C++ named requirements: UniformRandomBitGenerator (od C++11)
A uniform random bit generator is a function object returning unsigned integer values such that each value in the range of possible results has (ideally) equal probability.
Uniform random bit generators are not intended to be used as random number generators: they are used as the source of random bits (generated in bulk, for efficiency). Any uniform random bit generator may be plugged into any random number distribution in order to obtain a random number (formally, a random variate).
Requirements
The type G
satisfies UniformRandomBitGenerator if given
T
, the type named byG::result_type
g
, a value of type G The following expressions must be valid and have their specified effects:
Expression | Return type | Requirements |
---|---|---|
G::result_type | T | T is an unsigned integer type |
G::min() | T | Returns the smallest value that G's operator() may return. The value is strictly less than G::max() . The function must be constexpr . |
G::max() | T | Returns the largest value that G's operator() may return. The value is strictly greater than G::min() . The function must be constexpr . |
g() | T | Returns a value in the closed interval [G::min(), G::max()] . Has amortized constant complexity. |
Notes
All RandomNumberEngines satisfy this requirement.
Standard library
The following standard library facilities expect a UniformRandomBitGenerator type.
pub | random_shuffle (do C++17) shuffle(C++11) | randomly re-orders elements in a range |
pub | generate_canonical(C++11) | evenly distributes real values of given precision across [0, 1) |
pub | uniform_int_distribution(C++11) | produces integer values evenly distributed across a range |
pub | uniform_real_distribution(C++11) | produces real values evenly distributed across a range |
pub | all other random number distributions |
The following standard library facilities satisfy UniformRandomBitGenerator without additionally satisfying RandomNumberEngine:
pub | random_device(C++11) | non-deterministic random number generator using hardware entropy source |