std::mask_array
性病：面具[医]列阵
| Defined in header | | |
|---|---|---|
| template< class T > class mask_array; | | |
std::mask_array是由valArray下标运算符带着std::valarray<bool>争论。它具有引用语义，并提供对由索引对应于true中的值。std::valarray<bool>面具。
成员类型
| Type | Definition |
|---|---|
| value_type | T |
成员函数
| (constructor) | constructs a mask_array (public member function) |
|---|---|
| (destructor) | destroys a mask_array (public member function) |
| operator= | assigns contents (public member function) |
| operator+=operator-=operator*=operator/=operator%=operator&=operator|=operator^=operator<<=operator>>= | performs arithmetic operation on the array referred by mask. (public member function) |
例
二次
#include <iostream>
#include <valarray>
int main()
{
std::valarray<int> data = {0,1,2,3,4,5,6,7,8,9};
std::cout << "Initial valarray: ";
for(int n: data) std::cout << n << ' ';
std::cout << '\n';
data[data > 5] = -1;
// the type of data>5 is std::valarray<bool>
// the type of data[data>5] is std::mask_array<int>
std::cout << "After v[v>5]=-1: ";
for(int n: data) std::cout << n << ' ';
std::cout << '\n';
}
二次
产出：
二次
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
二次
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