sizeof... operator (since C++11)
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Queries the number of elements in a pack.
Contents
[edit] Syntax
sizeof...( pack )
Returns a constant of type std::size_t .
[edit] Explanation
Returns the number of elements in a pack.
[edit] Keywords
[edit] Example
Run this code
#include <array> #include <iostream> #include <type_traits> template<typename... Ts> constexpr auto make_array(Ts&&... ts) { using CT = std::common_type_t <Ts...>; return std::array <CT, sizeof...(Ts)>{std::forward <CT>(ts)...}; } int main() { std::array <double, 4ul> arr = make_array(1, 2.71f, 3.14, '*'); std::cout << "arr = { "; for (auto s{arr.size()}; double elem : arr) std::cout << elem << (--s ? ", " : " "); std::cout << "}\n"; }
Output:
arr = { 1, 2.71, 3.14, 42 }