// implementazione della classe fraction
#include <iostream>
#include <stdlib.h>
#include "fraction.h"  // includo l'interfaccia

using namespace std;
 // 3 costruttori
 fraction::fraction() {
   this->n = this->d = 1;
 }
 
 fraction::fraction(int a) {
   this->n=a;
   this->d=1;
 }
 
 fraction::fraction(int a, int b) {
    if (b==0) {
       cout << "Error: division by zero! "
            << "... fraction now is equal to 1 \n\n";
       this->n = this->d = 1;
    } else {
       this->n = a;
       this->d = b;
       this->reduce();
    }     
 }


 // test di positivit�
 bool fraction::is_pos(){
   return (this->n > 0);
 }
  
     
 // operazioni di lettura
 int fraction::get_numerator() {
    return this->n;
 }
 
 int fraction::get_denumerator() {
    return this->d;
 }
 
  // operazioni di scrittura
 void fraction::set_numerator(int a) {
    this->n=a;
    this->reduce();
 }
 
 void fraction::set_denumerator(int a) {
    if (a==0) {
       cout << "Error: divisione by zero! "
            << "Fraction not modified! \n";
       return;
    }
    
    this->d = a;
    this->reduce();
 }
     
 // operazioni aritmetiche
 fraction fraction::sum(const fraction & f) {
    fraction tmp;
    tmp.n = this->n * f.d + this->d * f.n;
    tmp.d = this->d * f.d;
    tmp.reduce();
    return tmp;
 }
     
 fraction fraction::sub(const fraction & f) {
    fraction tmp;
    tmp.n = this->n * f.d - this->d * f.n;
    tmp.d = this->d * f.d;
    tmp.reduce();
    return tmp;
 }
 
 fraction fraction::mul(const fraction & f) {
    fraction tmp;
    tmp.n = this->n * f.n;
    tmp.d = this->d * f.d;
    tmp.reduce();
    return tmp;
 }
 
 fraction fraction::div( const fraction & f) {
    if (f.n==0) {
       cout << "Error: division by zero! " 
            << "Return 1 by default \n\n";
       fraction x;
       return x; 
    }
    
    fraction tmp(f.d,f.n);
    return this->mul(tmp);
 }
                 
 // operazione di stampa
 void fraction::print() {
    cout << this->n << "/" << this->d;
 }
 
 //---------------------------------------------------
 // funzione di utilit�
 //--------------------------------------------------- 
 void fraction::reduce() {
    if ( this->n == 0 ) {  // frazione uguale a zero
       this->d=1;
       return;
    }
    
    if ( this->d < 0 ) {    // rendo il denominatore positivo
       this->n *= -1;
       this->d *= -1;   
    }
    
    int nn=abs(this->n), dd=abs(this->d);
                                   
    while ( nn != dd )  { 
      
        if ( nn > dd )
           nn -= dd;
        else
           dd -= nn;
    }
        
    this->n /= nn;
    this->d /= nn;
 }