C++

参考

<queue>

queue

public member function
<queue>

std::queue::size

size_type size() const;
Return size
Returns the number of elements in the queue.

This member function effectively calls member size of the underlying container object.

参数

无

返回值

The number of elements in the underlying container.

Member type size_type is an unsigned integral type.

示例

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// queue::size
#include <iostream>       // std::cout
#include <queue>          // std::queue

int main ()
{
  std::queue<int> myints;
  std::cout << "0. size: " << myints.size() << '\n';

  for (int i=0; i<5; i++) myints.push(i);
  std::cout << "1. size: " << myints.size() << '\n';

  myints.pop();
  std::cout << "2. size: " << myints.size() << '\n';

  return 0;
}

输出
0. size: 0
1. size: 5
2. size: 4


复杂度

Constant (calling size on the underlying container).

数据竞争

访问容器。

异常安全

Provides the same level of guarantees as the operation performed on the container (no-throw guarantee for standard container types).

另见

queue::empty
测试容器是否为空 (公开成员函数)