std::seed_seq::seed_seq
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seed_seq() noexcept;
(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)
seed_seq( InputIt begin, InputIt end );
template< class T >
seed_seq( std::initializer_list <T> il );
(4)
(since C++11)
seed_seq( std::initializer_list <T> il );
1) The default constructor. After construction,
v is empty.2) The copy constructor is deleted:
std::seed_seq is not copyable.3) Constructs a
.
std::seed_seq with the values in the range [begin, end). Equivalent to default-initializing v followed by for (InputIt s = begin; s != end; ++s) v .push_back(modseed(*s));, where \(\scriptsize \mathrm{modseed}(x)=x \mod 2^{32} \)mod_seed(x)=x mod 232.
If std::iterator_traits <InputIt>::value_type is not an integer type, the program is ill-formed.
If
InputIt does not satisfy the requirements of LegacyInputIterator, the behavior is undefined.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.[edit] Parameters
begin, end
-
the pair of iterators denoting the initial seed sequence
il
-
the initial seed sequence
[edit] 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 }
[edit] 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 2180 | C++11 | all constructors were non-throwing | only overload (1) is non-throwing |
| LWG 3422 | C++11 | 1. overload (1) was not noexcept 2. overload (4) was not constrainted |
1.made noexcept 2. constrained |