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deduction guides for std::vector

From cppreference.com
< cpp‎ | container‎ | vector
Defined in header <vector>
template< class InputIt,

          class Alloc = std::allocator<typename std::iterator_traits<InputIt>::value_type>>
vector(InputIt, InputIt, Alloc = Alloc())

  -> vector<typename std::iterator_traits<InputIt>::value_type, Alloc>;
(since C++17)

This deduction guide is provided for vector to allow deduction from an iterator range. This overload only participates in overload resolution if InputIt satisfies InputIterator and Alloc satisfies Allocator

Note: the extent to which the library determines that a type does not satisfy InputIterator 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.

[edit] Example

#include <vector>
 
int main() {
   std::vector<int> v = {1, 2, 3, 4};
   std::vector x{v.begin(), v.end()}; // uses explicit deduction guide
}