NAME¶

std::mask_array::operator= - std::mask_array::operator=

Synopsis¶

void operator=( const T& value ) const; (1)
void operator=( const std::valarray<T>& val_arr ) const; (2)
const mask_array& operator=( const mask_array& other_arr ) const; (3)

Assigns values to all referred elements.

1) Assigns value to all of the elements.
2) Assigns the elements of val_arr to the referred to elements of *this.
3) Assigns the selected elements from other_arr to the referred to elements of
*this.

Parameters¶

value - a value to assign to all of the referred elements
val_arr - std::valarray to assign
other_arr - std::mask_array to assign

Return value¶

1,2) (none)
3) *this

Example¶

// Run this code

#include <iomanip>
#include <iostream>
#include <valarray>

void print(std::valarray<int> const& v)
{
for (int e : v)
std::cout << std::setw(2) << e << ' ';
std::cout << '\n';
}

int main()
{
const auto init = {1, 2, 3, 4, 5, 6, 7, 8};
std::valarray<int> v;

v = init;
v[(v % 2) == 0] = 0; // (1)
print(v);

v = init;
v[(v % 2) == 1] = std::valarray<int>{-1, -2, -3, -4}; // (2)
print(v);

v = init;
v[(v % 2) == 0] = v[(v % 2) == 1]; // (3)
print(v);
}

Output:¶

1 0 3 0 5 0 7 0
-1 2 -2 4 -3 6 -4 8
1 1 3 3 5 5 7 7

Defect reports

The following behavior-changing defect reports were applied retroactively to
previously published C++ standards.

DR Applied to Behavior as published Correct behavior
LWG 123 C++98 overload (2) was non-const made const
LWG 253 C++98 the copy assignment operator was private made public
LWG 621 C++98 the copy assignment operator was non-const made const