C++ Fractions Program

[ajoshi20]

I have a program I need to make, it must add, subtract, and multiply fractions. I get the following errors on the bottom.

The program must run on void functions.

/*
Fraction Calculator
*/

#include <iostream>

using namespace std;

// Declare a fraction (defines an implicit typedef)


struct fraction
{
    int num;                        // Declare Numerator Variable
    int den;                        // Declare Denominator Variable
};

void functadd(fraction a, fraction b);


void functsubtr(fraction a, fraction b);


void functmulti(fraction a, fraction b);



void functdivide(fraction a, fraction b);


int main()
{
	int ans;
    fraction number[2];          
    char c;                         // Declare c, a dummy character to "eat"
                                    //  the slashes in the input fractions
    char oprtr;                     // Declare oprtr, the operator in the
                                    //  input expression
    fraction result;                // Declare result, a fraction to store the
                                    //  result of the computation
    fraction reduced;               // Declare reduced, a fraction to store the
                                    //  reduced result of the computation
    bool n = true;                  // Declare n, a boolean determining whether
                                    //  the program continues, defaults to true
    bool showans;                   // Declare showans, a boolean determining
                                    //  whether the answer is shown
    char cont; 

    do  
    {
        showans = true;

        // Prompt user for input fractions
        cout << "\nEnter Values in this form  2/3+94/3: ";
        cin >> number[0].num >> c >> number[0].den >>    // 1st fraction
                oprtr >>                             // Operator
                number[1].num >> c >> number[1].den;    // 2nd fraction

        switch(oprtr)
        {
        case '+':
            // User entered a addition sign, add the fractions
            return ans;
            break;

        case '-':
            // User entered a subtraction sign, subtract the fractions
            return ans;
            break;

        case '*':
            // User entered a multiplication sign, multiply the fractions
            return ans;
            break;

        case '/':
            // User entered a division sign, divide the fractions
            return ans;
            break;

        default:
            // User entered something else, show an error message and don't
            //  display the answer
            cout << "You have used an invalid operator.\n";
            cout << "Please use any one of following operators: +, -, *, /\n";
            showans = false;
            break;
        }


        if(showans)
        {
           
            // Display the un-reduced result
            cout << "Answer = " << result.num << "/" << result.den;

            // User will be stuck in this loop until they enter either: y,Y,n,N
            do{
                // Ask the user about whether to continue / repeat
                cout << "\n";
                cout << "Continue? y/n \n";
                // Accept user input
                cin >> cont;
            } while((cont != 'y')&&(cont != 'Y')&&(cont != 'n')&&(cont != 'N'));

            // If the user entered n, break out of this loop.
            //  (If the user entered y, don't do anything, n = true).
            if((cont == 'n') || (cont == 'N'))
            {
                n = false;
            }

        }
    } while(n);
	
    // Return 0 for a successful exit
    return 0;

}

void functadd(fraction a,fraction b);
{

    // Declare ans, the fraction resulting from the operation
    fraction ans;                 
    // Calculate the numerator and denominator of the resulting fraction
    ans.num = (a.num * b.den) + (b.num * a.den);
    ans.den = a.den * b.den;
    // Return the resulting fraction
    result = functadd(number[0], number[1]);
	return result;
}

void functsubtr(fraction a, fraction b);
{
    // Declare ans, the fraction resulting from the operation
    fraction ans;                 
    // Calculate the numerator and denominator of the resulting fraction
    ans.num = (a.num * b.den) - (b.num * a.den);
    ans.den = a.den * b.den;
    // Return the resulting fraction
    result = functsubtr(number[0], number[1]);
	return ans;
}


void functmulti(fraction a, fraction b);
{
    // Declare ans, the fraction resulting from the operation
    fraction ans;                 
    // Calculate the numerator and denominator of the resulting fraction
    ans.num = a.num * b.num;
    ans.den = a.den * b.den;
    // Return the resulting fraction
	result = functmulti(number[0], number[1]);
    ;
}


void functdivide(fraction a, fraction b);
{
    // Declare ans, the fraction resulting from the operation
    fraction ans;                 
    // Calculate the numerator and denominator of the resulting fraction
    ans.num = a.num * b.den;
    ans.den = a.den * b.num;
    // Return the resulting fraction
	result = functdivide(number[0], number[1])
    return ans;
}

1>.\fract.cpp(122) : error C2447: '{' : missing function header (old-style formal list?)
1>.\fract.cpp(135) : error C2447: '{' : missing function header (old-style formal list?)
1>.\fract.cpp(148) : error C2447: '{' : missing function header (old-style formal list?)
1>.\fract.cpp(161) : error C2447: '{' : missing function header (old-style formal list?)

[z05DSL3A]

Lines 121, 134, 147, and 160 have an ; at then end that should not be there.

[Galik]

Also you can not use return to return the result with a void function.

If you MUST use void functions then you need to return the result as one of the parameters.

One way to do this is to declare a return parameter as a reference:

void functdivide(fraction a, fraction b, fraction& answer)
{
}

Note that the fraction answer is passed using the & symbol making it a reference. This means that setting the value of answer sets the value in the variable you pass in:

fraction a;
fraction b;

fraction c;

functdivide(a, b, c);

// now c contains the answer

[Athar]

Are you sure you understood the task description properly? The add/muliply functions should be operators of the fraction class, everything else doesn't make much sense. Least of all functions that return void. Even though it would work the way Galik proposed, it's an unnatural solution.

[bluecoder]

I am using Visual studio 2008 .When i make some of the correction in the program and try to compile the program i get the error as .

error C2061: syntax error : identifier '_TCHAR'

in the start of the program in main()

int _tmain(int argc, _TCHAR* argv[])

.
Any suggestion is welcome one .
Thanks .