Why it fails to take address of bool from vector

Question

Hi

Please refer code below:

It works fine with existing code. If I uncomment the code from main function, it fails to compile for bool.

How to solve this?
https://sololearn.com/compiler-playground/c5P3n3O7R6dk/?ref=app

Answer 1

vector<bool> is implented differently for optimization reasons

https://en.cppreference.com/w/cpp/container/vector_bool

you can't access the items by reference.

vector<bool> v = {false,false,true,false};

// you can't do this
for(auto& b: v)
cout << b << endl;

// but you can do this
for(auto b: v)
cout << b << endl;

Answer 2

😁 maybe. but the committee decided otherwise. perhaps to avoid breaking things.

it is what it is.

interesting discussion about vector<bool> and various pros and cons, use cases, alternatives, etc

https://www.reddit.com/r/cpp/s/eP6LzMF8Rz

Answer 3

you said it. optimization.

Answer 4

Yeah now i recall that vector<bool> is space optimized

Just curious why such exception was approved by committee for vector of bool

Answer 5

But it is an exception and One has to keep this exception in mind always