Time class
Version 1.4

DOCUMENTATION


NEW IN THIS VERSION: The class now has operators -, >> and << instead of the methods minus, read and print (for more natural user code).  


Each Time value represents a time on a 24-hour clock (0:00 to 23:59).

Constructors:

    Time()    
    Time( int h ) 
    Time( int h, int m ) 
        Initializes the time to either 99:99 (an invalid value), h:00 or h:m.

Methods:
    
    int hours() const 
    int minutes() const 
        Returns the hours or minutes of the time.
    
    void set_hours( int new_hours )   
    void set_minutes( int new_minutes ) 
        Sets the hours or minutes of the time.

Standalone functions:

    istream & operator>>( istream & in, Time & t )
        Reads t from in the format h:mm or hh:mm, where each h and m stands for a single digit.  Returns in.  No error-checking.
        
    ostream & operator<<( ostream & out, const Time & t )
        Prints t to out in the format described for read.  Returns out. 

    double operator-( const Time & t1, const Time & t2 )
        Computes the difference, in hours, between t1 and t2.  The difference is positive if t1 occurs after t2.  (I.e., the difference is computed as "t1 - t2".)
        
Implementation notes: Each time is stored as a pair of integers (hours, minutes) by using a class.  The data is private.