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std::initializer_list<T>::initializer_list

From cppreference.com
 
 
Utilities library
General utilities
Date and time
Function objects
Formatting library (C++20)
(C++11)
Relational operators (deprecated in C++20)
Integer comparison functions
(C++20)
Swap and type operations
(C++14)
(C++11)
(C++11)
(C++11)
(C++17)
Common vocabulary types
(C++11)
(C++17)
(C++17)
(C++17)
(C++17)

Elementary string conversions
(C++17)
(C++17)
 
std::initializer_list
Member functions
initializer_list::initializer_list
Capacity
Iterators
Non-member functions
 
initializer_list() noexcept;
(since C++11)
(until C++14)
constexpr initializer_list() noexcept;
(since C++14)

Constructs an empty initializer list.

Contents

[edit] Parameters

(none)

[edit] Complexity

Constant

[edit] Example

#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';
}

Output:

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

[edit] Notes

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