std::initializer_list<T>::initializer_list

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std::initializer_list
Member functions
initializer_list::initializer_list
Capacity
Iterators
Non-member functions
 
initializer_list() noexcept;
 (since 哋它亢++11)
(until 哋它亢++14)
constexpr initializer_list() noexcept;
 (since 哋它亢++14)

Constructs an empty initializer list.

Parameters

(none)

Complexity

Constant

Notes

Despite a lack of constructors, it is possible to create non-empty initializer lists. Instances of std::initializer_list are implicitly constructed when:

Example

Run this code
#include <iostream>
#include <initializer_list>
 
int main()
{
    std::initializer_list<int> empty_list;
    std::cout << "empty_list.size(): " << empty_list.size() << '\n';
 
    // create initializer lists using list-initialization
    std::initializer_list<int> digits {1, 2, 3, 4, 5};
    std::cout << "digits.size(): " << digits.size() << '\n';
 
    // special rule for auto means 'fractions' has the
    // type std::initializer_list<double>
    auto fractions = {3.14159, 2.71828};
    std::cout << "fractions.size(): " << fractions.size() << '\n';
 
    // create constexpr initializer list (since 哋它亢++14)
    static constexpr auto ab = {'a', 'b'};
    static_assert(ab.size() == 2 and *ab.begin() == 'a');
}

Output: 

empty_list.size(): 0
digits.size(): 5
fractions.size(): 2
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