Boost C++ Libraries

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posix_time::time_iterator

Introduction

Time iterators provide a mechanism for iteration through times. Time iterators are similar to Bidirectional Iterators. However, time_iterators are different than standard iterators in that there is no underlying sequence, just a calculation function. In addition, time_iterators are directly comparable against instances of class ptime. Thus a second iterator for the end point of the iteration is not required, but rather a point in time can be used directly. For example, the following code iterates using a 15 minute iteration interval. The print hours example also illustrates the use of the time_iterator.

#include "boost/date_time/posix_time/posix_time.hpp"
#include <iostream>


int
main()
{
  using namespace boost::gregorian;
  using namespace boost::posix_time;
  date d(2000,Jan,20);
  ptime start(d);
  ptime end = start + hours(1);
  time_iterator titr(start,minutes(15)); //increment by 15 minutes
  //produces 00:00:00, 00:15:00, 00:30:00, 00:45:00
  while (titr < end) {
    std::cout << to_simple_string(*titr) << std::endl;
    ++titr;
  }
  std::cout << "Now backward" << std::endl;
  //produces 01:00:00, 00:45:00, 00:30:00, 00:15:00
  while (titr > start) {
    std::cout << to_simple_string(*titr) << std::endl;
    --titr;
  }
}

Header

Class Overview

Class	Construction Parameters	Description
time_iterator	ptime start_time, time_duration increment	Iterate incrementing by the specified duration.

Operators

Syntax	Description	Example
operator==(const ptime& rhs), operator!=(const ptime& rhs), operator>, operator< operator>=, operator<=	A full complement of comparison operators	date d(2002,Jan,1); ptime start_time(d, hours(1)); //increment by 10 minutes time_iterator titr(start_time, minutes(10)); ptime end_time = start_time + hours(2); if (titr == end_time) // false if (titr != end_time) // true if (titr >= end_time) // false if (titr <= end_time) // true
prefix increment	Increment the iterator by the specified duration.	//increment by 10 milli seconds time_iterator titr(start_time, milliseconds(10)); ++titr; // == start_time + 10 milliseconds
prefix decrement	Decrement the iterator by the specified time duration.	Example time_iterator titr(start_time, time_duration(1,2,3)); --titr; // == start_time - 1 hour, 2 minutes, and 3 seconds