Overload operator << print backwards

Question

I was overloaded the two operators: operator<< and operator++

operator<<

ArithmeticSequence & ArithmeticSequence::operator++()
{
    this->lastElement += goToNext;
    this->sum += lastElement;

    return *this;
}

operator++

ostream & operator<<(ostream & out, const ArithmeticSequence as)
{
    out << as.sum;
    return out;
}

now the main is:

ArithmeticSequence AS(1.3, 2.5);
cout << "++AS sum: " << ++AS << " ++AS sum: " << ++AS << endl;

output:

++AS sum: 20.2 ++AS sum: 11.4

the correct output need to be:

++AS sum: 11.4 ++AS sum: 20.2

why the output is revers?

Also see: http://stackoverflow.com/questions/4176328/undefined-behavior-and-sequence-points — NathanOliver, Jan 12 '16 at 19:08
Note: Not the order of << is unspecified, but the order of the two `++AS` calls — , Jan 12 '16 at 19:10

score 0 · Answer 1 · answered Jan 12 '16 at 19:03

0

There's no sequence point in between your two ++A5 so they can be evaluated in any order.

This will work as expected:

 cout << "++AS sum: " << ++AS;
 cout << " ++AS sum: " << ++AS << endl;

answered Jan 12 '16 at 19:03

Paul Evans

1 Answers1