148 lines
5.5 KiB
HTML
148 lines
5.5 KiB
HTML
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<!-- Copyright (C) 2010-2016 Free Software Foundation, Inc.
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.2 or
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any later version published by the Free Software Foundation; with no
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Invariant Sections, with the Front-Cover Texts being "A GNU Manual,"
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and with the Back-Cover Texts as in (a) below. A copy of the
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License."
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<!-- Created by GNU Texinfo 5.2, http://www.gnu.org/software/texinfo/ -->
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<head>
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<title>GCC libquadmath: quadmath_snprintf</title>
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<meta name="description" content="GCC libquadmath: quadmath_snprintf">
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<link href="index.html#Top" rel="start" title="Top">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="I_002fO-Library-Routines.html#I_002fO-Library-Routines" rel="up" title="I/O Library Routines">
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<link href="GNU-Free-Documentation-License.html#GNU-Free-Documentation-License" rel="next" title="GNU Free Documentation License">
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<link href="strtoflt128.html#strtoflt128" rel="prev" title="strtoflt128">
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<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
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<a name="quadmath_005fsnprintf"></a>
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<div class="header">
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<p>
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Previous: <a href="strtoflt128.html#strtoflt128" accesskey="p" rel="prev">strtoflt128</a>, Up: <a href="I_002fO-Library-Routines.html#I_002fO-Library-Routines" accesskey="u" rel="up">I/O Library Routines</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>]</p>
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</div>
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<hr>
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<a name="quadmath_005fsnprintf-_002d_002d_002d-Convert-to-string"></a>
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<h3 class="section">3.2 <code>quadmath_snprintf</code> — Convert to string</h3>
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<p>The function <code>quadmath_snprintf</code> converts a <code>__float128</code> floating-point
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number into a string. It is a specialized alternative to <code>snprintf</code>, where
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the format string is restricted to a single conversion specifier with <code>Q</code>
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modifier and conversion specifier <code>e</code>, <code>E</code>, <code>f</code>, <code>F</code>, <code>g</code>,
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<code>G</code>, <code>a</code> or <code>A</code>, with no extra characters before or after the
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conversion specifier. The <code>%m$</code> or <code>*m$</code> style must not be used in
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the format.
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</p>
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<dl compact="compact">
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<dt>Syntax</dt>
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<dd><p><code>int quadmath_snprintf (char *s, size_t size, const char *format, ...)</code>
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</p>
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</dd>
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<dt><em>Arguments</em>:</dt>
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<dd><table>
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<tr><td width="15%"><var>s</var></td><td width="70%">output string</td></tr>
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<tr><td width="15%"><var>size</var></td><td width="70%">byte size of the string, including tailing NUL</td></tr>
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<tr><td width="15%"><var>format</var></td><td width="70%">conversion specifier string</td></tr>
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</table>
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</dd>
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<dt>Note</dt>
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<dd><p>On some targets when supported by the C library hooks are installed
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for <code>printf</code> family of functions, so that <code>printf ("%Qe", 1.2Q);</code>
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etc. works too.
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</p>
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</dd>
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<dt>Example</dt>
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<dd><div class="smallexample">
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<pre class="smallexample">#include <quadmath.h>
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#include <stdlib.h>
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#include <stdio.h>
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int main ()
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{
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__float128 r;
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int prec = 20;
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int width = 46;
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char buf[128];
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r = 2.0q;
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r = sqrtq (r);
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int n = quadmath_snprintf (buf, sizeof buf, "%+-#*.20Qe", width, r);
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if ((size_t) n < sizeof buf)
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printf ("%s\n", buf);
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/* Prints: +1.41421356237309504880e+00 */
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quadmath_snprintf (buf, sizeof buf, "%Qa", r);
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if ((size_t) n < sizeof buf)
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printf ("%s\n", buf);
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/* Prints: 0x1.6a09e667f3bcc908b2fb1366ea96p+0 */
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n = quadmath_snprintf (NULL, 0, "%+-#46.*Qe", prec, r);
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if (n > -1)
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{
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char *str = malloc (n + 1);
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if (str)
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{
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quadmath_snprintf (str, n + 1, "%+-#46.*Qe", prec, r);
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printf ("%s\n", str);
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/* Prints: +1.41421356237309504880e+00 */
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}
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free (str);
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}
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return 0;
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}
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</pre></div>
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</dd>
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</dl>
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</body>
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</html>
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