Sorta, yes. It can evaluate one of the operator<<'s before doing the timer. The following: cout << "smarter sum " << N/(1000.0*time.split()) << endl; Is sem

Sorta, yes. It can evaluate one of the operator<<'s before doing the timer. The following: cout << "smarter sum " << N/(1000.0*time.split()) << endl; Is semantically equivalent to: operator<<(endl, operator<<(N/1000.0*time.split(), operator<<(cout, "smarter sum ") ) ); The code with the timer in it can be called after the first call to operator<<; all parameters to functions have to be evaluated before the function is called, but there's no order the parameters themselves have to be evaluated in.