C++ priority_queue::swap()用法及代码示例

优先级队列是一种容器适配器，经过专门设计，使得队列的第一个元素在队列中的所有元素中占最大。

priority_queue::swap()

此函数用于将一个优先级队列的内容与相同类型和大小的另一个优先级队列交换。

用法:

priorityqueuename1.swap(priorityqueuename2)
参数：
The name of the priority queue with which
the contents have to be swapped.
Result:
All the elements of the 2 priority queues are swapped.

例子：

Input :mypqueue1 = {1, 2, 3, 4}
         mypqueue2 = {3, 5, 7, 9}
         mypqueue1.swap(mypqueue2);
Output:mypqueue1 = {9, 7, 5, 3}
         mypqueue2 = {4, 3, 2, 1}

Input :mypqueue1 = {1, 3, 5, 7}
         mypqueue2 = {2, 4, 6, 8}
         mypqueue1.swap(mypqueue2);
Output:mypqueue1 = {8, 6, 4, 2}
         mypqueue2 = {7, 5, 3, 1}

Note: In priority_queue container, the elements are printed
      in reverse order because the top is printed first
      then moving on to other elements.

错误和异常

1.如果优先级队列的类型不同，则会引发错误。
2.它具有基本的无异常抛出保证。

// CPP program to illustrate 
// Implementation of swap() function 
#include <iostream> 
#include <queue> 
using namespace std; 
  
int main() 
{ 
    // priority_queue container declaration 
    priority_queue<int> mypqueue1; 
    priority_queue<int> mypqueue2; 
  
    // pushing elements into the 1st priority queue 
    mypqueue1.push(1); 
    mypqueue1.push(2); 
    mypqueue1.push(3); 
    mypqueue1.push(4); 
  
    // pushing elements into the 2nd priority queue 
    mypqueue2.push(3); 
    mypqueue2.push(5); 
    mypqueue2.push(7); 
    mypqueue2.push(9); 
  
    // using swap() function to swap elements of priority queues 
    mypqueue1.swap(mypqueue2); 
  
    // printing the first priority queue 
    cout << "mypqueue1 = "; 
    while (!mypqueue1.empty()) { 
        cout << mypqueue1.top() << " "; 
        mypqueue1.pop(); 
    } 
  
    // printing the second priority queue 
    cout << endl 
         << "mypqueue2 = "; 
    while (!mypqueue2.empty()) { 
        cout << mypqueue2.top() << " "; 
        mypqueue2.pop(); 
    } 
    return 0; 
}

输出：

mypqueue1 = 9 7 5 3 
mypqueue2 = 4 3 2 1

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注：本文由纯净天空筛选整理自AyushSaxena大神的英文原创作品 priority_queue::swap() in C++ STL。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。