.cpp
//
// calculator.cpp
//
#include "Fraction.h"
#include<iostream>
#include<stdexcept>
using namespace std;
int main()
{
Fraction x,y; //ERROR IS RIGHT HERE. It says "No matching constructor for initialization of 'Fraction'
char op;
try
{
cin >> x;
cin >> op;
while ( cin && ( op == '+' || op == '-' ) )
{
cin >> y;
if ( op == '+' )
x = x + y;
else
x = x - y;
cin >> op;
}
cout << x << endl;
}
catch ( invalid_argument& e )
{
cout << "Error: " << e.what() << endl;
}
}
.h
#ifndef Fraction_Calculator_Fraction_h
#define Fraction_Calculator_Fraction_h
#include<iostream>
#include<cstdlib>
//Fraction class definition
class Fraction
{
public:
Fraction (int a, int b);
int fraction(int a, int b);
void set(int, int);
int get_numerator(void);
int get_denomenator(void);
int find_gcd (int n1, int n2);
void reduce_fraction(int nump, int denomp);
Fraction& operator+(const Fraction& n);
Fraction& operator-(const Fraction& n);
friend std::ostream& operator<<(std::ostream &os, const Fraction& n);
friend std::istream& operator>>(std::istream &is, Fraction& n);
Fraction& operator= (const Fraction& n);
int denom;
int numera;
private:
int numerator;
int denomenator;
int denomp;
int nump;
};
#endif
It says "No matching constructor for initialization of 'Fraction' on the first line of the cpp file
I don't understand what it means.
The problem is that your Fraction constructor takes 2 arguments.
Fraction (int a, int b);
and you are invoking it with none
Fraction x,y; //ERROR IS RIGHT HERE. It says "No matching constructor for initialization of 'Fraction'
You should either invoke x and y with the 2 int parameters or define another constructor that takes no arguments.
Provide default constructor like
Fraction()
{
numerator=0;
denomenator0;
denomp0;
nump=0;
}
Related
I'm doing an exercise for homework where i have to create a class for a fraction , but when i was coding i got in trouble with the overloading of the operator << ,and i don't understand where's the error because when the program reads the input the two numbers(numerator,denominator) are saved correctly, but when i try to print in output the fraction it gives me a random number; why?
#include <iostream>
using namespace std;
class Frazione{
private:
int num;
int den;
public:
Frazione operator+(Frazione f2){
Frazione risultato;
risultato.den=MCM(f2.den);
risultato.num=(num*(risultato.den/den))+(f2.num*(risultato.den/f2.den));
return risultato;
}
int MCM(int a){
int min;
int k;
if(den>a){
min=a;
}
else{
min=den;
}
for(int i=min;!(den%i==0 && a%min==0);i+=min){
k=i;
}
return k;
}
void setn(int a){
num=a;
}
void setd(int a){
den=a;
}
int getn(){
return num;
}
int getd(){
return den;
}
};
istream& operator>>(istream& in,Frazione f){
int n,d;
cout<<"Dimmi il numeratore"<<endl;
in>>n;
cout<<"Dimmi il denominatore"<<endl;
in>>d;
f.setn(n);
f.setd(d);
return in;
}
ostream& operator<<(ostream& out,Frazione& f){
out<<f.getn();
out<<"/";
out<<f.getd();
return out;
}
int main(){
Frazione f1,f2,f3;
cin>>f1;
cout<<f1;
cin.get();
return 0;
}
Currently don't pay attention to funciont MCM and operator+ because they are function that i have to implement then i'll solve this plobem.
You have missed the reference of the second parameter here:
istream& operator>>(istream& in,Frazione &f)
The parameter f is only accessible by reference.
I created a code by using operator overloading concept in c++ for addition of two rational numbers by overloading the +(plus) and the <<(Insertion) operator and I am not able to get a function being accessed from the scope of operator overloading of + operator. How to access the LCM() function from the scope of operator+ overloaded?
I tried using the friend function to access my LCM() function from within the scope of operator+ overloaded function but it didn't work!
#include <iostream>
using namespace std;
class Rational {
private:
int num, den;
public:
int getnum()
{
return this->num;
}
int getden()
{
return this->den;
}
Rational(int num = 0, int den = 0)
{
this->num = num;
this->den = den;
}
int LCM(int a, int b);
friend ostream& operator<<(ostream& out, Rational& r);
friend Rational operator+(Rational x, Rational y);
};
int Rational::LCM(int a, int b)
{
int i = a > b ? a : b;
for (i; i <= a * b; i++) {
if (i % a == 0 && i % b == 0) {
break;
}
}
return i;
}
ostream& operator<<(ostream& out, Rational& r)
{
out << r.getnum() << "/" << r.getden();
return out;
}
Rational operator+(Rational x, Rational y)
{
Rational temp;
int temp1;
int div;
temp1 = LCM(x.den, y.den);
temp.num = (int(temp1 / x.den) * x.num) + (int(temp1 / y.den) * y.num);
temp.den = temp1;
return temp;
}
int main()
{
Rational r1(3, 2);
Rational r2(9, 4);
Rational r3;
r3 = r1 + r2;
cout << r3;
return 0;
}
And I get the error:
error: ‘LCM’ was not declared in this scope
I would say that int Rational::LCM(int a,int b) does not really have anything to do with the Rational class and should probably be a utility function (non-member function), then you would be able to use it anywhere
I am making a class Fraction with global functions usage
My code looks like below:
#include<iostream>
using namespace std;
ostream & operator<<(ostream & os, Fraction & fr)
{
return os << fr.get_num() << '/' << fr.get_den();
}
class Fraction
{
private:
int num, den;
public:
int get_num()
{
return num;
}
int get_den()
{
return den;
}
};
Main function has call : `cout << f2 << endl;
But i am getting following build erros while compilation:
Error C2805 binary 'operator <<' has too few parameters
fr: undeclared identifier
left of get_num must be struct/union/class
You should change the order of your code like this:
class Fraction
{
private:
int num, den;
public:
int get_num()
{
return num;
}
int get_den()
{
return den;
}
};
ostream & operator<<(ostream & os, Fraction & fr)
{
return os << fr.get_num() << '/' << fr.get_den();
}
I know there are plenty of questions like these, but I couldn't find a solution that worked for me.
I am trying to make simple fraction calculator than can add or subtract any number of functions and write the answer as a reduced fraction.
Example: input=
3/2 + 4/
8
, output =
2
I am trying overload operators in order to accomplish this.
So in the program I am trying to develop, the input consists of an expression made of fractions separated by the operators + or -.
The number of fractions in the expression is arbitrary.
Each of the following 6 lines is an example of a valid input expression:
1/2 + 3/4
1/2 -5/7+3/5
355/113
3 /9-21/ -7
4/7-5/-8
-2/-3+7/5
***The problem that I am having is that in when I run my program it has an overload operating error: *error: overloaded 'operator<<' must be a binary operator (has 3 parameters)****
/Users/Spicycurryman/Desktop/ECS40/hw1/fraction.cpp:61:22: error: overloaded 'operator<<' must be a binary operator (has 3 parameters)
ostream& Fraction::operator<<(ostream &os, Fraction& n)
^
/Users/Spicycurryman/Desktop/ECS40/hw1/fraction.cpp:80:22: error: overloaded 'operator>>' must be a binary operator (has 3 parameters)
istream& Fraction::operator>>(istream &os, Fraction& n)
I don't understand why that is an error.
My following code is below:
CPP FILE
#include "Fraction.h"
Fraction::Fraction(int a, int b)
{
}
int Fraction::find_gcd (int n1, int n2)
{
int gcd, remainder;
remainder = n1 % n2;
while ( remainder != 0 )
{
n1 = n2;
n2 = remainder;
remainder = n1 % n2;
}
gcd = n2;
return (gcd);
}
void Fraction::reduce_fraction(int nump, int denomp)
{
this->nump = nump;
this->denomp = denomp;
int gcd;
gcd = find_gcd(nump, denomp);
nump = nump / gcd;
denomp = denomp / gcd;
if ((denomp<0 && nump < 0 ))
{
denomp*=-1;
nump*=-1;
}
else if (denomp < 0 && nump >0){
denomp*=-1;
}
if ( denomp ==0) {
throw invalid_argument( "Error: zero denominator" );
}
}
Fraction& Fraction::operator+(const Fraction& n) {
denom = denomp * n.denom;
numera = (nump * n.numera) + (n.denom * n.nump);
return (*this);
}
Fraction& Fraction::operator-(const Fraction& n) {
denom = denomp * n.denom;
numera = (nump * n.numera) - (n.denom* n.nump);
return (*this);
}
ostream& Fraction::operator<<(ostream &os, Fraction& n)
{
if (n.numera == 0)
{
cout << 0 << endl;
return os;
}
else if (n.numera == n.denom)
{
cout << 1 << endl;
return os;
}
else
{
cout << n.numera << '/' << n.denom << endl;
return os;
}
}
istream& Fraction::operator>>(istream &os, Fraction& n)
{
char slash = 0;
return os >> n.numera >> slash >> n.denom;
}
Header File
#ifndef FRACTION_H
#define FRACTION_H
#include <iostream>
#include <stdexcept>
using namespace std;
class Fraction{
public:
Fraction(int a, int b);
int fraction(int a,int b);
int find_gcd(int n1, int n2);
void reduce_fraction(int nump, int denomp);
Fraction& operator+(const Fraction& n);
Fraction& operator-(const Fraction& n);
friend ostream& operator<<(ostream &os, const Fraction& n);
friend istream& operator>>(istream &is, const Fraction& n);
private:
int denom;
int numera;
int denomp;
int nump;
};
#endif
MAIN CPP FILE
#include "Fraction.h"
#include <iostream>
using namespace std;
int main()
{
Fraction x(2,3);
Fraction y(6,-2);
cout << x << endl;
cout << y << endl;
cin >> y;
cout << y << endl;
Fraction z = x + y;
cout << x << " + " << y << " = " << z << endl;
}
I know that the operators are member functions and a member function takes an implicit first parameter, meaning my operators now takes three parameters it may be fixed being a non-member function; however, that would not work in this program. How exactly in my case would I fix it so the program would work?
Thank you very much!
The problem is that you declared operator>> and operator<< as non-member functions, but defined as a member function.
This should fix that problem (but open another set of problems). So instead of
ostream& Fraction::operator<<(ostream &os, Fraction& n)
{
...
istream& Fraction::operator>>(istream &os, Fraction& n)
{
...
implement as :
ostream& operator<<(ostream &os, Fraction& n)
{
...
istream& operator>>(istream &os, Fraction& n)
{
...
Also, take a note that you declared functions as :
friend ostream& operator<<(ostream &os, const Fraction& n);
friend istream& operator>>(istream &is, const Fraction& n);
but defined as (therefore you changed the signature) :
ostream& Fraction::operator<<(ostream &os, Fraction& n)
istream& Fraction::operator>>(istream &os, Fraction& n)
Proper way is to declare and define as :
ostream& Fraction::operator<<(ostream &os, const Fraction& n)
istream& Fraction::operator>>(istream &os, Fraction& n)
I am adding just changes. The rest is the same as in the question:
class Fraction{
friend ostream& operator<<(ostream &os, const Fraction& n);
friend istream& operator>>(istream &is, Fraction& n);
// the rest is the same
};
ostream& operator<<(ostream &os, const Fraction& n)
{
if (n.numera == 0)
{
cout << 0 << endl;
return os;
}
else if (n.numera == n.denom)
{
cout << 1 << endl;
return os;
}
else
{
cout << n.numera << '/' << n.denom << endl;
return os;
}
}
istream& operator>>(istream &os, Fraction& n)
{
char slash = 0;
return os >> n.numera >> slash >> n.denom;
}
I know there are plenty of questions like these, but I couldn't find a solution that worked for me.
Okay, I am trying to make simple fraction calculator than can add or subtract any number of functions and write the answer as a reduced fraction.
Example: input=
3/2 + 4/
8
, output =
2
I am trying overload operators in order to accomplish this.
So in the program, I am trying to develop the input consists of an expression made of fractions separated by the operators '+'or '-'.
The number of fractions in the expression is arbitrary.
Each of the following 6 lines is an example of valid input expression:
1/2 + 3/4
1/2 -5/7+3/5
355/113
3 /9-21/ -7
4/7-5/-8
-2/-3+7/5
The problem that I am having is that in when I run my Main CPP program it has a class redefinition error:
fraction.cpp:6:7: error: redefinition of 'Fraction'
class Fraction
^
./Fraction.h:7:7: note: previous definition is here
class Fraction{
However, that should not be a problem because I declared the class and member functions in my header files and defined them in my CPP file.
My following code is below:
Header File
#ifndef FRACTION_H
#define FRACTION_H
#include <iostream>
using namespace std;
class Fraction{
public:
Fraction(int , int );
int fraction(int,int);
void reduce_fraction(int *, int *);
Fraction& operator+(const Fraction& n);
Fraction& operator-(const Fraction& n);
friend ostream& operator<<(ostream &os, const Fraction& n);
friend istream& operator>>(istream &is, const Fraction& n);
};
#endif
CPP File
#include <iostream>
using namespace std;
#include "Fraction.h"
#include <stdexcept>
class Fraction
{
public:
Fraction::Fraction(int a, int b);
int find_gcd(int n1, int n2);
void reduce_fraction(int *nump, int *denomp)
{
int gcd;
gcd = find_gcd(*nump, *denomp);
*nump = *nump / gcd;
*denomp = *denomp / gcd;
if ((*denomp<0 && *nump < 0 ))
{
*denomp*=-1;
*nump*=-1;
}
else if (*denomp < 0 && *nump >0){
*denomp*=-1;
}
if ( *denomp ==0) {
throw invalid_argument( "Error: zero denominator" );
}
}
Fraction& Fraction::operator+(const Fraction& n) {
int denom = *denomp * n.denom;
int numera = (*nump * n.numera) + (n.denom * n.nump);
return Fraction(numera,denom);
}
Fraction& Fraction::operator-(const Fraction& n) {
int denom = *denomp * n.denom;
int numera = (*nump * n.numera) - (n.denom* n.nump);
return Fraction(numera, denom);
}
friend ostream& operator<<(ostream &os, Fraction& n)
{
if (n.numera == 0)
{
cout << 0 << endl;
return os;
}
else if (n.numera == n.denom)
{
cout << 1 << endl;
return os
}
else
{
cout << n.numera << '/' << n.denom << endl;
return os;
}
}
friend istream& operator>>(istream &os, Fraction& n)
{
char slash = 0;
return is >> n.numera >> slash >> n.denom;
}
};
#include <iostream>
using namespace std;
#include "Fraction.h"
#include <stdexcept>
class Fraction
{
public:
Fraction::Fraction(int a, int b);
int find_gcd(int n1, int n2);
void reduce_fraction(int *nump, int *denomp)
{
int gcd;
gcd = find_gcd(*nump, *denomp);
*nump = *nump / gcd;
*denomp = *denomp / gcd;
if ((*denomp<0 && *nump < 0 ))
{
*denomp*=-1;
*nump*=-1;
}
else if (*denomp < 0 && *nump >0){
*denomp*=-1;
}
if ( *denomp ==0) {
throw invalid_argument( "Error: zero denominator" );
}
}
Fraction& Fraction::operator+(const Fraction& n) {
int denom = *denomp * n.denom;
int numera = (*nump * n.numera) + (n.denom * n.nump);
return Fraction(numera,denom);
}
Fraction& Fraction::operator-(const Fraction& n) {
int denom = *denomp * n.denom;
int numera = (*nump * n.numera) - (n.denom* n.nump);
return Fraction(numera, denom);
}
friend ostream& operator<<(ostream &os, Fraction& n)
{
if (n.numera == 0)
{
cout << 0 << endl;
return os;
}
else if (n.numera == n.denom)
{
cout << 1 << endl;
return os
}
else
{
cout << n.numera << '/' << n.denom << endl;
return os;
}
}
friend istream& operator>>(istream &os, Fraction& n)
{
char slash = 0;
return is >> n.numera >> slash >> n.denom;
}
};
MAIN CPP FILE
#include "Fraction.h"
#include <iostream>
using namespace std;
int main()
{
Fraction x(2,3);
Fraction y(6,-2);
cout << x << endl;
cout << y << endl;
cin >> y;
cout << y << endl;
Fraction z = x + y;
cout << x << " + " << y << " = " << z << endl;
}
I am essentially having trouble with understanding why I am getting the previous definition error and how exactly to fix it. Also, if you see anything else wrong with my implementation in this program I would appreciate you telling me!
Thank you very much!
The way to define member functions in Fraction.cpp is not like this:
class Fraction
{
public:
void reduce_fraction(int *nump, int *denomp)
{
...
}
}
but rather like this:
void Fraction::reduce_fraction(int *nump, int *denomp)
{
...
}
More generally, you should not write this much code before testing any of it.