std::seed_seq::seed_seq
|
(1) | (since C++11) |
|
(2) | (since C++11) |
|
(3) | (since C++11) |
|
(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 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
#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 |
|---|---|---|---|
| LWG 3422 | C++11 | the default constructor never fails but might be not noexcept; the initializer list constructor disabled list-initialization from iterator pairs |
made noexcept; constrained |
© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
https://en.cppreference.com/w/cpp/numeric/random/seed_seq/seed_seq