Defined in header <random>
template <class G>
concept uniform_random_bit_generator =
  std::invocable<G&> && std::unsigned_integral<std::invoke_result_t<G&>> &&
  requires {
    { G::min() } -> std::same_as<std::invoke_result_t<G&>>;
    { G::max() } -> std::same_as<std::invoke_result_t<G&>>;
    requires std::bool_constant<(G::min() < G::max())>::value;
(since C++20)

The concept uniform_random_bit_generator<G> specifies that G is the type of a uniform random bit generator, that is, objects of type G is a function object returning unsigned integer values such that each value in the range of possible results has (ideally) equal probability of being returned.

Semantic requirements

uniform_random_bit_generator<G> is modeled only if, given any object g of type G:

  • g() is in the range [G::min(), G::max()]
  • g() has amortized constant complexity.


In order to satisfy the requirement std::bool_constant<(G::min() < G::max())>::value, both G::min() and G::max() must be constant expressions, and the result of the comparison must be true.

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