c++ - Overloading an operator as a member function -

i'm working on vector class , trying overload operators. i've looked @ countless examples, tried every alteration can think of, , still g++ complaining

include/vector.cpp:9:38: error: no ‘vec vec::operator+(const vec&)’ member function declared in class ‘vec’ 

obviously g++ telling me i'm defining member function haven't declared operator member function.

here code (i've omitted of working fine , not relevant): vec.h

#ifndef _ben_vector #define _ben_vector  #include <math.h> #include <string> #include <sstream> class vec{ public:     /* constructor */     vec(double x, double y);     /* operators */     vec operator+( const vec& other);  private:     int dims;     double x;     double y; }; #endif /* _ben_vector */ 

vec.cpp:

#include "vector.h"  /* constructors */ vec::vec(double x, double y){     x = x; y = y; dims = 2; }  /* operators */ vec vec::operator+( const vec& other ){     vec v(this->gety() + other->getx(), this->gety() + other->gety());     return v; } 

sorry if duplicate -- i've been scouring interwebz hours , haven't found anything. i'm sure i'll embarrassed when see how obvious mistake :) thanks

here part of vector2 class maybe you.

class vector2 { public:     union {         float m_f2[2];         struct {             float m_fx;             float m_fy;         };     };      inline vector2();     inline vector2( float x, float y );     inline vector2( float* pfv );      // ~vector2(); // default okay      // operators     inline vector2 operator+() const;     inline vector2 operator+( const vector2 &v2 ) const;     inline vector2& operator+=( const vector2 &v2 );  };  inline vector2::vector2() :  m_fx( 0.0f ), m_fy( 0.0f ) { }  inline vector2::vector2( float x, float y ) : m_fx( x ), m_fy( y ) { }  inline vector2::vector2( float* pfv ) : m_fx( pfv[0] ), m_fy( pfv[1] ) { }  // operator+() - unary inline vector2 vector2::operator+() const {     return *this;  }  // operator+() - binary inline vector2 vector2::operator+( const vector2 &v2 ) {     return vector2( m_fx + v2.m_fx, m_fy + v2.m_fy ); }  // operator+=() inline vector2& vector2::operator+=( const vector2 &v2 ) {     m_fx += v2.m_fx;     m_fy += v2.m_fy;     return *this; }