NAME

std::seed_seq::seed_seq - std::seed_seq::seed_seq

Synopsis

seed_seq() noexcept; (1) (since C++11)
seed_seq( const seed_seq& ) = delete; (2) (since C++11)
template< class InputIt > (3) (since C++11)
seed_seq( InputIt begin, InputIt end );
template< class T > (4) (since C++11)
seed_seq( std::initializer_list<T> il );

1) The default constructor creates a std::seed_seq object with an initial seed
sequence of length zero.
2) The copy constructor is deleted: std::seed_seq is not copyable.
3) Constructs a std::seed_seq with the initial seed sequence obtained by iterating
over the range [begin, end) and copying the values obtained by dereferencing the
iterator, modulo 232
(that is, the lower 32 bits are copied)
4) Equivalent to seed_seq(il.begin(), il.end()). This constructor enables
list-initialization from the list of seed values. This overload participates in
overload resolution only if T is an integer type.

Parameters

begin, end - the initial seed sequence represented as a pair of input iterators
whose std::iterator_traits<>::value_type is an integer type
il - std::initializer_list of objects of integer type, providing the initial
seed sequence

Type requirements

-
InputIt must meet the requirements of LegacyInputIterator.

Exceptions

3-4) Throws std::bad_alloc on allocation failure.

Example

// Run this code

#include <random>
#include <sstream>
#include <iterator>
int main()
{
std::seed_seq s1; // default-constructible
std::seed_seq s2{1, 2, 3}; // can use list-initialization
std::seed_seq s3 = {-1, 0, 1}; // another form of list-initialization
int a[10] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
std::seed_seq s4(a, a + 10); // can use iterators
std::istringstream buf("1 2 3 4 5");
std::istream_iterator<int> beg(buf), end;
std::seed_seq s5(beg, end); // even stream input iterators
}

Defect reports

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

DR Applied to Behavior as published Correct behavior
the default constructor never fails but might
LWG 3422 C++11 be not noexcept; made noexcept;
the initializer list constructor disabled constrained
list-initialization from iterator pairs