std::seed_seq

 

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Defined in header <random>
class seed_seq;		(since C++11)

std::seed_seq consumes a sequence of integer-valued data and produces a requested number of unsigned integer values i, 0 ≤ i < 232
, based on the consumed data. The produced values are distributed over the entire 32-bit range even if the consumed values are close.

It provides a way to seed a large number of random number engines or to seed a generator that requires a lot of entropy, given a small seed or a poorly distributed initial seed sequence.

std::seed_seq meets the requirements of SeedSequence.

Member types

Member type	Definition
result_type	uint_least32_t

Member functions

(constructor)	constructs and seeds the std::seed_seq object (public member function)
operator= (deleted)	not copy-assignable (public member function)
generate	calculates the bias-eliminated, evenly distributed 32-bit values (public member function)
size	obtains the number of 32-bit values stored in std::seed_seq (public member function)
param	obtains the 32-bit values stored in std::seed_seq (public member function)

Example

#include <random>
#include <iostream>
int main()
{
    std::seed_seq seq({1,2,3,4,5});
    std::vector<std::uint32_t> seeds(10);
    seq.generate(seeds.begin(), seeds.end());
    for(std::uint32_t n : seeds)
        std::cout << n << '\n';
}

Output:

3890079369
567513683
1868094942
738085780
2849436979
1267185068
3817490445
2911200628
2374022914
1233116465