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      <i><b>Contents</b></i></td>
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    <td width="100%" bgcolor="#E8F5FF">
      <a href="#Introduction">Introduction</a><br>
      <a href="#C++11">C++11</a><br>
      <a href="#Macros">Macros</a><br>
      <a href="#Deprecated-names">Deprecated names</a><br>
      <a href="#Breaking-changes">Breaking changes</a><br>
      <a href="#Header-error_code">Header &lt;boost/system/error_code.hpp&gt;</a><br>
      <a href="#Class-error_category">Class <code>error_category</code></a><br>
      &nbsp;&nbsp;&nbsp;<a href="#Class-error_category-synopsis">Class <code>error_category</code> synopsis</a><br>
      &nbsp;&nbsp;&nbsp;<a href="#Class-error_category-virtual-members">Class <code>error_category</code> virtual members</a><br>
      &nbsp;&nbsp;&nbsp;<a href="#Class-error_category-non-virtual-members">Class <code>error_category</code> non-virtual members</a><br>
&nbsp;&nbsp; <a href="#Class-error_category-non-member-functions">Class <code>error_category</code> 
      non-member functions</a><br>
      &nbsp;&nbsp;&nbsp;<a href="#Class-error_category-predefined-objects">Class <code>error_category</code> predefined objects</a><br>
      <a href="#Class-error_code">Class <code>error_code</code></a><br>
      &nbsp;&nbsp;&nbsp;<a href="#Class-error_code-synopsis">Class <code>error_code</code> synopsis</a><br>
      &nbsp;&nbsp;&nbsp;<a href="#Class-error_code-constructors">Class <code>error_code</code> constructors</a><br>
      &nbsp;&nbsp;&nbsp;<a href="#Class-error_code-modifiers">Class <code>error_code</code> modifiers</a><br>
      &nbsp;&nbsp;&nbsp;<a href="#Class-error_code-observers">Class <code>error_code</code> observers</a><br>
      <a href="#Class-error_condition">Class <code>error_condition</code></a><br>
      &nbsp;&nbsp;&nbsp;<a href="#Class-error_condition-synopsis">Class <code>error_condition</code> synopsis</a><br>
      &nbsp;&nbsp;&nbsp;<a href="#Class-error_condition-constructors">Class <code>error_condition</code> constructors</a><br>
      &nbsp;&nbsp;&nbsp;<a href="#Class-error_condition-modifiers">Class <code>error_condition</code> modifiers</a><br>
      &nbsp;&nbsp;&nbsp;<a href="#Class-error_condition-observers">Class <code>error_condition</code> observers</a><br>
      <a href="#throws-object"><code>throws</code> object</a><br>
      <a href="#Semantics-of-throws">Semantics of <code>throws</code> object</a><br>
      <a href="#Non-member-functions">Non-member functions</a><br>
      <a href="#Header-system_error">Header &lt;boost/system/system_error.hpp&gt;</a><br>
      &nbsp;&nbsp;&nbsp;<a href="#Class-system_error">Class <code>system_error</code></a><br>
    </td>
  </tr>
</table>

<h2><a name="Introduction">Introduction</a></h2>

<p>This reference documentation describes components that&nbsp;programs may use to report error conditions originating from the operating 
system or other low-level application program interfaces.</p>
<p>Boost.System library components never change the value of <code>
errno</code>.</p>
<h2><a name="C++11">C++11</a></h2>
<p>The library is documented to use several C++11 features, including <code>
noexcept</code> and explicit conversion operators. The actual implementation 
uses C++11 features only when they are available, and otherwise falls back on 
C++03 features.</p>
<h2><a name="Macros">Macros</a></h2>
<p>Users may defined the following macros if desired. Sensible defaults are 
provided, so users may ignore these macros if they prefer.</p>
<table border="1" cellpadding="5" cellspacing="0" style="border-collapse: collapse" bordercolor="#111111" height="368">
  <tr>
    <td height="16"><b><i>Macro Name</i></b></td>
    <td height="16"><b><i>Default</i></b></td>
    <td height="16"><b><i>Effect if defined</i></b></td>
  </tr>
  <tr>
    <td valign="top" height="64"><code>BOOST_ERROR_CODE_HEADER_ONLY</code></td>
    <td valign="top" height="64">Not defined.</td>
    <td valign="top" height="64">The implementation is header-only, and the 
    Boost.System library is not built. Overrides other link and library macros.</td>
  </tr>
  <tr>
    <td valign="top" height="64"><code>BOOST_SYSTEM_DYN_LINK</code></td>
    <td valign="top" height="64">Defined if <code>BOOST_ALL_DYN_LINK</code> is defined, 
    otherwise not defined.</td>
    <td valign="top" height="64">Boost.System library is dynamically linked. If not defined, 
    static linking is assumed.</td>
  </tr>
  <tr>
    <td valign="top" height="47"><code>BOOST_SYSTEM_NO_LIB</code></td>
    <td valign="top" height="47">Defined if <code>BOOST_ALL_NO_LIB</code> is defined, 
    otherwise not defined.</td>
    <td valign="top" height="47">Boost.System library does not use the Boost auto-link 
    facility.</td>
  </tr>
  <tr>
    <td valign="top" height="32"><code>BOOST_SYSTEM_NO_DEPRECATED</code></td>
    <td valign="top" height="32">Not defined.</td>
    <td valign="top" height="32">Deprecated features are excluded.</td>
  </tr>
  </table>
<h2><a name="Deprecated-names">Deprecated names</a></h2>
<p>In the process of adding Boost.System to C++0x standard library, the C++ 
committee changed some  
names. To ease transition, Boost.System deprecates the old 
names, but continues to provide them unless macro <code>BOOST_SYSTEM_NO_DEPRECATED</code> 
is defined.</p>
<table border="1" cellpadding="5" cellspacing="1" style="border-collapse: collapse" bordercolor="#111111">
  <tr>
    <td><b><i>Old usage, now deprecated</i></b></td>
    <td><b><i>Replacement</i></b></td>
  </tr>
  <tr>
    <td><code>get_generic_category()</code></td>
    <td><code>generic_category()</code></td>
  </tr>
  <tr>
    <td><code>get_system_category()</code></td>
    <td><code>system_category()</code></td>
  </tr>
  <tr>
    <td><code>namespace posix</code></td>
    <td><code>namespace errc</code></td>
  </tr>
  <tr>
    <td><code>namespace posix_error</code></td>
    <td><code>namespace errc</code></td>
  </tr>
  <tr>
    <td><code>enum posix_errno</code></td>
    <td><code>enum errc_t</code></td>
  </tr>
  <tr>
    <td><code>get_posix_category()</code></td>
    <td><code>generic_category()</code></td>
  </tr>
  <tr>
    <td><code>posix_category</code></td>
    <td><code>generic_category()</code></td>
  </tr>
  <tr>
    <td><code>errno_ecat</code></td>
    <td><code>generic_category()</code></td>
  </tr>
  <tr>
    <td><code>native_ecat</code></td>
    <td><code>system_category()</code></td>
  </tr>
</table>
<h2><a name="Breaking-changes">Breaking changes</a></h2>
<p>Two static consts are replaced by functions. These are breaking changes best 
fixed by globally adding () to these names to turn them into function calls.</p>
<table border="1" cellpadding="5" cellspacing="1" style="border-collapse: collapse" bordercolor="#111111">
  <tr>
    <td><b><i>Old usage, now broken</i></b></td>
    <td><b><i>Replacement</i></b></td>
  </tr>
  <tr>
    <td><code>generic_category</code></td>
    <td><code>generic_category()</code></td>
  </tr>
  <tr>
    <td><code>system_category</code></td>
    <td><code>system_category()</code></td>
  </tr>
  </table>
<p>User-defined BOOST_POSIX_API and BOOST_WINDOWS_API macros are no longer supported.</p>
<h2><a name="Header-error_code">Header &lt;boost/system/error_code.hpp&gt;</a></h2>
<h3>&lt;boost/system/error_code.hpp&gt; synopsis</h3>
<blockquote>
<pre>namespace boost
{
  namespace system
  {
    class <a href="#Class-error_category">error_category</a>;
    const error_category &amp;  <a href="#system_category">system_category</a>() noexcept;
    const error_category &amp;  <a href="#generic_category">generic_category</a>() noexcept;

    class <a href="#Class-error_code">error_code</a>;
    class <a href="#Class-error_condition">error_condition</a>;

    //  "Concept" helpers
    template< class T="" >
      struct is_error_code_enum { static const bool value = false; };

    template< class T="" >
      struct is_error_condition_enum { static const bool value = false; };

    //  generic error_conditions
    namespace errc
    {
      enum errc_t
      {
        success = 0,
        address_family_not_supported,   //EAFNOSUPPORT
        address_in_use,                 //EADDRINUSE
        address_not_available,          //EADDRNOTAVAIL
        already_connected,              //EISCONN
        argument_list_too_long,         //E2BIG
        argument_out_of_domain,         //EDOM
        bad_address,                    //EFAULT
        bad_file_descriptor,            //EBADF
        bad_message,                    //EBADMSG
        broken_pipe,                    //EPIPE
        connection_aborted,             //ECONNABORTED
        connection_already_in_progress, //EALREADY
        connection_refused,             //ECONNREFUSED
        connection_reset,               //ECONNRESET
        cross_device_link,              //EXDEV
        destination_address_required,   //EDESTADDRREQ
        device_or_resource_busy,        //EBUSY
        directory_not_empty,            //ENOTEMPTY
        executable_format_error,        //ENOEXEC
        file_exists,                    //EEXIST
        file_too_large,                 //EFBIG
        filename_too_long,              //ENAMETOOLONG
        function_not_supported,         //ENOSYS
        host_unreachable,               //EHOSTUNREACH
        identifier_removed,             //EIDRM
        illegal_byte_sequence,          //EILSEQ
        inappropriate_io_control_operation,//ENOTTY
        interrupted,                    //EINTR
        invalid_argument,               //EINVAL
        invalid_seek,                   //ESPIPE
        io_error,                       //EIO
        is_a_directory,                 //EISDIR
        message_size,                   //EMSGSIZE
        network_down,                   //ENETDOWN
        network_reset,                  //ENETRESET
        network_unreachable,            //ENETUNREACH
        no_buffer_space,                //ENOBUFS
        no_child_process,               //ECHILD
        no_link,                        //ENOLINK
        no_lock_available,              //ENOLCK
        no_message_available,           //ENODATA
        no_message,                     //ENOMSG
        no_protocol_option,             //ENOPROTOOPT
        no_space_on_device,             //ENOSPC
        no_stream_resources,            //ENOSR
        no_such_device_or_address,      //ENXIO
        no_such_device,                 //ENODEV
        no_such_file_or_directory,      //ENOENT
        no_such_process,                //ESRCH
        not_a_directory,                //ENOTDIR
        not_a_socket,                   //ENOTSOCK
        not_a_stream,                   //ENOSTR
        not_connected,                  //ENOTCONN
        not_enough_memory,              //ENOMEM
        not_supported,                  //ENOTSUP
        operation_canceled,             //ECANCELED
        operation_in_progress,          //EINPROGRESS
        operation_not_permitted,        //EPERM
        operation_not_supported,        //EOPNOTSUPP
        operation_would_block,          //EWOULDBLOCK
        owner_dead,                     //EOWNERDEAD
        permission_denied,              //EACCES
        protocol_error,                 //EPROTO
        protocol_not_supported,         //EPROTONOSUPPORT
        read_only_file_system,          //EROFS
        resource_deadlock_would_occur,  //EDEADLK
        resource_unavailable_try_again, //EAGAIN
        result_out_of_range,            //ERANGE
        state_not_recoverable,          //ENOTRECOVERABLE
        stream_timeout,                 //ETIME
        text_file_busy,                 //ETXTBSY
        timed_out,                      //ETIMEDOUT
        too_many_files_open_in_system,  //ENFILE
        too_many_files_open,            //EMFILE
        too_many_links,                 //EMLINK
        too_many_synbolic_link_levels,  //ELOOP
        value_too_large,                //EOVERFLOW
        wrong_protocol_type             //EPROTOTYPE
      };

    } // namespace errc

    template<> struct is_error_condition_enum<posix::posix_errno>&lt;errc::errc_t&gt;
      { static const bool value = true; };

    //  <a href="#Non-member-functions">non-member functions</a>

    bool operator==( const error_code &amp; lhs, const error_code &amp; rhs ) noexcept;
    bool operator==( const error_code &amp; code, const error_condition &amp; condition ) noexcept;
    bool operator==( const error_condition &amp; condition, const error_code &amp; code ) noexcept;
    bool operator==( const error_condition &amp; lhs, const error_condition &amp; rhs ) noexcept;

    bool operator!=( const error_code &amp; lhs, const error_code &amp; rhs ) noexcept;
    bool operator!=( const error_code &amp; code, const error_condition &amp; condition ) noexcept;
    bool operator!=( const error_condition &amp; condition, const error_code &amp; code ) noexcept;
    bool operator!=( const error_condition &amp; lhs, const error_condition &amp; rhs ) noexcept;

    bool operator&lt;( const error_code &amp; lhs, const error_code &amp; rhs ) noexcept;
    bool operator&lt;( const error_condition &amp; lhs, const error_condition &amp; rhs ) noexcept;

    error_code make_error_code( errc::errc_t e ) noexcept;
    error_condition make_error_condition( errc::errc_t e ) noexcept;

    template &lt;class charT, class traits&gt;
      std::basic_ostream&lt;charT,traits&gt;&amp;
        operator&lt;&lt;( basic_ostream&lt;charT,traits&gt;&amp; os, const error_code &amp; ec );

    size_t hash_value( const error_code &amp; ec );
  }
}</pre>
</blockquote>
<p>The value of each<code> errc_t</code> constant shall be the same as the 
value of the <code>&lt;cerrno&gt;</code> macro shown in the above synopsis.</p>
<p>Users may specialize <code>is_error_code_enum</code> and <code>
is_error_condition_enum</code> templates to indicate that a type is eligible for 
class <code>error_code</code> and <code>error_condition</code> automatic 
conversions respectively.</p>

<pre>const error_category &amp; <a name="system_category">system_category</a>();</pre>
<blockquote>
  <p><i>Returns:</i> A reference to a <code>error_category</code> object 
  identifying errors originating from the operating system.</p>
</blockquote>
<pre>const error_category &amp; <a name="generic_category">generic_category</a>();</pre>
<blockquote>
  <p><i>Returns:</i> A reference to a <code>error_category</code> object 
  identifying portable error conditions.</p>
</blockquote>

<h2><a name="Class-error_category">Class <code>error_category</code></a></h2>
<p>The class <code>error_category</code> defines the base class for types used 
to identify the source and encoding of a particular category of error code.</p>
<p><i>[Note:</i> Classes may be derived from <code>error_category</code> 
to support additional categories of errors. <i>--end note]</i></p>
<p>The class <code>error_category</code> serves as a base class for types used 
to identify the source and encoding of a particular category of error code. 
Classes may be derived from <code>error_category</code> to support categories of 
errors in addition to those defined in the Boost System library. Such classes 
shall behave as specified in this subclause. [<i> Note:</i> <code>error_category</code> 
objects are passed by reference, and two such objects are equal if they have the 
same address. This means that applications using custom <code>error_category</code>
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	36	<i><b>Contents</b></i></td>
	37	</tr>
	38	<tr>
	39	<td width="100%" bgcolor="#E8F5FF">
	40	<a href="#Introduction">Introduction</a><br>
	41	<a href="#C++11">C++11</a><br>
	42	<a href="#Macros">Macros</a><br>
	43	<a href="#Deprecated-names">Deprecated names</a><br>
	44	<a href="#Breaking-changes">Breaking changes</a><br>
	45	<a href="#Header-error_code">Header <boost/system/error_code.hpp></a><br>
	46	<a href="#Class-error_category">Class <code>error_category</code></a><br>
	47	<a href="#Class-error_category-synopsis">Class <code>error_category</code> synopsis</a><br>
	48	<a href="#Class-error_category-virtual-members">Class <code>error_category</code> virtual members</a><br>
	49	<a href="#Class-error_category-non-virtual-members">Class <code>error_category</code> non-virtual members</a><br>
	50	<a href="#Class-error_category-non-member-functions">Class <code>error_category</code>
	51	non-member functions</a><br>
	52	<a href="#Class-error_category-predefined-objects">Class <code>error_category</code> predefined objects</a><br>
	53	<a href="#Class-error_code">Class <code>error_code</code></a><br>
	54	<a href="#Class-error_code-synopsis">Class <code>error_code</code> synopsis</a><br>
	55	<a href="#Class-error_code-constructors">Class <code>error_code</code> constructors</a><br>
	56	<a href="#Class-error_code-modifiers">Class <code>error_code</code> modifiers</a><br>
	57	<a href="#Class-error_code-observers">Class <code>error_code</code> observers</a><br>
	58	<a href="#Class-error_condition">Class <code>error_condition</code></a><br>
	59	<a href="#Class-error_condition-synopsis">Class <code>error_condition</code> synopsis</a><br>
	60	<a href="#Class-error_condition-constructors">Class <code>error_condition</code> constructors</a><br>
	61	<a href="#Class-error_condition-modifiers">Class <code>error_condition</code> modifiers</a><br>
	62	<a href="#Class-error_condition-observers">Class <code>error_condition</code> observers</a><br>
	63	<a href="#throws-object"><code>throws</code> object</a><br>
	64	<a href="#Semantics-of-throws">Semantics of <code>throws</code> object</a><br>
65	<a href="#Non-member-functions">Non-member functions</a><br>
66	<a href="#Header-system_error">Header <boost/system/system_error.hpp></a><br>
67	<a href="#Class-system_error">Class <code>system_error</code></a><br>
68	</td>
69	</tr>
70	</table>
71
72	<h2><a name="Introduction">Introduction</a></h2>
73
74	<p>This reference documentation describes components that programs may use to report error conditions originating from the operating
75	system or other low-level application program interfaces.</p>
76	<p>Boost.System library components never change the value of <code>
77	errno</code>.</p>
78	<h2><a name="C++11">C++11</a></h2>
79	<p>The library is documented to use several C++11 features, including <code>
80	noexcept</code> and explicit conversion operators. The actual implementation
81	uses C++11 features only when they are available, and otherwise falls back on
82	C++03 features.</p>
83	<h2><a name="Macros">Macros</a></h2>
84	<p>Users may defined the following macros if desired. Sensible defaults are
85	provided, so users may ignore these macros if they prefer.</p>
86	<table border="1" cellpadding="5" cellspacing="0" style="border-collapse: collapse" bordercolor="#111111" height="368">
87	<tr>
88	<td height="16"><b><i>Macro Name</i></b></td>
89	<td height="16"><b><i>Default</i></b></td>
90	<td height="16"><b><i>Effect if defined</i></b></td>
91	</tr>
92	<tr>
93	<td valign="top" height="64"><code>BOOST_ERROR_CODE_HEADER_ONLY</code></td>
94	<td valign="top" height="64">Not defined.</td>
95	<td valign="top" height="64">The implementation is header-only, and the
96	Boost.System library is not built. Overrides other link and library macros.</td>
97	</tr>
98	<tr>
99	<td valign="top" height="64"><code>BOOST_SYSTEM_DYN_LINK</code></td>
100	<td valign="top" height="64">Defined if <code>BOOST_ALL_DYN_LINK</code> is defined,
101	otherwise not defined.</td>
102	<td valign="top" height="64">Boost.System library is dynamically linked. If not defined,
103	static linking is assumed.</td>
104	</tr>
105	<tr>
106	<td valign="top" height="47"><code>BOOST_SYSTEM_NO_LIB</code></td>
107	<td valign="top" height="47">Defined if <code>BOOST_ALL_NO_LIB</code> is defined,
108	otherwise not defined.</td>
109	<td valign="top" height="47">Boost.System library does not use the Boost auto-link
110	facility.</td>
111	</tr>
112	<tr>
113	<td valign="top" height="32"><code>BOOST_SYSTEM_NO_DEPRECATED</code></td>
114	<td valign="top" height="32">Not defined.</td>
115	<td valign="top" height="32">Deprecated features are excluded.</td>
116	</tr>
117	</table>
118	<h2><a name="Deprecated-names">Deprecated names</a></h2>
119	<p>In the process of adding Boost.System to C++0x standard library, the C++
120	committee changed some
121	names. To ease transition, Boost.System deprecates the old
122	names, but continues to provide them unless macro <code>BOOST_SYSTEM_NO_DEPRECATED</code>
123	is defined.</p>
124	<table border="1" cellpadding="5" cellspacing="1" style="border-collapse: collapse" bordercolor="#111111">
125	<tr>
126	<td><b><i>Old usage, now deprecated</i></b></td>
127	<td><b><i>Replacement</i></b></td>
128	</tr>
129	<tr>
130	<td><code>get_generic_category()</code></td>
131	<td><code>generic_category()</code></td>
132	</tr>
133	<tr>
134	<td><code>get_system_category()</code></td>
135	<td><code>system_category()</code></td>
136	</tr>
137	<tr>
138	<td><code>namespace posix</code></td>
139	<td><code>namespace errc</code></td>
140	</tr>
141	<tr>
142	<td><code>namespace posix_error</code></td>
143	<td><code>namespace errc</code></td>
144	</tr>
145	<tr>
146	<td><code>enum posix_errno</code></td>
147	<td><code>enum errc_t</code></td>
148	</tr>
149	<tr>
150	<td><code>get_posix_category()</code></td>
151	<td><code>generic_category()</code></td>
152	</tr>
153	<tr>
154	<td><code>posix_category</code></td>
155	<td><code>generic_category()</code></td>
156	</tr>
157	<tr>
158	<td><code>errno_ecat</code></td>
159	<td><code>generic_category()</code></td>
160	</tr>
161	<tr>
162	<td><code>native_ecat</code></td>
163	<td><code>system_category()</code></td>
164	</tr>
165	</table>
166	<h2><a name="Breaking-changes">Breaking changes</a></h2>
167	<p>Two static consts are replaced by functions. These are breaking changes best
168	fixed by globally adding () to these names to turn them into function calls.</p>
169	<table border="1" cellpadding="5" cellspacing="1" style="border-collapse: collapse" bordercolor="#111111">
170	<tr>
171	<td><b><i>Old usage, now broken</i></b></td>
172	<td><b><i>Replacement</i></b></td>
173	</tr>
174	<tr>
175	<td><code>generic_category</code></td>
176	<td><code>generic_category()</code></td>
177	</tr>
178	<tr>
179	<td><code>system_category</code></td>
180	<td><code>system_category()</code></td>
181	</tr>
182	</table>
183	<p>User-defined BOOST_POSIX_API and BOOST_WINDOWS_API macros are no longer supported.</p>
184	<h2><a name="Header-error_code">Header <boost/system/error_code.hpp></a></h2>
185	<h3><boost/system/error_code.hpp> synopsis</h3>
186	<blockquote>
187	<pre>namespace boost
188	{
189	namespace system
190	{
191	class <a href="#Class-error_category">error_category</a>;
192	const error_category & <a href="#system_category">system_category</a>() noexcept;
193	const error_category & <a href="#generic_category">generic_category</a>() noexcept;
194
195	class <a href="#Class-error_code">error_code</a>;
196	class <a href="#Class-error_condition">error_condition</a>;
197
198	// "Concept" helpers
199	template< class T="" >
200	struct is_error_code_enum { static const bool value = false; };
201
202	template< class T="" >
203	struct is_error_condition_enum { static const bool value = false; };
204
205	// generic error_conditions
206	namespace errc
207	{
208	enum errc_t
209	{
210	success = 0,
211	address_family_not_supported, //EAFNOSUPPORT
212	address_in_use, //EADDRINUSE
213	address_not_available, //EADDRNOTAVAIL
214	already_connected, //EISCONN
215	argument_list_too_long, //E2BIG
216	argument_out_of_domain, //EDOM
217	bad_address, //EFAULT
218	bad_file_descriptor, //EBADF
219	bad_message, //EBADMSG
220	broken_pipe, //EPIPE
221	connection_aborted, //ECONNABORTED
222	connection_already_in_progress, //EALREADY
223	connection_refused, //ECONNREFUSED
224	connection_reset, //ECONNRESET
225	cross_device_link, //EXDEV
226	destination_address_required, //EDESTADDRREQ
227	device_or_resource_busy, //EBUSY
228	directory_not_empty, //ENOTEMPTY
229	executable_format_error, //ENOEXEC
230	file_exists, //EEXIST
231	file_too_large, //EFBIG
232	filename_too_long, //ENAMETOOLONG
233	function_not_supported, //ENOSYS
234	host_unreachable, //EHOSTUNREACH
235	identifier_removed, //EIDRM
236	illegal_byte_sequence, //EILSEQ
237	inappropriate_io_control_operation,//ENOTTY
238	interrupted, //EINTR
239	invalid_argument, //EINVAL
240	invalid_seek, //ESPIPE
241	io_error, //EIO
242	is_a_directory, //EISDIR
243	message_size, //EMSGSIZE
244	network_down, //ENETDOWN
245	network_reset, //ENETRESET
246	network_unreachable, //ENETUNREACH
247	no_buffer_space, //ENOBUFS
248	no_child_process, //ECHILD
249	no_link, //ENOLINK
250	no_lock_available, //ENOLCK
251	no_message_available, //ENODATA
252	no_message, //ENOMSG
253	no_protocol_option, //ENOPROTOOPT
254	no_space_on_device, //ENOSPC
255	no_stream_resources, //ENOSR
256	no_such_device_or_address, //ENXIO
257	no_such_device, //ENODEV
258	no_such_file_or_directory, //ENOENT
259	no_such_process, //ESRCH
260	not_a_directory, //ENOTDIR
261	not_a_socket, //ENOTSOCK
262	not_a_stream, //ENOSTR
263	not_connected, //ENOTCONN
264	not_enough_memory, //ENOMEM
265	not_supported, //ENOTSUP
266	operation_canceled, //ECANCELED
267	operation_in_progress, //EINPROGRESS
268	operation_not_permitted, //EPERM
269	operation_not_supported, //EOPNOTSUPP
270	operation_would_block, //EWOULDBLOCK
271	owner_dead, //EOWNERDEAD
272	permission_denied, //EACCES
273	protocol_error, //EPROTO
274	protocol_not_supported, //EPROTONOSUPPORT
275	read_only_file_system, //EROFS
276	resource_deadlock_would_occur, //EDEADLK
277	resource_unavailable_try_again, //EAGAIN
278	result_out_of_range, //ERANGE
279	state_not_recoverable, //ENOTRECOVERABLE
280	stream_timeout, //ETIME
281	text_file_busy, //ETXTBSY
282	timed_out, //ETIMEDOUT
283	too_many_files_open_in_system, //ENFILE
284	too_many_files_open, //EMFILE
285	too_many_links, //EMLINK
286	too_many_synbolic_link_levels, //ELOOP
287	value_too_large, //EOVERFLOW
288	wrong_protocol_type //EPROTOTYPE
289	};
290
291	} // namespace errc
292
293	template<> struct is_error_condition_enum<posix::posix_errno><errc::errc_t>
294	{ static const bool value = true; };
295
296	// <a href="#Non-member-functions">non-member functions</a>
297
298	bool operator==( const error_code & lhs, const error_code & rhs ) noexcept;
299	bool operator==( const error_code & code, const error_condition & condition ) noexcept;
300	bool operator==( const error_condition & condition, const error_code & code ) noexcept;
301	bool operator==( const error_condition & lhs, const error_condition & rhs ) noexcept;
302
303	bool operator!=( const error_code & lhs, const error_code & rhs ) noexcept;
304	bool operator!=( const error_code & code, const error_condition & condition ) noexcept;
305	bool operator!=( const error_condition & condition, const error_code & code ) noexcept;
306	bool operator!=( const error_condition & lhs, const error_condition & rhs ) noexcept;
307
308	bool operator<( const error_code & lhs, const error_code & rhs ) noexcept;
309	bool operator<( const error_condition & lhs, const error_condition & rhs ) noexcept;
310
311	error_code make_error_code( errc::errc_t e ) noexcept;
312	error_condition make_error_condition( errc::errc_t e ) noexcept;
313
314	template <class charT, class traits>
315	std::basic_ostream<charT,traits>&
316	operator<<( basic_ostream<charT,traits>& os, const error_code & ec );
317
318	size_t hash_value( const error_code & ec );
319	}
320	}</pre>
321	</blockquote>
322	<p>The value of each<code> errc_t</code> constant shall be the same as the
323	value of the <code><cerrno></code> macro shown in the above synopsis.</p>
324	<p>Users may specialize <code>is_error_code_enum</code> and <code>
325	is_error_condition_enum</code> templates to indicate that a type is eligible for
326	class <code>error_code</code> and <code>error_condition</code> automatic
327	conversions respectively.</p>
328
329	<pre>const error_category & <a name="system_category">system_category</a>();</pre>
330	<blockquote>
331	<p><i>Returns:</i> A reference to a <code>error_category</code> object
332	identifying errors originating from the operating system.</p>
333	</blockquote>
334	<pre>const error_category & <a name="generic_category">generic_category</a>();</pre>
335	<blockquote>
336	<p><i>Returns:</i> A reference to a <code>error_category</code> object
337	identifying portable error conditions.</p>
338	</blockquote>
339
340	<h2><a name="Class-error_category">Class <code>error_category</code></a></h2>
341	<p>The class <code>error_category</code> defines the base class for types used
342	to identify the source and encoding of a particular category of error code.</p>
343	<p><i>[Note:</i> Classes may be derived from <code>error_category</code>
344	to support additional categories of errors. <i>--end note]</i></p>
345	<p>The class <code>error_category</code> serves as a base class for types used
346	to identify the source and encoding of a particular category of error code.
347	Classes may be derived from <code>error_category</code> to support categories of
348	errors in addition to those defined in the Boost System library. Such classes
349	shall behave as specified in this subclause. [<i> Note:</i> <code>error_category</code>
350	objects are passed by reference, and two such objects are equal if they have the
351	same address. This means that applications using custom <code>error_category</code>
352