ceph/src/boost/libs/date_time/xmldoc/ptime_class.xml

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   5 <!-- Copyright (c) 2001-2005 CrystalClear Software, Inc.
   6      Subject to the Boost Software License, Version 1.0.
   7      (See accompanying file LICENSE_1_0.txt or  http://www.boost.org/LICENSE_1_0.txt)
   8 -->
   9
  10 <section id="date_time.posix_time.ptime_class">
  11   <title>Ptime</title>
  12
  13   <link linkend="ptime_intro">Introduction</link> --
  14   <link linkend="ptime_header">Header</link> --
  15   <link linkend="ptime_constr">Construction</link> --
  16   <link linkend="ptime_from_string">Construct from String</link> --
  17   <link linkend="ptime_from_clock">Construct from Clock</link> --
  18   <link linkend="ptime_from_funcs">Construct using Conversion functions</link> --
  19   <link linkend="ptime_accessors">Accessors</link> --
  20   <link linkend="ptime_to_string">Conversion To String</link> --
  21   <link linkend="ptime_operators">Operators</link> --
  22   <link linkend="ptime_struct_tm">Struct tm, time_t, and FILETIME Functions</link>
  23
  24   <anchor id="ptime_intro" />
  25   <bridgehead renderas="sect3">Introduction</bridgehead>
  26   <para>
  27     The class boost::posix_time::ptime is the primary interface for time point manipulation. In general, the ptime class is immutable once constructed although it does allow assignment.
  28   </para>
  29   <para>
  30     Class ptime is dependent on <link linkend="date_time.gregorian.date_class">gregorian::date</link> for the interface to the date portion of a time point.
  31   </para>
  32   <para>
  33     Other techniques for creating times include <link linkend="date_time.posix_time.time_iterators">time iterators</link>.
  34   </para>
  35
  36   <anchor id="ptime_header" />
  37   <bridgehead renderas="sect3">Header</bridgehead>
  38   <para>
  39     <programlisting>#include "boost/date_time/posix_time/posix_time.hpp" //include all types plus i/o
  40 or
  41 #include "boost/date_time/posix_time/posix_time_types.hpp" //no i/o just types</programlisting>
  42   </para>
  43
  44   <anchor id="ptime_constr" />
  45   <bridgehead renderas="sect3">Construction</bridgehead>
  46   <para>
  47     <informaltable frame="all">
  48       <tgroup cols="2">
  49         <thead>
  50           <row>
  51             <entry valign="top" morerows="1">Syntax</entry>
  52             <entry>Description</entry>
  53           </row>
  54           <row>
  55             <entry>Example</entry>
  56           </row>
  57         </thead>
  58         <tbody>
  59           <row>
  60             <entry valign="top" morerows="1"><screen>ptime(date,time_duration)</screen></entry>
  61             <entry>Construct from a date and offset</entry>
  62           </row>
  63           <row>
  64             <entry><screen>ptime t1(date(2002,Jan,10),
  65          time_duration(1,2,3));
  66 ptime t2(date(2002,Jan,10),
  67          hours(1)+nanosec(5));</screen>
  68             </entry>
  69           </row>
  70
  71           <row>
  72             <entry valign="top" morerows="1"><screen>ptime(ptime)</screen></entry>
  73             <entry>Copy constructor</entry>
  74           </row>
  75           <row>
  76             <entry><screen>ptime t3(t1)</screen></entry>
  77           </row>
  78
  79           <row>
  80             <entry valign="top" morerows="1"><screen>ptime(special_values sv)</screen></entry>
  81             <entry>Constructor for infinities, not-a-date-time, max_date_time, and min_date_time</entry>
  82           </row>
  83           <row>
  84             <entry><screen>ptime d1(neg_infin);
  85 ptime d2(pos_infin);
  86 ptime d3(not_a_date_time);
  87 ptime d4(max_date_time);
  88 ptime d5(min_date_time);</screen></entry>
  89           </row>
  90
  91           <row>
  92             <entry valign="top" morerows="1"><screen>ptime;</screen></entry>
  93             <entry>Default constructor. Creates a ptime object initialized to not_a_date_time. NOTE: this constructor can be disabled by defining DATE_TIME_NO_DEFAULT_CONSTRUCTOR (see compiler_config.hpp)</entry>
  94           </row>
  95           <row>
  96             <entry><screen>ptime p; // p =&gt; not_a_date_time</screen></entry>
  97           </row>
  98         </tbody>
  99       </tgroup>
 100     </informaltable>
 101   </para>
 102
 103
 104   <anchor id="ptime_from_string" />
 105   <bridgehead renderas="sect3">Construct from String</bridgehead>
 106   <para>
 107     <informaltable frame="all">
 108       <tgroup cols="2">
 109         <thead>
 110           <row>
 111             <entry valign="top" morerows="1">Syntax</entry>
 112             <entry>Description</entry>
 113           </row>
 114           <row>
 115             <entry>Example</entry>
 116           </row>
 117         </thead>
 118         <tbody>
 119           <row>
 120             <entry valign="top" morerows="1"><screen>ptime time_from_string(std::string)</screen></entry>
 121             <entry>From delimited string. NOTE: Excess digits in fractional seconds will be dropped. Ex: "1:02:03.123456999" =&gt; 1:02:03.123456. This behavior is affected by the precision the library is compiled with (see <link linkend="date_time.buildinfo">Build-Compiler Information</link>.</entry>
 122           </row>
 123           <row>
 124             <entry><screen>std::string ts("2002-01-20 23:59:59.000");
 125 ptime t(time_from_string(ts))</screen></entry>
 126           </row>
 127
 128           <row>
 129             <entry valign="top" morerows="1"><screen>ptime from_iso_string(std::string)</screen></entry>
 130             <entry>From non delimited iso form string.</entry>
 131           </row>
 132           <row>
 133             <entry><screen>std::string ts("20020131T235959");
 134 ptime t(from_iso_string(ts))</screen></entry>
 135           </row>
 136
 137           <row>
 138             <entry valign="top" morerows="1"><screen>ptime from_iso_extended_string(std::string)</screen></entry>
 139             <entry>From delimited iso form string.</entry>
 140           </row>
 141           <row>
 142             <entry><screen>std::string ts("2020-01-31T23:59:59.123");
 143 ptime t(from_iso_extended_string(ts))</screen></entry>
 144           </row>
 145         </tbody>
 146       </tgroup>
 147     </informaltable>
 148   </para>
 149
 150
 151   <anchor id="ptime_from_clock" />
 152   <bridgehead renderas="sect3">Construct from Clock</bridgehead>
 153   <para>
 154     <informaltable frame="all">
 155       <tgroup cols="2">
 156         <thead>
 157           <row>
 158             <entry valign="top" morerows="1">Syntax</entry>
 159             <entry>Description</entry>
 160           </row>
 161           <row>
 162             <entry>Example</entry>
 163           </row>
 164         </thead>
 165         <tbody>
 166           <row>
 167             <entry valign="top" morerows="1"><screen>ptime second_clock::local_time()</screen></entry>
 168             <entry>Get the local time, second level resolution, based on the time zone settings of the computer.</entry>
 169           </row>
 170           <row>
 171             <entry><screen>ptime t(second_clock::local_time());</screen></entry>
 172           </row>
 173
 174           <row>
 175             <entry valign="top" morerows="1"><screen>ptime second_clock::universal_time()</screen></entry>
 176             <entry>Get the UTC time.</entry>
 177           </row>
 178           <row>
 179             <entry><screen>ptime t(second_clock::universal_time())</screen></entry>
 180           </row>
 181
 182           <row>
 183             <entry valign="top" morerows="1"><screen>ptime microsec_clock::local_time()</screen></entry>
 184             <entry>Get the local time using a sub second resolution clock.  On Unix systems this is implemented using gettimeofday.  On most Win32 platforms it is implemented using ftime.  Win32 systems often do not achieve microsecond resolution via this API.  If higher resolution is critical to your application test your platform to see the achieved resolution.</entry>
 185           </row>
 186           <row>
 187             <entry><screen>ptime t(microsec_clock::local_time());</screen></entry>
 188           </row>
 189
 190           <row>
 191             <entry valign="top" morerows="1"><screen>ptime microsec_clock::universal_time()</screen></entry>
 192             <entry>Get the UTC time using a sub second resolution clock.  On Unix systems this is implemented using gettimeofday.  On most Win32 platforms it is implemented using ftime.  Win32 systems often do not achieve microsecond resolution via this API.  If higher resolution is critical to your application test your platform to see the achieved resolution.</entry>
 193           </row>
 194           <row>
 195             <entry><screen>ptime t(microsec_clock::universal_time());</screen></entry>
 196           </row>
 197         </tbody>
 198       </tgroup>
 199     </informaltable>
 200   </para>
 201
 202
 203   <anchor id="ptime_from_funcs" />
 204   <bridgehead renderas="sect3">Construct using Conversion Functions</bridgehead>
 205   <para>
 206     <informaltable frame="all">
 207       <tgroup cols="2">
 208         <thead>
 209           <row>
 210             <entry valign="top" morerows="1">Syntax</entry>
 211             <entry>Description</entry>
 212           </row>
 213           <row>
 214             <entry>Example</entry>
 215           </row>
 216         </thead>
 217         <tbody>
 218           <row>
 219             <entry valign="top" morerows="1"><screen>ptime from_time_t(time_t t);</screen></entry>
 220             <entry>Converts a time_t into a ptime.</entry>
 221           </row>
 222           <row>
 223             <entry><screen>ptime t = from_time_t(tt);</screen></entry>
 224           </row>
 225
 226           <row>
 227             <entry valign="top" morerows="1"><screen>ptime from_ftime&lt;ptime&gt;(FILETIME ft);</screen></entry>
 228             <entry>Creates a ptime object from a FILETIME structure.</entry>
 229           </row>
 230           <row>
 231             <entry><screen>ptime t = from_ftime&lt;ptime&gt;(ft);</screen></entry>
 232           </row>
 233         </tbody>
 234       </tgroup>
 235     </informaltable>
 236   </para>
 237
 238
 239   <anchor id="ptime_accessors" />
 240   <bridgehead renderas="sect3">Accessors</bridgehead>
 241   <para>
 242     <informaltable frame="all">
 243       <tgroup cols="2">
 244         <thead>
 245           <row>
 246             <entry valign="top" morerows="1">Syntax</entry>
 247             <entry>Description</entry>
 248           </row>
 249           <row>
 250             <entry>Example</entry>
 251           </row>
 252         </thead>
 253         <tbody>
 254           <row>
 255             <entry valign="top" morerows="1"><screen>date date()</screen></entry>
 256             <entry>Get the date part of a time.</entry>
 257           </row>
 258           <row>
 259             <entry><screen>date d(2002,Jan,10);
 260 ptime t(d, hour(1));
 261 t.date() --> 2002-Jan-10;</screen>
 262             </entry>
 263           </row>
 264
 265           <row>
 266             <entry valign="top" morerows="1"><screen>time_duration time_of_day()</screen></entry>
 267             <entry>Get the time offset in the day.</entry>
 268           </row>
 269           <row>
 270             <entry><screen>date d(2002,Jan,10);
 271 ptime t(d, hour(1));
 272 t.time_of_day() --> 01:00:00;</screen>
 273             </entry>
 274           </row>
 275
 276           <row>
 277             <entry valign="top" morerows="1"><screen>bool is_infinity() const</screen></entry>
 278             <entry>Returns true if ptime is either positive or negative infinity</entry>
 279           </row>
 280           <row>
 281             <entry><screen>ptime pt(pos_infin);
 282 pt.is_infinity(); // --> true</screen></entry>
 283           </row>
 284
 285           <row>
 286             <entry valign="top" morerows="1"><screen>bool is_neg_infinity() const</screen></entry>
 287             <entry>Returns true if ptime is negative infinity</entry>
 288           </row>
 289           <row>
 290             <entry><screen>ptime pt(neg_infin);
 291 pt.is_neg_infinity(); // --> true</screen></entry>
 292           </row>
 293
 294           <row>
 295             <entry valign="top" morerows="1"><screen>bool is_pos_infinity() const</screen></entry>
 296             <entry>Returns true if ptime is positive infinity</entry>
 297           </row>
 298           <row>
 299             <entry><screen>ptime pt(neg_infin);
 300 pt.is_pos_infinity(); // --> true</screen></entry>
 301           </row>
 302
 303           <row>
 304             <entry valign="top" morerows="1"><screen>bool is_not_a_date_time() const</screen></entry>
 305             <entry>Returns true if value is not a ptime</entry>
 306           </row>
 307           <row>
 308             <entry><screen>ptime pt(not_a_date_time);
 309 pt.is_not_a_date_time(); // --> true</screen></entry>
 310           </row>
 311
 312           <row>
 313             <entry valign="top" morerows="1"><screen>bool is_special() const</screen></entry>
 314             <entry>Returns true if ptime is any <code>special_value</code></entry>
 315           </row>
 316           <row>
 317             <entry><screen>ptime pt(pos_infin);
 318 ptime pt2(not_a_date_time);
 319 ptime pt3(date(2005,Mar,1), hours(10));
 320 pt.is_special(); // --> true
 321 pt2.is_special(); // --> true
 322 pt3.is_special(); // --> false</screen></entry>
 323           </row>
 324
 325         </tbody>
 326       </tgroup>
 327     </informaltable>
 328   </para>
 329
 330
 331   <anchor id="ptime_to_string" />
 332   <bridgehead renderas="sect3">Conversion to String</bridgehead>
 333   <para>
 334     <informaltable frame="all">
 335       <tgroup cols="2">
 336         <thead>
 337           <row>
 338             <entry valign="top" morerows="1">Syntax</entry>
 339             <entry>Description</entry>
 340           </row>
 341           <row>
 342             <entry>Example</entry>
 343           </row>
 344         </thead>
 345         <tbody>
 346           <row>
 347             <entry valign="top" morerows="1"><screen>std::string to_simple_string(ptime)</screen></entry>
 348             <entry>To <code>YYYY-mmm-DD HH:MM:SS.fffffffff</code> string where <code>mmm</code> 3 char month name. Fractional seconds only included if non-zero.</entry>
 349           </row>
 350           <row>
 351             <entry><screen>2002-Jan-01 10:00:01.123456789</screen></entry>
 352           </row>
 353
 354           <row>
 355             <entry valign="top" morerows="1"><screen>std::string to_iso_string(ptime)</screen></entry>
 356             <entry>Convert to form <code>YYYYMMDDTHHMMSS,fffffffff</code> where <code>T</code> is the date-time separator</entry>
 357           </row>
 358           <row>
 359             <entry><screen>20020131T100001,123456789</screen></entry>
 360           </row>
 361
 362           <row>
 363             <entry valign="top" morerows="1"><screen>std::string to_iso_extended_string(ptime)</screen></entry>
 364             <entry>Convert to form <code>YYYY-MM-DDTHH:MM:SS,fffffffff</code> where <code>T</code> is the date-time separator</entry>
 365           </row>
 366           <row>
 367             <entry><screen>2002-01-31T10:00:01,123456789</screen></entry>
 368           </row>
 369         </tbody>
 370       </tgroup>
 371     </informaltable>
 372   </para>
 373
 374
 375   <anchor id="ptime_operators" />
 376   <bridgehead renderas="sect3">Operators</bridgehead>
 377   <para>
 378     <informaltable frame="all">
 379       <tgroup cols="2">
 380         <thead>
 381           <row>
 382             <entry valign="top" morerows="1">Syntax</entry>
 383             <entry>Description</entry>
 384           </row>
 385           <row>
 386             <entry>Example</entry>
 387           </row>
 388         </thead>
 389         <tbody>
 390           <row>
 391             <entry valign="top" morerows="1"><screen>operator&lt;&lt;, operator&gt;&gt;</screen></entry>
 392             <entry>Streaming operators. <emphasis role="strong">Note:</emphasis> As of version 1.33, streaming operations have been greatly improved. See <link linkend="date_time.date_time_io">Date Time IO System</link> for more details (including exceptions and error conditions).</entry>
 393           </row>
 394           <row>
 395             <entry><screen>ptime pt(not_a_date_time);
 396 stringstream ss("2002-Jan-01 14:23:11");
 397 ss &gt;&gt; pt;
 398 std::cout &lt;&lt; pt; // "2002-Jan-01 14:23:11"
 399   </screen>
 400             </entry>
 401           </row>
 402
 403           <row>
 404             <entry valign="top" morerows="1"><screen>operator==, operator!=,
 405 operator>, operator&lt;,
 406 operator>=, operator&lt;=</screen>
 407             </entry>
 408             <entry>A full complement of comparison operators</entry>
 409           </row>
 410           <row>
 411             <entry><screen>t1 == t2, etc</screen></entry>
 412           </row>
 413
 414           <row>
 415             <entry valign="top" morerows="1"><screen>ptime operator+(days)</screen></entry>
 416             <entry>Return a ptime adding a day offset</entry>
 417           </row>
 418           <row>
 419             <entry><screen>date d(2002,Jan,1);
 420 ptime t(d,minutes(5));
 421 days dd(1);
 422 ptime t2 = t + dd;</screen>
 423             </entry>
 424           </row>
 425
 426           <row>
 427             <entry valign="top" morerows="1"><screen>ptime operator-(days)</screen></entry>
 428             <entry>Return a ptime subtracting a day offset</entry>
 429           </row>
 430           <row>
 431             <entry><screen>date d(2002,Jan,1);
 432 ptime t(d,minutes(5));
 433 days dd(1);
 434 ptime t2 = t - dd;</screen>
 435             </entry>
 436           </row>
 437
 438           <row>
 439             <entry valign="top" morerows="1"><screen>ptime operator+(time_duration)</screen></entry>
 440             <entry>Return a ptime adding a time duration</entry>
 441           </row>
 442           <row>
 443             <entry><screen>date d(2002,Jan,1);
 444 ptime t(d,minutes(5));
 445 ptime t2 = t + hours(1) + minutes(2);</screen>
 446             </entry>
 447           </row>
 448
 449           <row>
 450             <entry valign="top" morerows="1"><screen>ptime operator-(time_duration)</screen></entry>
 451             <entry>Return a ptime subtracting a time duration</entry>
 452           </row>
 453           <row>
 454             <entry><screen>date d(2002,Jan,1);
 455 ptime t(d,minutes(5));
 456 ptime t2 = t - minutes(2);</screen>
 457             </entry>
 458           </row>
 459
 460           <row>
 461             <entry valign="top" morerows="1"><screen>time_duration operator-(ptime)</screen></entry>
 462             <entry>Take the difference between two times.</entry>
 463           </row>
 464           <row>
 465             <entry><screen>date d(2002,Jan,1);
 466 ptime t1(d,minutes(5));
 467 ptime t2(d,seconds(5));
 468 time_duration t3 = t2 - t1;//negative result</screen>
 469             </entry>
 470           </row>
 471         </tbody>
 472       </tgroup>
 473     </informaltable>
 474   </para>
 475
 476   <anchor id="ptime_struct_tm" />
 477   <bridgehead renderas="sect3">Struct tm, time_t, and FILETIME Functions</bridgehead>
 478   <para>Functions for converting posix_time objects to, and from, <code>tm</code> structs are provided as well as conversion from <code>time_t</code> and <code>FILETIME</code>.</para>
 479   <informaltable frame="all">
 480     <tgroup cols="2">
 481       <thead>
 482         <row>
 483           <entry valign="top" morerows="1">Syntax</entry>
 484           <entry>Description</entry>
 485         </row>
 486         <row>
 487           <entry>Example</entry>
 488         </row>
 489       </thead>
 490       <tbody>
 491         <row>
 492           <entry valign="top" morerows="1"><screen>tm to_tm(ptime)</screen></entry>
 493           <entry>A function for converting a <code>ptime</code> object to a <code>tm</code> struct. The <code>tm_isdst</code> field is set to -1.</entry>
 494         </row>
 495         <row>
 496           <entry><screen>ptime pt(date(2005,Jan,1), time_duration(1,2,3));
 497 tm pt_tm = to_tm(pt);
 498 /* tm_year => 105
 499    tm_mon  => 0
 500    tm_mday => 1
 501    tm_wday => 6 (Saturday)
 502    tm_yday => 0
 503    tm_hour => 1
 504    tm_min  => 2
 505    tm_sec  => 3
 506    tm_isdst => -1 */</screen>
 507           </entry>
 508         </row>
 509
 510         <row>
 511           <entry valign="top" morerows="1"><screen>ptime ptime_from_tm(tm timetm)</screen></entry>
 512           <entry>A function for converting a <code>tm</code> struct to a <code>ptime</code> object. The fields: <code>tm_wday </code>, <code>tm_yday </code>, and <code>tm_isdst</code> are ignored.</entry>
 513         </row>
 514         <row>
 515           <entry><screen>tm pt_tm;
 516 pt_tm.tm_year = 105;
 517 pt_tm.tm_mon  = 0;
 518 pt_tm.tm_mday = 1;
 519 pt_tm.tm_hour = 1;
 520 pt_tm.tm_min  = 2;
 521 pt_tm.tm_sec  = 3;
 522 ptime pt = ptime_from_tm(pt_tm);
 523 // pt => 2005-Jan-01 01:02:03</screen>
 524           </entry>
 525         </row>
 526
 527         <row>
 528           <entry valign="top" morerows="1"><screen>tm to_tm(time_duration)</screen></entry>
 529           <entry>A function for converting a <code>time_duration</code> object to a <code>tm</code> struct. The fields: <code>tm_year</code>, <code>tm_mon</code>, <code>tm_mday</code>, <code>tm_wday</code>, <code>tm_yday</code> are set to zero. The <code>tm_isdst</code> field is set to -1.</entry>
 530         </row>
 531         <row>
 532           <entry><screen>time_duration td(1,2,3);
 533 tm td_tm = to_tm(td);
 534 /* tm_year => 0
 535    tm_mon  => 0
 536    tm_mday => 0
 537    tm_wday => 0
 538    tm_yday => 0
 539    tm_hour => 1
 540    tm_min  => 2
 541    tm_sec  => 3
 542    tm_isdst => -1 */</screen>
 543           </entry>
 544         </row>
 545
 546         <row>
 547           <entry valign="top" morerows="1"><screen>ptime from_time_t(std::time_t)</screen></entry>
 548           <entry>Creates a <code>ptime</code> from the time_t parameter. The seconds held in the time_t are added to a time point of 1970-Jan-01.</entry>
 549         </row>
 550         <row>
 551           <entry><screen>ptime pt(not_a_date_time);
 552 std::time_t t;
 553 t = 1118158776;
 554 pt = from_time_t(t);
 555 // pt => 2005-Jun-07 15:39:36</screen></entry>
 556         </row>
 557
 558         <row>
 559           <entry valign="top" morerows="1"><screen>ptime from_ftime&lt;ptime>(FILETIME)</screen></entry>
 560           <entry>A template function that constructs a <code>ptime</code> from a FILETIME struct.</entry>
 561         </row>
 562         <row>
 563           <entry><screen>FILETIME ft;
 564 ft.dwHighDateTime = 29715317;
 565 ft.dwLowDateTime = 3865122988UL;
 566 ptime pt = from_ftime&lt;ptime>(ft);
 567 // pt => 2005-Jun-07 15:30:57.039582000</screen></entry>
 568         </row>
 569
 570       </tbody>
 571     </tgroup>
 572   </informaltable>
 573
 574 </section>