Advantage or disadvantage of using = operator or uniform initializer while using auto keyword

Question

Most examples of auto use the = operator.

#include <iostream>

int main()
{
    auto a = 1;
    std::cout << a << '\n';
}

Why don't they use the uniform initializer like this?

#include <iostream>

int main()
{
    auto a {1};
    std::cout << a << '\n';
}

Is there any advantage or disadvantage of using one syntax over another while using the auto keyword?

Answer 1

Well, there's one reason. Until C++17, auto a {1}; did the wrong thing (probably). See, the assumption was that if you were using a braced-init-list to initialize a placeholder-declared variable, then you wanted to create an initializer_list<T>. So unless you wanted a to be an initializer_list<int> containing 1 value...

So only in C++17 does auto a {1}; actually do the thing you (probably) wanted: a will be a genuine int. Of course, auto a = {1}; will still be an initializer_list<int>, because that's totally obvious, right?

So yeah, probably best to stick with auto a = 1;.