public member function
<vector>

std::vector::operator=

copy (1)
 vector& operator= (const vector& x);
copy (1)
vector& operator= (const vector& x);
move (2)
vector& operator= (vector&& x);
initializer list (3)
vector& operator= (initializer_list<value_type> il);
Assign content
Assigns new contents to the container, replacing its current contents, and modifying its size accordingly.

Copies all the elements from x into the container.

The container preserves its current allocator, which is used to allocate storage in case of reallocation.
The copy assignment (1) copies all the elements from x into the container (with x preserving its contents).

The move assignment (2) moves the elements of x into the container (x is left in an unspecified but valid state).

The initializer list assignment (3) copies the elements of il into the container.

The container preserves its current allocator, except if the allocator traits indicate that x's allocator should propagate. This allocator is used (through its traits) to allocate and deallocate storage if a reallocation happens, and to construct or destroy elements, if needed.

Any elements held in the container before the call are either assigned to or destroyed.

Parameters

x
A vector object of the same type (i.e., with the same template parameters, T and Alloc).
il
An initializer_list object. The compiler will automatically construct such objects from initializer list declarators.
Member type value_type is the type of the elements in the container, defined in vector as an alias of its first template parameter (T).

Return value

*this

Example

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// vector assignment
#include <iostream>
#include <vector>

int main ()
{
  std::vector<int> foo (3,0);
  std::vector<int> bar (5,0);

  bar = foo;
  foo = std::vector<int>();

  std::cout << "Size of foo: " << int(foo.size()) << '\n';
  std::cout << "Size of bar: " << int(bar.size()) << '\n';
  return 0;
}


Output:
Size of foo: 0
Size of bar: 3

Complexity

Linear in size.

Iterator validity

All iterators, references and pointers related to this container before the call are invalidated.

In the move assignment, iterators, pointers and references referring to elements in x are also invalidated.

Data races

All copied elements are accessed.
The move assignment (2) modifies x.
The container and all its elements are modified.

Exception safety

Basic guarantee: if an exception is thrown, the container is in a valid state.
If allocator_traits::construct is not supported with the appropriate arguments for the element constructions, or if value_type is not copy assignable (or move assignable for (2)), it causes undefined behavior.

See also

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