What do I do when I get the error, "undefined reference to WinMain@16"

[spano693]

Hi everyone,

I'm new to programming with C++ and I'm using Code::Blocks as my compiler. I keep getting the error "undefined reference to WinMain@16" and I have no idea how to fix it. My code is supposed to do different things with fractions, but anyway here is my code:(all code is in a project)

myFracDr.cpp

#include "frac.h"
#include "gcd.h"
#include <iostream>
 
using namespace std;
 
int main()
{
    int x,y;
    cout << "Enter positive integer x: ";
    cin >> x;
    cout << "Enter positive integer y: ";
    cin >> y;
    cout << FractionType::Initialize(x,y) << endl;
 
    system("pause"); //keeps window open
    return 0;
}
 

myFrac.cpp

#include "frac.h"
#include "gcd.h"
 
void FractionType::Initialize(int numerator, int denominator)
// Function: Initialize the fraction
// Pre:  None
// Post: numerator is stored in num; denominator is stored in
//       denom
{
    num = numerator;
    denom = denominator;
    int cfactor = gcd(num, denom); // finds commom factor
    num = num/cfactor; //reduces numerator
    denom = denom/cfactor; //reduces denominator
}
int FractionType::NumeratorIs()
// Function: Returns the value of the numerator
// Pre:  Fraction has been initialized
// Post: numerator is returned
{
    return num;
}
int FractionType::DenominatorIs()
// Function: Returns the value of the denominator
// Pre:  Reaction has been initialized
// Post: denominator is returned
{
    return denom;
}
 
bool FractionType::IsZero()
// Function: Determines if fraction is zero
// Pre:  Fraction has been initialized
// Post: Returns true if numerator is zero
{
    return (num == 0);
}
 
bool FractionType::IsNotProper()
// Function: Determines if fraction is a proper fraction
// Pre:  Fraction has been initialized
// Post: Returns true if num is greater than or equal to denom
{
    return (num >= denom);
}
 
int FractionType::ConvertToProper()
// Function: Converts the fraction to a whole number and a
//       fractional part
// Pre:  Fraction has been initialized, is in reduced form, and
//       is not a proper fraction
// Post: Returns num divided by denom
//       num is original num % denom; denom is not changed
{
    int result;
    result = num / denom;
    num = num % denom;
    return result;
}
 

gcd.cpp (finds greatest common divisor)

int gcd(int x, int y)
{
    if (y==0)
    {
        return x;
    }
    else
    {
        while (y>0)
        {
            int step1 = x%y;
            x = y;
            y = step1;
            if (x%y==0)
            {
                return y;
            }
        }
    }
    return 0;
}
 

then I just have to two header files (frac.h and gcd.h)that I know are correct

Thank you for looking!

[weaknessforcats]

You have created a project for a Windows program rather than a console application. A Windows program has a WinMain() rather than a main().

[spano693]

I thought so too, but when I go into "Project/Target Options" and under "Type" is says "Console". I changed it to WinMain() just to try but I got the same error.

[weaknessforcats]

This is the same error Visual C++ puts out when yu have a Windows project instead of a console application project.

I don't use your compiler so I can't provide exact corrective steps.

[spano693]

Ok so I remade the project with the same code just to see if anything got messed while I was making it and now I'm getting a different error message: "In function 'int main()': (line 17) error: cannot call member function 'void FractionType::Initialize(int, int)' without object"

Any idea what to do about that?

Thank you for trying to help me.

[weaknessforcats]

You need an object to call a member function:

FractionType obj;
             obj.Initialize();

otherwise the compiler has no idea what object you want initialized.

BTW: These kinds of initializing functions in C++ are called constructors. So if FractionType::Initialize(int,int) becomes FractionType::FractionType(int,int) then the compiler will call it withour you needing to remember to code the call:

FractionType obj(3,4);   
//
//when you get here FractionType::FractionType(3,4) has already been called
//

BTW2: If you do this remember that constructors have no return types so remove the void.

[spano693]

I don't completely understand what you are telling me to do. I'm sorry, I'm really new to programming

[spano693]

Never mind. I got what you were saying. Thank you so much for your time!

[lerions]

I have the same problem did u fixed it??

[weaknessforcats]

@lerions
Please start a new thread. I don't know what problem you are talking about since several were talked about here.