564 lines
11 KiB
HTML
564 lines
11 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of ISALPHA</TITLE>
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</HEAD><BODY>
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<H1>ISALPHA</H1>
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Section: Linux Programmer's Manual (3)<BR>Updated: 2017-09-15<BR><A HREF="#index">Index</A>
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<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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isalnum, isalpha, isascii, isblank, iscntrl, isdigit, isgraph, islower,
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isprint, ispunct, isspace, isupper, isxdigit,
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isalnum_l, isalpha_l, isascii_l, isblank_l, iscntrl_l,
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isdigit_l, isgraph_l, islower_l,
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isprint_l, ispunct_l, isspace_l, isupper_l, isxdigit_l
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- character classification functions
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<PRE>
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<B>#include <<A HREF="file:///usr/include/ctype.h">ctype.h</A>></B>
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<B>int isalnum(int </B><I>c</I><B>);</B>
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<B>int isalpha(int </B><I>c</I><B>);</B>
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<B>int iscntrl(int </B><I>c</I><B>);</B>
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<B>int isdigit(int </B><I>c</I><B>);</B>
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<B>int isgraph(int </B><I>c</I><B>);</B>
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<B>int islower(int </B><I>c</I><B>);</B>
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<B>int isprint(int </B><I>c</I><B>);</B>
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<B>int ispunct(int </B><I>c</I><B>);</B>
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<B>int isspace(int </B><I>c</I><B>);</B>
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<B>int isupper(int </B><I>c</I><B>);</B>
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<B>int isxdigit(int </B><I>c</I><B>);</B>
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<B>int isascii(int </B><I>c</I><B>);</B>
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<B>int isblank(int </B><I>c</I><B>);</B>
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<B>int isalnum_l(int </B><I>c</I><B>, locale_t </B><I>locale</I><B>);</B>
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<B>int isalpha_l(int </B><I>c</I><B>, locale_t </B><I>locale</I><B>);</B>
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<B>int isblank_l(int </B><I>c</I><B>, locale_t </B><I>locale</I><B>);</B>
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<B>int iscntrl_l(int </B><I>c</I><B>, locale_t </B><I>locale</I><B>);</B>
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<B>int isdigit_l(int </B><I>c</I><B>, locale_t </B><I>locale</I><B>);</B>
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<B>int isgraph_l(int </B><I>c</I><B>, locale_t </B><I>locale</I><B>);</B>
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<B>int islower_l(int </B><I>c</I><B>, locale_t </B><I>locale</I><B>);</B>
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<B>int isprint_l(int </B><I>c</I><B>, locale_t </B><I>locale</I><B>);</B>
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<B>int ispunct_l(int </B><I>c</I><B>, locale_t </B><I>locale</I><B>);</B>
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<B>int isspace_l(int </B><I>c</I><B>, locale_t </B><I>locale</I><B>);</B>
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<B>int isupper_l(int </B><I>c</I><B>, locale_t </B><I>locale</I><B>);</B>
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<B>int isxdigit_l(int </B><I>c</I><B>, locale_t </B><I>locale</I><B>);</B>
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<B>int isascii_l(int </B><I>c</I><B>, locale_t </B><I>locale</I><B>);</B>
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</PRE>
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<P>
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Feature Test Macro Requirements for glibc (see
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<B><A HREF="/cgi-bin/man/man2html?7+feature_test_macros">feature_test_macros</A></B>(7)):
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<P>
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<B>isascii</B>():
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<DL COMPACT><DT id="1"><DD>
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_XOPEN_SOURCE
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<BR> || /* Glibc since 2.19: */ _DEFAULT_SOURCE
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<BR> || /* Glibc versions <= 2.19: */ _SVID_SOURCE
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</DL>
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<P>
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<B>isblank</B>():
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<DL COMPACT><DT id="2"><DD>
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_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
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</DL>
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<P>
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<B>isalnum_l</B>(),
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<B>isalpha_l</B>(),
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<B>isblank_l</B>(),
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<B>iscntrl_l</B>(),
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<B>isdigit_l</B>(),
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<B>isgraph_l</B>(),
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<B>islower_l</B>(),
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<B>isprint_l</B>(),
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<B>ispunct_l</B>(),
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<B>isspace_l</B>(),
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<B>isupper_l</B>(),
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<B>isxdigit_l</B>():
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<DL COMPACT><DT id="3"><DD>
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<DL COMPACT>
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<DT id="4">Since glibc 2.10:<DD>
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_XOPEN_SOURCE >= 700
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<DT id="5">Before glibc 2.10:<DD>
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_GNU_SOURCE
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</DL>
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</DL>
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<P>
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<B>isascii_l</B>():
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<DL COMPACT><DT id="6"><DD>
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<DL COMPACT>
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<DT id="7">Since glibc 2.10:<DD>
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_XOPEN_SOURCE >= 700 && (_SVID_SOURCE || _BSD_SOURCE)
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<DT id="8">Before glibc 2.10:<DD>
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_GNU_SOURCE
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</DL>
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</DL>
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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These functions check whether
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<I>c</I>,
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which must have the value of an
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<I>unsigned char</I>
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or
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<B>EOF</B>,
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falls into a certain character class according to the specified locale.
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The functions without the
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"_l" suffix perform the check based on the current locale.
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<P>
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The functions with the "_l" suffix perform the check
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based on the locale specified by the locale object
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<I>locale</I>.
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The behavior of these functions is undefined if
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<I>locale</I>
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is the special locale object
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<B>LC_GLOBAL_LOCALE</B>
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(see
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<B><A HREF="/cgi-bin/man/man2html?3+duplocale">duplocale</A></B>(3))
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or is not a valid locale object handle.
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<P>
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The list below explains the operation of the functions without
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the "_l" suffix;
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the functions with the "_l" suffix differ only in using the locale object
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<I>locale</I>
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instead of the current locale.
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<DL COMPACT>
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<DT id="9"><B>isalnum</B>()
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<DD>
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checks for an alphanumeric character; it is equivalent to
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<B>(isalpha(</B><I>c</I><B>) || isdigit(</B><I>c</I><B>))</B><I></I>.
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<DT id="10"><B>isalpha</B>()
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<DD>
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checks for an alphabetic character; in the standard <B>"C"</B>
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locale, it is equivalent to
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<B>(isupper(</B><I>c</I><B>) || islower(</B><I>c</I><B>))</B><I></I>.
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In some locales, there may be additional characters for which
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<B>isalpha</B>()
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is true---letters which are neither uppercase nor lowercase.
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<DT id="11"><B>isascii</B>()
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<DD>
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checks whether <I>c</I> is a 7-bit
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<I>unsigned char</I>
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value that fits into
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the ASCII character set.
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<DT id="12"><B>isblank</B>()
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<DD>
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checks for a blank character; that is, a space or a tab.
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<DT id="13"><B>iscntrl</B>()
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<DD>
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checks for a control character.
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<DT id="14"><B>isdigit</B>()
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<DD>
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checks for a digit (0 through 9).
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<DT id="15"><B>isgraph</B>()
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<DD>
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checks for any printable character except space.
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<DT id="16"><B>islower</B>()
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<DD>
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checks for a lowercase character.
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<DT id="17"><B>isprint</B>()
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<DD>
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checks for any printable character including space.
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<DT id="18"><B>ispunct</B>()
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<DD>
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checks for any printable character which is not a space or an
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alphanumeric character.
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<DT id="19"><B>isspace</B>()
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<DD>
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checks for white-space characters.
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In the
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<B>C</B>
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and
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<B>POSIX</B>
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locales, these are: space, form-feed
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(<B>'\f'</B>),
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newline
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(<B>'\n'</B>),
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carriage return
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(<B>'\r'</B>),
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horizontal tab
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(<B>'\t'</B>),
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and vertical tab
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(<B>'\v'</B>).
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<DT id="20"><B>isupper</B>()
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<DD>
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checks for an uppercase letter.
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<DT id="21"><B>isxdigit</B>()
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<DD>
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checks for hexadecimal digits, that is, one of
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<BR>
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<B>0 1 2 3 4 5 6 7 8 9 a b c d e f A B C D E F</B>.
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</DL>
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<A NAME="lbAE"> </A>
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<H2>RETURN VALUE</H2>
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The values returned are nonzero if the character
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<I>c</I>
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falls into the tested class, and zero if not.
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<A NAME="lbAF"> </A>
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<H2>VERSIONS</H2>
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<B>isalnum_l</B>(),
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<B>isalpha_l</B>(),
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<B>isblank_l</B>(),
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<B>iscntrl_l</B>(),
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<B>isdigit_l</B>(),
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<B>isgraph_l</B>(),
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<B>islower_l</B>(),
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<B>isprint_l</B>(),
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<B>ispunct_l</B>(),
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<B>isspace_l</B>(),
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<B>isupper_l</B>(),
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<B>isxdigit_l</B>(),
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and
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<B>isascii_l</B>()
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are available since glibc 2.3.
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<A NAME="lbAG"> </A>
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<H2>ATTRIBUTES</H2>
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For an explanation of the terms used in this section, see
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<B><A HREF="/cgi-bin/man/man2html?7+attributes">attributes</A></B>(7).
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<TABLE BORDER>
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<TR VALIGN=top><TD><B>Interface</B></TD><TD><B>Attribute</B></TD><TD><B>Value</B><BR></TD></TR>
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<TR VALIGN=top><TD>
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<B>isalnum</B>(),
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<B>isalpha</B>(),
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<B>isascii</B>(),
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<B>isblank</B>(),
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<B>iscntrl</B>(),
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<B>isdigit</B>(),
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<B>isgraph</B>(),
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<B>islower</B>(),
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<B>isprint</B>(),
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<B>ispunct</B>(),
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<B>isspace</B>(),
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<B>isupper</B>(),
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<B>isxdigit</B>()
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</TD><TD>Thread safety</TD><TD>MT-Safe<BR></TD></TR>
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</TABLE>
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<A NAME="lbAH"> </A>
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<H2>CONFORMING TO</H2>
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C89 specifies
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<B>isalnum</B>(),
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<B>isalpha</B>(),
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<B>iscntrl</B>(),
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<B>isdigit</B>(),
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<B>isgraph</B>(),
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<B>islower</B>(),
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<B>isprint</B>(),
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<B>ispunct</B>(),
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<B>isspace</B>(),
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<B>isupper</B>(),
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and
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<B>isxdigit</B>(),
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but not
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<B>isascii</B>()
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and
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<B>isblank</B>().
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POSIX.1-2001
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also specifies those functions, and also
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<B>isascii</B>()
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(as an XSI extension)
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and
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<B>isblank</B>().
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C99 specifies all of the preceding functions, except
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<B>isascii</B>().
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<P>
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POSIX.1-2008 marks
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<B>isascii</B>()
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as obsolete,
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noting that it cannot be used portably in a localized application.
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<P>
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POSIX.1-2008 specifies
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<B>isalnum_l</B>(),
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<B>isalpha_l</B>(),
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<B>isblank_l</B>(),
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<B>iscntrl_l</B>(),
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<B>isdigit_l</B>(),
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<B>isgraph_l</B>(),
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<B>islower_l</B>(),
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<B>isprint_l</B>(),
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<B>ispunct_l</B>(),
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<B>isspace_l</B>(),
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<B>isupper_l</B>(),
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and
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<B>isxdigit_l</B>().
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<P>
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<B>isascii_l</B>()
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is a GNU extension.
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<A NAME="lbAI"> </A>
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<H2>NOTES</H2>
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The standards require that the argument
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<I>c</I>
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for these functions is either
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<B>EOF</B>
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or a value that is representable in the type
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<I>unsigned char</I>.
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If the argument
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<I>c</I>
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is of type
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<I>char</I>,
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it must be cast to
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<I>unsigned char</I>,
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as in the following example:
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<P>
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char c;
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...
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res = toupper((unsigned char) c);
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<P>
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This is necessary because
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<I>char</I>
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may be the equivalent of
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<I>signed char</I>,
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in which case a byte where the top bit is set would be sign extended when
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converting to
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<I>int</I>,
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yielding a value that is outside the range of
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<I>unsigned char</I>.
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<P>
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The details of what characters belong to which class depend on the
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locale.
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For example,
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<B>isupper</B>()
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will not recognize an A-umlaut (Ä) as an uppercase letter in the default
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<B>C</B>
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locale.
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<A NAME="lbAJ"> </A>
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<H2>SEE ALSO</H2>
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<B><A HREF="/cgi-bin/man/man2html?3+iswalnum">iswalnum</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+iswalpha">iswalpha</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+iswblank">iswblank</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+iswcntrl">iswcntrl</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+iswdigit">iswdigit</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+iswgraph">iswgraph</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+iswlower">iswlower</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+iswprint">iswprint</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+iswpunct">iswpunct</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+iswspace">iswspace</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+iswupper">iswupper</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+iswxdigit">iswxdigit</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+newlocale">newlocale</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+setlocale">setlocale</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+toascii">toascii</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+tolower">tolower</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+toupper">toupper</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+uselocale">uselocale</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?7+ascii">ascii</A></B>(7),
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<B><A HREF="/cgi-bin/man/man2html?7+locale">locale</A></B>(7)
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<A NAME="lbAK"> </A>
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<H2>COLOPHON</H2>
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This page is part of release 5.05 of the Linux
|
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<I>man-pages</I>
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project.
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A description of the project,
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information about reporting bugs,
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and the latest version of this page,
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can be found at
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<A HREF="https://www.kernel.org/doc/man-pages/.">https://www.kernel.org/doc/man-pages/.</A>
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<P>
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT id="22"><A HREF="#lbAB">NAME</A><DD>
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<DT id="23"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="24"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="25"><A HREF="#lbAE">RETURN VALUE</A><DD>
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<DT id="26"><A HREF="#lbAF">VERSIONS</A><DD>
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<DT id="27"><A HREF="#lbAG">ATTRIBUTES</A><DD>
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<DT id="28"><A HREF="#lbAH">CONFORMING TO</A><DD>
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<DT id="29"><A HREF="#lbAI">NOTES</A><DD>
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<DT id="30"><A HREF="#lbAJ">SEE ALSO</A><DD>
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<DT id="31"><A HREF="#lbAK">COLOPHON</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="/cgi-bin/man/man2html">man2html</A>,
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using the manual pages.<BR>
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Time: 00:05:46 GMT, March 31, 2021
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</BODY>
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</HTML>
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