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<a href="../libudev/index.html">gudev </a><span style="float:right">systemd 202</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>[33], 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="idp3964784"></a><h2>Description</h2><p><code class="function">sd_id128_to_string()</code>

formats a 128 bit ID as 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 NUL

byte.</p><p><code class="function">sd_id128_from_string()</code>

implements the reverse operation: it takes a 33

character array with 32 hexadecimal digits

(terminated by NUL) and parses them back into an

128 bit ID returned in

<em class="parameter"><code>ret</code></em>.</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>.</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="idp24752"></a><h2>Return Value</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="idp27952"></a><h2>Notes</h2><p>The <code class="function">sd_id128_to_string()</code>

and <code class="function">sd_id128_from_string()</code> interfaces are

available as shared library, which can be compiled and

linked to with the <code class="literal">libsystemd-id128</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="idp32240"></a><h2>See Also</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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