Thread: Operator Overloading - RHS object is modified by assignment operation

Dear cBoard,

I wrote a 3d vector class, and it works pretty well. I was hoping to overload some operators to make the class a bit easier to use.

Where * operator is over loaded to scale the vector by a scalar float.

Code:

Vec3f a, b;
//assign relevant values to a.x, a.y, and a.z
a.normalize();
b = a * CONST_FLOAT_0; //This modifies a
//b is used for something
b = a * CONST_FLOAT_1

I've never used operator overloading much. I read a couple pages about operator overloading and realized that I didn't understand references very well. I read the eternally confuzzled page about pointers and references. I won't lie it left me pretty confused, but gave me a better idea of what's going on.

The problem is very clear to me. It's doing what I expect it to, but not what I want it to.
Somehow, during an assignment operation nothing on the right side should be modified.

Here is = and *

Code:

Vec3f& Vec3f::operator=(const Vec3f& rhs)
{
    x = rhs.x;
    y = rhs.y;
    z = rhs.z;
    return *this;
}

Vec3f& Vec3f::operator*(const float& rhs)
{
    x *= rhs;
    y *= rhs;
    z *= rhs;
    return *this;
}

I think I could fix it if I understood how data is flowing in these functions.

Why would an assignment operator return a value? when operator= is called, isn't it being called by the left hand side? So what is that return value doing, seems like this function should be void to me.

I guess using references allows you to have multiple assignments on one line, I'll have to figure that one out.

When I use
b = a * float;
how can the * operator know that it shouldn't change a?
I tried creating a temporary Vec3f in operator* and then modifying it and returning it, but that didn't fix the problem.

How should these overloaded operators work?
Thank You

EDIT:
Here's the class declaration:

Code:

class Vec3f {
	public:
        	Vec3f();
        	Vec3f(float xi, float yi, float zi);
        	~Vec3f();
        	float x,y,z;

        	Vec3f operator+(Vec3f rhs);
	        Vec3f operator-(Vec3f rhs);
	        Vec3f& operator*(const float& rhs);
	        Vec3f operator/(float rhs);
	        Vec3f operator+=(Vec3f rhs);
	        Vec3f& operator=(const Vec3f& rhs);
	
	        float dot(Vec3f rhs);
	        Vec3f cross(Vec3f rhs);
	        float getMag();
	        float getXAngle();
	        float getYAngle();
	        void setAngle(float a);
	        void setAngles(float xa, float ya);
	        void normalize();
	        void print();
	protected:
	        float xAngle_;
	        float yAngle_;
};