C++

參考

<forward_list>

forward_list

public member function
<forward_list>

std::forward_list::assign

range (1)
template <class InputIterator>  void assign (InputIterator first, InputIterator last);
fill (2)
void assign (size_type n, const value_type& val);
initializer list (3)
void assign (initializer_list<value_type> il);
Assign content
Assigns new contents to the forward_list container, replacing its current contents, and modifying its size accordingly.

In the range version (1), the new contents are elements constructed from each of the elements in the range between first and last, in the same order.

In the fill version (2), the new contents are n elements, each initialized to a copy of val.

In the initializer list version (3), the new contents are copies of the values passed as initializer list, in the same order.

Any elements held in the container before the call are destroyed and replaced by newly constructed elements (no assignments of elements take place).

If there are changes in storage, the internal allocator is used (through its traits). It is also used to destroy all existing elements, and to construct the new ones.

引數

first, last
Input iterators to the initial and final positions in a sequence. The range used is[first,last)，它包括first和last之間的所有元素，包括first指向的元素，但不包括last指向的元素。
函式模板引數InputIteratorshall be an input iterator type that points to elements of a type from whichvalue_type物件的型別的元素。
n
New size for the container.
成員型別size_type是一種無符號整型型別。
val
Value to fill the container with. Each of the n elements in the container will be initialized to a copy of this value.
成員型別value_typeis the type of the elements in the container, defined in forward_list as an alias of its first template parameter (T).
il
一個 initializer_list 物件。編譯器將自動從初始化列表宣告器建立此類物件。
成員型別value_typeis the type of the elements in the container, defined in forward_list as an alias of its first template parameter (T).

返回值

無

示例

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// forward_list::assign
#include <iostream>
#include <forward_list>

int main ()
{
  std::forward_list<int> first;
  std::forward_list<int> second;

  first.assign (4,15);                           // 15 15 15 15

  second.assign (first.begin(),first.end());     // 15 15 15 15

  first.assign ( {77, 2, 16} );                  // 77 2 16

  std::cout << "first contains: ";
  for (int& x : first) std::cout << ' ' << x;
  std::cout << '\n';

  std::cout << "second contains: ";
  for (int& x : second) std::cout << ' ' << x;
  std::cout << '\n';

  return 0;
}
輸出
first contains: 77 2 16
second contains: 15 15 15 15


複雜度

Linear in initial and final container sizes (destructions, constructions).

迭代器有效性

All iterators, references and pointers related to this container are invalidated, except the end iterators.

資料競爭

All copied elements are accessed.
The container is modified.
所有包含的元素都被修改。

異常安全

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 the range specified by[first,last)無效，則會導致未定義行為。

另見

forward_list::operator=
賦新值 (公開成員函式)
forward_list::forward_list
構造 forward_list 物件 (公開成員函式)
forward_list::insert_after
插入元素 (公開成員函式)