deduction guides for std::valarray
From cppreference.com
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 <iostream>
#include <valarray>
int main()
{
int a[] = {1, 2, 3, 4};
std::valarray va(a, 3); // uses explicit deduction guide
for (int x : va)
std::cout << x << ' ';
std::cout << '\n';
}
Output:
1 2 3
