一个简单计时器的C++实现

头文件：

/*
 * Copyright (c) 2008-2011 Zhang Ming (M. Zhang), [email protected]
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation, either version 2 or any later version.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details. A copy of the GNU General Public License is available at:
 * http://www.fsf.org/licensing/licenses
 */


/*****************************************************************************
 *                                 timing.h
 *
 * Making a coarse estimation for programm's running time. The time unit
 * is second.
 *
 * Zhang Ming, 2010-01, Xi'an Jiaotong University.
 *****************************************************************************/


#ifndef TIMING_H
#define TIMING_H


#include <ctime>


inline static double seconds()
{
	const double secs_per_tick = 1.0 / CLOCKS_PER_SEC;
	return ( double(clock()) ) * secs_per_tick;
}


namespace splab
{

    class Timing
    {

        public:

            Timing();
            ~Timing();

            void start();
            void stop();
            double read();

        private:

            bool    running;
            double  startTime;
            double  total;

    };
    // class Timing


    #include <timing-impl.h>

}
// namespace splab


#endif
//	TIMING_H

实现文件：

/*
 * Copyright (c) 2008-2011 Zhang Ming (M. Zhang), [email protected]
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation, either version 2 or any later version.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details. A copy of the GNU General Public License is available at:
 * http://www.fsf.org/licensing/licenses
 */


/*****************************************************************************
 *                               timing-impl.h
 *
 * Implementation for Timing class.
 *
 * Zhang Ming, 2010-01, Xi'an Jiaotong University.
 *****************************************************************************/


/**
 * constructor and destructor
 */
Timing::Timing() : running(false), startTime(0), total(0)
{
}

Timing::~Timing()
{
}


/**
 * timing start
 */
inline void Timing::start()
{
	running = true;
	total = 0;
	startTime = seconds();
}


/**
 * timing stop
 */
inline void Timing::stop()
{
	if( running )
	{
		 total += ( seconds() - startTime );
		 running = false;
	}
}


/**
 * Get the time between start() and stop().
 */
inline double Timing::read()
{
	if( running )
		stop();

	return total;
}

测试代码：

/*****************************************************************************
 *                               time_test.cpp
 *
 * Timing function testing.
 *
 * Zhang Ming, 2010-01, Xi'an Jiaotong University.
 *****************************************************************************/


#include <iostream>
#include <cmath>
#include <timing.h>


using namespace std;
using namespace splab;


int main()
{
    double  var = 1;
    double  runTime = 0;
    Timing  time;

    time.start();
    for( int i=0; i<10000; ++i )
        for( int j=0; j<10000; ++j )
            var = sqrt(1.0*i*j);
    time.stop();
    runTime = time.read();

    cout << "The running time is : " << runTime << endl << endl;

    return 0;
}

运行结果：

The running time is : 7.239


Process returned 0 (0x0)   execution time : 7.332 s
Press any key to continue.