NAME¶

std::slice_array::operator= - std::slice_array::operator=

Synopsis¶

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

Return value¶

1,2) (none)
3) *this

Example¶

// Run this code

#include <iostream>
#include <valarray>

void print(char const* remark, std::valarray<int> const& v = {})
{
std::cout << remark;
if (v.size() != 0)
{
std::cout << ':';
for (int e : v)
std::cout << ' ' << e;
}
std::cout << '\n';
}

int main()
{
std::valarray<int> v1{1, 2, 3, 4, 5, 6, 7, 8};
std::slice_array<int> s1 = v1[std::slice(1, 4, 2)];
print("v1", v1);
print("s1", s1);

print("\n(1) operator=( const T& )");
print("s1 = 42");
s1 = 42; // (1)
print("s1", s1);
print("v1", v1);

print("\n(2) operator=( const std::valarray<T>& )");
std::valarray<int> v2{10, 11, 12, 13, 14, 15};
print("v2", v2);
print("s1 = v2");
s1 = v2; // (2)
print("s1", s1);
print("v1", v1);

print("\n(3) operator=( const slice_array& )");
v1 = {1, 2, 3, 4, 5, 6, 7, 8};
std::slice_array<int> s2 = v1[std::slice(0, 4, 1)];
std::slice_array<int> s3 = v2[std::slice(1, 4, 1)];
print("v1", v1);
print("v2", v2);
print("s2", s2);
print("s3", s3);
print("s2 = s3");
s2 = s3; // (3) Note: LHS and RHS must have same size.
print("s2", s2);
print("v1", v1);
}

Output:¶

v1: 1 2 3 4 5 6 7 8
s1: 2 4 6 8

(1) operator=( const T& )
s1 = 42
s1: 42 42 42 42
v1: 1 42 3 42 5 42 7 42

(2) operator=( const std::valarray<T>& )
v2: 10 11 12 13 14 15
s1 = v2
s1: 10 11 12 13
v1: 1 10 3 11 5 12 7 13

(3) operator=( const slice_array& )
v1: 1 2 3 4 5 6 7 8
v2: 10 11 12 13 14 15
s2: 1 2 3 4
s3: 11 12 13 14
s2 = s3
s2: 11 12 13 14
v1: 11 12 13 14 5 6 7 8

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