std::mask_array - cppreference.com (original) (raw)

| | | | | --------------------------------------- | | | | template< class T > class mask_array; | | |

std::mask_array is a helper template used by the valarray subscript operator with std::valarray<bool> argument. It has reference semantics and provides access to the subset of the valarray consisting of the elements whose indices correspond to true values in the std::valarray<bool> mask.

[edit] Member types

[edit] Member functions

[edit] Example

#include #include   void println(auto rem, const auto& data) { for (std::cout << rem; int n : data) std::cout << n << ' '; std::cout << '\n'; }   int main() { std::valarray data{0, 1, 2, 3, 4, 5, 6, 7, 8, 9};   println("Initial valarray: ", data);   data[data > 5] = -1; // the type of data>5 is std::valarray // the type of data[data>5] is std::mask_array   println("After v[v>5]=-1: ", data); }

Output:

Initial valarray: 0 1 2 3 4 5 6 7 8 9 After v[v>5]=-1: 0 1 2 3 4 5 -1 -1 -1 -1

[edit] See also

| | convenience alias template for basic_simd_mask that can specify its width(alias template)[edit] | | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | | data-parallel type with the element type bool (class template) [edit] |