       None.
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APPLICATION USAGE

53       To ensure applications  portability,  especially  across  natural  lan‐
54       guages,  only  these functions and the functions in the reference pages
55       listed in the SEE ALSO section should be used for character classifica‐
56       tion.
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RATIONALE

59       None.
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FUTURE DIRECTIONS

62       None.
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SEE ALSO

65       isalnum(),   isblank(),  iscntrl(),  isdigit(),  isgraph(),  islower(),
66       isprint(), ispunct(), isspace(),  isupper(),  isxdigit(),  setlocale(),
67       uselocale()
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69       The  Base  Definitions  volume  of  POSIX.1‐2017,  Chapter  7,  Locale,
70       <ctype.h>, <locale.h>, <stdio.h>
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73       Portions of this text are reprinted and reproduced in  electronic  form
74       from  IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
75       table Operating System Interface (POSIX), The Open Group Base  Specifi‐
76       cations  Issue  7, 2018 Edition, Copyright (C) 2018 by the Institute of
77       Electrical and Electronics Engineers, Inc and The Open Group.   In  the
78       event of any discrepancy between this version and the original IEEE and
79       The Open Group Standard, the original IEEE and The Open Group  Standard
80       is  the  referee document. The original Standard can be obtained online
81       at http://www.opengroup.org/unix/online.html .
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83       Any typographical or formatting errors that appear  in  this  page  are
84       most likely to have been introduced during the conversion of the source
85       files to man page format. To report such errors,  see  https://www.ker‐
86       nel.org/doc/man-pages/reporting_bugs.html .
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90IEEE/The Open Group                  2017                          ISALPHA(3P)
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