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std::seed_seq

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Revision as of 15:30, 24 July 2013 by P12 (Talk | contribs)

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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.

[edit] Member types

Member type Definition
result_type std::uint_least32_t

[edit] Member functions

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

[edit] Example

#include <random>
#include <cstdint>
#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:

4204997637
4246533866
1856049002
1129615051
690460811
1075771511
46783058
3904109078
1534123438
1495905678