MSN: When are year 6 SATs 2025? Key dates for parents and pupils
Year 6 students in England are gearing up for the key stage 2 (KS2) national curriculum tests, commonly known as SATs. These assessments serve to gauge school performance and ensure each student is ...
When are year 6 SATs 2025? Key dates for parents and pupils
The class template std::optional manages an optional contained value, i.e. a value that may or may not be present. A common use case for optional is the return value of a function that may fail. As opposed to other approaches, such as std::pair
, optional handles expensive-to-construct objects well and is more readable, as the intent is expressed explicitly. Any instance of optional at ...
6) Constructs an optional object that contains a value, initialized as if direct-initializing (but not direct-list-initializing) an object of type T from the arguments std::forward(args).... If the selected constructor of T is a constexpr constructor, this constructor is a constexpr constructor. The function does not participate in the overload resolution unless std::is_constructible_v
If *this contains a value, returns a reference to the contained value. Otherwise, throws a std::bad_optional_access exception.
1-7) Compares two optional objects, lhs and rhs. The contained values are compared (using the corresponding operator of T) only if both lhs and rhs contain values.
If *this contains a value, invokes f with the contained value as an argument, and returns the result of that invocation; otherwise, returns an empty std::optional.
An optional object op may be turned into an empty optional with both op = {}; and op = nullopt;. The first expression constructs an empty optional object with {} and assigns it to op.