Error using header and operator+

Question

As sugested in the course, I'm using a header .h and a .cpp file to each class in the Code Blocks IDE.
When I try to put the MyClass operator+(MyClass &obj) in the cpp file this error is showed:

/home/marianeg/Documents/cpp/SoloLearn/main.cpp|19|error: no match for ‘operator+’ (operand types are ‘MyClass’ and ‘MyClass’)|

When the method is placed in the .h file, it works.
How to make it work in the .cpp file?
It's good practice use the header file or should I use only use the .cpp one?

Answer 1

You were close, In the header file you have a function definition and body, you only need the definition here.

In the source File, You have again have a function definition and body, when you require return type (MyClass2) / function (MyClass2::operator+) / body (implementation)

See below:
Header File:
#ifndef MYCLASS2_H
#define MYCLASS2_H
using namespace std;

class MyClass2
{
public:
int var;
MyClass2();
MyClass2(int a);

MyClass2 operator+(MyClass2 & obj);

};

#endif // MYCLASS2_H

SOURCE FILE:
#include "Class.h"
using namespace std;

MyClass2::MyClass2()
{

}

MyClass2::MyClass2(int a) :var(a)
{

}

MyClass2 MyClass2::operator+(MyClass2 &obj)
{
MyClass2 res;
res.var = this->var + obj.var;
return res;
}

Answer 2

I will have a look see for you 😊

Answer 3

Good practise to use both header and cpp files

Might be a silly question, but did you include the .h file in the .cpp file?

Answer 4

Hi Jay, the Code::Blocks generate those includes for me.
I think there is something wrong with the syntax, and as the course always provide the code in one file, I'm not figuring out what. This is the code that works:

HEADER
#ifndef MYCLASS2_H
#define MYCLASS2_H
using namespace std;

class MyClass2
{
public:
int var;
MyClass2();
MyClass2(int a);

MyClass2 operator+(MyClass2 &obj)
{
MyClass2 res;
res.var = this->var+obj.var;
return res;
}

};

#endif // MYCLASS2_H

If I move the operator code to the source file, as the code bellow, it doesn't work:

SOURCE
#include "MyClass2.h"
using namespace std;

MyClass2::MyClass2()
{

}

MyClass2::MyClass2(int a):var(a)
{

}

MyClass2::MyClass2 operator+(MyClass2 &obj)
{
MyClass2 res;
res.var = this->var+obj.var;
return res;
}

Thanks!

Answer 5

Now it works!! Thanks!