Description : The C++ function std::is_heap returns true if the elements in the range [first, last) form a max heap, such as is constructed by make_heap, and false otherwise.
Example :
#include <algorithm>
#include <iostream>
#include <vector>
int main()
{
std::vector<int> v { 8, 6, 7, 5, 3, 0, 9 };
std::cout << "Intial value for v: ";
for (auto i : v) std::cout << i << ' ';
std::cout << '\n';
if (!std::is_heap(v.begin(), v.end())) {
std::cout << "Creating heap:\n";
std::make_heap(v.begin(), v.end());
}
std::cout << "After call to make_heap, v: ";
for (auto i : v) std::cout << i << ' ';
std::cout << '\n';
}