Question

I have a use case
If I have 5 classes A,B,C,D,E and their instances as a,b,c,d,e

If there is an expression
a = b + c + d + e;

What is the order of invocation of operator+ and operator=.
Also what would be the temporary object created.

Can you please help me

Answer 1

+ is left associative. = is right associative. The order would be

• d + e makes a temporary de
• de + c makes temporary cde. This is done by a call to class C‘s operator + taking an argument of whatever class the temporary de is an instance of.
• cde + b makes temporary bcde. This is done by a call to class B‘s operator + taking an argument of the class of cde.
• The value of bcde is assigned to variable a.

Temporaries here are a general case, it depends on what you actually do with your overload what will happen. The class to the left of the temporary will be called using that temporary as an argument, not the other way around.

While the evaluation goes from left to right when using +, the actual computation goes the other way.