Error: (function) undeclared -first use of this function

crystalattice · #1 28-Oct-2004, 21:36

I don't understand why I'm getting these error messages. I have the .h file included in both the main program and the implementation file. The "undeclared" functions are reduce, gcf, and lcd, all having a problem in the main file. Do I need to move these functions to the main program file or am I not referencing them correctly in the header?

Here's the main file (rationalnum.cpp)

CPP / C++ / C Code:

/**************************************************************************
 *   Purpose:  Perform rational number arithmetic, where a rational number is
 *		of the form "a/b", where a and b are integers and b != 0.
 ***************************************************************************/
#include <iostream>
#include <algorithm>
#include "ratnum.h"

using namespace std;

void enterFunction(RatNum& n1, RatNum& n2);

int main ()
{
	cout << "This program performs rational number operations.  A rational number is\n"
		<< "in the form \"a/b\", where a and b are integers and b != 0.\n\n"
		<< "The following operations are available (with examples given):\n"
		<< "1. Addition (3/8 + 1/6 = 13/24)\n"
		<< "2. Subtraction (3/8 - 1/6 = 5/24)\n"
		<< "3. Multiplication (3/8 * 1/6 = 1/16)\n"
		<< "4. Division (3/8 / 1/6 = 9/4)\n"
		<< "5. Inversion (3/8 I = 8/3)\n"
		<< "6. Mixed fraction (8/3 M = 2 + 2/3)\n"
		<< "7. Reduce (6/8 R = 3/4)\n"
		<< "8. Greatest common divisor (6/8 G = 2)\n"
		<< "9. Lowest common denominator (1/6 L 3/8 = 24)\n"
		<< "10. Less than? (1/6 < 3/8 = true)\n"
		<< "11. Less than or equal to? (1/6 <= 3/8 = true)\n"
		<< "12. Greater than? (1/6 > 3/8 = false)\n"
		<< "13. Greater than or equal to? (1/6 >= 3/8 = false)\n"
		<< "14. Equality (3/8 = 9/24 = true)\n"
		<< "15. Linear equation (2/3 X +2 = 4/5) (X = -9/5)\n"
		<< "16. Quit this program\n"
		<< endl;

		int op_choice;
		do
		{
			cout << "Enter the number of one of the operations listed above."
				<< endl;
			RatNum num1, num2;
			cin >> op_choice;

			//choose number operation
			switch (op_choice)
			{
				case 1:	//add
				{
					enterFunction(num1, num2);
					RatNum sum = num1 + num2;
					cout << "\n" << num1 << "+" << num2 << "=" << sum << endl;
				}
				break;

				case 2:	//subtract
				{
					enterFunction(num1, num2);
					RatNum difference = num1 - num2;
					cout << "\n" << num1 << "-" << num2 << "=" << difference << endl;
				}
				break;

				case 3:	//multiply
				{
					enterFunction(num1, num2);
					RatNum product = num1 * num2;
					cout << "\n" << num1 << "*" << num2 << "=" << product << endl;
				}
				break;

				case 4:	//divide
				{
					enterFunction(num1, num2);
					RatNum quotient = num1 / num2;
					cout << "\n" << num1 << "/" << num2 << "=" << quotient << endl;
				}
				break;

				case 5:	//invert
				{
					RatNum invert;
					int top = invert.A(), bottom = invert.B();
					cout << "Enter the number to invert." << endl;
					cin >> invert;
					swap(top, bottom);
					cout << invert;
				}
				break;

				case 6:
				//mixed fraction
				break;

				case 7:	//reduce
				{
					RatNum input;
					cout << "Enter the number to reduce." << endl;
					cin >> input;
					RatNum red = reduce(input);
					cout << red;
				}
				break;

				case 8:	//gcd
				{
					RatNum input;
					cout << "Enter the number to find GCD." << endl;
					cin >> input;
					int gcd = gcf(input.A(), input.B());
					cout << gcd;
				}
				break;

				case 9:	//lcd
				{
					cout << "Enter the 2 numbers to find the LCD, seperated by 'L'" << endl;
					RatNum n1, n2;
					char sep;
					cin >> n1 >> sep >> n2;
					int least = lcd(n1, n2);
					cout << least;
				}
				break;

				case 10:	//less than
				{
					enterFunction(num1, num2);
					bool less = num1 < num2;
					if (less == true)
						cout << "True" << endl;
					else cout << "False" << endl;
				}
				break;

				case 11:	//less than, equal to
				{
					enterFunction(num1, num2);
					bool less_equal = num1 <= num2;
					if (less_equal == true)
						cout << "True" << endl;
					else cout << "False" << endl;
				}
				break;

				case 12:	//greater than
				{
					enterFunction(num1, num2);
					bool great = num1 > num2;
					if (great == true)
						cout << "True" << endl;
					else cout << "False" << endl;
				}
				break;

				case 13:	//greater than, equal to
				{
					enterFunction(num1, num2);
					bool great_equal = num1 >= num2;
					if (great_equal == true)
						cout << "True" << endl;
					else cout << "False" << endl;
				}
				break;

				case 14: 	//equal
				{
					enterFunction(num1, num2);
					bool equal = num1 == num2;
					if (equal == true)
						cout << "True" << endl;
					else cout << "False" << endl;
				}
				break;

				case 15:	//linear equation
				{
					;
				}
				break;

				default:
					cerr << "Incorrect number entered." << endl;
			}
		}while (op_choice != 16);
		return 0;
}

//enterFunction() accepts input of two rational numbers
void enterFunction(RatNum& n1, RatNum& n2)
{
	cout << "Enter the equation you wish to solve.  Example: 2/3 +4/5"
		<< endl;
	char oper;	//type of arithmetic to perform (+, -, *, /)
	cin >> n1 >> oper >> n2;	//input will be in form of 'a/b + c/d'
}

Here's the header file (ratnum.h)

CPP / C++ / C Code:

/**************************************************************************  *RatNum.h 
 *
 *  Purpose:  Declares the class RatNum (RatNumNumber)
****************************************************************************/
#ifndef RATNUM		//compile-once wrapper
#define RATNUM

#include <iostream>
using namespace std;

class RatNum
{
      public:

		RatNum ();												//default-value constructor
		RatNum (int numerator, int denominator);	//explicit-value constructor

		void SetA(int numerator);							//Change value of A
		void SetB(int denominator);						//Change value of B
		int A() const;											//Gives value of A
		int B() const;											//Gives value of B

		//overloaded operators
		RatNum operator +( const RatNum &r ) const;
		RatNum operator -( const RatNum &r ) const;
		RatNum operator *( const RatNum &r ) const;
		RatNum operator /( const RatNum &r ) const;
		bool operator ==( const RatNum &r ) const;
		bool operator >( const RatNum &r ) const;
		bool operator <( const RatNum &r ) const;
		bool operator >=( const RatNum &r ) const;
		bool operator <=( const RatNum &r ) const;

		//rational number functions
		int lcd( RatNum r1, RatNum r2 ) const;
		int gcf( int num1, int num2 ) const;
		RatNum reduce( RatNum &r ) const;

      private:

		int  myA,	//numerator
			myB;	//denominator
};

//-----------Default-value constructor-----------
RatNum::RatNum ()
{
	myA = 0;
	myB = 1;
}

//-----------Explicit-value constructor----------
RatNum::RatNum (int numerator, int denominator)
{
	myA = numerator;
	myB = denominator;
	assert (myB != 0);
	if (myB == 0)
		cerr << "Denominator can not be 0." << endl;
}

//----------Change value of A----------------
inline void RatNum::SetA (int numerator)
{
	myA = numerator;
}

//--------Change value of B-----------
inline void RatNum::SetB (int denominator)
{
	myB = denominator;
}

//-------Return value of A-----------
inline int RatNum::A () const
{
	return myA;
}

//-------Return value of B----------
inline int RatNum::B () const
{
	return myB;
}

//--------Overload output operator--------------
inline ostream & operator<< (ostream & out, RatNum & num)
{
	out << num.A() << "/" << num.B();
	return out;
}

//--------Overload input operator---------------
inline istream & operator>> (istream & in, RatNum & num)
{
	char punc;
	int a, b;
	in >> a >> punc >> b; //input will be in form of 'a/b'
	num.SetA(a);
	num.SetB(b);
	return in;
}

#endif

Here's the implementation file (ratnum.ccp)

CPP / C++ / C Code:

/************************************************************************
 *   Purpose:  Implementation file for RatNum class
 ************************************************************************/
#include <iostream>
#include <algorithm>
#include "ratnum.h"

using namespace std;

//Reduce number to lowest terms
RatNum RatNum::reduce(RatNum &r) const
{
	int gcf_num = gcf(r.myA, r.myB);
	r.myA /= gcf_num;
	r.myB /= gcf_num;
	return r;
}

//Greatest common factor
int RatNum::gcf(int num1, int num2) const
{
	int i;
	if (num2 > num1)
		swap(num1, num2);
	for (i = num1; i > 1; i--)
	{
		if ((num1 % i == 0) && (num2 % i == 0))
		{
			num1 /= i;
			num2 /= i;
		}
	}
	return i;
}

//Least common denominator
int RatNum::lcd(RatNum r1, RatNum r2) const
{
	int num1 = r1.B(), num2 = r2.B();
	int common_factor = gcf(num1, num2);
	int product = num1 * num2;
	if (product < 0)
		product = -product;
	return product/common_factor;
}

//overload '+'
RatNum RatNum::operator +(const RatNum& r) const
{
	RatNum temp;
	temp.myA = myA + r.myA;
	temp.myB = myB + r.myB;
	return reduce(temp);
}

//overload '-'
RatNum RatNum::operator -(const RatNum &r) const
{
	RatNum temp;
	temp.myA = myA - r.myA;
	temp.myB = myB - r.myB;
	return reduce(temp);
}

//overload '*'
RatNum RatNum::operator *(const RatNum &r) const
{
	RatNum temp;
	temp.myA = myA * r.myA;
	temp.myB = myB * r.myB;
	return reduce(temp);
}

//overload '/'
RatNum RatNum::operator /(const RatNum &r) const
{
	RatNum temp;
	temp.myA = myA / r.myA;
	temp.myB = myB / r.myB;
	return reduce(temp);
}

bool RatNum::operator ==(const RatNum& r) const
{
	//'this' refers to the rational number object being executed
	return (this->myA ==r.myA && this->myB == r.myB);
}

bool RatNum::operator <(const RatNum& r) const
{
	//'this' refers to the rational number object being executed
	RatNum tmp_num = *this - r;
	return (tmp_num.myA < 0 || tmp_num.myB < 0);
}

bool RatNum::operator >(const RatNum& r) const
{
	//'this' refers to the rational number object being executed
	RatNum tmp_num = *this -r;
	return (tmp_num.myA > 0 && tmp_num.myB > 0);
}

bool RatNum::operator <=(const RatNum& r) const
{
	//'this' refers to the rational number object being executed
	RatNum tmp_num = *this -r;
	return (tmp_num.myA <= 0 || tmp_num.myB < 0);
}

bool RatNum::operator >=(const RatNum& r) const
{
	//'this' refers to the rational number object being executed
	RatNum tmp_num = *this -r;
	return (tmp_num.myA >= 0 && tmp_num.myB > 0);
}

Thanks for the help.

WaltP · #2 28-Oct-2004, 22:21

Quote:

Originally Posted by crystalattice

I don't understand why I'm getting these error messages.

these error messages? What error messages? Ya gotta post 'em!

LuciWiz · #3 29-Oct-2004, 05:05

Quote:

The "undeclared" functions are reduce, gcf, and lcd, all having a problem in the main file. Do I need to move these functions to the main program file or am I not referencing them correctly in the header?

These functions are actually methods belonging to the RatNum class. You need to use them appropriately:

CPP / C++ / C Code:

// RatNum red = reduce(input);  Wrong!
 RatNum red1, red2;
 red1 = red2.reduce(input); // Something like this
                            //I didn't look to what reduce does; modify accordingly

Best regards,
Luci

crystalattice · #4 29-Oct-2004, 11:09

Quote:

Originally Posted by WaltP

these error messages? What error messages? Ya gotta post 'em!

Sorry, I put the error message in the title of my posting; thought it would be easiest. Didn't think to relist it in the actual posting.

For reference, the error was

Code:

(function) undeclared-first use of this function

where (function) is actually 3 functions: reduce, gcf, lcd.

WaltP · #5 29-Oct-2004, 17:54

Quote:

Originally Posted by crystalattice

Sorry, I put the error message in the title of my posting; thought it would be easiest. Didn't think to relist it in the actual posting.

Oh, OK. I for one ignore titles because 95% of the time they are useless. "Please Help", "What's wrong with my program" and so on. The message is where I expect to see the information to solve the problem.

crystalattice · #6 31-Oct-2004, 11:00

I figured out the fix for the original problem (needed to move the default and explict constructors from the header file to the implementation file). Now I have a question about overloading operators.

If I want to overload a '+' sign, it's fairly easy w/ integers.

CPP / C++ / C Code:

//Assume class Number is a two-dimensional vector
Number Number::operator+ (Number param)
{
Number tmp;
tmp.x = x + param.x;
tmp.y = y + param.y;
return tmp;
}

However, since my program deals w/ rational numbers, how do I pass the rational numbers into the overload function? Originally I used the this keyword until I realized that the compiler didn't understand what I wanted by telling me there was no matching function.

Code:

/home/cody/Projects/rationalnum/src/ratnum.cpp:73: 
no matching function for call to `RatNum::lcd(const RatNum* const, const RatNum&) const'

Here's what I originally had:

CPP / C++ / C Code:

RatNum RatNum::operator +(const RatNum& r) const
{
	//"this" refers to the first rational number, "r" refers to the second
	RatNum temp;
	int lcd_num = lcd(this, r);	//find the common denominator
	int n1 = this->A() * (lcd_num / this->B());	//find the first number's numerator
	int n2 = r.A() * (lcd_num / r.B())	//find the second number's numerator
	temp.SetA(n1 + n2);
	temp.SetB(lcd_num);
	return reduce(temp);
}

The way I interpret the error message is that I can't use this because it's a pointer, not an object. If this is true, then how can I pass the original numbers to the overloaded operator? Is it as easy as adding another argument to the operator function? (The books I've looked at only show one argument).

LuciWiz · #7 01-Nov-2004, 04:36

Quote:

Originally Posted by LuciWiz

These functions are actually methods belonging to the RatNum class. You need to use them appropriately:

CPP / C++ / C Code:

// RatNum red = reduce(input);  Wrong!
 RatNum red1, red2;
 red1 = red2.reduce(input); // Something like this
                            //I didn't look to what reduce does; modify accordingly

Best regards,
Luci

Sorry about this answer, I didn't look through your entire program (missed/disregarded the overloading stuff). So I suggest you also "disregard" my answer, OK

?

Sorry again,
Luci

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Error: (function) undeclared -first use of this function

Fixed one problem, now have another