std::seed_seq::seed_seq(3)

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 <iterator>
 #include <random>
 #include <sstream>
 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