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110 lines
4.6 KiB
HTML
110 lines
4.6 KiB
HTML
4 years ago
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<!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ -->
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<head>
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<title>tolower (The Red Hat newlib C Library)</title>
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<meta name="description" content="tolower (The Red Hat newlib C Library)">
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<link href="index.html#Top" rel="start" title="Top">
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<link href="Document-Index.html#Document-Index" rel="index" title="Document Index">
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<link href="Document-Index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Ctype.html#Ctype" rel="up" title="Ctype">
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<link href="toupper.html#toupper" rel="next" title="toupper">
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</head>
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<body lang="en">
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<a name="tolower"></a>
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<div class="header">
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<p>
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Next: <a href="toupper.html#toupper" accesskey="n" rel="next">toupper</a>, Previous: <a href="toascii.html#toascii" accesskey="p" rel="prev">toascii</a>, Up: <a href="Ctype.html#Ctype" accesskey="u" rel="up">Ctype</a> [<a href="Document-Index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Document-Index.html#Document-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<a name="tolower_002c-tolower_005fl_002d_002d_002dtranslate-characters-to-lowercase"></a>
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<h3 class="section">3.14 <code>tolower</code>, <code>tolower_l</code>—translate characters to lowercase</h3>
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<a name="index-tolower"></a>
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<a name="index-tolower_005fl"></a>
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<a name="index-_005ftolower"></a>
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<p><strong>Synopsis</strong>
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</p><div class="example">
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<pre class="example">#include <ctype.h>
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int tolower(int <var>c</var>);
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int _tolower(int <var>c</var>);
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#include <ctype.h>
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int tolower_l(int <var>c</var>, locale_t <var>locale</var>);
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</pre></div>
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<p><strong>Description</strong><br>
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<code>tolower</code> is a macro which converts uppercase characters to lowercase,
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leaving all other characters unchanged. It is only defined when
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<var>c</var> is an integer in the range <code>EOF</code> to <code>255</code>.
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</p>
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<p><code>tolower_l</code> is like <code>tolower</code> but performs the function based on the
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locale specified by the locale object locale. If <var>locale</var> is
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LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
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</p>
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<p>You can use a compiled subroutine instead of the macro definition by
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undefining this macro using ‘<code>#undef tolower</code>’ or ‘<code>#undef tolower_l</code>’.
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</p>
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<p><code>_tolower</code> performs the same conversion as <code>tolower</code>, but should
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only be used when <var>c</var> is known to be an uppercase character (<code>A</code>–<code>Z</code>).
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</p>
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<br>
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<p><strong>Returns</strong><br>
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<code>tolower</code>, <code>tolower_l</code> return the lowercase equivalent of <var>c</var> when
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<var>c</var> is an uppercase character, and <var>c</var> otherwise.
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</p>
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<p><code>_tolower</code> returns the lowercase equivalent of <var>c</var> when it is a
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character between <code>A</code> and <code>Z</code>. If <var>c</var> is not one of these
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characters, the behaviour of <code>_tolower</code> is undefined.
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</p>
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<br>
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<p><strong>Portability</strong><br>
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<code>tolower</code> is ANSI C. <code>_tolower</code> is not recommended for portable programs.
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<code>tolower_l</code> is POSIX-1.2008.
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</p>
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<p>No supporting OS subroutines are required.
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</p>
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<br>
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</body>
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</html>
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