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<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>sd_id128_to_string</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><style>
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<a href="../libudev/index.html">gudev </a><span style="float:right">systemd 215</span><hr><div class="refentry"><a name="sd_id128_to_string"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>sd_id128_to_string, sd_id128_from_string — Format or parse 128-bit IDs as strings</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><div class="funcsynopsis"><pre class="funcsynopsisinfo">#include <systemd/sd-id128.h></pre><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">char *<b class="fsfunc">sd_id128_to_string</b>(</code></td><td>sd_id128_t <var class="pdparam">id</var>, char <var class="pdparam">s</var>[33]<code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_id128_from_string</b>(</code></td><td>const char *<var class="pdparam">s</var>, sd_id128_t *<var class="pdparam">ret</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a name="idm214171729760"></a><h2 id="Description">Description<a class="headerlink" title="Permalink to this headline" href="#Description">¶</a></h2><p><code class="function">sd_id128_to_string()</code>
formats a 128-bit ID as a character string. It expects
the ID and a string array capable of storing 33
characters. The ID will be formatted as 32 lowercase
hexadecimal digits and be terminated by a
<code class="constant">NUL</code> byte.</p><p><code class="function">sd_id128_from_string()</code>
implements the reverse operation: it takes a 33
character string with 32 hexadecimal digits (either
lowercase or uppercase, terminated by
<code class="constant">NUL</code>) and parses them back into a
128-bit ID returned in
<em class="parameter"><code>ret</code></em>. Alternatively, this call
can also parse a 37-character string with a 128-bit ID
formatted as RFC UUID.</p><p>For more information about the
"<code class="literal">sd_id128_t</code>" type see
<a href="sd-id128.html"><span class="citerefentry"><span class="refentrytitle">sd-id128</span>(3)</span></a>. Note
that these calls operate the same way on all
architectures, i.e. the results do not depend on
endianness.</p><p>When formatting a 128-bit ID into a string, it is
often easier to use a format string for
<a href="printf.html"><span class="citerefentry"><span class="refentrytitle">printf</span>(3)</span></a>. This
is easily done using the
<code class="function">SD_ID128_FORMAT_STR</code> and
<code class="function">SD_ID128_FORMAT_VAL()</code> macros. For
more information see
<a href="sd-id128.html"><span class="citerefentry"><span class="refentrytitle">sd-id128</span>(3)</span></a>.</p></div><div class="refsect1"><a name="idm214171795728"></a><h2 id="Return Value">Return Value<a class="headerlink" title="Permalink to this headline" href="#Return%20Value">¶</a></h2><p><code class="function">sd_id128_to_string()</code> always
succeeds and returns a pointer to the string array
passed in. <code class="function">sd_id128_from_string</code>
returns 0 on success, in which case
<em class="parameter"><code>ret</code></em> is filled in, or a negative
errno-style error code.</p></div><div class="refsect1"><a name="idm214171792528"></a><h2 id="Notes">Notes<a class="headerlink" title="Permalink to this headline" href="#Notes">¶</a></h2><p>The <code class="function">sd_id128_to_string()</code>
and <code class="function">sd_id128_from_string()</code> interfaces are
available as a shared library, which can be compiled and
linked to with the "<code class="literal">libsystemd</code>" <a href="pkg-config.html"><span class="citerefentry"><span class="refentrytitle">pkg-config</span>(1)</span></a>
file.</p></div><div class="refsect1"><a name="idm214171788160"></a><h2 id="See Also">See Also<a class="headerlink" title="Permalink to this headline" href="#See%20Also">¶</a></h2><p>
<a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>,
<a href="sd-id128.html"><span class="citerefentry"><span class="refentrytitle">sd-id128</span>(3)</span></a>,
<a href="printf.html"><span class="citerefentry"><span class="refentrytitle">printf</span>(3)</span></a>
</p></div></div></body></html>
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