在C ++中编译复数类时出错

Question

I have code that is supposed to show addition, subtraction, etc. of complex numbers with no input from the user necessary. I have three classes: test.cpp, complex.cpp, and complex.h to run the program, define the constructors and methods, and create a header class respectively. However, when I run my code I get a series of errors that I've been trying to figure out for a while now.

complex.h

//complex class definition
#ifndef COMPLEX_H
#define COMPLEX_H


//class complex
class Complex
{
public:
    Complex(); //default no arg constructor
    Complex(double a); //one arg constructor
    Complex(double a, double b); //two arg constructor
    Complex operator+(const Complex &) const; //addition method
    Complex operator-(const Complex &) const; //subtraction method
    Complex operator*(const Complex &) const; //multiplication method
    Complex operator/(const Complex &) const; //division method
    void print() const; //output
private:
    double a; //real number
    double b; //imaginary number
}; //end class Complex

#endif

complex.cpp

#include "stdafx.h"
#include <iostream>
#include "complex.h"
using namespace std;

//no arg constructor
Complex::Complex()
{
    a = 0;
    b = 0;
}

//one arg instructor
Complex::Complex(double real)
{
    a = real;
    b = 0;
}

//two arg constructor
Complex::Complex(double real, double imaginary)
{
    a = real;
    b = imaginary;
}

//addition
Complex Complex::operator+(const Complex &number2) const
{
    return a + number2.a, b + number2.b;
}

//subtraction
Complex Complex::operator-(const Complex &number2) const
{
    return a - number2.a, b - number2.b;
}

//multiplication
Complex Complex::operator*(const Complex &number2) const
{
    return a * number2.a, b * number2.b;
}

//division
Complex Complex::operator/(const Complex &number2) const
{
    return a / number2.a, b / number2.b;
}

//output display for complex number
void Complex::print() const
{
    cout << '(' << a << ", " << b << ')';
}

test.cpp

#include <iostream>
#include <complex>
#include "complex.h"
#include "stdafx.h"
using namespace std;

int main()
{
    Complex b(1.0, 0.0);
    Complex c(3.0, -1.0);

    /*cout << "a: ";
    a.print();

    system ("PAUSE");*/

};

In test right now as the code shows the lower parts are commented out and I have attempted to only call two of the three constructors to see if I can get any of this working.

The errors I receive:

    error C2065: 'Complex' : undeclared identifier
    error C2065: 'Complex' : undeclared identifier
    error C2146: syntax error : missing ';' before identifier 'b'
    error C2146: syntax error : missing ';' before identifier 'c'
    error C3861: 'b': identifier not found  
    error C3861: 'c': identifier not found

I am trying to run this in Visual Studio 2010. Can someone please help?

Answer 1

I think the problem is in your Complex.cpp. If there are errors compiling the code of the class, the class is unknown and so the identifier Complex, too.

After a quick view, everthing seem to be correct but your operator functions have some errors:

Incorrect:

    //addition
    Complex Complex::operator+(const Complex &number2) const
    {
        return a + number2.a, b + number2.b;
    }

Correct:

    //addition
    Complex Complex::operator+(const Complex &number2) const
    {          
        return Complex(a + number2.a, b + number2.b);
    }

The problems are the return types of your operator methods. They have to be the same as declared. Also you cannot return two variables at the same time. If you want to do so, you have to use structs or classes (by calling the constructor of your class Complex with the new values).

If you want to manipulate the members a and b, you cannot define the methods as "const". If you say a function is const, it means all class members values won't be manipulated by calling this method.

Answer 2

You may facing a problem with stdafx.h issue

At least you should try to put #include "stdafx.h before every other include Or you could try to set your project property to not use stdafx.h

1. right click on project and select Properties
2. go to C/C++ -> Precompiled Headers 
3. select "Not Using Precompiled Headers"

Answer 3

#include <complex>
#include "complex.h"

That's a bad smell. It's possible that both those #include files use the same name for the header guard.

Try changing yours like this.

#ifndef MY_COMPLEX_H
#define MY_COMPLEX_H

.. And maybe rename your module from "complex" to something else, to avoid clashes with the system header file of the same name.

Answer 4

Try making it as simple as possible. Then add parts back until you find your error.

Does this work?

#include "complex.h"

int main()
{
    Complex c(3.0, -1.0);

    return 0;
};