Defined in header <random>  

template< class UIntType, std::size_t w, std::size_t s, std::size_t r > class subtract_with_carry_engine;  (since C++11) 
Is a random number engine that uses subtract with carry algorithm.
The state of a subtract_with_carry_engine
consists of a sequence \(\small{\{ X_i\}(0 \le i <r)}\){X
i} (0 ≤ i <r), every \(\small{X_i}\)X
i is in interval \(\small{[0, 2^w)}\)[0, 2w
).
Let all subscripts applied to sequence be taken modulo r
, c
be the carry value which is either 0
or 1
. The state transition is performed as follows:
c
to 1
, if \(\small{Y<0}\)Y<0, to 0
otherwise. The following typedefs define the random number engine with two commonly used parameter sets:
Defined in header <random> 


Type  Definition 
ranlux24_base (C++11)  std::subtract_with_carry_engine<std::uint_fast32_t, 24, 10, 24> 
ranlux48_base (C++11)  std::subtract_with_carry_engine<std::uint_fast64_t, 48, 5, 12> 
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 . 
w    The word size, in bits, of the state sequence, 10 < w <= std::numeric_limits<UIntType>::digits . 
s    The short lag. 
r    The long lag, where 0 < s < r . 
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. 
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) 
(C++11)(C++11)(removed in C++20)  compares the internal states of two pseudorandom number engines (function) 
(C++11)  performs stream input and output on pseudorandom number engine (function template) 
constexpr size_t word_size
[static] (C++11)  template parameter w , the word size (public static member constant) 
constexpr size_t short_lag
[static] (C++11)  template parameter s , the short lag (public static member constant) 
constexpr size_t long_lag
[static] (C++11)  template parameter r , the long lag (public static member constant) 
constexpr UIntType default_seed
[static] (C++11)  constant value 19780503u (public static member constant) 
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