std::priority_queue<T,Container,Compare>::top
来自cppreference.com
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const_reference top() const; |
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返回到优先级队列顶元素的引用。此元素将在调用 pop() 时被移除。若使用默认比较函数，则返回的元素亦为优先队列中最大的元素。
返回值
到顶元素的引用，如同以调用 c.front() 获得。
复杂度
常数。
示例
运行此代码
#include <iostream>
#include <queue>
struct Event
{
int priority{};
char data{' '};
friend bool operator<(Event const& lhs, Event const& rhs)
{
return lhs.priority < rhs.priority;
}
friend std::ostream& operator<<(std::ostream& os, Event const& e)
{
return os << '{' << e.priority << ", '" << e.data << "'}";
}
};
int main()
{
std::priority_queue<Event> events;
std::cout << "Fill the events queue:\t";
for (auto const e : {Event{6,'L'}, {8,'I'}, {9,'S'}, {1,'T'}, {5,'E'}, {3,'N'}})
{
std::cout << e << ' ';
events.push(e);
}
std::cout << "\nProcess events:\t\t";
for (; !events.empty(); events.pop())
{
Event const& e = events.top();
std::cout << e << ' ';
}
std::cout << '\n';
}
输出：
Fill the events queue: {6, 'L'} {8, 'I'} {9, 'S'} {1, 'T'} {5, 'E'} {3, 'N'}
Process events: {9, 'S'} {8, 'I'} {6, 'L'} {5, 'E'} {3, 'N'} {1, 'T'}
参阅
| 移除队首元素 (公开成员函数) |