deductionguidesforstd::vector(3) | C++ Standard Libary | deductionguidesforstd::vector(3) |
NAME¶
deductionguidesforstd::vector - deductionguidesforstd::vector
Synopsis¶
Defined in header <vector>
template< class InputIt,
class Alloc = std::allocator<typename
std::iterator_traits<InputIt>::value_type>> (since C++17)
vector(InputIt, InputIt, Alloc = Alloc())
-> vector<typename std::iterator_traits<InputIt>::value_type,
Alloc>;
This deduction guide is provided for vector to allow deduction from an
iterator
range. This overload participates in overload resolution only if InputIt
satisfies
LegacyInputIterator and Alloc satisfies Allocator.
Note: the extent to which the library determines that a type does not satisfy
LegacyInputIterator is unspecified, except that as a minimum integral types
do not
qualify as input iterators. Likewise, the extent to which it determines that
a type
does not satisfy Allocator is unspecified, except that as a minimum the
member type
Alloc::value_type must exist and the expression
std::declval<Alloc&>().allocate(std::size_t{}) must be well-formed
when treated as
an unevaluated operand.
Example¶
// Run this code
#include <vector>
int main() {
std::vector<int> v = {1, 2, 3, 4};
// uses explicit deduction guide to deduce std::vector<int>
std::vector x(v.begin(), v.end());
// deduces std::vector<std::vector<int>::iterator>
// first phase of overload resolution for list-initialization selects the
candidate
// synthesized from the initializer-list constructor; second phase is not
performed and
// deduction guide has no effect
std::vector y{v.begin(), v.end()};
}
2022.07.31 | http://cppreference.com |