mirror of https://github.com/mkerrisk/man-pages
70 lines
2.3 KiB
Groff
70 lines
2.3 KiB
Groff
.\" (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
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.\"
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\" License.
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.\" Modified Sat Jul 24 17:45:39 1993 by Rik Faith (faith@cs.unc.edu)
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.\" Modified 2000-02-13 by Nicolás Lichtmaier <nick@debian.org>
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.TH TOUPPER 3 1993-04-04 "GNU" "Linux Programmer's Manual"
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.SH NAME
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toupper, tolower \- convert letter to upper or lower case
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.SH SYNOPSIS
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.nf
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.B #include <ctype.h>
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.sp
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.BI "int toupper(int " "c" );
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.nl
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.BI "int tolower(int " "c" );
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.fi
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.SH DESCRIPTION
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.B toupper()
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converts the letter
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.I c
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to upper case, if possible.
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.PP
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.B tolower()
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converts the letter
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.I c
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to lower case, if possible.
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.PP
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If
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.I c
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is not an unsigned char value, or EOF, the behaviour of these functions
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is undefined.
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.SH "RETURN VALUE"
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The value returned is that of the converted letter, or
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.I c
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if the conversion was not possible.
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.SH "CONFORMING TO"
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ANSI C, 4.3BSD
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.SH BUGS
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The details of what constitutes an uppercase or lowercase letter depend
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on the current locale. For example, the default
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.B """C"""
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locale does not know about umlauts, so no conversion is done for them.
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.PP
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In some non-English locales, there are lowercase letters with no
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corresponding uppercase equivalent; the German sharp s is one
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example.
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.SH "SEE ALSO"
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.BR isalpha (3),
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.BR setlocale (3),
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.BR locale (7)
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