NAME¶

std::indirect_array::operator= - std::indirect_array::operator=

Synopsis¶

void operator=( const T& value ) const; (1)
void operator=( const std::valarray<T>& val_arr ) const; (2)
const indirect_array& operator=( const indirect_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::indirect_array to assign

Return value¶

1,2) (none)
3) *this

Example¶

// Run this code

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

void print(int n, std::valarray<int> const& v)
{
std::cout << n << ':';
for (int e : v)
std::cout << std::setw(3) << e;
std::cout << '\n';
}

int main()
{
std::valarray<int> v(8);
std::iota(std::begin(v), std::end(v), 0);
print(1, v);

std::valarray<std::size_t> idx{1, 3, 5, 7};
const std::indirect_array<int> ia = v[idx];
// 'ia' refers to v[1], v[3], v[5], v[7]
ia = -1; // (1), effectively:
// v[1] = v[3] = v[5] = v[7] = -1;
print(2, v);

ia = /*std::valarray<int>*/{-1, -2, -3, -4}; // (2),
// effectively: v[1] = -1, v[3] = -2, v[5] = -3, v[7] = -4;
print(3, v);

std::valarray<std::size_t> idx2{0, 2, 4, 6};
const std::indirect_array<int> ia2 = v[idx2];
// 'ia2' refers to v[0], v[2], v[4], v[6]
ia = ia2; // (3), effectively:
// v[1] = v[0], v[3] = v[2], v[5] = v[4], v[7] = v[6];
print(4, v);
}

Output:¶

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

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