problem with class

[myoni]

I don't understand why the constrctors are defined by program and other functions not.

this is the code:

heade file:

#ifndef RationalNums_H
#define RationalNums_H

#include <iostream>
#include <cstring>
using namespace std;


class RationalNums// define the class
{
int numerator,denominatore;

public:
RationalNums(int , int);
RationalNums(int);
RationalNums();

int get_numerator();
void set_numerator(int);
int get_denominatore();
void set_denominatore(int);
void printFraction();
bool chkEquality(int, int);


private:
void reduction(int &a, int &b);
};

#endif

implementation file:

#include "RationalNums.h"

//constructors
RationalNums::RationalNums(int _numerator, int _denominatore)
{
numerator=_numerator;
denominatore=_denominatore;
}

RationalNums::RationalNums(int _numerator)
{
numerator=_numerator;
denominatore=0;
}

RationalNums::RationalNums()
{
numerator=0;
denominatore=0;
}

// get & set functions
int get_numerator()
{
return numerator;
}

void set_numerator(int _numerator)
{
numerator=_numerator;
}

int get_denominatore()
{
return denominatore;
}

void set_denominatore(int _denominatore)
{
denominatore=_denominatore;
}

//print the class values
void printFraction()
{
cout<<numerator<<"/"<<denominatore<<endl;
}

//compare between 2 rational numbers
bool chkEquality(int otherNumerator, int otherDenominatore)
{
reduction(otherNumerator,otherDenominatore);
reduction(numerator,denominatore);
if(numerator==otherNumerator && denominatore==otherDenominatore)
return true;
else
return false;
}

//reduce the fraction
void reduction(int &a, int &b)
{
int lower;
if (a>b)
lower=b;
else
lower=a;

for(int i=lower; i>1; --i)
{
if ((a % i==0) && (b % i ==0))
{
a/=i;
b/=i;
}
}
}

main file:

#include <iostream>
#include <cstring>
#include "RationalNums.h"
using namespace std;


bool validation(char *a, int &x, int &y)
{
int z=0, mone=0, pos, result=true;
char temp[15]={NULL};

while(a[z]!=0 && a[z]!='/')
{
if (a[z]<'0' || a[z]>'9')
result=false;
mone++;
z++;
}

if (mone==0)
result=false;

pos=mone;

if (a[z]!='/')
result=false;

z++;
mone=0;
while(a[z]!=0 && a[z]!='/')
{
if (a[z]<'0' || a[z]>'9')
result=false;
mone++;
z++;
}
if (mone==0)
result=false;

if (result)
{
strncpy(temp, a, pos);
x=atoi(temp); // if left side is valid

strncpy(temp, a+pos,mone);
y=atoi(temp);
}
else
cout<<"ERROR";

cout<<"y:"<<y;
if (y==0)// to prevent division by zero
{
cout<<"ERROR";
result=false;
}
return result;
}
int main()
{
int x,y;
char a[15],b[15];
RationalNums rational;


cout<<"enter two rational numbers:\n";
//get first rational number and set in the class object
cin>>a;
//cin>>b;

if (validation(a,x,y))
{
rational.set_numerator(x);
rational.set_denominatore(y);

// get second rational number
cin>>b;
if (validation(b,x,y))
{
////comapre the 2 rational numbers
if(rational.chkEquality(x,y))
cout<<"equal";
else
cout<<"different";
cout<<endl;
}
}

system("pause");
return 0;
}

[Disch]

int get_numerator()  // <- defines a global function named get_numerator
{
return numerator;
}

int RationalNums::get_numerator()  // <- defines a function within the RationalNums class
{
return numerator;
}