CODEWITHSUNDEEP
c++cc++11operator-precedence
uchar
uchar

Reputation: 2590

Operator precedence doesn't behave as expected in c++

Consider this code :

int func1()
{
    cout<<"Plus"<<endl;
    return 1;
}
int func2()
{
   cout<<"Multiplication"<<endl;
   return 2;
}
int main()
{
  cout<<func1()+4*func2();
}

According to this page * operator has higher precedence than + operator So I expect the result to be :

Multiplication 
Plus
9

But the result is

Plus 
Multipication
9

!! What is going on in compiler parser ?! Does compiler prefer Operator associaty ? Is the output same in all c/c++ compilers?

Upvotes: 1

Views: 419

Answers (2)

Antti Haapala -- Слава Україні
Antti Haapala -- Слава Україні

Reputation: 133879

The compiler is free to evaluate functions in any order it pleases - the only cases within expressions where the order of evaluation is guaranteed are the sequence points; operators ||, &&, ,, and ? of the ternary conditional operator ? : are sequence points. In each case the left side has all its values and side effects evaluated before the right side is touched.

Upvotes: 8

Paul R
Paul R

Reputation: 212949

Operator precedence is not the same thing as order of evaluation.

You have no guarantee about the order of evaluation - the compiler is free to call functions in whatever order it likes within an expression so long as you get the correct result.

(A minor qualification: anything which introduces a sequence point (which includes short circuit operators), will have an effect on order of evaluation, but there are no sequence points within the expression in this particular case.)

Upvotes: 27

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