deduction guides for std::vector

 

C++

Language

Standard Library Headers

Freestanding and hosted implementations

Named requirements

Language support library

Concepts library (C++20)

Diagnostics library

Utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

Filesystem library (C++17)

Technical Specifications

 

Containers library

array (C++11)

vector

deque

forward_list (C++11)

list

set

multiset

map

multimap

unordered_set (C++11)

unordered_multiset (C++11)

unordered_map (C++11)

unordered_multimap (C++11)

stack

queue

priority_queue

span (C++20)

 

std::vector

Member functions

vector::vector

vector::~vector

vector::operator=

vector::assign

vector::get_allocator

Element access

vector::at

vector::operator[]

vector::front

vector::back

vector::data (C++11)

Iterators

vector::beginvector::cbegin (C++11)

vector::endvector::cend (C++11)

vector::rbeginvector::crbegin (C++11)

vector::rendvector::crend (C++11)

Capacity

vector::empty

vector::size

vector::max_size

vector::reserve

vector::capacity

vector::shrink_to_fit (C++11)

Modifiers

vector::clear

vector::insert

vector::emplace (C++11)

vector::erase

vector::push_back

vector::emplace_back (C++11)

vector::pop_back

vector::resize

vector::swap

Deduction guides(C++17)

 

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 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()}; 
}