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22 | <a href="../libudev/index.html">gudev </a><span style="float:right">systemd 219</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="idm140369556398160"></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 |
| 23 | ID as a character string. It expects the ID and a string array | |
| 24 | capable of storing 33 characters. The ID will be formatted as 32 | |
| 25 | lowercase hexadecimal digits and be terminated by a | |
| 26 | <code class="constant">NUL</code> byte.</p><p><code class="function">sd_id128_from_string()</code> implements the | |
| 27 | reverse operation: it takes a 33 character string with 32 | |
| 28 | hexadecimal digits (either lowercase or uppercase, terminated by | |
| 29 | <code class="constant">NUL</code>) and parses them back into a 128-bit ID | |
| 30 | returned in <em class="parameter"><code>ret</code></em>. Alternatively, this call | |
| 31 | can also parse a 37-character string with a 128-bit ID formatted | |
| 32 | as RFC UUID.</p><p>For more information about the "<code class="literal">sd_id128_t</code>" | |
| 33 | type see | |
| 34 | <a href="sd-id128.html"><span class="citerefentry"><span class="refentrytitle">sd-id128</span>(3)</span></a>. | |
| 35 | Note that these calls operate the same way on all architectures, | |
| 36 | i.e. the results do not depend on endianness.</p><p>When formatting a 128-bit ID into a string, it is often | |
| 37 | easier to use a format string for | |
| 38 | <a href="http://man7.org/linux/man-pages/man3/printf.3.html"><span class="citerefentry"><span class="refentrytitle">printf</span>(3)</span></a>. | |
| 39 | This is easily done using the | |
| 40 | <code class="function">SD_ID128_FORMAT_STR</code> and | |
| 41 | <code class="function">SD_ID128_FORMAT_VAL()</code> macros. For more | |
| 42 | information see | |
| 43 | <a href="sd-id128.html"><span class="citerefentry"><span class="refentrytitle">sd-id128</span>(3)</span></a>.</p></div><div class="refsect1"><a name="idm140369560290192"></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 | |
| 44 | and returns a pointer to the string array passed in. | |
| 45 | <code class="function">sd_id128_from_string</code> returns 0 on success, in | |
| 46 | which case <em class="parameter"><code>ret</code></em> is filled in, or a negative | |
| 47 | errno-style error code.</p></div><div class="refsect1"><a name="idm140369560287104"></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 | |
| 48 | <code class="function">sd_id128_from_string()</code> interfaces are | |
| 49 | available as a shared library, which can be compiled and linked to | |
| 50 | with the | |
| 51 | "<code class="literal">libsystemd</code>" <a href="http://linux.die.net/man/1/pkg-config"><span class="citerefentry"><span class="refentrytitle">pkg-config</span>(1)</span></a> | |
| 52 | file.</p></div><div class="refsect1"><a name="idm140369560282528"></a><h2 id="See Also">See Also<a class="headerlink" title="Permalink to this headline" href="#See%20Also">¶</a></h2><p> | |
| 53 | <a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>, | |
| 54 | <a href="sd-id128.html"><span class="citerefentry"><span class="refentrytitle">sd-id128</span>(3)</span></a>, | |
| 55 | <a href="http://man7.org/linux/man-pages/man3/printf.3.html"><span class="citerefentry"><span class="refentrytitle">printf</span>(3)</span></a> | |
| 56 | </p></div></div></body></html> |