How Does Default Initialization Work with `std::array` in C 11?

Default Initialization in std::array

Default initialization is the initialization that occurs when no explicit initializer is provided. With C 11 std::array, the syntax std::array x; guarantees that all elements of the array will be default-initialized.

According to the C 11 standard (§8.5/11), any object without an explicit initializer is default initialized. This includes std::array objects and traditional C-style arrays. Notably, default initialization has no effect on non-class, non-array types, leaving their value indeterminate.

Value Initialization on All Arrays

While default initialization leaves non-class, non-array types indeterminate, value initialization sets elements to their default values. In C 11, value initialization is achieved by providing an empty initializer for each array element:

int plain_int{};
int c_style_array[13]{};
std::array<int, 13> cxx_style_array{};

This will value-initialize all elements of the arrays, resulting in plain_int and all array elements being initialized to zero.

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