Re: Convertion problem
From: Chiller (..._at_...)
Date: 04/12/04
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Date: Mon, 12 Apr 2004 05:43:50 GMT
I've implemented the function to change all values to "mm" when calling to a
comparison function; however, it just isn't working. In my TEST_DRIVER at
the bottom of the .cpp file I've inluded a greater than test for two values;
however it believes that 5 m is greater than 4 km, so I've obviously done
something wrong.
I've included my revised .cpp file and .h file below. I'd appreciate some
advice on what I'm doing wrong.
Thanks for any help
.cpp file
***********************
#include "Distance.h"
#include <iostream>
using namespace std;
/*-------------------------------------------------------*\
| implementation of member functions |
\*-------------------------------------------------------*/
// constructors
Distance :: Distance (int n, char m) : nu(n), me(m) {}
Distance :: Distance (void) : nu(0), me(2) {}
enum {mm, cm, m, km};
// access functions
int Distance :: number (void)
{
return nu;
}
char Distance :: measure (void)
{
return me;
}
//Convertion function to ensure all values are in the same unit of measure
void Distance::to_mm()
{
if ( me == km)
{
nu = nu/1000000;
me = mm;
}
else if (me == m)
{
nu = nu/1000;
me = mm;
}
else if (me == cm)
{
nu = nu/10;
me = cm;
}
}
// Overload of the "=" operator
Distance & Distance::operator= (Distance const & right_operand)
{
nu = right_operand.nu;
me = right_operand.me;
return *this;
}
// Overload of the "==" operator
bool Distance::operator == ( Distance const & rhs )
{
to_mm();
return ( nu == rhs.nu && me == rhs.me );
}
//Overload of the != operator
bool Distance::operator != ( Distance const & rhs )
{
to_mm();
return ( nu != rhs.nu && me != rhs.me );
}
//Overload of the < operator
bool Distance::operator < (Distance const & rhs)
{
to_mm();
return ( nu < rhs.nu && me < rhs.me );
}
//Overload of the <= operator
bool Distance::operator <= (Distance const & rhs)
{
to_mm();
return (nu <= rhs.nu && me <= rhs.me);
}
//Overload of the > operator
bool Distance::operator > (Distance const & rhs)
{
to_mm();
return (nu > rhs.nu && me > rhs.me);
}
//Overload of the >= operator
bool Distance::operator >= (Distance const & rhs)
{
to_mm();
return (nu >= rhs.nu && me >= rhs.me);
}
// provide an overload of "<<" for easy display
ostream& operator<< (ostream& out, Distance& d)
{
out << "(" << d.number() << ", ";
switch (d.measure())
{
case mm:
out << "mm";
case cm:
out << "cm";
break;
case m:
out << "m";
break;
case km:
out << "km";
break;
}
out << ")";
return out;
}
/*-------------------------------------------------------*\
| test driver for the Distance class |
\*-------------------------------------------------------*/
#ifdef TEST_DISTANCE // .... Distance class .... test driver
int main (void)
{
// create test input
Distance a = Distance (6, cm);
Distance b (4, km);
Distance c (2, m);
Distance d;
Distance e (5, m);
Distance z1 = a = b;
cout << a << endl << b << endl << c << endl << d << endl << e << endl <<
endl;
cout << a <<endl << endl;
cout << "The results of comparing various Distance values :" << endl;
cout << "Distance a == Distance e : ";
cout << (a == e ? "true" : "false") << endl;
cout << "Distance a != Distance e : ";
cout << (a != e ? "true" : "false") << endl;
cout << "Distance a < Distance c : ";
cout << (a < c ? "true" : "false") << endl;
cout << "Distance a <= Distance c : ";
cout << (a <= c ? "true" : "false") << endl;
cout << "Distance a > Distance c : ";
cout << (a > c ? "true" : "false") << endl;
cout << "Distance a >= Distance b : ";
cout << (a >= c ? "true" : "false") << endl;
cout << "Distance a > Distance e : ";
cout << (a > e ? "true" : "false") << endl;
cin.ignore();
return 0; // normal termination
}
#endif
.h file
*************************
#ifndef DISTANCE_H
#define DISTANCE_H
#include <iostream>
using namespace std;
class Distance
{
public :
Distance (int, char) ; // constructor - takes int and char values
Distance (void) ; // default - zero
//access member functions
int number (void);
char measure (void);
//overloads
Distance & Distance::operator= (Distance const & right_operand);
bool operator == ( Distance const &rhs );
bool operator != ( Distance const &rhs );
bool operator < ( Distance const &rhs );
bool operator <= ( Distance const &rhs );
bool operator > ( Distance const &rhs );
bool operator >= ( Distance const &rhs );
void Distance::to_mm();
private :
int nu ; // the value
char me ; // the unit of measure (m)
} ;
// provide an overload of "<<" for easy display
ostream& operator<< (ostream&, const Distance&);
#endif
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