std::deque::clear

void clear() noexcept;

Removes all elements from the deque (which are destroyed), leaving
the container with a size of 0.

移除deque的所有元素（并且销毁）,使容器大小为0.

例子：

#include <iostream>
#include <deque>
#include <vector>
using namespace std;
int main()
{
	deque<int> di{1,2,3,4,5};
	for(int i:di)
		cout<<i<<" ";
	cout<<endl;

	di.clear();
	cout<<"after di.clear()"<<endl;
	for(int i:di)
		cout<<i<<" ";
	cout<<endl;

}

运行截图：

Parameters

none

Return value

none

Example

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// clearing deques
#include <iostream>
#include <deque>

int main ()
{
  unsigned int i;
  std::deque<int> mydeque;
  mydeque.push_back (100);
  mydeque.push_back (200);
  mydeque.push_back (300);

  std::cout << "mydeque contains:";
  for (std::deque<int>::iterator it = mydeque.begin(); it!=mydeque.end(); ++it)
    std::cout << ' ' << *it;
  std::cout << '\n';

  mydeque.clear();
  mydeque.push_back (1101);
  mydeque.push_back (2202);

  std::cout << "mydeque contains:";
  for (std::deque<int>::iterator it = mydeque.begin(); it!=mydeque.end(); ++it)
    std::cout << ' ' << *it;
  std::cout << '\n';

  return 0;
}

Output:

mydeque contains: 100 200 300
mydeque contains: 1101 2202

Complexity

Linear in size (destructions).

与大小线性相关。

Iterator validity

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

所有的迭代器，引用以及值朕都将失效。

Data races

The container is modified.
All contained elements are modified.

容器将被修改。

容器所有元素都将被修改。

Exception safety

No-throw guarantee: this member function never throws exceptions.

该方法不会抛出异常。