Παράδειγμα
Το παρακάτω παράδειγμα ορίζει και χρησιμοποιεί
την κλάση point που - εξεζητημένα - εκμεταλλεύεται όλα τα στοιχεία που
έχουν αναφερθεί:
point.h
class point {
private:
int x, y;
static int numpoints;
public:
point(); // Default contructor
point(int sx, int sy); // Other constructor
~point(); // Destructor
int getx() const; // Access functions
int gety() const;
void display(); // Display member function
void setpos(int sx, int sy); // Set position
static int points_used(); // Return number of points
friend double distance(point p1, point p2); // Display friend function
friend void display(point &p); // Display friend function
};
point.cpp
#include "point.h"
#include <iostream.h>
#include <math.h>
int point::numpoints = 0;
point::point(int sx, int sy)
{
x = sx;
y = sy;
numpoints++;
}
point::point()
{
x = y = 0;
numpoints++;
}
point::~point()
{
numpoints--;
}
int
point::getx() const
{
return (x);
}
int
point::gety() const
{
return (y);
}
// Member function; used as a.display();
void
point::display()
{
cout << "(" << x << "," << y << ")\n";
}
// Friend function; used as display(a)
void
display(point& p)
{
cout << "(" << p.x << "," << p.y << ")\n";
}
double
sqr(double x)
{
return (x * x);
}
double
distance(point p1, point p2)
{
return (sqrt(sqr(p1.x - p2.x) + sqr(p1.y - p2.y)));
}
void
point::setpos(int sx, int sy)
{
this->x = sx;
point::y = sy;
}
int
point::points_used()
{
return (numpoints);
}
main.cpp
#include <iostream.h>
#include "point.h"
main()
{
point a(1, 2);
point b, *c;
c = new point(5, 5);
b.setpos(6, 6);
a.display(); // Member function
display(b); // Friend function
c->display();
cout << "Distance from a to b = " << distance(a, b) << "\n";
cout << "points used = " << point::points_used() << "\n";
delete(c);
cout << "points used = " << point::points_used() << "\n";
return (0);
}
Τελευταία αλλαγή: Πέμπτη, 18 Οκτωβρίου 2001 11:31 μμ