Safely initializing a std::array of bools

Question

Given this array declaration and initialization:

std::array<bool, 20> invalid_params{};

Can I assume that all the elements in the array will always be initialized to false, or is it better to do it explicitly?

Answer 1

It's guaranteed to be filled with false values.

std::array is an aggregate, hence it has no user-defined constructors, hence value-initializing it performs zero-initialization.

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But if you remove {} (turning it into default-initialization), the elements will be uninitialized.

Answer 2

Documentation says: "default initialization may result in indeterminate values for non-class T". So, it seems that you can not assume that it will be initialized.