dtime.h

AbsoluteC++中文第二版书上的源代码

//This is the header file dtime.h. 
#ifndef DTIME_H
#define DTIME_H

#include <iostream>
using std::istream;
using std::ostream;

namespace DTimeSavitch
{

    class DigitalTime
    {
    public:
        DigitalTime(int theHour, int theMinute);

        DigitalTime( );
        //Initializes the time value to 0:00 (which is midnight).

        getHour( ) const;

        getMinute( ) const;

        void advance(int minutesAdded);
        //Changes the time to minutesAdded minutes later.

        void advance(int hoursAdded, int minutesAdded);
        //Changes the time to hoursAdded hours plus minutesAdded minutes later.

        friend bool operator ==(const DigitalTime& time1, 
                                const DigitalTime& time2);

        friend istream& operator >>(istream& ins, DigitalTime& theObject);

        friend ostream& operator <<(ostream& outs, const DigitalTime& theObject);
    private:
        int hour;
        int minute;
 
        static void readHour(int& theHour);
        //Precondition: Next input in to be read from the keyboard is 
        //a time in notation, like 9:45 or 14:45.
        //Postcondition: theHour has been set to the hour part of the time. 
        //The colon has been discarded and the next input to be read is the minute.

        static void readMinute(int& theMinute);
        //Reads the minute from the keyboard after readHour has read the hour.

        static int digitToInt(char c);
        //Precondition: c is one of the digits '0' through '9'.
        //Returns the integer for the digit; that is, digitToInt('3') returns 3.
    };


}// DTimeSavitch

#endif //DTIME_H