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| <!DOCTYPE library PUBLIC "-//Boost//DTD BoostBook XML V1.0//EN" |
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| |
| <!-- Copyright (c) 2001-2005 CrystalClear Software, Inc. |
| Subject to the Boost Software License, Version 1.0. |
| (See accompanying file LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt) |
| --> |
| |
| <section id="date_time.posix_time.time_duration"> |
| <title>Time Duration</title> |
| |
| <link linkend="time_duration_intro">Introduction</link> -- |
| <link linkend="time_duration_header">Header</link> -- |
| <link linkend="time_duration_constr">Construction</link> -- |
| <link linkend="time_duration_count_constr">Count Based Construction</link> -- |
| <link linkend="time_duration_from_string">Construct from String</link> -- |
| <link linkend="time_duration_accessors">Accessors</link> -- |
| <link linkend="time_duration_to_string">Conversion To String</link> -- |
| <link linkend="time_duration_operators">Operators</link> -- |
| <link linkend="time_duration_struct_tm">Struct tm Functions</link> |
| |
| <anchor id="time_duration_intro" /> |
| <bridgehead renderas="sect3">Introduction</bridgehead> |
| <para> |
| The class boost::posix_time::time_duration the base type responsible for representing a length of time. A duration can be either positive or negative. The general time_duration class provides a constructor that takes a count of the number of hours, minutes, seconds, and fractional seconds count as shown in the code fragment below. The resolution of the time_duration is configure able at compile time. See <link linkend="date_time.buildinfo">Build-Compiler Information</link> for more information. |
| </para> |
| <para> |
| <programlisting>using namespace boost::posix_time; |
| time_duration td(1,2,3,4); //01:02:03.000000004 when resolution is nano seconds |
| time_duration td(1,2,3,4); //01:02:03.000004 when resolution is micro seconds</programlisting> |
| </para> |
| <para> |
| Several small helper classes that derive from a base time_duration, as shown below, to adjust for different resolutions. These classes can shorten code and make the intent clearer. |
| </para> |
| <imagedata fileref="../../libs/date_time/doc/time_duration_inherit.png" /> |
| <para> |
| As an example: |
| <programlisting>using namespace boost::posix_time; |
| |
| time_duration td = hours(1) + seconds(10); //01:00:01 |
| td = hours(1) + nanoseconds(5); //01:00:00.000000005</programlisting> |
| Note that the existence of the higher resolution classes (eg: nanoseconds) depends on the installation of the library. See <link linkend="date_time.buildinfo">Build-Compiler Information</link> for more information. |
| </para> |
| |
| <para> |
| Another way to handle this is to utilize the ticks_per_second() method of time_duration to |
| write code that is portable no matter how the library is compiled. The general equation |
| for calculating a resolution independent count is as follows: |
| |
| <programlisting> |
| count*(time_duration_ticks_per_second / count_ticks_per_second) |
| </programlisting> |
| |
| For example, let's suppose we want to construct using a count that represents tenths |
| of a second. That is, each tick is 0.1 second. |
| <programlisting> |
| int number_of_tenths = 5; |
| //create a resolution independent count -- divide by 10 since there are |
| //10 tenths in a second. |
| int count = number_of_tenths*(time_duration::ticks_per_second()/10); |
| time_duration td(1,2,3,count); //01:02:03.5 //no matter the resolution settings |
| </programlisting> |
| </para> |
| |
| <anchor id="time_duration_header" /> |
| <bridgehead renderas="sect3">Header</bridgehead> |
| <para> |
| <programlisting>#include "boost/date_time/posix_time/posix_time.hpp" //include all types plus i/o |
| or |
| #include "boost/date_time/posix_time/posix_time_types.hpp" //no i/o just types</programlisting> |
| </para> |
| |
| <anchor id="time_duration_constr" /> |
| <bridgehead renderas="sect3">Construction</bridgehead> |
| <para> |
| <informaltable frame="all"> |
| <tgroup cols="2"> |
| <thead> |
| <row> |
| <entry valign="top" morerows="1">Syntax</entry> |
| <entry>Description</entry> |
| </row> |
| <row> |
| <entry>Example</entry> |
| </row> |
| </thead> |
| <tbody> |
| <row> |
| <entry valign="top" morerows="1"><screen>time_duration(hours, |
| minutes, |
| seconds, |
| fractional_seconds)</screen></entry> |
| <entry>Construct a duration from the counts. The fractional_second parameter is a number of units and is therefore affected by the resolution the application is compiled with (see <link linkend="compile_options">Build-Compiler Information</link>). If the fractional_seconds argument exceeds the limit of the compiled precision, the excess value will be "carried over" into the seconds field. See above for techniques to creating a resolution independent count.</entry> |
| </row> |
| <row> |
| <entry><screen>time_duration td(1,2,3,9); |
| //1 hr 2 min 3 sec 9 nanoseconds |
| time_duration td2(1,2,3,123456789); |
| time_duration td3(1,2,3,1000); |
| // with microsecond resolution (6 digits) |
| // td2 => "01:04:06.456789" |
| // td3 => "01:02:03.001000" |
| // with nanosecond resolution (9 digits) |
| // td2 => "01:02:03.123456789" |
| // td3 => "01:02:03.000001000"</screen></entry> |
| </row> |
| |
| <row> |
| <entry valign="top"><screen>time_duration(special_value sv)</screen></entry> |
| <entry>Special values constructor. <emphasis role="strong">Important note</emphasis>: When a time_duration is a special value, either by construction or other means, the following accessor functions will give unpredictable results: <screen>hours(), minutes(), seconds(), ticks(), |
| fractional_seconds(), total_nanoseconds(), |
| total_microseconds(), total_milliseconds(), |
| total_seconds()</screen>The remaining accessor functions will work as expected.</entry> |
| </row> |
| |
| </tbody> |
| </tgroup> |
| </informaltable> |
| </para> |
| |
| |
| <anchor id="time_duration_count_constr" /> |
| <bridgehead renderas="sect3">Count Based Construction</bridgehead> |
| <para> |
| <informaltable frame="all"> |
| <tgroup cols="2"> |
| <thead> |
| <row> |
| <entry valign="top" morerows="1">Syntax</entry> |
| <entry>Description</entry> |
| </row> |
| <row> |
| <entry>Example</entry> |
| </row> |
| </thead> |
| <tbody> |
| <row> |
| <entry valign="top" morerows="1"><screen>hours(long)</screen></entry> |
| <entry>Number of hours</entry> |
| </row> |
| <row> |
| <entry><screen>time_duration td = hours(3);</screen></entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>minutes(long)</screen></entry> |
| <entry>Number of minutes</entry> |
| </row> |
| <row> |
| <entry><screen>time_duration td = minutes(3);</screen></entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>seconds(long)</screen></entry> |
| <entry> Number of seconds</entry> |
| </row> |
| <row> |
| <entry><screen>time_duration td = seconds(3);</screen></entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>milliseconds(long)</screen></entry> |
| <entry>Number of milliseconds.</entry> |
| </row> |
| <row> |
| <entry><screen>time_duration td = milliseconds(3);</screen></entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>microseconds(long)</screen></entry> |
| <entry>Number of microseconds.</entry> |
| </row> |
| <row> |
| <entry><screen>time_duration td = microseconds(3);</screen></entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>nanoseconds(long)</screen></entry> |
| <entry>Number of nanoseconds.</entry> |
| </row> |
| <row> |
| <entry><screen>time_duration td = nanoseconds(3);</screen></entry> |
| </row> |
| </tbody> |
| </tgroup> |
| </informaltable> |
| </para> |
| |
| |
| <anchor id="time_duration_from_string" /> |
| <bridgehead renderas="sect3">Construct from String</bridgehead> |
| <para> |
| <informaltable frame="all"> |
| <tgroup cols="2"> |
| <thead> |
| <row> |
| <entry valign="top" morerows="1">Syntax</entry> |
| <entry>Description</entry> |
| </row> |
| <row> |
| <entry>Example</entry> |
| </row> |
| </thead> |
| <tbody> |
| <row> |
| <entry valign="top" morerows="1"><screen>time_duration duration_from_string(std::string)</screen></entry> |
| <entry>From delimited string. NOTE: Excess digits in fractional seconds will be dropped. Ex: "1:02:03.123456999" => 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> |
| </row> |
| <row> |
| <entry><screen>std::string ts("23:59:59.000"); |
| time_duration td(duration_from_string(ts));</screen> |
| </entry> |
| </row> |
| </tbody> |
| </tgroup> |
| </informaltable> |
| </para> |
| |
| |
| <anchor id="time_duration_accessors" /> |
| <bridgehead renderas="sect3">Accessors</bridgehead> |
| <para> |
| <informaltable frame="all"> |
| <tgroup cols="2"> |
| <thead> |
| <row> |
| <entry valign="top" morerows="1">Syntax</entry> |
| <entry>Description</entry> |
| </row> |
| <row> |
| <entry>Example</entry> |
| </row> |
| </thead> |
| <tbody> |
| <row> |
| <entry valign="top" morerows="1"><screen>long hours()</screen></entry> |
| <entry>Get the number of normalized hours (will give unpredictable results if calling <code>time_duration</code> is a <code>special_value</code>).</entry> |
| </row> |
| <row> |
| <entry><screen>time_duration td(1,2,3); |
| time_duration neg_td(-1,2,3); |
| td.hours(); // --> 1 |
| neg_td.hours(); // --> -1</screen></entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>long minutes()</screen></entry> |
| <entry>Get the number of minutes normalized +/-(0..59) (will give unpredictable results if calling <code>time_duration</code> is a <code>special_value</code>).</entry> |
| </row> |
| <row> |
| <entry><screen>time_duration td(1,2,3); |
| time_duration neg_td(-1,2,3); |
| td.minutes(); // --> 2 |
| neg_td.minutes(); // --> -2</screen></entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>long seconds()</screen></entry> |
| <entry>Get the normalized number of second +/-(0..59) (will give unpredictable results if calling <code>time_duration</code> is a <code>special_value</code>).</entry> |
| </row> |
| <row> |
| <entry><screen>time_duration td(1,2,3); |
| time_duration neg_td(-1,2,3); |
| td.seconds(); // --> 3 |
| neg_td.seconds(); // --> -3</screen></entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>long total_seconds()</screen></entry> |
| <entry>Get the total number of seconds truncating any fractional seconds (will give unpredictable results if calling <code>time_duration</code> is a <code>special_value</code>).</entry> |
| </row> |
| <row> |
| <entry><screen>time_duration td(1,2,3,10); |
| td.total_seconds(); |
| // --> (1*3600) + (2*60) + 3 == 3723</screen> |
| </entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>long total_milliseconds()</screen></entry> |
| <entry>Get the total number of milliseconds truncating any remaining digits (will give unpredictable results if calling <code>time_duration</code> is a <code>special_value</code>).</entry> |
| </row> |
| <row> |
| <entry><screen>time_duration td(1,2,3,123456789); |
| td.total_milliseconds(); |
| // HMS --> (1*3600) + (2*60) + 3 == 3723 seconds |
| // milliseconds is 3 decimal places |
| // (3723 * 1000) + 123 == 3723123</screen> |
| </entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>long total_microseconds()</screen></entry> |
| <entry>Get the total number of microseconds truncating any remaining digits (will give unpredictable results if calling <code>time_duration</code> is a <code>special_value</code>).</entry> |
| </row> |
| <row> |
| <entry><screen>time_duration td(1,2,3,123456789); |
| td.total_microseconds(); |
| // HMS --> (1*3600) + (2*60) + 3 == 3723 seconds |
| // microseconds is 6 decimal places |
| // (3723 * 1000000) + 123456 == 3723123456</screen> |
| </entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>long total_nanoseconds()</screen></entry> |
| <entry>Get the total number of nanoseconds truncating any remaining digits (will give unpredictable results if calling <code>time_duration</code> is a <code>special_value</code>).</entry> |
| </row> |
| <row> |
| <entry><screen>time_duration td(1,2,3,123456789); |
| td.total_nanoseconds(); |
| // HMS --> (1*3600) + (2*60) + 3 == 3723 seconds |
| // nanoseconds is 9 decimal places |
| // (3723 * 1000000000) + 123456789 |
| // == 3723123456789</screen> |
| </entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>long fractional_seconds()</screen></entry> |
| <entry>Get the number of fractional seconds (will give unpredictable results if calling <code>time_duration</code> is a <code>special_value</code>).</entry> |
| </row> |
| <row> |
| <entry><screen>time_duration td(1,2,3, 1000); |
| td.fractional_seconds(); // --> 1000</screen></entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>bool is_negative()</screen></entry> |
| <entry>True if duration is negative.</entry> |
| </row> |
| <row> |
| <entry><screen>time_duration td(-1,0,0); |
| td.is_negative(); // --> true</screen></entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>time_duration invert_sign()</screen></entry> |
| <entry>Generate a new duration with the sign inverted/</entry> |
| </row> |
| <row> |
| <entry><screen>time_duration td(-1,0,0); |
| td.invert_sign(); // --> 01:00:00</screen></entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>date_time::time_resolutions resolution()</screen></entry> |
| <entry>Describes the resolution capability of the time_duration class. time_resolutions is an enum of resolution possibilities ranging from seconds to nanoseconds.</entry> |
| </row> |
| <row> |
| <entry><screen>time_duration::resolution() --> nano</screen></entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>time_duration::num_fractional_digits()</screen></entry> |
| <entry>Returns an unsigned short holding the number of fractional digits the time resolution has.</entry> |
| </row> |
| <row> |
| <entry><screen>unsigned short secs; |
| secs = time_duration::num_fractional_digits(); |
| // 9 for nano, 6 for micro, etc.</screen></entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>time_duration::ticks_per_second()</screen></entry> |
| <entry>Return the number of ticks in a second. For example, if the duration supports nanoseconds then the returned result will be 1,000,000,000 (1e+9).</entry> |
| </row> |
| <row> |
| <entry><screen>std::cout << time_duration::ticks_per_second();</screen></entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>boost::int64_t ticks()</screen></entry> |
| <entry>Return the raw count of the duration type (will give unpredictable results if calling <code>time_duration</code> is a <code>special_value</code>).</entry> |
| </row> |
| <row> |
| <entry><screen>time_duration td(0,0,0, 1000); |
| td.ticks() // --> 1000</screen></entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>time_duration unit()</screen></entry> |
| <entry>Return smallest possible unit of duration type (1 nanosecond).</entry> |
| </row> |
| <row> |
| <entry><screen>time_duration::unit() --> time_duration(0,0,0,1)</screen></entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>bool is_neg_infinity() const</screen></entry> |
| <entry>Returns true if time_duration is negative infinity</entry> |
| </row> |
| <row> |
| <entry><screen>time_duration td(neg_infin); |
| td.is_neg_infinity(); // --> true</screen></entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>bool is_pos_infinity() const</screen></entry> |
| <entry>Returns true if time_duration is positive infinity</entry> |
| </row> |
| <row> |
| <entry><screen>time_duration td(neg_infin); |
| td.is_pos_infinity(); // --> true</screen></entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>bool is_not_a_date_time() const</screen></entry> |
| <entry>Returns true if value is not a time</entry> |
| </row> |
| <row> |
| <entry><screen>time_duration td(not_a_date_time); |
| td.is_not_a_date_time(); // --> true</screen></entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>bool is_special() const</screen></entry> |
| <entry>Returns true if time_duration is any <code>special_value</code></entry> |
| </row> |
| <row> |
| <entry><screen>time_duration td(pos_infin); |
| time_duration td2(not_a_date_time); |
| time_duration td3(2,5,10); |
| td.is_special(); // --> true |
| td2.is_special(); // --> true |
| td3.is_special(); // --> false</screen></entry> |
| </row> |
| |
| </tbody> |
| </tgroup> |
| </informaltable> |
| </para> |
| |
| |
| <anchor id="time_duration_to_string" /> |
| <bridgehead renderas="sect3">Conversion To String</bridgehead> |
| <para> |
| <informaltable frame="all"> |
| <tgroup cols="2"> |
| <thead> |
| <row> |
| <entry valign="top" morerows="1">Syntax</entry> |
| <entry>Description</entry> |
| </row> |
| <row> |
| <entry>Example</entry> |
| </row> |
| </thead> |
| <tbody> |
| <row> |
| <entry valign="top" morerows="1"><screen>std::string to_simple_string(time_duration)</screen></entry> |
| <entry>To <code>HH:MM:SS.fffffffff</code> were <code>fff</code> is fractional seconds that are only included if non-zero.</entry> |
| </row> |
| <row> |
| <entry><screen>10:00:01.123456789</screen></entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>std::string to_iso_string(time_duration)</screen></entry> |
| <entry>Convert to form <code>HHMMSS,fffffffff</code>.</entry> |
| </row> |
| <row> |
| <entry><screen>100001,123456789</screen></entry> |
| </row> |
| </tbody> |
| </tgroup> |
| </informaltable> |
| </para> |
| |
| |
| <anchor id="time_duration_operators" /> |
| <bridgehead renderas="sect3">Operators</bridgehead> |
| <para> |
| <informaltable frame="all"> |
| <tgroup cols="2"> |
| <thead> |
| <row> |
| <entry valign="top" morerows="1">Syntax</entry> |
| <entry>Description</entry> |
| </row> |
| <row> |
| <entry>Example</entry> |
| </row> |
| </thead> |
| <tbody> |
| <row> |
| <entry valign="top" morerows="1"><screen>operator<<, operator>></screen></entry> |
| <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> |
| </row> |
| <row> |
| <entry><screen>time_duration td(0,0,0); |
| stringstream ss("14:23:11.345678"); |
| ss >> td; |
| std::cout << td; // "14:23:11.345678" |
| </screen> |
| </entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>operator==, operator!=, |
| operator>, operator<, |
| operator>=, operator<=</screen> |
| </entry> |
| <entry>A full complement of comparison operators</entry> |
| </row> |
| <row> |
| <entry><screen>dd1 == dd2, etc</screen></entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>time_duration operator+(time_duration)</screen></entry> |
| <entry>Add durations.</entry> |
| </row> |
| <row> |
| <entry><screen>time_duration td1(hours(1)+minutes(2)); |
| time_duration td2(seconds(10)); |
| time_duration td3 = td1 + td2;</screen> |
| </entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>time_duration operator-(time_duration)</screen></entry> |
| <entry>Subtract durations.</entry> |
| </row> |
| <row> |
| <entry><screen>time_duration td1(hours(1)+nanoseconds(2)); |
| time_duration td2 = td1 - minutes(1);</screen> |
| </entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>time_duration operator/(int)</screen></entry> |
| <entry>Divide the length of a duration by an integer value. Discards any remainder.</entry> |
| </row> |
| <row> |
| <entry><screen>hours(3)/2 == time_duration(1,30,0); |
| nanosecond(3)/2 == nanosecond(1);</screen> |
| </entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>time_duration operator*(int)</screen></entry> |
| <entry>Multiply the length of a duration by an integer value.</entry> |
| </row> |
| <row> |
| <entry><screen>hours(3)*2 == hours(6);</screen></entry> |
| </row> |
| </tbody> |
| </tgroup> |
| </informaltable> |
| </para> |
| |
| <anchor id="time_duration_struct_tm" /> |
| <bridgehead renderas="sect3">Struct tm, time_t, and FILETIME Functions</bridgehead> |
| <para>Function for converting a time_duration to a <code>tm</code> struct is provided.</para> |
| <informaltable frame="all"> |
| <tgroup cols="2"> |
| <thead> |
| <row> |
| <entry valign="top" morerows="1">Syntax</entry> |
| <entry>Description</entry> |
| </row> |
| <row> |
| <entry>Example</entry> |
| </row> |
| </thead> |
| <tbody> |
| <row> |
| <entry valign="top" morerows="1"><screen>tm to_tm(time_duration)</screen></entry> |
| <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> |
| </row> |
| <row> |
| <entry><screen>time_duration td(1,2,3); |
| tm td_tm = to_tm(td); |
| /* tm_year => 0 |
| tm_mon => 0 |
| tm_mday => 0 |
| tm_wday => 0 |
| tm_yday => 0 |
| tm_hour => 1 |
| tm_min => 2 |
| tm_sec => 3 |
| tm_isddst => -1 */</screen> |
| </entry> |
| </row> |
| |
| </tbody> |
| </tgroup> |
| </informaltable> |
| |
| </section> |
