Can I avoid an ambiguity, when I declare a fixed length vector in class?

Question

I want to declare a vector of 2 elements as a class member. But next code generates an error:

class A {
private:
   std::vector v (2);
   ...
}


        

Answer 1

You can safely use this syntax:

std::vector<int> v = std::vector<int>(2);

Alternatively, use brace initialization, but you must be careful: the std::initializer_list<int> constructor will be picked, so to initialize a vector with two value- (therefore zero-) initialized ints you need

std::vector<int> v{0, 0};

Answer 2

An in-class initialiser has to use braces or the equals sign; so this could be

std::vector<int> v = std::vector<int>(2);

or

std::vector<int> v {0,0};  // Careful! not {2}

Alternatively, you could use old-school initialisation in the constructor(s):

A() : v(2) {}