priority_queue Functions
Illustrates how to use the priority_queue::push, priority_queue::pop, priority_queue::empty, priority_queue::top, and priority_queue::size Standard Template Library (STL) functions in Visual C++.
priority_queue::push( );
priority_queue::pop( );
priority_queue::empty( );
priority_queue::top( );
priority_queue::size( );
Remarks
Note
The class/parameter names in the prototype do not match the version in the header file. Some have been modified to improve readability.
The sample shows the priority_queue implementation using deque and vector containers.
Example
// priority_queue.cpp
// compile with: /EHsc
//
// Functions:
// priority_queue::push(), priority_queue::pop(),
// priority_queue::empty(), priority_queue::top(), queue::size()
#include <iostream>
#include <queue>
#include <deque>
#include <vector>
#include <functional>
using namespace std ;
// Using priority_queue with deque
// Use of function less sorts the items in ascending order
typedef deque<int> INTDQU;
typedef priority_queue<int, INTDQU, less<int> > INTPRQUE;
// Using priority_queue with vector
// Use of function greater sorts the items in descending order
typedef vector<char> CHVECTOR;
typedef priority_queue<char, CHVECTOR, greater<char> > CHPRQUE;
int main(void)
{
size_t size_q;
INTPRQUE q;
CHPRQUE p;
// Insert items in the priority_queue(uses deque)
q.push(42);
q.push(100);
q.push(49);
q.push(201);
// Output the item at the top using top()
cout << q.top() << endl;
// Output the size of priority_queue
size_q = q.size();
cout << "size of q is:" << size_q << endl;
// Output items in priority_queue using top()
// and use pop() to get to next item until
// priority_queue is empty
while (!q.empty())
{
cout << q.top() << endl;
q.pop();
}
// Insert items in the priority_queue(uses vector)
p.push('c');
p.push('a');
p.push('d');
p.push('m');
p.push('h');
// Output the item at the top using top()
cout << p.top() << endl;
// Output the size of priority_queue
size_q = p.size();
cout << "size of p is:" << size_q << endl;
// Output items in priority_queue using top()
// and use pop() to get to next item until
// priority_queue is empty
while (!p.empty())
{
cout << p.top() << endl;
p.pop();
}
}
Output
201
size of q is:4
201
100
49
42
a
size of p is:5
a
c
d
h
m
Requirements
Header: <queue>