Fraction program

#1 16-Feb-2005, 20:24

I wrote this to perform arithmetic and relational operations on fractions but getting a few errors and was hoping someone could clue me in.

fraction.h

CPP / C++ / C Code:

#ifndef Fraction
#define Fraction

class fraction
{
    public:
        fraction();
		void get();
		void display();
		double evaluate();
		friend fraction operator+ (fraction, fraction);
	private:
		int numerator;
        int denominator;
};
#endif

fraction.cpp

CPP / C++ / C Code:

#include <iostream>
#include <cmath>

#include "fraction.h"

void main ()
{
	fraction x,y,z;
	double i;
	x.get();
	x.display();
	i = x.evaluate();
	cout << i << endl;
	y.get();
	y.display();
	z = x + y;
	cout << "The sum of " ;
        x.display();
	cout << " and ";
	y.display();
	cout <<  " is " ;
	z.display();
}

fractionmain.cpp

CPP / C++ / C Code:

#include <iostream>
#include <cmath>

#include "fraction.h"

	fraction::fraction()
	{
        numerator=0;
        denominator=1;
	}
	void fraction::get()
	{
        cout << "numerator?" <<endl;
		cin >> numerator;
		cout << "denominator?"  << endl;
		cin >> denominator;
	}
	void fraction::display()
	{
		cout << numerator << "/" << denominator << endl;
	}
	double fraction::evaluate()
	{
		double temp;
		temp = (double) numerator / (double)denominator;
        return temp;
	}
	fraction operator+ (fraction f1, fraction f2)
	{
		fraction sum;
		sum.numerator = f1.numerator*f2.denominator + f2.numerator*f1.denominator;
		sum.denominator = f1.denominator*f2.denominator;
		return sum;
	}

Errors:

fractionmain.cpp
error C2065: 'cout' : undeclared identifier
error C2065: 'endl' : undeclared identifier
error C2065: 'cin' : undeclared identifier
error C3861: 'cout': identifier not found, even with argument-dependent lookup
error C3861: 'endl': identifier not found, even with argument-dependent lookup
error C3861: 'cin': identifier not found, even with argument-dependent lookup
error C3861: 'cout': identifier not found, even with argument-dependent lookup
error C3861: 'endl': identifier not found, even with argument-dependent lookup

fraction.cpp
error C2065: 'cout' : undeclared identifier
error C2065: 'endl' : undeclared identifier
error C3861: 'cout': identifier not found, even with argument-dependent lookup
error C3861: 'cout': identifier not found, even with argument-dependent lookup
error C3861: 'cout': identifier not found, even with argument-dependent lookup

It's obvious that the errors are with cout, cin, and endl
but what did I miss?

Thanks
Spuds

QED · #2 16-Feb-2005, 22:02

The identifiers cout, cin, and endl are all defined in the std namespace. To use them, either
a) insert the statement "using namespace std;" at the top of your cpp files, or
b) use the identifiers std::cout, std::cin, and std::endl

Matthew

#3 17-Feb-2005, 19:05

Quote:

Originally Posted by QED

The identifiers cout, cin, and endl are all defined in the std namespace. To use them, either
a) insert the statement "using namespace std;" at the top of your cpp files, or
b) use the identifiers std::cout, std::cin, and std::endl

Matthew

Worked like a champ, all my exercises have that statement. I just forgot about it, at least now I know what happens without it.

Thanks

Javed · #4 21-Sep-2006, 05:57

I also faced this problem
error C2065: 'cout' : undeclared identifier

and I TRIED WITH NAMESPACE But it did not work. The real problem was the

#include <StdAfx.h>
was not the first line of my .cpp file.
Do remember anything before this header is not compiled and hance #include<iostream.h> was not getting compiled.

WaltP · #5 22-Sep-2006, 09:28

Quote:

Originally Posted by Javed

I also faced this problem
error C2065: 'cout' : undeclared identifier

and I TRIED WITH NAMESPACE But it did not work. The real problem was the

#include <StdAfx.h>
was not the first line of my .cpp file.
Do remember anything before this header is not compiled and hance #include<iostream.h> was not getting compiled.

The

CPP / C++ / C Code:

#include <StdAfx.h>

line should not even be in the file. It's not needed -- and it's not portable.

Javed · #6 25-Sep-2006, 02:23

so what should I do. if I am havind
#include "StdAfx.h"
and I need to port the program

WaltP · #7 25-Sep-2006, 04:50

Quote:

Originally Posted by Javed

so what should I do. if I am havind
#include "StdAfx.h"
and I need to port the program

This doesn't give you a clue?

Quote:

Originally Posted by WaltP

The

CPP / C++ / C Code:

#include <StdAfx.h>

line should not even be in the file. It's not needed -- and it's not portable.

Delete the line...

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