C++ Simple Overloading of operator+ Not Compiling

Question

I have a simple vector class, and I'm trying to overload the operator+ to add vectors. When it didn't work in my main program, I created a new project and stripped it down to the bare minimum, and it still didn't work.

Bare minimum code:

main.cpp

#include "vector3f.h"

int main()
{
    Vector3f* a = new Vector3f();
    Vector3f* b = new Vector3f();
    Vector3f* c = a + b;
}

vector.h

#ifndef __VECTOR3F_H__
#define __VECTOR3F_H__

class Vector3f
{
public:
    float x;
    float y;
    float z;

    Vector3f();
    Vector3f(float x, float y, float z);
    ~Vector3f();

    Vector3f operator+(const Vector3f& rhs);
}; 

#endif

vector.cpp

#include "vector3f.h"

Vector3f::Vector3f()
{
    x = 0;
    y = 0;
    z = 0;
}

Vector3f::Vector3f(float x, float y, float z)
{
    this->x = x;
    this->y = y;
    this->z = z;
}

Vector3f::~Vector3f()
{

}

Vector3f Vector3f::operator+(const Vector3f& rhs)
{
    return Vector3f(x + rhs.x, y + rhs.y, z + rhs.z);
}

Here is the compile error:

main.cpp: In function 'int main()':
main.cpp:7: error: invalid operands of types 'Vector3f*' and 'Vector3f*' to binary 'operator+'

main.cpp line 7 is Vector3f* c = a + b;.

So my question, as is expected on Stack Overflow, is: what am I doing wrong?

Side note: I have a very lame IDE and the problem may be a faulty compiler, though I don't expect this to be the case.

Any help is appreciated. Thanks in advance!!

notice I edited my comment to make `c` not a pointer. See my answer posted below for more. — AndyG, Mar 19 '14 at 05:30

AndyG · Accepted Answer · 2014-03-19T05:37:18.213

3

You dynamically allocated your Vectors, and the + operator is not defined for pointers to vectors.

So you need to change:

 Vector3f* a = new Vector3f();
 Vector3f* b = new Vector3f();
 //... assigning of and b
 Vector3f* c = a + b;

To

Vector3f* a = new Vector3f();
Vector3f* b = new Vector3f();
Vector3f* c = new Vector3f();
*c = *a + *b;

edited Mar 19 '14 at 05:37

answered Mar 19 '14 at 05:29

AndyG

39,700
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Sure, no problem :-). You may also want to define a copy constructor for your vector class so you can say `Vector3f* c = new Vector3f(*a + *b);` which may be more concise. – AndyG Mar 19 '14 at 05:34
Why the parenthesis around the *a and *b? Point me to some website? – Joshua Hyatt Mar 19 '14 at 05:35
I know more about Java than C++, so if my question is too stupid, disregard it. :) – Joshua Hyatt Mar 19 '14 at 05:35
It's a bit overkill on my part. The parenthesis were just to make sure that `a` and `b` were de-referenced before the `+` operation. I tend to overuse parenthesis to ensure order of operations instead of just looking up precedence. – AndyG Mar 19 '14 at 05:36
I removed the parenthesis. Operator precedence declares dereference before addition. – AndyG Mar 19 '14 at 05:37

score 2 · Answer 2 · edited May 23 '17 at 10:26

2

I'm surprised this hasn't been said, but why are you using pointers at all?

Vector3f a;
Vector3f b;
Vector3f c = a + b;

No more trying to add pointers. No more awkward syntax. No more memory leaks.

Apart from this, you have some other things you should change:

__VECTOR3F_H__ is a reserved identifier.
You should get used to using constructor initializer lists (: x(0), y(0), z(0) and : x(x), y(y), z(z)) instead of assigning to data members after they've already been initialized.
You don't need a destructor here, as one will be provided for you.
operator+ should be implemented using operator+=, which you should also provide.

edited May 23 '17 at 10:26

Community

1
1

answered Mar 19 '14 at 05:37

chris

60,560
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Pointers are awesome, dude. – Joshua Hyatt Mar 19 '14 at 05:40
@Josh, In what way? They add extra typing in order to do anything, have unclear ownership semantics, and can easily lead to memory leaks (or double frees, or deleting a stack-allocated object, or trying to dereference an invalid pointer). – chris Mar 19 '14 at 05:42
I actually don't know why I use pointers. Like I said in a previous comment, I don't know as much about C++ as I do about Java, where everything is gloriously pointer-free. – Joshua Hyatt Mar 19 '14 at 05:43
Also, thanks for the additional tips, I was hoping I would get those. :) – Joshua Hyatt Mar 19 '14 at 05:44
@Josh, Java still has "pointers". They're just called references and are garbage collected. You'd be wise to pick up some "C++ for Java Programmers" book. – chris Mar 19 '14 at 05:44
Java doesn't have so much explicit pointers like C++ does. That's what I meant. – Joshua Hyatt Mar 19 '14 at 05:45

score 1 · Answer 3 · answered Mar 19 '14 at 05:28

1

Try this ,

 Vector3f c = *a + *b;

Now this will overload your operator else it was an pointer addition

answered Mar 19 '14 at 05:28

balaji

81
6

Now I get a different error, `cannot convert from Vector3f to Vector3f* in initialization` – Joshua Hyatt Mar 19 '14 at 05:30

score 1 · Answer 4 · answered Mar 19 '14 at 05:32

1

You have overloaded objects not object pointers. Use this

Vector3f c = (*a) + (*b);

answered Mar 19 '14 at 05:32

Dipika

584
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This will not work. You cannot assign a `Vector3f*` to a `Vector3f`. Lose the `*` on `c` – AndyG Mar 19 '14 at 05:33

C++ Simple Overloading of operator+ Not Compiling

4 Answers4