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std::linear_congruential_engine

Defined in header <random>
template<
    class UIntType, 
    UIntType a, 
    UIntType c, 
    UIntType m
> class linear_congruential_engine;
(since C++11)

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
minstd_rand0(C++11) std::linear_congruential_engine<std::uint_fast32_t, 16807, 0, 2147483647>

Discovered in 1969 by Lewis, Goodman and Miller, adopted as "Minimal standard" in 1988 by Park and Miller.

minstd_rand(C++11) std::linear_congruential_engine<std::uint_fast32_t, 48271, 0, 2147483647>

Newer "Minimum standard", recommended by Park, Miller, and Stockmeyer in 1993.

Template parameters

UIntType - The result type generated by the generator. The effect is undefined if 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
(C++11)
constructs the engine
(public member function)
(C++11)
sets the current state of the engine
(public member function)
Generation
(C++11)
advances the engine's state and returns the generated value
(public member function)
(C++11)
advances the engine's state by a specified amount
(public member function)
Characteristics
[static] (C++11)
gets the smallest possible value in the output range
(public static member function)
[static] (C++11)
gets the largest possible value in the output range
(public static member function)

Non-member functions

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

Member constants

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

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