NAME¶

std::flat_map::operator= - std::flat_map::operator=

Synopsis¶

flat_map& operator=( const flat_map& other ); (1) (since C++23)
(implicitly declared)
flat_map& operator=( flat_map&& other ); (2) (since C++23)
(implicitly declared)
flat_map& operator=( std::initializer_list<value_type> (3) (since C++23)
ilist );

Replaces the contents of the container adaptor with the contents of given argument.

1) Copy assignment operator. Replaces the contents with a copy of the contents of
other. Effectively calls c = other.c; comp = other.comp;.
2) Move assignment operator. Replaces the contents with those of other using move
semantics. Effectively calls c = std::move(other.c); comp = std::move(other.comp);.
3) Replaces the contents with those identified by initializer list ilist.

Parameters¶

other - another container adaptor to be used as source
ilist - initializer list to be used as source

Return value¶

*this

Complexity¶

1,2) Equivalent to that of operator= of the underlying container.
3) Linear in the size of *this and ilist.

Example¶

// Run this code

#include <flat_map>
#include <initializer_list>
#include <print>
#include <utility>

int main()
{
std::flat_map<int, int> x{{1, 1}, {2, 2}, {3, 3}}, y, z;
const auto w = {std::pair<const int, int>{4, 4}, {5, 5}, {6, 6}, {7, 7}};

std::println("Initially:");
std::println("x = {}", x);
std::println("y = {}", y);
std::println("z = {}", z);

y = x; // overload (1)
std::println("Copy assignment copies data from x to y:");
std::println("x = {}", x);
std::println("y = {}", y);

z = std::move(x); // overload (2)
std::println("Move assignment moves data from x to z, modifying both x and z:");
std::println("x = {}", x);
std::println("z = {}", z);

z = w; // overload (3)
std::println("Assignment of initializer_list w to z:");
std::println("w = {}", w);
std::println("z = {}", z);
}

Output:¶

Initially:
x = {1: 1, 2: 2, 3: 3}
y = {}
z = {}
Copy assignment copies data from x to y:
x = {1: 1, 2: 2, 3: 3}
y = {1: 1, 2: 2, 3: 3}
Move assignment moves data from x to z, modifying both x and z:
x = {}
z = {1: 1, 2: 2, 3: 3}
Assignment of initializer_list w to z:
w = {4: 4, 5: 5, 6: 6, 7: 7}
z = {4: 4, 5: 5, 6: 6, 7: 7}

See also¶

constructor constructs the flat_map
(public member function)
replace replaces the underlying containers
(public member function)