Overloading operator

[GoDaddy]

Is it better to return a reference or a new instance of the object?

For example :




class A
{

private :
int seed;

A(int s):seed(s){};

A& operator + (const A &a);
{
seed+=a.seed;
return *this;
}

A operator + (const A &a);
{
return A(seed+a.seed);
}



Which one is better ?

[Kheun]

You should use the second one for this case. This is because operator+ should not have any side effect on it's operands.

[laserlight]

One of my first few discussions here was about overloading arithmetic operators :)

The answer I eventually settled on was:
Declare operator+= as a member function taking an object passed by const reference, returning by reference.
Declare operator+ as a global function taking two objects passed by const reference, returning by value.
Implement operator+ in terms of operator+=

A& A::operator+=(const A& rhs) {
seed += rhs.seed;
return *this;
}

A operator+(const A& lhs, const A& rhs) {
return A(lhs) += rhs;
}

The idea is to keep to the same semantics as the native operator+ and operator+=

[exterminator]

Here is the link to it - Overloading an operator... I'm really not getting it (http://www.codeguru.com/forum/showthread.php?t=373719&page=1&pp=15&highlight=RVO). ;) Regards.

[sreehari]

Operator Overloading FAQ (http://www.parashift.com/c++-faq-lite/operator-overloading.html)