# deduction guides for `std::valarray`

From cppreference.com
< cpp‎ | numeric‎ | valarray

Defined in header `<valarray>` |  |
template<typename T, std::size_t cnt> valarray(const T(&)[cnt], std::size_t) -> valarray<T>; |  | (since C++17)

This deduction guide is provided for std::valarray to allow deduction from array and size (note that deduction from pointer and size is covered by the implicit guides)

### Example

Run this code

    #include <valarray>
    int main() {
      int a[] = {1, 2, 3};
      std::valarray va(a, 3); // uses explicit deduction guide
    }

Retrieved from "https://en.cppreference.com/mwiki/index.php?title=cpp/numeric/valarray/deduction_guides&oldid=94035"