std::seed_seq

 

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std::seed_seq

Member functions

seed_seq::seed_seq

seed_seq::generate

seed_seq::size

seed_seq::param

 

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 32-bit unsigned integer values, 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.

Nested types

Type	Definition
result_type	std::uint_least32_t

Data members

Member	Description
std::vector<result_type> v	the underlying seed sequence (exposition-only member object*)

Member functions

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

Example

Run this code

#include <cstdint>
#include <iostream>
#include <random>
 
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';
}

Possible output:

4204997637
4246533866
1856049002
1129615051
690460811
1075771511
46783058
3904109078
1534123438
1495905678