# std::linear_congruential_engine

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< cpp‎ | numeric‎ | random

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
(constructor) (C++11) | constructs the engine (public member function)
seed (C++11) | sets the current state of the engine (public member function)
##### Generation
operator() (C++11) | advances the engine's state and returns the generated value (public member function)
discard (C++11) | advances the engine's state by a specified amount (public member function)
##### Characteristics
min [static] (C++11) | gets the smallest possible value in the output range (public static member function)
max [static] (C++11) | gets the largest possible value in the output range (public static member function)

### Non-member functions

operator==operator!= (C++11)(C++11)(removed in C++20) | compares the internal states of two pseudo-random number engines (function)
operator<<operator>> (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)

### Example

| This section is incomplete Reason: no example

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