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<h1>C++11 use in Chromium</h1>
<p><i>This document lives at src/styleguide/c++/c++11.html in a Chromium
checkout.</i></p>
<p>This document summarizes the features of C++11 (both in the language itself
and in enhancements to the Standard Library) and describes which features are
allowed in Chromium and contains pointers to more detailed information. The
Guide applies to Chromium and its subprojects. Subprojects can choose to be
more restrictive if they need to compile on more toolchains than Chromium.</p>
<p>You can propose to make a feature available or to ban a
feature by sending an email to chromium-dev. Ideally include a short blurb
on what the feature is, and why you think it should or should not be allowed.
Ideally, the list will arrive at some consensus and the wiki page will be
updated to mention that consensus. If there's no consensus,
<code>src/styleguide/C++/OWNERS</code> get to decide -- for divisive features, we expect
the decision to be to not use the feature yet and possibly discuss it again a
few months later, when we have more experience with the language.</p>
<p class="warning">Unless otherwise noted, <strong>no</strong> C++11
<strong>library</strong> features are allowed.</p>
<h2 id="whitelist">C++11 Allowed Features</h2>
<p>The following features are currently allowed.</p>
<table id="whitelist_lang_list" class="unlined striped">
<tbody>
<tr>
<th style='width:220px;'>Feature</th>
<th style='width:260px;'>Snippet</th>
<th style='width:240px;'>Description</th>
<th style='width:240px;'>Documentation Link</th>
<th style='width:240px;'>Notes and Discussion Thread</th>
</tr>
<tr>
<td>Aliases</td>
<td><code>using <i>new_alias</i> = <i>typename</i></code></td>
<td>Allow parameterized typedefs</td>
<td><a href="http://en.cppreference.com/w/cpp/language/type_alias">Type alias (using syntax)</a></td>
<td>Use instead of typedef, unless the header needs to be compatible with C. <a href="https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/8dOAMzgR4ao">Discussion thread</a></td>
</tr>
<tr>
<td>Angle Bracket Parsing in Templates</td>
<td><code>&gt;&gt;</code> for <code>&gt; &gt;</code> and <br />
<code>&lt;::</code> for <code>&lt; ::</code></td>
<td>More intuitive parsing of template parameters</td>
<td><a href="http://stackoverflow.com/questions/15785496/c-templates-angle-brackets-pitfall-what-is-the-c11-fix">
C++ Templates Angle Brackets Pitfall</a></td>
<td>Recommended to increase readability. Approved without discussion.</td>
</tr>
<tr>
<td>Automatic Types</td>
<td><code>auto</code></td>
<td>Automatic type deduction</td>
<td>TODO: documentation link</td>
<td>Use according to the <a
href="https://google-styleguide.googlecode.com/svn/trunk/cppguide.html#auto">Google
Style Guide on <code>auto</code></a>. <a href="https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/OQyYSfH9m2M">Discussion thread</a></td>
</tr>
<tr>
<td>Enumerated Type Classes</td>
<td><code>enum class <i>classname</i></code></td>
<td>Provide enums as full classes, with no implicit
conversion to booleans or integers</td>
<td><a href="http://stackoverflow.com/questions/6936030/do-we-really-need-enum-class-in-c11">
enum-class</a></td>
<td>Enum classes are still enums and follow enum naming rules
(which means SHOUTY_CASE in the <a href="http://www.chromium.org/developers/coding-style#Naming">current style guide</a>).
<a href="https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/Q5WmkAImanc">Discussion thread</a></td>
</tr>
<tr>
<td>Final Specifier</td>
<td><code>final</code></td>
<td> Indicates that a class or function is final and cannot be overridden</td>
<td><a href="http://en.cppreference.com/w/cpp/language/final">final Language Reference</a></td>
<td>Recommended for new code. Existing uses of the <code>FINAL</code> macro will be <a href="https://crbug.com/417463">replaced throughout the codebase</a>. <a href="https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/VTNZzizN0zo">Discussion thread</a></td>
</tr>
<tr>
<td>Local Types as Template Arguments</td>
<td></td>
<td>Allows local and unnamed types as template arguments</td>
<td><a href="http://stackoverflow.com/questions/742607/using-local-classes-with-stl-algorithms">
Local types, types without linkage and unnamed types as template arguments</a></td>
<td>Usage should be rare. Approved without discussion.</td>
</tr>
<tr>
<td>Null Pointer Constant</td>
<td><code>nullptr</code></td>
<td>Declares a type-safe null pointer</td>
<td>TODO: documentation link</td>
<td>Recommended for new code.
<a href="https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/4mijeJHzxLg">Discussion thread</a>.
<a href="https://google-styleguide.googlecode.com/svn/trunk/cppguide.html#0_and_nullptr/NULL">Google Style Guide</a>.
Note: <code>std::nullptr_t</code> is a library feature and not available.
</td>
</tr>
<tr>
<td>Override Specifier</td>
<td><code>override</code></td>
<td>Indicates that a class or function overrides a base implementation</td>
<td><a href="http://en.cppreference.com/w/cpp/language/override">override Language Reference</a></td>
<td>Recommended for new code. Existing uses of the <code>OVERRIDE</code> macro will be <a href="https://crbug.com/417463">replaced throughout the codebase</a>. <a href="https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/VTNZzizN0zo">Discussion</a></td>
</tr>
<tr>
<td>Range-Based For Loops</td>
<td><code>for (<i>type</i> <i>var</i> : <i>range</i>)</code></td>
<td>Facilitates a more concise syntax for iterating over the elements
of a container (or a range of iterators) in a <code>for</code> loop</td>
<td>TODO: documentation link</td>
<td>As a rule of thumb, use <code>for (const auto& ...)</code>, <code>for (auto& ...)</code>, or <code>for (<i>concrete type</i> ...)</code>. For pointers, use <code>for (auto* ...)</code> to make clear that the copy of the loop variable is intended, and only a pointer is copied. <a href="https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/hpzz4EqbVmc">Discussion thread</a></td>
</tr>
<tr>
<td>Standard Integers</td>
<td>Typedefs within <code>&lt;stdint.h&gt;</code>
and <code>&lt;inttypes&gt;</code></td>
<td>Provides fixed-size integers independent of platforms</td>
<td><a href="http://www.cplusplus.com/reference/cstdint/">
&lt;stdint.h&gt; (cstdint)</a></td>
<td>Already in common use in the codebase. Approved without discussion.</td>
</tr>
<tr>
<td>Static Assertions</td>
<td><code>static_assert(<i>bool</i>, <i>string</i>)</code></td>
<td>Tests compile-time conditions</td>
<td><a href="http://en.cppreference.com/w/cpp/language/static_assert">Static Assertion</a></td>
<td><a href="https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/POISBQEhGzU">Discussion thread</a></td>
</tr>
<tr>
<td>Variadic Macros</td>
<td><code>#define <i>MACRO</i>(...) <i>Impl</i>(<i>args</i>, __VA_ARGS__)</code></td>
<td>Allows macros that accept a variable number of arguments</td>
<td><a href="http://stackoverflow.com/questions/4786649/are-variadic-macros-nonstandard">
Are Variadic macros nonstandard?</a></td>
<td>Usage should be rare. <a href="https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/sRx9j3CQqyA">Discussion thread</a></td>
</tr>
<tr>
<td>Variadic Templates</td>
<td><code>template &lt;<i>typename</i> ... <i>arg</i>&gt;</code></td>
<td>Allows templates that accept a variable number of arguments</td>
<td>TODO: documentation link</td>
<td>Usage should be rare. Use instead of .pump files. <a href="https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/6ItymeMXpMc">Discussion thread</a></td>
</tr>
</tbody>
</table>
<h2 id="blacklist">C++11 Blacklist (Disallowed and Banned Features)</h2>
<p>This section lists features that are not allowed to be used yet.
<h3 id="blacklist_banned">C++11 Banned Features</h3>
<p>This section will list C++11 features that are not allowed in the Chromium
codebase.
</p>
<table id="banned_list" class="unlined striped">
<tbody>
<tr>
<th style='width:240px;'>Feature or Library</th>
<th style='width:240px;'>Snippet</th>
<th style='width:240px;'>Description</th>
<th style='width:240px;'>Documentation Link</th>
<th style='width:240px;'>Notes</th>
</tr>
<tr>
<td>Constant Expressions</td>
<td><code>constexpr</code></td>
<td>Compile-time constant expressions</td>
<td>TODO: documentation link</td>
<td>Doesn't work in MSVS2013. Reevalute once it does. <a
href="https://google-styleguide.googlecode.com/svn/trunk/cppguide.html#Use_of_constexpr">Google
Style Guide on <code>constexpr</code></a></td>
</tr>
<tr>
<td>Explicit Conversion Operators</td>
<td><code>explicit operator <i>type</i>() {
<br />&nbsp;&nbsp;// code<br /> }</code></td>
<td>Allows conversion operators that cannot be implicitly invoked</td>
<td><a href="http://en.cppreference.com/w/cpp/language/explicit">
explicit specifier</a></td>
<td><a href="https://connect.microsoft.com/VisualStudio/feedback/details/811334/bug-in-vs-2013-support-for-explicit-conversion-operators">Doesn't work in MSVS2013</a>. Reevaluate once it does. <a href="https://groups.google.com/a/chromium.org/d/msg/chromium-dev/zGF1SrQ-1HQ/BAiC12vwPeEJ">Discussion thread</a></td>
</tr>
<tr>
<td>Function Local Variable</td>
<td><code>__func__</code></td>
<td>Provides a local variable of the name of the enclosing
function for logging purposes</td>
<td><a href="http://www.informit.com/guides/content.aspx?g=cplusplus&amp;seqNum=338">
The __func__ Predeclared Identifier is Coming to C++</a></td>
<td>Doesn't work in MSVS2013. Reevaluate once it does. <a href="https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/ojGfcgSDzHM">Discussion thread</a></td>
</tr>
<tr>
<td>Rvalue References (and Move Semantics)</td>
<td><code>T(T&amp;&amp; t)</code> and <code>T&amp; operator=(T&amp;&amp; t)</code></td>
<td>Reference that only binds to a temporary object</td>
<td>TODO: documentation link</td>
<td>To be revisited in the future. Allowed in exceptional cases where approved by the OWNERS of src/styleguide/c++/.</td>
</tr>
<tr>
<td>UTF-16 and UTF-32 Support (16-Bit and 32-Bit Character Types)</td>
<td><code>char16_t</code> and <code>char32_t</code></td>
<td>Provides character types for handling 16-bit
and 32-bit code units (useful for encoding
UTF-16 and UTF-32 string data)</td>
<td><a href="http://en.cppreference.com/w/cpp/language/types">
Fundamental types</a></td>
<td>Doesn't work in MSVS2013. Reevaluate once it does. Non-UTF-8 text is
banned by the
<a href="https://google-styleguide.googlecode.com/svn/trunk/cppguide.html#Non-ASCII_Characters">
C++ Style Guide</a>. However, may be useful for
consuming non-ASCII data. <a href="https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/ME2kL7_Kvyk">Discussion thread</a></td>
</tr>
<tr>
<td>UTF-8, UTF-16, UTF-32 String Literals</td>
<td><code>u8&quot;<i>string</i>&quot;, u&quot;<i>string</i>&quot;, U&quot;<i>string</i>&quot;</code></td>
<td>Enforces UTF-8, UTF-16, UTF-32 encoding on all string literals</td>
<td><a href="http://en.cppreference.com/w/cpp/language/string_literal">
string literal</a></td>
<td>Does not yet work in MSVS2013. Reevaluate once it does. <a href="https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/gcoUbcjfsII">Discussion thread</a></td>
</tr>
</tbody>
</table>
<h3 id="blacklist_review">C++11 Features To Be Discussed</h3>
<p>The following C++ language features are currently disallowed.
See the top of this page on how to propose moving a feature from this list
into the allowed or banned sections. Note that not all of these features
work in all our compilers yet.</p>
<table id="blacklist_review_list" class="unlined striped">
<tbody>
<tr>
<th style='width:240px;'>Feature</th>
<th style='width:240px;'>Snippet</th>
<th style='width:240px;'>Description</th>
<th style='width:240px;'>Documentation Link</th>
<th style='width:240px;'>Notes</th>
</tr>
<tr>
<td>Alignment Features</td>
<td>
<code>alignas</code> specifier,
<code>std::alignment_of&lt;T&gt;</code>,
<code>std::aligned_union&lt;Size, ...Types&gt;</code> and
<code>std::max_align_t</code></td>
<td>Object alignment</td>
<td><a href="http://en.cppreference.com/w/cpp/types/alignment_of">std::alignment_of</a></td>
<td></td>
</tr>
<tr>
<td>Attributes</td>
<td><code>[[<i>attribute_name</i>]]</code></td>
<td>Attaches properties to declarations that
specific compiler implementations may use.</td>
<td><a href="http://www.codesynthesis.com/~boris/blog/2012/04/18/cxx11-generalized-attributes/">
C++11 generalized attributes</a></td>
<td></td>
</tr>
<tr>
<td>Declared Type Accessor</td>
<td><code>decltype(<i>expression</i>)</code></td>
<td>Provides a means to determine the type of an expression at compile-time,
useful most often in templates.</td>
<td><a href="http://en.cppreference.com/w/cpp/language/decltype">
decltype specifier</a></td>
<td><a href="https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/_zoNvZd_dSo">Discussion thread</a></td>
</tr>
<tr>
<td>Default Function Creation</td>
<td><code><i>Function</i>(<i>arguments</i>) = default;</code></td>
<td>Instructs the compiler to generate a default version
of the indicated function</td>
<td><a href="http://stackoverflow.com/questions/823935/whats-the-point-in-defaulting-functions-in-c11">
What's the point in defaulting functions in C++11?</a></td>
<td><a href="https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/qgU4mh_MpGA">Discussion thread</a></td>
</tr>
<tr>
<td>Default Function Template Arguments</td>
<td><code>template &lt;typename T = <i>type</i>&gt; <br />
&nbsp;&nbsp;<i>type</i> <i>Function</i>(T <i>var</i>) {}</code></td>
<td>Allow function templates, like classes, to have default arguments</td>
<td><a href="http://stackoverflow.com/questions/2447458/default-template-arguments-for-function-templates">
Default Template Arguments for Function Templates</a></td>
<td></td>
</tr>
<tr>
<td>Delegated Constructors</td>
<td><code>Class() : Class(0) {}</code><br />
<code>Class(<i>type</i> <i>var</i>) : Class(<i>var</i>, 0)</code></td>
<td>Allow overloaded constructors to use common initialization code</td>
<td><a href="https://www.ibm.com/developerworks/community/blogs/5894415f-be62-4bc0-81c5-3956e82276f3/entry/introduction_to_the_c_11_feature_delegating_constructors?lang=en">
Introduction to the C++11 feature: delegating constructors</a></td>
<td><a href="https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/0zVA8Ctx3Xo">Discussion thread</a></td>
</tr>
<tr>
<td>Exception Features</td>
<td><code>noexcept</code>, <code>exception_ptr</code>,
<code>current_exception()</code>, <code>rethrow_exception</code>,
and <code>nested_exception</code></td>
<td>Enhancements to exception throwing and handling</td>
<td><a href="http://en.cppreference.com/w/cpp/error/exception">
std::exception</a></td>
<td>Exceptions are banned by the
<a href="https://google-styleguide.googlecode.com/svn/trunk/cppguide.html#Exceptions"> C++ Style Guide</a>. <a href="https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/8i4tMqNpHhg">Discussion thread</a></td>
</tr>
<tr>
<td>Function Suppression</td>
<td><code><i>Function</i>(<i>arguments</i>) = delete;</code></td>
<td>Suppresses the implementation of a function, especially a
synthetic function such as a copy constructor</td>
<td>TODO: documentation link</td>
<td><a href="https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/i1o7-RNRnMs">Discussion thread</a></td>
</tr>
<tr>
<td>(Uniform) Initialization Syntax</td>
<td><code><i>type</i> <i>name</i> { [<i>value</i> ..., <i>value</i>]};</code></td>
<td>Allows any object of primitive, aggregate or class
type to be initialized using brace syntax</td>
<td>TODO: documentation link</td>
<td><a href="https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/GF96FshwHLw">Discussion thread</a></td>
</tr>
<tr>
<td>Inline Namespaces</td>
<td><code>inline</code></td>
<td>Allows better versioning of namespaces</td>
<td><a href="http://en.cppreference.com/w/cpp/language/namespace">Namespaces</a></td>
<td>Unclear how it will work with components</td>
</tr>
<tr>
<td>Lambda Expressions</td>
<td><code>[<i>captures</i>](<i>params</i>) -&gt; <i>ret</i> { <i>body</i> }</code></td>
<td>Anonymous functions</td>
<td><a href="http://en.cppreference.com/w/cpp/language/lambda">Lambda functions</a></td>
<td>No default captures (<a href="https://google-styleguide.googlecode.com/svn/trunk/cppguide.html#Lambda_expressions">Google Style Guide</a>). <a href="https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/D9UnnxBnciQ">Discussion thread</a></td>
</tr>
<tr>
<td><code>long long</code> Type</td>
<td><code>long long <i>var</i>= <i>value</i>;</code></td>
<td>An integer of at least 64 bits</td>
<td><a href="http://en.cppreference.com/w/cpp/language/types">
Fundamental types</a></td>
<td><a href="https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/RxugZ-pIDxk">Discussion thread</a></td>
</tr>
<tr>
<td>Non-Static Class Member Initializers</td>
<td>
<code>
class C {<br />
<i>type</i> <i>var</i> = <i>value</i>;<br/>
C() // copy-initializes <i>var</i><br/>
</code>
<td>Allows non-static class members to be initialized at their definitions (outside constructors)</td>
<td><a href="http://en.cppreference.com/w/cpp/language/data_members">
Non-static data members</a></td>
<td><a href="https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/zqB-DySA4V0">Discussion thread</a></td>
</tr>
<tr>
<td>Raw String Literals</td>
<td><code>string <i>var</i>=R&quot;(<i>raw_string</i>)&quot;;</code></td>
<td>Allows a string to be encoded without any escape
sequences, easing parsing in regex expressions, for example</td>
<td>TODO: documentation link</td>
<td><a href="https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/2kWQHbbuMHI">Discussion thread</a></td>
</tr>
<tr>
<td>Union Class Members</td>
<td><code>union <i>name</i> { <i>class</i> <i>var</i>}</code></td>
<td>Allows class type members</td>
<td><a href="http://en.cppreference.com/w/cpp/language/union">
Union declarations</a></td>
<td></td>
</tr>
<tr>
<td>User-Defined Literals</td>
<td><code><i>type</i> <i>var</i> = <i>literal_value</i>_<i>type</i></code></td>
<td>Allows user-defined literal expressions</td>
<td>TODO: documentation link</td>
<td></td>
</tr>
</tbody>
</table>
<h3 id="blacklist_stdlib">C++11 Standard Library features</h3>
<details>
<p><summary class="note">All C++11 <strong>Standard Library features are currently
banned</strong>, because they are not supported on all of our toolchains yet.
In particular, chromium/android is currently using STLport, and chromium/mac is
currently using libstdc++4.2, which predate C++11.
</summary></p>
<table id="banned_stdlib" class="unlined striped">
<tbody>
<tr>
<th style='width:240px;'>Feature</th>
<th style='width:240px;'>Snippet</th>
<th style='width:240px;'>Description</th>
<th style='width:240px;'>Documentation Link</th>
<th style='width:240px;'>Style Guide Usage</th>
</tr>
<tr>
<td>Address Retrieval</td>
<td><code>std::addressof()</code></td>
<td>Obtains the address of an object even with overloaded <code>operator&amp;</code></td>
<td><a href="http://en.cppreference.com/w/cpp/memory/addressof">std::addressof</a></td>
<td>Usage should be rare as
<a href="https://google-styleguide.googlecode.com/svn/trunk/cppguide.html#Operator_Overloading">
Operator Overloading</a> is rare and <code>&amps;</code>
should suffice in most cases. May be preferable
over <code>&amps;</code> for performing object
identity checks.</td>
</tr>
<tr>
<td>Aligned Storage</td>
<td><code>std::aligned_storage&lt;Size, Align&gt;::type</code></td>
<td>Declare uninitialized storage having a specified alignment.</td>
<td><a href="http://en.cppreference.com/w/cpp/types/aligned_storage">std::aligned_storage</a></td>
<td>Note: <code>std::aligned_storage</code> is allowed, but some other C++11
alignment features are still disallowed.</td>
</tr>
<tr>
<td>Allocator Traits</td>
<td><code>std::allocator_traits</code></td>
<td>Provides an interface for accessing custom allocators</td>
<td><a href="http://en.cppreference.com/w/cpp/memory/allocator_traits">
std::allocator_traits</a></td>
<td>Usage should be rare.</td>
</tr>
<tr>
<td>Atomics</td>
<td><code>std::atomic</code> and others in <code>&lt;atomic&gt;</code></td>
<td>Fine-grained atomic types and operations</td>
<td><a href="http://en.cppreference.com/w/cpp/atomic">&lt;atomic&gt;</a></td>
<td></td>
</tr>
<tr>
<td>Arrays</td>
<td><code>std::array</code></td>
<td>A fixed-size replacement for built-in arrays, with STL support</td>
<td><a href="http://en.cppreference.com/w/cpp/container/array">
std::array</a></td>
<td></td>
</tr>
<tr>
<td>Begin and End Non-Member Functions</td>
<td><code>std::begin()</code> and <code>std::end()</code></td>
<td>Allows use of free functions on any container, including
built-in arrays</td>
<td><a href="http://en.cppreference.com/w/cpp/iterator/begin">
std::begin</a> and
<a href="http://en.cppreference.com/w/cpp/iterator/end">
std::end</a></td>
<td>Useful for built-in arrays.</td>
</tr>
<tr>
<td>Bind Operations</td>
<td><code>std::bind(<i>function</i>, <i>args</i>, ...)</code></td>
<td>Declares a function object bound to certain arguments</td>
<td>TODO: documentation link</td>
<td></td>
</tr>
<tr>
<td>C Floating-Point Environment</td>
<td><code>&lt;cfenv&gt;</code></td>
<td>Provides floating point status flags and control modes for C-compatible code</td>
<td><a href="http://en.cppreference.com/w/cpp/header/cfenv">Standard library header &lt;cfenv&gt;</a></td>
<td>Compilers do not support use</td>
</tr>
<tr>
<td>Chrono Library</td>
<td><code>&lt;chrono&gt;</code></td>
<td>Provides a standard date and time library</td>
<td><a href="http://en.cppreference.com/w/cpp/chrono">Date and time utilities</a></td>
<td></td>
</tr>
<tr>
<td>Complex Inverse Trigonometric and Hyperbolic Functions</td>
<td>Functions within <code>&lt;complex&gt;</code></td>
<td>Adds inverse trigonomentric and hyperbolic non-member functions to
the <code>&lt;complex&gt;</code> library.</td>
<td><a href="http://en.cppreference.com/w/cpp/numeric/complex">std::complex</a></td>
<td></td>
</tr>
<tr>
<td>Conditional Type Selection</td>
<td><code>std::enable_if</code> and <code>std::conditional</code></td>
<td>Enables compile-time conditional type selection</td>
<td><a href="http://en.cppreference.com/w/cpp/types/enable_if">
std::enable_if</a> and
<a href="http://en.cppreference.com/w/cpp/types/conditional">
conditional</a></td>
<td></td>
</tr>
<tr>
<td>Constant Iterator Methods on Containers</td>
<td><code>std::cbegin()</code> and <code>std::cend()</code></td>
<td>Enforces iteration methods that don't change container contents</td>
<td>TODO: documentation link</td>
<td></td>
</tr>
<tr>
<td>Construct Elements in Containers</td>
<td><code>emplace()</code>,<code>emplace_back()</code>,
<code>emplace_front()</code>, <code>emplace_hint()</code></td>
<td>Constructs elements directly within a container without a copy
or a move</td>
<td>TODO: documentation link</td>
<td>Use where element construction within a container
is needed.</td>
</tr>
<tr>
<td>Container Compaction Functions</td>
<td><code>std::vector::shrink_to_fit()</code>,
<code>std::deque::shrink_to_fit()</code>, and
<code>std::string::shrink_to_fit()</code></td>
<td>Requests the removal of unused space
in the container</td>
<td><a href="http://en.cppreference.com/w/cpp/container/vector/shrink_to_fit">
std::vector::shrink_to_fit</a>,
<a href="http://en.cppreference.com/w/cpp/container/deque/shrink_to_fit">
std::deque::shrink_to_fit</a>, and
<a href="http://en.cppreference.com/w/cpp/string/basic_string/shrink_to_fit">
std::basic_string::shrink_to_fit</a></td>
<td></td>
</tr>
<tr>
<td>Date/Time String Formatting Specifiers</td>
<td><code>std::strftime()</code></td>
<td>Converts date and time information into a
formatted string using new specifiers</td>
<td><a href="http://en.cppreference.com/w/cpp/chrono/c/strftime">
std::strftime</a></td>
<td></td>
</tr>
<tr>
<td>Function Return Type Deduction</td>
<td><code>std::result_of&lt;<i>Functor(ArgTypes...)</i>&gt;</code></td>
<td>Extracts the return type from the type signature of
a function call invocation at compile-time.</td>
<td><a href="http://en.cppreference.com/w/cpp/types/result_of">
std::result_of</a></td>
<td>
<a href="http://stackoverflow.com/questions/15486951/why-does-stdresult-of-take-an-unrelated-function-type-as-a-type-argument">
Why does std::result_of take an (unrelated) function type as a type argument?
</a></td>
</tr>
<tr>
<td>Function Objects</td>
<td><code>std::function</code></td>
<td>Wraps a standard polymorphic function</td>
<td>TODO: documentation link</td>
<td></td>
</tr>
<tr>
<td>Forward Lists</td>
<td><code>std::forward_list</code></td>
<td>Provides an efficient singly linked list</td>
<td><a href="http://en.cppreference.com/w/cpp/container/forward_list">
std::forward_list</a></td>
<td></td>
</tr>
<tr>
<td>Gamma Natural Log</td>
<td><code>std::lgamma()</code></td>
<td>Computes the natural log of the gamma of a
floating point value</td>
<td><a href="http://en.cppreference.com/w/cpp/numeric/math/lgamma">
std::lgamma</a></td>
<td></td>
</tr>
<tr>
<td>Garbage Collection Features</td>
<td><code>std::{un}declare_reachable()</code> and
<code>std::{un}declare_no_pointers()</code></td>
<td>Enables garbage collection implementations</td>
<td><a href="http://en.cppreference.com/w/cpp/memory/gc/declare_reachable">
std::declare_reachable</a>
and <a href="http://en.cppreference.com/w/cpp/memory/gc/declare_no_pointers">
std::declare_no_pointers</a></td>
<td></td>
</tr>
<tr>
<td>Heap Validation</td>
<td><code>std::is_heap()</code></td>
<td>Checks whether an iterator range is in fact a heap</td>
<td>TODO: documentation link</td>
<td></td>
</tr>
<tr>
<td>Is Nan</td>
<td><code>std::isnan()</code></td>
<td>Determines if a floating point value is not-a-number</td>
<td><a href="http://en.cppreference.com/w/cpp/numeric/math/isnan">std::isnan</a></td>
<td></td>
</tr>
<tr>
<td>Iterator Operators</td>
<td><code>std::next()</code> and <code>std::prev()</code></td>
<td>Copies an iterator and increments or decrements the copy by
some value</td>
<td><a href="http://en.cppreference.com/w/cpp/iterator/next">std::next</a>
and <a href="http://en.cppreference.com/w/cpp/iterator/prev">std::prev</a>
</td>
<td></td>
</tr>
<tr>
<td>Initializer Lists</td>
<td><code>std::initializer_list&lt;T&gt;</code></td>
<td>Allows containers to be initialized with aggregate elements</td>
<td>TODO: documentation link</td>
<td></td>
</tr>
<tr>
<td>Move Semantics</td>
<td><code>std::move()</code></td>
<td>Facilitates efficient move operations</td>
<td><a href="http://en.cppreference.com/w/cpp/utility/move">
<code>std::move</code> reference</a></td>
<td></td>
</tr>
<tr>
<td>Pointer Traits Class Template</td>
<td><code>std::pointer_traits</code></td>
<td>Provides a standard way to access properties
of pointers and pointer-like types</td>
<td><a href="http://en.cppreference.com/w/cpp/memory/pointer_traits">
std::pointer_traits</a></td>
<td>Useful for determining the element type
pointed at by a (possibly smart) pointer.</td>
</tr>
<tr>
<td>Random Number Generators</td>
<td>Functions within <code>&lt;random&gt;</code></td>
<td>Random number generation algorithms and utilities</td>
<td><a href="http://en.cppreference.com/w/cpp/numeric/random">
Pseudo-random number generation</a></td>
<td></td>
</tr>
<tr>
<td>Ratio Template Class</td>
<td><code>std::ratio&lt;<i>numerator</i>, <i>denominator</i>&gt;</code></td>
<td>Provides compile-time rational numbers</td>
<td>TODO: documentation link</td>
<td></td>
</tr>
<tr>
<td>Reference Wrapper Classes</td>
<td><code>std::reference_wrapper</code> and
<code>std::ref()</code>, <code>std::cref()</code></td>
<td>Allows you to wrap a reference within a standard
object (and use those within containers)</td>
<td><a href="http://www.informit.com/guides/content.aspx?g=cplusplus&amp;seqNum=217">
Reference Wrappers</a></td>
<td></td>
</tr>
<tr>
<td>Regex Library</td>
<td><code>&lt;regex&gt;</code></td>
<td>Provides a standard regular expressions library</td>
<td><a href="http://en.cppreference.com/w/cpp/regex">Regular expressions library</a></td>
<td></td>
</tr>
<tr>
<td>Shared Pointers</td>
<td><code>std::shared_ptr</code></td>
<td>Allows shared ownership of a pointer through reference counts</td>
<td><a href="http://en.cppreference.com/w/cpp/memory/shared_ptr">std::shared_ptr</a></td>
<td><a href="https://google-styleguide.googlecode.com/svn/trunk/cppguide.html#Ownership_and_Smart_Pointers">
Ownership and Smart Pointers</a></td>
</tr>
<tr>
<td>Soft Program Exits</td>
<td><code>std::at_quick_exit()</code>
and <code>std::quick_exit()</code></td>
<td>Allows registration of functions to be called upon exit,
allowing cleaner program exit than <code>abort()</code> or
<code>exit</code></td>
<td><a href="http://en.cppreference.com/w/cpp/utility/program/quick_exit">
std:quick_exit</a></td>
<td></td>
</tr>
<tr>
<td>String Direct Reference Functions</td>
<td><code>std::string::front()</code> and <code>std::string::back()</code></td>
<td>Returns a reference to the front or back of a string</td>
<td><a href="http://en.cppreference.com/w/cpp/string/basic_string/front">
std::basic_string::front</a> and
<a href="http://en.cppreference.com/w/cpp/string/basic_string/back">
std::basic_string::back</a></td>
<td></td>
</tr>
<tr>
<td>String to Number Functions</td>
<td><code>std::stoi()</code>, <code>std::stol()</code>,
<code>std::stoul()</code>, <code>std::stoll</code>, <code>std::stoull()</code>,
<code>std::stof()</code>, <code>std::stod()</code>, <code>std::stold()</code>,
and <code>std::to_string()</code></td>
<td>Converts strings to numbers</td>
<td><a href="http://en.cppreference.com/w/cpp/string/basic_string/stol">
std::stoi, std::stol, std::stoll</a>,
<a href="http://en.cppreference.com/w/cpp/string/basic_string/stoul">
std::stoul, std::stoull</a>, and
<a href="http://en.cppreference.com/w/cpp/string/basic_string/stof">
std::stof, std::stod, std::stold</a> </td>
<td></td>
</tr>
<tr>
<td>STL Algorithms</td>
<td>Functions within <code>&lt;algorithm&gt;</code>.</td>
<td>Enhancements to the set of STL algorithms</td>
<td>See the <a href="http://en.cppreference.com/w/cpp/algorithm">
Algorithms library</a> for a complete list.</td>
<td></td>
</tr>
<tr>
<td>System Errors</td>
<td><code>&lt;system_error&gt;</code></td>
<td>Provides a standard system error library</td>
<td><a href="http://en.cppreference.com/w/cpp/error/system_error">std::system_error</a></td>
<td></td>
</tr>
<tr>
<td>Trailing Return Types</td>
<td><code>auto <i>function declaration</i> -> <i>return_type</i></code></td>
<td>Allows trailing function return value syntax</td>
<td><a href="http://en.cppreference.com/w/cpp/language/function">
Declaring functions</a></td>
<td><a href="https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/OQyYSfH9m2M">Discussion thread</a></td>
</tr>
<tr>
<td>Thread Library</td>
<td><code>&lt;thread&gt; support, including &lt;future&gt;,
&lt;mutex&gt;, &lt;condition_variable&gt;</code></td>
<td>Provides a standard mulitthreading library using <code>std::thread</code> and associates</td>
<td><a href="http://en.cppreference.com/w/cpp/thread">Thread support library</a></td>
<td></td>
</tr>
<tr>
<td>Tuples</td>
<td><code>std::tuple</code></td>
<td>A fixed-size ordered collection of values of mixed types</td>
<td>TODO: documentation link</td>
<td></td>
</tr>
<tr>
<td>Type-Generic Math Functions</td>
<td>Functions within <code>&lt;ctgmath&gt;</code></td>
<td>Provides a means to call real or complex functions
based on the type of arguments</td>
<td><a href="http://en.cppreference.com/w/cpp/header/ctgmath">
Standard library header &lt;ctgmath&gt;</a></td>
<td></td>
</tr>
<tr>
<td>Type Info Enhancements</td>
<td><code>std::type_index</code> and <code>std::type_info::hash_code()</code></td>
<td>Allows type information (most often within containers)
that can be copied, assigned, or hashed</td>
<td><a href="http://en.cppreference.com/w/cpp/types/type_index">
std::type_index</a> and
<a href="http://en.cppreference.com/w/cpp/types/type_info/hash_code">
std::type_info::hash_code</a></td>
<td><code>std::type_index</code> is a thin wrapper for
<code>std::type_info</code>, allowing you to use it directly
within both associative and unordered containers</td>
</tr>
<tr>
<td>Type Traits</td>
<td>Class templates within <code>&lt;type_traits&gt;</code></td>
<td>Allows compile-time inspection of the properties of types</td>
<td><a href="http://en.cppreference.com/w/cpp/header/type_traits">
Standard library header &lt;type_traits&gt;</a></td>
<td></td>
</tr>
<tr>
<td>Unique Pointers</td>
<td><code>std::unique_ptr&lt;<i>type</i>&gt;</code></td>
<td>Defines a pointer with clear and unambiguous ownership</td>
<td>TODO: documentation link</td>
<td><a href="https://google-styleguide.googlecode.com/svn/trunk/cppguide.html#Ownership_and_Smart_Pointers">
Ownership and Smart Pointers</a></td>
</tr>
<tr>
<td>Unordered Associative Containers</td>
<td><code>std::unordered_set</code>, <code>std::unordered_map</code>,
<code>std::unordered_multiset</code>, and <code>std::unordered_multimap</code></td>
<td>Allows efficient containers of key/value pairs</td>
<td><a href="http://en.cppreference.com/w/cpp/container/unordered_map">std::unordered_map</a>
and <a href="http://en.cppreference.com/w/cpp/container/unordered_set">std::unordered_set</a>
</td>
<td></td>
</tr>
<tr>
<td>Variadic Copy Macro</td>
<td><code>va_copy(va_list <i>dest</i>, va_list <i>src</i>)</code></td>
<td>Makes a copy of the variadic function arguments</td>
<td></td>
<td></td>
</tr>
<tr>
<td>Weak Pointers</td>
<td><code>std::weak_ptr</code></td>
<td>Allows a weak reference to a <code>std::shared_ptr</code></td>
<td><a href="http://en.cppreference.com/w/cpp/memory/weak_ptr">
std::weak_ptr</a></td>
<td><a href="https://google-styleguide.googlecode.com/svn/trunk/cppguide.html#Ownership_and_Smart_Pointers">
Ownership and Smart Pointers</a></td>
</tr>
<tr>
<td>Wide String Support</td>
<td><code>std::wstring_convert</code>,
<code>std::wbuffer_convert</code>.
<code>std::codecvt_utf8</code>, <code>std::codecvt_utf16</code>,
and <code>std::codecvt_utf8_utf16</code></td>
<td>Converts between string encodings</td>
<td><a href="http://en.cppreference.com/w/cpp/locale/wstring_convert">
std::wstring_convert</a>,
<a href="http://en.cppreference.com/w/cpp/locale/wbuffer_convert">
std::wbuffer_convert</a>,
<a href="http://en.cppreference.com/w/cpp/locale/codecvt_utf8">
std::codecvt_utf8</a>,
<a href="http://en.cppreference.com/w/cpp/locale/codecvt_utf16">
std::codecvt_utf16</a>, and
<a href="http://en.cppreference.com/w/cpp/locale/codecvt_utf8_utf16">
std::codecvt_utf8_utf16</a>
</td>
<td>Non-UTF-8 text is banned by the
<a href="https://google-styleguide.googlecode.com/svn/trunk/cppguide.html#Non-ASCII_Characters">
C++ Style Guide</a>. However, may be useful for
consuming non-ASCII data.</td>
</tr>
</tbody>
</table>
</details>
</div>
</body>
</html>