Defined in header <algorithm>  

(1)  
template< class RandomIt > void sort_heap( RandomIt first, RandomIt last );  (until C++20)  
template< class RandomIt > constexpr void sort_heap( RandomIt first, RandomIt last );  (since C++20)  
(2)  
template< class RandomIt, class Compare > void sort_heap( RandomIt first, RandomIt last, Compare comp );  (until C++20)  
template< class RandomIt, class Compare > constexpr void sort_heap( RandomIt first, RandomIt last, Compare comp );  (since C++20) 
Converts the max heap [first, last)
into a sorted range in ascending order. The resulting range no longer has the heap property.
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 to sort 
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:
While the signature does not need to have 
Type requirements  
RandomIt must meet the requirements of ValueSwappable and LegacyRandomAccessIterator. 

The type of dereferenced RandomIt must meet the requirements of MoveAssignable and MoveConstructible. 
(none).
At most 2×N×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 = lf
, for all 0 < i < N
, f[(i1)/2]
does not compare less than f[i]
. std::push_heap
, in \(\scriptsize \mathcal{O}(\log N)\)𝓞(log N) time. std::pop_heap
, in \(\scriptsize \mathcal{O}(\log N)\)𝓞(log N) time. First version 

template< class RandomIt > void sort_heap( RandomIt first, RandomIt last ) { while (first != last) std::pop_heap(first, last); } 
Second version 
template< class RandomIt, class Compare > void sort_heap( RandomIt first, RandomIt last, Compare comp ) { while (first != last) std::pop_heap(first, last, comp); } 
#include <algorithm> #include <vector> #include <iostream> int main() { std::vector<int> v = {3, 1, 4, 1, 5, 9}; std::make_heap(v.begin(), v.end()); std::cout << "heap:\t"; for (const auto &i : v) { std::cout << i << ' '; } std::sort_heap(v.begin(), v.end()); std::cout << "\nsorted:\t"; for (const auto &i : v) { std::cout << i << ' '; } std::cout << '\n'; }
Output:
heap: 9 4 5 1 1 3 sorted: 1 1 3 4 5 9
The following behaviorchanging defect reports were applied retroactively to previously published C++ standards.
DR  Applied to  Behavior as published  Correct behavior 

LWG 2444  C++98  complexity requirement was wrong by a factor of 2  corrected 
(C++11)  checks if the given range is a max heap (function template) 
(C++11)  finds the largest subrange that is a max heap (function template) 
creates a max heap out of a range of elements (function template) 

removes the largest element from a max heap (function template) 

adds an element to a max heap (function template) 

(C++20)  turns a max heap into a range of elements sorted in ascending order (niebloid) 
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