Question

I’m getting errors for my class called Point3D and I really don’t understand why.

Here is my header:

#ifndef POINT3D_H
#define POINT3D_H

using namespace std;
class Point3D {

public:
    Point3D(float x, float y, float z);
    float operator[] (const int i);
private:
    float xyz[3];

};

#endif

And here is the cpp file:

#include "point3d.h"

Point3D::Point3D(float x, float y, float z){
    xyz[0] = x;
    xyz[1] = y;
    xyz[2] = z;
}

float Point3D::operator[](int i )
{

    if(i == 0){
        return xyz[0];
    }
    else if(i == 1){
        return xyz[1];
    }
    else if(i == 2){
        return xyz[2];
    }

    return -1;

}

There are the complier errors:

/tmp/ccyDEfcW.o: In function `Point3D::Point3D(float, float, float)':
vector3d.cc:(.text+0x0): multiple definition of `Point3D::Point3D(float, float, float)'
/tmp/ccqDasr3.o:point3d.cc:(.text+0x0): first defined here
/tmp/ccyDEfcW.o: In function `Point3D::Point3D(float, float, float)':
vector3d.cc:(.text+0x10): multiple definition of `Point3D::Point3D(float, float, float)'
/tmp/ccqDasr3.o:point3d.cc:(.text+0x10): first defined here
/tmp/ccyDEfcW.o: In function `Point3D::operator[](int)':
vector3d.cc:(.text+0x20): multiple definition of `Point3D::operator[](int)'
/tmp/ccqDasr3.o:point3d.cc:(.text+0x20): first defined here
collect2: ld returned 1 exit status

Answer 1

1) You have different declaration in the header:

float operator[] (const int i);

and definition in .cpp:

float Point3D::operator[](int i )

Make both of them with the same parameter

const int i

2) Look at vector3d.cc (and please share it here),
You probably have defined Point3D code twice.