Both are valid, and were the only ways of initializing objects before C++11, I think.

Brace initialization has an advantage in that it allows you to initialize compound values, like containers and structs, even if they're nested:

    std::map<int, std::string> m = { // nested list-initialization
           {1, "a"},
           {2, {'a', 'b', 'c'} },
           {3, s1}
    };
 

Ref: https://en.cppreference.com/w/cpp/language/list_initializati... https://en.cppreference.com/w/cpp/language/aggregate_initial...