Defined in header <algorithm>  

template< class RandomIt > void pop_heap( RandomIt first, RandomIt last );  (1)  
template< class RandomIt, class Compare > void pop_heap( RandomIt first, RandomIt last, Compare comp );  (2) 
Swaps the value in the position first
and the value in the position last1
and makes the subrange [first, last1)
into a max heap. This has the effect of removing the first (largest) element from the heap defined by the range [first, last)
.
The first version of the function uses operator<
to compare the elements, the second uses the given comparison function comp
.
first, last    the range of elements defining the valid nonempty heap to modify 
comp    comparison function object (i.e. an object that satisfies the requirements of Compare ) which returns true if the first argument is less than the second. The signature of the comparison function should be equivalent to the following:
The signature does not need to have 
Type requirements  
RandomIt must meet the requirements of ValueSwappable and RandomAccessIterator . 

The type of dereferenced RandomIt must meet the requirements of MoveAssignable and MoveConstructible . 
(none).
At most 2×log(N) comparisons where N=std::distance(first, last)
.
A max heap is a range of elements [f,l)
that has the following properties:
N = l  f
, for all 0 < i < N
, f[floor(
i1
2
)]
does not compare less than f[i]
. std::push_heap()
std::pop_heap()
#include <iostream> #include <algorithm> #include <vector> int main() { std::vector<int> v { 3, 1, 4, 1, 5, 9 }; std::make_heap(v.begin(), v.end()); std::cout << "v: "; for (auto i : v) std::cout << i << ' '; std::cout << '\n'; std::pop_heap(v.begin(), v.end()); // moves the largest to the end std::cout << "after pop_heap: "; for (auto i : v) std::cout << i << ' '; std::cout << '\n'; int largest = v.back(); v.pop_back(); // actually removes the largest element std::cout << "largest element: " << largest << '\n'; std::cout << "heap without largest: "; for (auto i : v) std::cout << i << ' '; std::cout << '\n'; }
Output:
v: 9 5 4 1 1 3 after pop_heap: 5 3 4 1 1 9 largest element: 9 heap without largest: 5 3 4 1 1
adds an element to a max heap (function template) 

creates a max heap out of a range of elements (function template) 
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