Please, tell me why it doesn't want to work

Question

How can I fix this?
https://code.sololearn.com/cG5p18pqTX95/?ref=app

Answer 1

Hello Rainbow Pie ,
I'm not good with maths, and have no idea what that formula about. But I.managed to get the code to run by wrapping the expressions for these lines:

cout << "f = "<< (f+=f) << endl;
cout << "f = "<< (f*=f) << endl;
cout << "f = "<< (f%=f) << endl;
cout << "f = "<< (f/=f) << endl;

The +=, *=, %= and /= operation apparently need to be wrapped in parentheses. I think it's about statement vs expression or something. But I can't explain, don't know enough about it : )

Answer 2

Ipang Hi, assignments in C++ are expressions instead of statements, they all return a reference of their left hand operand. Operator precedence defines the order of which operations are grouped, much like PEMDAS/BODMAS in math. That means something like a=b+=c and if ((buf = f()) != nullptr) is valid. Here is a list of operators and their precedence https://en.cppreference.com/w/cpp/language/operator_precedence

Answer 3

The bitwise left shift operator has higher precedence than all the compound assignment operators, adding parentheses around the compound assignment may be what you want.
https://en.cppreference.com/w/cpp/language/operator_precedence

Answer 4

jtrh
Thanks, I saw that link on your initial response too : )