std::initializer_list::initializer_list - cppreference.com

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# std::initializer_list::initializer_list

From cppreference.com
< cpp‎ | utility‎ | initializer list

initializer_list(); |  | (since C++11) (until C++14)
constexpr initializer_list(); |  | (since C++14)

Constructs an empty initializer list.

### [edit] Parameters

(none)

### [edit] Exceptions

`noexcept` specification:
noexcept

### [edit] Complexity

Constant

### [edit] 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';
    }

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:

- a braced-init-list is used in list-initialization, including function-call list initialization and assignment expressions (not to be confused with constructor initializer lists)
- a braced-init-list is bound to auto, including in a ranged for loop

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Category:

- unconditionally noexcept