# posix_time::time_iterator

Overall Index -- Gregorian Index -- Posix Time Index

Time Iterators

Introduction -- Header -- Class Overview -- Operators

## 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

    #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

## 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