Language: C++

#include <stdio.h>
#include <iostream>
#include <string>
using namespace std;

int main() {
  string ans;
  int32_t n;
  cin >> n;
  while (n) {
    if (n%2) ans += "1";
    else ans += "0";
  	// ans += n%2;
    n /= -2;
  }
  // ans = reverse(ans.begin(), ans.end());
  string anss = "";
  for (int i=ans.end(); i>=ans.begin(); i--)
    anss += ans[i];
  cout << anss << "\n";
  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:18:21: error: cannot convert 'std::__cxx11::basic_string<char>::iterator' to 'int' in initialization
   18 |   for (int i=ans.end(); i>=ans.begin(); i--)
      |              ~~~~~~~^~
      |                     |
      |                     std::__cxx11::basic_string<char>::iterator
a.cc:18:26: error: no match for 'operator>=' (operand types are 'int' and 'std::__cxx11::basic_string<char>::iterator')
   18 |   for (int i=ans.end(); i>=ans.begin(); i--)
      |                         ~^~~~~~~~~~~~~
      |                         |           |
      |                         int         std::__cxx11::basic_string<char>::iterator
In file included from /usr/include/c++/14/string:48,
                 from /usr/include/c++/14/bits/locale_classes.h:40,
                 from /usr/include/c++/14/bits/ios_base.h:41,
                 from /usr/include/c++/14/ios:44,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:2:
/usr/include/c++/14/bits/stl_iterator.h:476:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator>=(const reverse_iterator<_Iterator>&, const reverse_iterator<_Iterator>&)'
  476 |     operator>=(const reverse_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:476:5: note:   template argument deduction/substitution failed:
a.cc:18:38: note:   mismatched types 'const std::reverse_iterator<_Iterator>' and 'int'
   18 |   for (int i=ans.end(); i>=ans.begin(); i--)
      |                                      ^
/usr/include/c++/14/bits/stl_iterator.h:520:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator>=(const reverse_iterator<_Iterator>&, const reverse_iterator<_IteratorR>&)'
  520 |     operator>=(const reverse_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:520:5: note:   template argument deduction/substitution failed:
a.cc:18:38: note:   mismatched types 'const std::reverse_iterator<_Iterator>' and 'int'
   18 |   for (int i=ans.end(); i>=ans.begin(); i--)
      |                                      ^
/usr/include/c++/14/bits/stl_iterator.h:1724:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator>=(const move_iterator<_IteratorL>&, const move_iterator<_IteratorR>&)'
 1724 |     operator>=(const move_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1724:5: note:   template argument deduction/substitution failed:
a.cc:18:38: note:   mismatched types 'const std::move_iterator<_IteratorL>' and 'int'
   18 |   for (int i=ans.end(); i>=ans.begin(); i--)
      |                                      ^
/usr/include/c++/14/bits/stl_iterator.h:1781:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator>=(const move_iterator<_IteratorL>&, const move_iterator<_IteratorL>&)'
 1781 |     operator>=(const move_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1781:5: note:   template argument deduction/substitution failed:
a.cc:18:38: note:   mismatched types 'const std::move_iterator<_IteratorL>' and 'int'
   18 |   for (int i=ans.end(); i>=ans.begin(); i--)
      |                                      ^
In file included from /usr/include/c++/14/bits/stl_algobase.h:64,
                 from /usr/include/c++/14/string:51:
/usr/include/c++/14/bits/stl_pair.h:1070:5: note: candidate: 'template<class _T1, class _T2> constexpr bool std::operator>=(const pair<_T1, _T2>&, const pair<_T1, _T2>&)'
 1070 |     operator>=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:1070:5: note:   template argument deduction/substitution failed:
a.cc:18:38: note:   mismatched types 'const std::pair<_T1, _T2>' and 'int'
   18 |   for (int i=ans.end(); i>=ans.begin(); i--)
      |                                      ^
In file included from /usr/include/c++/14/bits/basic_string.h:47,
                 from /usr/include/c++/14/string:54:
/usr/include/c++/14/string_view:739:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator>=(basic_string_view<_CharT, _Traits>, basic_string_view<_CharT, _Traits>)'
  739 |     operator>=(basic_string_view<_CharT, _Traits> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:739:5: note:   template argument deduction/substitution failed:
a.cc:18:38: note:   mismatched types 'std::basic_string_view<_CharT, _Traits>' and 'int'
   18 |   for (int i=ans.end(); i>=ans.begin(); i--)
      |                                      ^
/usr/include/c++/14/string_view:746:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator>=(basic_string_view<_CharT, _Traits>, __type_identity_t<basic_string_view<_CharT, _Traits> >)'
  746 |     operator>=(basic_string_view<_CharT, _Traits> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:746:5: note:   template argument deduction/substitution failed:
a.cc:18:38: note:   mismatched types 'std::basic_string_view<_CharT, _Traits>' and 'int'
   18 |   for (int i=ans.end(); i>=ans.begin(); i--)
      |                                      ^
/usr/include/c++/14/string_view:754:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator>=(__type_identity_t<basic_string_view<_CharT, _Traits> >, basic_string_view<_CharT, _Traits>)'
  754 |     operator>=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:754:5: note:   template argument deduction/substitution failed:
a.cc:18:38: note:   '__gnu_cxx::__normal_iterator<char*, std::__cxx11::basic_string<char> >' is not derived from 'std::basic_string_view<_CharT, _Traits>'
   18 |   for (int i=ans.end(); i>=ans.begin(); i--)
      |                                      ^
/usr/include/c++/14/bits/basic_string.h:3997:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> bool std::operator>=(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3997 |     operator>=(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3997:5: note:   template argument deduction/substitution failed:
a.cc:18:38: note:   mismatched types 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>' and 'int'
   18 |   for (int i=ans.end(); i>=ans.begin(); i--)
      |                                      ^
/usr/include/c++/14/bits/basic_string.h:4011:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> bool std::operator>=(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const _CharT*)'
 4011 |     operator>=(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:4011:5: note:   template argument deduction/substitution failed:
a.cc:18:38: note:   mismatched types 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>' and 'int'
   18 |   for (int i=ans.end(); i>=ans.begin(); i--)
      |                                      ^
/usr/include/c++/14/bits/basic_string.h:4024:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> bool std::operator>=(const _CharT*, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 4024 |     operator>=(const _CharT* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:4024:5: note:   template argument deduction/substitution failed:
a.cc:18:38: note:   mismatched types 'const _CharT*' and 'int'
   18 |   for (int i=ans.end(); i>=ans.begin(); i--)
      |                                      ^
In file included from /usr/include/c++/14/bits/memory_resource.h:47,
                 from /usr/include/c++/14/string:68:
/usr/include/c++/14/tuple:2631:5: note: candidate: 'template<class ... _TElements, class ... _UElements> constexpr bool std::operator>=(const tuple<_UTypes ...>&, const tuple<_Elements ...>&)'
 2631 |     operator>=(const tuple<_TElements...>& __t,
      |     ^~~~~~~~
/usr/include/c++/14/tuple:2631:5: note:   template argument deduction/substitution failed:
a.cc:18:38: note:   mismatched types 'const std::tuple<_UTypes ...>' and 'int'
   18 |   for (int i=ans.end(); i>=ans.begin(); i--)
      |                                      ^
/usr/include/c++/14/bits/stl_iterator.h:1289:5: note: candidate: 'template<class _IteratorL, class _IteratorR, class _Container> bool __gnu_cxx::operator>=(const __normal_iterator<_IteratorL, _Container>&, const __normal_iterator<_IteratorR, _Container>&)'
 1289 |     operator>=(const __normal_iterator<_IteratorL, _Container>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1289:5: note:   template argument deduction/substitution failed:
a.cc:18:38: note:   mismatched types 'const __gnu_cxx::__normal_iterator<_IteratorL, _Container>' and 'int'
   18 |   for (int i=ans.end(); i>=ans.begin(); i--)
      |                                      ^
/usr/include/c++/14/bits/stl_iterator.h:1297:5: note: candidate: 'template<class _Iterator, class _Container> bool __gnu_cxx::operator>=(const __normal_iterator<_Iterator, _Container>&, const __normal_iterator<_Iterator, _Container>&)'
 1297 |     operator>=(const __normal_iterator<_Iterator, _Container>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1297:5: note:   template argument deduction/substitution failed:
a.cc:18:38: note:   mismatched types 'const __gnu_cxx::__normal_iterator<_Iterator, _Container>' and 'int'
   18 |   for (int i=ans.end(); i>=ans.begin(); i--)
      |                                      ^