max heap delete c++ code example

Example 1: max heap c++ stl;

// C++ program to show that priority_queue is by 
// default a Max Heap 
#include <bits/stdc++.h> 
using namespace std; 

// Driver code 
int main () 
{ 
	// Creates a max heap 
	priority_queue <int> pq; 
	pq.push(5); 
	pq.push(1); 
	pq.push(10); 
	pq.push(30); 
	pq.push(20); 

	// One by one extract items from max heap 
	while (pq.empty() == false) 
	{ 
		cout << pq.top() << " "; 
		pq.pop(); 
	} 

	return 0; 
}

Example 2: how to allocate on heap in c++

//placement new in c++
char *buf  = new char[sizeof(string)]; // pre-allocated buffer
string *p = new (buf) string("hi");    // placement new
string *q = new string("hi");          // ordinary heap allocation
/*Standard C++ also supports placement new operator, which constructs 
an object on a pre-allocated buffer. This is useful when building a 
memory pool, a garbage collector or simply when performance and exception 
safety are paramount (there's no danger of allocation failure since the memory
has already been allocated, and constructing an object on a pre-allocated
buffer takes less time):
*/