std::experimental::simd_mask<T,Abi>::operator[]
From cppreference.com
                    
                                        
                    < cpp | experimental | simd | simd mask
                    
                                                            
                    |   reference operator[]( size_t i );  | 
(1) | (parallelism TS v2) | 
|   bool operator[]( size_t i ) const;  | 
(2) | (parallelism TS v2) | 
The subscript operators allow reading and writing single elements of a simd_mask.
1) Returns a reference proxy to the i-th element. This proxy type should not be captured into an lvalue. Lvalues of 
simd_mask::reference can only convert to value_type. Rvalues of simd_mask::reference overload assignment and all compound assignment operators as well as swap.2) Returns a prvalue of the i-th element. In contrast to containers, which contain objects of type 
value_type, a simd_mask is not a container of individual objects and therefore cannot return an lvalue-reference.Parameters
| i | - |  the element index. Required to be less than size()
 | 
Example
Run this code
#include <cstddef> #include <experimental/simd> #include <iostream> namespace stdx = std::experimental; int main() { stdx::native_simd_mask<int> a{true}; a[1] = 0; for (std::size_t i = 0; i != a.size(); ++i) std::cout << a[i] << ' '; std::cout << '\n'; }
Possible output:
1 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1