#include <iostream> #include<boost/timer.hpp> using namespace std; using namespace boost;int _tmain(int argc, _TCHAR* argv[]) { timer t; //構造函數自動啟動計時工作cout<<"max timespan(hours): "<<t.elapsed_max()/3600<<endl;cout<<"min timespan(seconds): "<<t.elapsed_min()<<endl;//輸出已經流逝的時間cout<<"now time elapsed:"<<t.elapsed()<<"s"<<endl;return 0; }

由此可以看出來timer所能計算的最大實踐只有快600個小時而已，精度只能在毫秒。

下面是timer的實現代碼，很短。

// boost timer.hpp header file ---------------------------------------------//// Copyright Beman Dawes 1994-99. Distributed under the Boost // Software License, Version 1.0. (See accompanying file // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)// See http://www.boost.org/libs/timer for documentation.// Revision History // 01 Apr 01 Modified to use new <boost/limits.hpp> header. (JMaddock) // 12 Jan 01 Change to inline implementation to allow use without library // builds. See docs for more rationale. (Beman Dawes) // 25 Sep 99 elapsed_max() and elapsed_min() added (John Maddock) // 16 Jul 99 Second beta // 6 Jul 99 Initial boost version#ifndef BOOST_TIMER_HPP #define BOOST_TIMER_HPP#include <boost/config.hpp> #include <ctime> #include <boost/limits.hpp># ifdef BOOST_NO_STDC_NAMESPACEnamespace std { using ::clock_t; using ::clock; } # endifnamespace boost {// timer -------------------------------------------------------------------//// A timer object measures elapsed time.// It is recommended that implementations measure wall clock rather than CPU // time since the intended use is performance measurement on systems where // total elapsed time is more important than just process or CPU time.// Warnings: The maximum measurable elapsed time may well be only 596.5+ hours // due to implementation limitations. The accuracy of timings depends on the // accuracy of timing information provided by the underlying platform, and // this varies a great deal from platform to platform.class timer {public:timer() { _start_time = std::clock(); } // postcondition: elapsed()==0 // timer( const timer& src ); // post: elapsed()==src.elapsed() // ~timer(){} // timer& operator=( const timer& src ); // post: elapsed()==src.elapsed()void restart() { _start_time = std::clock(); } // post: elapsed()==0double elapsed() const // return elapsed time in seconds{ return double(std::clock() - _start_time) / CLOCKS_PER_SEC; }double elapsed_max() const // return estimated maximum value for elapsed()// Portability warning: elapsed_max() may return too high a value on systems// where std::clock_t overflows or resets at surprising values.{return (double((std::numeric_limits<std::clock_t>::max)())- double(_start_time)) / double(CLOCKS_PER_SEC); }double elapsed_min() const // return minimum value for elapsed(){ return double(1)/double(CLOCKS_PER_SEC); }private:std::clock_t _start_time; }; // timer} // namespace boost#endif // BOOST_TIMER_HPP

總結

以上是生活随笔為你收集整理的boost学习之 时间和日期 timer的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。