std::independent_bits_engine<Engine,W,UIntType>::independent_bits_engine

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Pseudo-random number generation
 
std::independent_bits_engine
Member functions
independent_bits_engine::independent_bits_engine
Generation
Characteristics
Non-member functions
(C++11)(C++11)(until C++20)
(C++11)(C++11)
 
independent_bits_engine();
 (1) (since C++11)
explicit independent_bits_engine( result_type s );
 (2) (since C++11)
template< class SeedSeq >
explicit independent_bits_engine( SeedSeq& seq );
 (3) (since C++11)
explicit independent_bits_engine( const Engine& e );
 (4) (since C++11)
explicit independent_bits_engine( Engine&& e );
 (5) (since C++11)

Constructs new pseudo-random engine adaptor.

1) Default constructor. The underlying engine is also default-constructed.
2) Constructs the underlying engine with s.
3) Constructs the underlying engine with seed sequence seq.
This overload participates in overload resolution only if Sseq satisfies the requirements of SeedSequence.
4) Constructs the underlying engine with a copy of e.
5) Move-constructs the underlying engine with e. e holds unspecified, but valid state afterwards.

Parameters

s - integer value to construct the underlying engine with
seq - seed sequence to construct the underlying engine with
e - pseudo-random number engine to initialize with

Exceptions

3) If SeedSeq is not std::seed_seq, throws the exceptions thrown by the seq.generate call.

Example

Run this code
#include <iostream>
#include <random>
 
int main()
{
    auto print = [](auto rem, auto engine, int count)
    {
        std::cout << rem << ": ";
        for (int i {}; i != count; ++i)
            std::cout << static_cast<unsigned>(engine()) << ' ';
        std::cout << '\n';
    };
 
    std::independent_bits_engine<std::mt19937, /*bits*/ 1, unsigned short>
        e1; // default-constructed
    print("e1", e1, 8);
 
    std::independent_bits_engine<std::mt19937, /*bits*/ 1, unsigned int>
        e2(1); // constructed with 1
    print("e2", e2, 8);
 
    std::random_device rd;
    std::independent_bits_engine<std::mt19937, /*bits*/ 3, unsigned long>
        e3(rd()); // seeded with rd()
    print("e3", e3, 8);
 
    std::seed_seq s {3, 1, 4, 1, 5};
    std::independent_bits_engine<std::mt19937, /*bits*/ 3, unsigned long long>
        e4(s); // seeded with seed-sequence s
    print("e4", e4, 8);
}

Possible output: 

e1: 0 0 0 1 0 1 1 1
e2: 1 1 0 0 1 1 1 1
e3: 3 1 5 4 3 2 3 4
e4: 0 2 4 4 4 3 3 6

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR Applied to Behavior as published Correct behavior
LWG 2181 C++11 overload (3) would not throw even if the seq.generate call throws propagates the exception
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