C++ Operator Overloading

http://stackoverflow.com/questions/4421706/operator-overloading/4421791#4421791

Assignment Operator

X& X::operator=(X rhs)

{

  swap(rhs);

  return *this;

}

Input and Output Operators

std::ostream& operator<<(std::ostream& os, const T& obj)

{

  // write obj to stream

  return os;

}

std::istream& operator>>(std::istream& is, T& obj)

{

  // read obj from stream

  if( /* no valid object of T found in stream */ )

    is.setstate(std::ios::failbit);

  return is;

}

Comparison operators

inline bool operator==(const X& lhs, const X& rhs){ /* do actual comparison */ }

inline bool operator!=(const X& lhs, const X& rhs){return !operator==(lhs,rhs);}

inline bool operator< (const X& lhs, const X& rhs){ /* do actual comparison */ }

inline bool operator> (const X& lhs, const X& rhs){return  operator< (rhs,lhs);}

inline bool operator<=(const X& lhs, const X& rhs){return !operator> (lhs,rhs);}

inline bool operator>=(const X& lhs, const X& rhs){return !operator< (lhs,rhs);}

Arithmetic Operatorsclass X {

  X& operator++()

  {

    // do actual increment

    return *this;

  }

  X operator++(int)

  {

    X tmp(*this);

    operator++();

    return tmp;

  }

};

Binary arithmetic operators

class X {

  X& operator+=(const X& rhs)

  {

    // actual addition of rhs to *this

    return *this;

  }

};

inline X operator+(X lhs, const X& rhs)

{

  lhs += rhs;

  return lhs;

}

Array Subscription

class X {

        value_type& operator[](index_type idx);

  const value_type& operator[](index_type idx) const;

  // ...

};

Operators for Pointer-like Types

class my_ptr {

        value_type& operator*();

  const value_type& operator*() const;

        value_type* operator->();

  const value_type* operator->() const;

};