std::seed_seq::seed_seq

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

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.

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 iniial seed sequence
Type requirements
- `InputIt` must meet the requirements of `InputIterator`.

Exceptions

1) Does not throw

Example

#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
}

Links:

http://en.cppreference.com/w/cpp/numeric/random/seed_seq/seed_seq

doc_CPP

2016-10-11 10:06:23

Comments