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std::linear_congruential_engine(3) C++ Standard Libary std::linear_congruential_engine(3)


std::linear_congruential_engine - std::linear_congruential_engine


Defined in header <random>

class UIntType,
UIntType a, (since C++11)
UIntType c,
UIntType m

> class linear_congruential_engine;

linear_congruential_engine is a random number engine based on Linear congruential
generator (LCG). A LCG has a state that consists of a single integer.

The transition algorithm of the LCG function is \(\small{x_{i+1}\leftarrow(a x_i +
c)\mod m}\)x
i+1 ← (ax
i+c) mod m.

The following typedefs define the random number engine with two commonly used
parameter sets:

Defined in header <random>
Type Definition
std::linear_congruential_engine<std::uint_fast32_t, 16807, 0,
Discovered in 1969 by Lewis, Goodman and Miller, adopted as
"Minimal standard" in 1988 by Park and Miller
std::linear_congruential_engine<std::uint_fast32_t, 48271, 0,
Newer "Minimum standard", recommended by Park, Miller, and
Stockmeyer in 1993

Template parameters

The result type generated by the generator. The effect is undefined if
UIntType - this is not one of unsigned short, unsigned int, unsigned long, or
unsigned long long.
a - the multiplier term
c - the increment term
m - the modulus term

Member types

Member type Definition
result_type(C++11) The integral type generated by the engine. Results are undefined
if this is not an unsigned integral type.

Member functions

Construction and Seeding

constructor constructs the engine
(C++11) (public member function)
seed sets the current state of the engine
(C++11) (public member function)


operator() advances the engine's state and returns the generated value
(C++11) (public member function)
discard advances the engine's state by a specified amount
(C++11) (public member function)


min gets the smallest possible value in the output range
[static] (C++11) (public static member function)
max gets the largest possible value in the output range
[static] (C++11) (public static member function)

Non-member functions

operator== compares the internal states of two pseudo-random number
operator!= engines
(C++11) (function)
(C++11)(removed in C++20)
operator<< performs stream input and output on pseudo-random number
operator>> engine
(C++11) (function template)

Member constants

constexpr UIntType multiplier the multiplier term (a).
[static] (C++11) (public static member constant)
constexpr UIntType increment the increment term (c).
[static] (C++11) (public static member constant)
constexpr UIntType modulus the modulus term (m).
[static] (C++11) (public static member constant)
constexpr UIntType default_seed the default seed (1).
[static] (C++11) (public static member constant)