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.
Member types
| Type | Definition |
value_type
|
T
|
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) |
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
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) |