deduction guides for std::

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

Execution support library (C++26)

Technical specifications

Symbols index

External libraries

 

Containers library

Sequence

array (C++11)

vector

vector<bool>

inplace_vector (C++26)

deque

forward_list (C++11)

list

Associative

set

multiset

map

multimap

Unordered associative

unordered_set (C++11)

unordered_multiset (C++11)

unordered_map (C++11)

unordered_multimap (C++11)

Adaptors

stack

queue

priority_queue

flat_set (C++23)

flat_multiset (C++23)

flat_map (C++23)

flat_multimap (C++23)

Views

span (C++20)

mdspan (C++23)

Tables

Iterator invalidation

Member function table

Non-member function table

 

template< class InputIt,           class Alloc = std::allocator<typename std::iterator_traits<InputIt>::value_type>> (InputIt, InputIt, Alloc = Alloc())   -> <typename std::iterator_traits<InputIt>::value_type, Alloc>;		(since C++17)

This deduction guide is provided for to allow deduction from an iterator range. This overload participates in overload resolution only if InputIt satisfies Template:concept and Alloc satisfies Template:concept.

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