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<td >Qt 5.12</td><td >Qt Core</td></tr></table><table class="buildversion"><tr>
<td id="buildversion" width="100%" align="right">Qt 5.12.6 Reference Documentation</td>
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<h3><a name="toc">Contents</a></h3>
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<li class="level1"><a href="#core-functionalities">Core Functionalities</a></li>
<li class="level1"><a href="#using-the-module">Using the Module</a></li>
<li class="level2"><a href="#building-with-cmake">Building with CMake</a></li>
<li class="level2"><a href="#building-with-qmake">Building with qmake</a></li>
<li class="level1"><a href="#threading-and-concurrent-programming">Threading and Concurrent Programming</a></li>
<li class="level1"><a href="#input-output-resources-and-containers">Input/Output, Resources, and Containers</a></li>
<li class="level1"><a href="#additional-frameworks">Additional Frameworks</a></li>
<li class="level1"><a href="#licenses-and-attributions">Licenses and Attributions</a></li>
<li class="level1"><a href="#reference">Reference</a></li>
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<h1 class="title">Qt Core</h1>
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<a name="core-functionalities"></a>
<h2 id="core-functionalities">Core Functionalities</h2>
<p>Qt Core adds these features to C++:</p>
<ul>
<li>a very powerful mechanism for seamless object communication called signals and slots</li>
<li>queryable and designable object properties</li>
<li>hierarchical and queryable object trees that organize</li>
<li>object ownership in a natural way with guarded pointers (<a href="qpointer.html">QPointer</a>)</li>
<li>a dynamic cast that works across library boundaries</li>
</ul>
<p>The following pages provide more information about Qt's core features:</p>
<ul>
<li><a href="metaobjects.html">The Meta-Object System</a></li>
<li><a href="properties.html">The Property System</a></li>
<li><a href="object.html">Object Model</a></li>
<li><a href="objecttrees.html">Object Trees & Ownership</a></li>
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<h2 id="using-the-module">Using the Module</h2>
<p>Using a Qt module requires linking against the module library, either directly or through other dependencies. Several build tools have dedicated support for this, including CMake and <a href="../qmake/qmake-manual.html">qmake</a>.</p>
<a name="building-with-cmake"></a>
<h3 id="building-with-cmake">Building with CMake</h3>
<p>Use the <code>find_package()</code> command to locate the needed module components in the <code>Qt5</code> package:</p>
<pre class="cpp">
find_package(Qt5 COMPONENTS Core REQUIRED)
target_link_libraries(mytarget Qt5::Core)
</pre>
<p>See also the <a href="qtcore-index.html#building-with-cmake">Building with CMake</a> overview.</p>
<a name="building-with-qmake"></a>
<h3 id="building-with-qmake">Building with qmake</h3>
<p>If you use <a href="../qmake/qmake-manual.html">qmake</a> to build your projects, Qt5Core is linked by default.</p>
<a name="threading-and-concurrent-programming"></a>
<h2 id="threading-and-concurrent-programming">Threading and Concurrent Programming</h2>
<p>Qt provides thread support in the form of platform-independent threading classes, a thread-safe way of posting events, and signal-slot connections across threads. Multithreaded programming is also a useful paradigm for performing time-consuming operations without freezing the user interface of an application.</p>
<p>The Thread Support in Qt page contains information on implementing threads in applications. Additional concurrent classes are provided by the <a href="../qtconcurrent/qtconcurrent-index.html">Qt Concurrent</a> module.</p>
<a name="input-output-resources-and-containers"></a>
<h2 id="input-output-resources-and-containers">Input/Output, Resources, and Containers</h2>
<p>Qt provides a resource system for organizing application files and assets, a set of containers, and classes for receiving input and printing output.</p>
<ul>
<li><a href="containers.html">Container Classes</a></li>
<li><a href="datastreamformat.html">Serializing Qt Data Types</a></li>
<li><a href="implicit-sharing.html">Implicit Sharing</a></li>
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<p>In addition, Qt Core provides a platform-independent mechanism for storing binary files in the application's executable.</p>
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<li><a href="resources.html">The Qt Resource System</a></li>
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<a name="additional-frameworks"></a>
<h2 id="additional-frameworks">Additional Frameworks</h2>
<p>Qt Core also provides some of Qt's key frameworks.</p>
<ul>
<li><a href="animation-overview.html">The Animation Framework</a></li>
<li><a href="json.html">JSON Support in Qt</a></li>
<li><a href="statemachine-api.html">The State Machine Framework</a></li>
<li>How to Create Qt Plugins</li>
<li><a href="eventsandfilters.html">The Event System</a></li>
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<a name="licenses-and-attributions"></a>
<h2 id="licenses-and-attributions">Licenses and Attributions</h2>
<p>Qt Core is available under commercial licenses from The Qt Company. In addition, it is available under free software licenses. Since Qt 5.4, these free software licenses are GNU Lesser General Public License, version 3, or the GNU General Public License, version 2. See Qt Licensing for further details.</p>
<p>Executables on Windows potentially link against The qtmain Library. This library is available under commercial licenses and also under the BSD 3-clause "New" or "Revised" License.</p>
<p>Furthermore, Qt Core in Qt 5.12.6 may contain third party modules under following permissive licenses:</p>
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<tr class="odd topAlign"><td class="tblName"><p><a href="qtcore-attribution-zlib.html">Data Compression Library (zlib), version 1.2.11</a></p></td><td class="tblDescr"><p>zlib License</p></td></tr>
<tr class="even topAlign"><td class="tblName"><p><a href="qtcore-attribution-easing.html">Easing Equations by Robert Penner</a></p></td><td class="tblDescr"><p>BSD 3-clause "New" or "Revised" License</p></td></tr>
<tr class="odd topAlign"><td class="tblName"><p><a href="qtcore-attribution-doubleconversion.html">Efficient Binary-Decimal and Decimal-Binary Conversion Routines for IEEE Doubles, version 3.1.1</a></p></td><td class="tblDescr"><p>BSD 3-clause "New" or "Revised" License</p></td></tr>
<tr class="even topAlign"><td class="tblName"><p><a href="qtcore-attribution-freebsd.html">FreeBSD strtoll and strtoull, version 18b29f3fb8abee5d57ed8f4a44f806bec7e0eeff</a></p></td><td class="tblDescr"><p>BSD 3-clause "New" or "Revised" License</p></td></tr>
<tr class="odd topAlign"><td class="tblName"><p><a href="qtcore-attribution-md4.html">MD4</a></p></td><td class="tblDescr"><p>Public Domain</p></td></tr>
<tr class="even topAlign"><td class="tblName"><p><a href="qtcore-attribution-md5.html">MD5</a></p></td><td class="tblDescr"><p>Public Domain</p></td></tr>
<tr class="odd topAlign"><td class="tblName"><p><a href="qtcore-attribution-pcre2-sljit.html">PCRE2 - Stack-less Just-In-Time Compiler, version 10.33</a></p></td><td class="tblDescr"><p>BSD 2-clause "Simplified" License</p></td></tr>
<tr class="even topAlign"><td class="tblName"><p><a href="qtcore-attribution-pcre2.html">PCRE2, version 10.33</a></p></td><td class="tblDescr"><p>BSD 3-clause "New" or "Revised" License</p></td></tr>
<tr class="odd topAlign"><td class="tblName"><p><a href="qtcore-attribution-qeventdispatcher-cf.html">QEventDispatcher on macOS</a></p></td><td class="tblDescr"><p>BSD 3-clause "New" or "Revised" License</p></td></tr>
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<tr class="odd topAlign"><td class="tblName"><p><a href="qtcore-attribution-rfc6234.html">Secure Hash Algorithms SHA-384 and SHA-512</a></p></td><td class="tblDescr"><p>BSD 3-clause "New" or "Revised" License</p></td></tr>
<tr class="even topAlign"><td class="tblName"><p><a href="qtcore-attribution-qeucjpcodec.html">Text Codec: EUC-JP</a></p></td><td class="tblDescr"><p>BSD 2-clause "Simplified" License</p></td></tr>
<tr class="odd topAlign"><td class="tblName"><p><a href="qtcore-attribution-qeuckrcodec.html">Text Codec: EUC-KR</a></p></td><td class="tblDescr"><p>BSD 2-clause "Simplified" License</p></td></tr>
<tr class="even topAlign"><td class="tblName"><p><a href="qtcore-attribution-qbkcodec.html">Text Codec: GBK</a></p></td><td class="tblDescr"><p>BSD 2-clause "Simplified" License</p></td></tr>
<tr class="odd topAlign"><td class="tblName"><p><a href="qtcore-attribution-qjiscodec.html">Text Codec: ISO 2022-JP (JIS)</a></p></td><td class="tblDescr"><p>BSD 2-clause "Simplified" License</p></td></tr>
<tr class="even topAlign"><td class="tblName"><p><a href="qtcore-attribution-qsjiscodec.html">Text Codec: Shift-JIS</a></p></td><td class="tblDescr"><p>BSD 2-clause "Simplified" License</p></td></tr>
<tr class="odd topAlign"><td class="tblName"><p><a href="qtcore-attribution-qtsciicodec.html">Text Codec: TSCII</a></p></td><td class="tblDescr"><p>BSD 2-clause "Simplified" License</p></td></tr>
<tr class="even topAlign"><td class="tblName"><p><a href="qtcore-attribution-qbig5codecs.html">Text Codecs: Big5, Big5-HKSCS</a></p></td><td class="tblDescr"><p>BSD 2-clause "Simplified" License</p></td></tr>
<tr class="odd topAlign"><td class="tblName"><p><a href="qtcore-attribution-psl.html">The Public Suffix List, version Generated on 2018-01-04</a></p></td><td class="tblDescr"><p>Mozilla Public License 2.0</p></td></tr>
<tr class="even topAlign"><td class="tblName"><p><a href="qtcore-attribution-tinycbor.html">TinyCBOR, version 0.6+patches</a></p></td><td class="tblDescr"><p>MIT License</p></td></tr>
<tr class="odd topAlign"><td class="tblName"><p><a href="qtcore-attribution-unicode-character-database.html">Unicode Character Database (UCD), version 20</a></p></td><td class="tblDescr"><p>Unicode License Agreement - Data Files and Software (2016)</p></td></tr>
<tr class="even topAlign"><td class="tblName"><p><a href="qtcore-attribution-unicode-cldr.html">Unicode Common Locale Data Repository (CLDR), version v35.1</a></p></td><td class="tblDescr"><p>Unicode License Agreement - Data Files and Software (2016)</p></td></tr>
<tr class="odd topAlign"><td class="tblName"><p><a href="qtcore-attribution-forkfd.html">forkfd</a></p></td><td class="tblDescr"><p>MIT License</p></td></tr>
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<h2 id="reference">Reference</h2>
<p>These are links to the API reference materials.</p>
<ul>
<li><a href="qtcore-module.html">C++ Classes</a><ul>
<li><a href="animation.html">Animation Classes</a></li>
<li>Threading Classes</li>
<li><a href="containers.html">Container Classes</a></li>
<li><a href="plugins.html">Plugin Classes</a></li>
<li><a href="implicit-sharing.html#implicitly-shared-classes">Implicitly Shared Classes</a></li>
<li><a href="statemachine.html">State Machine Classes</a></li>
<li><a href="io.html">Input/Output Classes</a></li>
<li><a href="events.html">Event Classes</a></li>
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Documentation contributions included herein are the copyrights of
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