std::mask_array
From cppreference.com
| Defined in header <valarray>
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| template< class T > class mask_array; |
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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.
Contents |
[edit] Member types
| Type | Definition |
value_type
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T
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[edit] Member functions
constructs a mask_array (public member function) | |
destroys a mask_array (public member function) | |
| assigns contents (public member function) | |
| performs arithmetic operation on the array referred by mask. (public member function) |
[edit] Example
Run this code
#include <iostream> #include <valarray> void println(auto rem, const auto& data) { for (std::cout << rem; int n : data) std::cout << n << ' '; std::cout << '\n'; } int main() { std::valarray<int> 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<bool> // the type of data[data>5] is std::mask_array<int> 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
| (C++26) |
convenience alias template for basic_simd_mask that can specify its width(alias template) |
| (parallelism TS v2) |
data-parallel type with the element type bool (class template) |
