std::initializer_list

 

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initializer_list (C++11)

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std::initializer_list

Member functions

initializer_list::initializer_list

Capacity

initializer_list::size

Iterators

initializer_list::begin

initializer_list::end

Non-member functions

std::begin

std::end

 

Defined in header <initializer_list>
template< class T > class initializer_list;		(since C++11)

An object of type std::initializer_list<T> is a thin wrapper around an array of objects of type T.

A std::initializer_list is passed by value to the constructor of an object when it is initialized using the initializer list syntax.

Initializer lists are typically implemented as a pair of pointers or pointer and length. Copying a std::initializer_list does not copy the underlying objects.

Member types

Member type	Definition
value_type	T
reference	const T&
const_reference	const T&
size_type	size_t
iterator	const T*
const_iterator	const T*

Member functions

(constructor)	creates an empty initializer list (public member function)
Capacity
size	returns the number of elements in the initializer list (public member function)
Iterators
begin	returns a pointer the first element (public member function)
end	returns a pointer to one past the last element (public member function)

Non-member functions

std::begin(std::initializer_list) (C++11)	specializes std::begin (function template)
std::end(std::initializer_list) (C++11)	specializes std::end (function template)

Example

#include <iostream>
#include <vector>
#include <initializer_list>
 
template<class T>
struct S {
    std::vector<T> v;
    S(std::initializer_list<T> l) : v(l) {
         std::cout << "constructed with a " << l.size() << "-element list\n";
    }
};
 
int main()
{
    S<int> s = {1,2,3,4,5};
    std::cout << "The vector now holds";
    for(auto n : s.v) std::cout << ' ' << n;
    std::cout << '\n';
}

Output:

constructed with a 5-element list
The vector now holds 1 2 3 4 5