运算符的两个不同结果 - 在 c++11 中

我对结果有问题。事实上，我创建了一个类 Vector，然后重新定义了运算符。但是，对于同一操作，运算符"-"给了我两个不同的结果。当我打印操作时，它给了我很好的答案，但是当我想将结果存储在变量中时，结果是不同的。

我错过了班上的操作员吗？

有我的主要：

#include "../include/Vecteur.hpp"

int main(){
  vec3f v0(1.0f, 1.0f, 1.0f);
  vec3f v1(1.0f, 0.0f, 0.0f);
  v1.x() += 3.0f;
  v0[1] -= 1.0f;
  cout << "v0 = " << v0 << endl;
  cout << "v1 = " << v1 << endl;
  float l = v0.length();
  v1 *= l;
  cout << "l = " << l << endl;
  cout << "v0 = " << v0 << endl;
  cout << "v1 = " << v1 << endl;
  auto v2 = v0 + v1;
  cout << "v2 = " << v2 << endl;
  auto v3 = v0 - v1; // The problem is there.
  cout << "v0 = " << v0 << endl;
  cout << "v1 = " << v1 << endl;
  cout << "v3 = " << v3 << endl; // Prints [1,0,1] instead of [-4.65685, 0, 1]
  cout << v0-v1 << endl; // Prints [-4.65685, 0, 1]
  if (v2 < v3){
    v2 += v3;
  }
  cout << "v2 = " << v2 << endl;
  return 0;
}

有我的课：

#include <iostream>
#include <math.h>
using namespace std;
class vec3f{
private:
  float tableau[3];
public:
  vec3f(){}
  vec3f(float f1, float f2, float f3){
    this->tableau[0] = f1;
    this->tableau[1] = f2;
    this->tableau[2] = f3;
  }
  float x() const{
    return this->tableau[0];
  }
  float y() const{
    return this->tableau[1];
  }
  float z() const{
    return this->tableau[2];
  }
  float & x(){
    return this->tableau[0];
  }
  float & y(){
    return this->tableau[1];
  }
  float & z(){
    return this->tableau[2];
  }
  float length() const{
    return sqrt(( pow(this->tableau[0],2) + pow(this->tableau[1],2) + pow(this->tableau[2],2) ));
  }
  /* Redifinition of operators */
  vec3f operator+(vec3f const & v){
    this->tableau[0] += v.x();
    this->tableau[1] += v.y();
    this->tableau[2] += v.z();
    return *this;
  }
  vec3f operator-(vec3f const & v){
    this->tableau[0] -= v.x();
    this->tableau[1] -= v.y();
    this->tableau[2] -= v.z();
    return *this;
  }
  vec3f operator*=(float const & f){
    this->tableau[0] *= f;
    this->tableau[1] *= f;
    this->tableau[2] *= f;
    return *this;
  }
  bool operator<(vec3f const & v){
    return (this->tableau[0]<v.x() && this->tableau[1]<v.y() && this->tableau[2]<v.z());
  }
  vec3f & operator=(vec3f const & v){
    return *this;
  }
  vec3f operator=(vec3f const & v) const{
    return *this;
  }
  float operator[](size_t i) const{
    return tableau[i];
  }
  float & operator[](size_t i){
    return tableau[i];
  }
};
ostream & operator<<(ostream & out, vec3f const & v){
  out << "[" << v.x() << ", " << v.y() << ", " << v.z() << "]";
  return out;
}
vec3f operator+(vec3f const & va, vec3f const & vb){
  return vec3f(va.x()+vb.x(),va.y()+vb.y(),va.z()+vb.z());
}
vec3f operator-(vec3f const & va, vec3f const & vb){
  return vec3f(va.x()-vb.x(),va.y()-vb.y(),va.z()-vb.z());
}
vec3f operator+=(vec3f const & va, vec3f const & vb){
  return vec3f(va.x()+vb.x(),va.y()+vb.y(),va.z()+vb.z());
}

谢谢:)