std::set<Key,Compare,Allocator>::operator=
set& operator=( const set& other ); |
(1) | |
(2) | ||
set& operator=( set&& other ); |
(since C++11) (until C++17) |
|
set& operator=( set&& other ) noexcept(/* see below */); |
(since C++17) | |
set& operator=( std::initializer_list<value_type> ilist ); |
(3) | (since C++11) |
Replaces the contents of the container.
other
.
If |
(since C++11) |
other
using move semantics (i.e. the data in
other
is moved from
other
into this container).
other
is in a valid but unspecified state afterwards.
std::allocator_traits<allocator_type>::propagate_on_container_move_assignment::value
is
true
, the allocator of
*this
is replaced by a copy of that of
other
. If it is
false
and the allocators of
*this
and
other
do not compare equal,
*this
cannot take ownership of the memory owned by
other
and must move-assign each element individually, allocating additional memory using its own allocator as needed. In any case, all elements originally belong to
*this
are either destroyed or replaced by element-wise move-assignment.
ilist
.
Parameters
other | - | another container to use as data source |
ilist | - | initializer list to use as data source |
Return value
*this
.
Complexity
*this
and
other
.
*this
unless the allocators do not compare equal and do not propagate, in which case linear in the size of
*this
and
other
.
size() + ilist.size()
. Linear if
ilist
is sorted with respect to
value_comp()
.
Exceptions
May throw implementation-defined exceptions. |
(until C++17) |
1,3) May throw implementation-defined exceptions. 2)
noexcept specification:
noexcept(std::allocator_traits<Allocator>::is_always_equal::value
|
(since C++17) |
Notes
After container move assignment (overload (2)), unless element-wise move assignment is forced by incompatible allocators, references, pointers, and iterators (other than the end iterator) to other
remain valid, but refer to elements that are now in *this
. The current standard makes this guarantee via the blanket statement in [container.requirements.general]/12, and a more direct guarantee is under consideration via LWG 2321.
Example
The following code uses operator=
to assign one std::set
to another:
#include <set> #include <iterator> #include <iostream> void print(auto const comment, auto const& container) { auto size = std::size(container); std::cout << comment << "{ "; for (auto const& element: container) std::cout << element << (--size ? ", " : " "); std::cout << "}\n"; } int main() { std::set<int> x { 1, 2, 3 }, y, z; const auto w = { 4, 5, 6, 7 }; std::cout << "Initially:\n"; print("x = ", x); print("y = ", y); print("z = ", z); std::cout << "Copy assignment copies data from x to y:\n"; y = x; print("x = ", x); print("y = ", y); std::cout << "Move assignment moves data from x to z, modifying both x and z:\n"; z = std::move(x); print("x = ", x); print("z = ", z); std::cout << "Assignment of initializer_list w to z:\n"; z = w; print("w = ", w); print("z = ", z); }
Output:
Initially: x = { 1, 2, 3 } y = { } z = { } Copy assignment copies data from x to y: x = { 1, 2, 3 } y = { 1, 2, 3 } Move assignment moves data from x to z, modifying both x and z: x = { } z = { 1, 2, 3 } Assignment of initializer_list w to z: w = { 4, 5, 6, 7 } z = { 4, 5, 6, 7 }
See also
constructs the set (public member function) |
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