make_heap() function parameters - what if i don't want to include certain elements?

Question

Question about make_heap function.
When making a heap in stl using make_heap
it takes v.begin() and v.end() // [front, end)
but what if I don't want to add 10 in to the heap..

I thought I could accomplish this by using:

make_heap(v.begin(),v.end()-1);

But this isn't giving me any different output.. I tried using make_heap(v.begin(),v.end()-1); instead of make_heap(v.begin(),v.end());
But output is the same...

What's happening here?..

Code #1:

#include <algorithm>    
#include <vector>     


int main () {
  int myints[] = {1,2,3,4,5,6,7,8,9,10};
  std::vector<int> v(myints,myints+10);




  std::make_heap (v.begin(),v.end());
  std::cout << "range :";
  for (unsigned i=0; i<v.size(); i++)
    std::cout << ' ' << v[i];

  std::cout << '\n';

  return 0;
}

Code #2:

#include <algorithm>   
#include <vector>      

int main () {
  int myints[] = {1,2,3,4,5,6,7,8,9,10};
  std::vector<int> v(myints,myints+10);




  std::make_heap (v.begin(),v.end()-1);

  std::cout << "range :";
  for (unsigned i=0; i<v.size(); i++)
    std::cout << ' ' << v[i];

  std::cout << '\n';

  return 0;
}

Both giving me same output.. (?)

Answer 1

This is not an answer per say, but I was unable to reproduce your results: I obtain two different outputs.

Program:

#include <algorithm>
#include <vector>
#include <iostream>

void code1() 
{
  int myints[] = {1,2,3,4,5,6,7,8,9,10};
  std::vector<int> v(myints,myints+10);

  std::make_heap (v.begin(),v.end());
  std::cout << "range :";
  for (unsigned i=0; i<v.size(); i++)
    std::cout << ' ' << v[i];

  std::cout << '\n';
}

void code2() 
{
  int myints[] = {1,2,3,4,5,6,7,8,9,10};
  std::vector<int> v(myints,myints+10);

  std::make_heap (v.begin(),v.end()-1);
  std::cout << "range :";
  for (unsigned i=0; i<v.size(); i++)
    std::cout << ' ' << v[i];

  std::cout << '\n';
}

// ------------------------------------------------------------------------

int main()
{
    code1();
    code2();
}

Compilation & Output:

john@---:/tmp$ g++ --version
g++ (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3
Copyright (C) 2011 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

john@---:/tmp$ g++ -o so2 so2.cpp
john@---:/tmp$ ./so2
range : 10 9 7 8 5 6 3 1 4 2
range : 9 8 7 4 5 6 3 2 1 10
john@---:/tmp$