Language: C++

#include <iostream>
#include <iomanip>
#include <cmath>
using namespace std;

struct Point {
  double x;
  double y;
};
void koch(int n,int a,int b) {
  if (n==0) {
    return;
  }
  Point s, t, u;
  double th=M_PI*60.0/180.0;
  s.x=(2.0*a.x+1.0*b.x)/3;
  s.y=(2.0*a.y+1.0*b.y)/3;
  t.x=(1.0*a.x+2.0*b.x)/3;
  t.y=(1.0*a.x+2.0*b.x)/3;
  u.x=(t.x-s.x)*cos(th)-(t.y-s.y)*sin(th)+s.x;
  u.y=(t.x-s.x)*sin(th)+(t.y-s.y)*cos(th)+s.y;
  koch(n-1,a,s);
  cout<<fixed<<setprecision(8)<<s.x<<s.y<<flush;
  koch(n-1,s,u);
  cout<<fixed<<setprecision(8)<<u.x<<u.y<flush;
  koch(n-1,u,t);
  cout<<fixed<<setprecision(8)<<t.x<<t.y<<flush;
  koch(n-1,t,b);
}
int main() {
  int n;
  cin>>n;
  Point a, b;
  a.x=0;
  a.y=0;
  b.x=100;
  b.y=0;
  cout<<fixed<<setprecision(8)<<a.x<<a.y<<endl;;
  koch(n,a,b);
  cout<<fixed<<setprecision(8)<<b.x<<b.y<<endl;
  return 0;
}



Compiler output:
a.cc: In function 'void koch(int, int, int)':
a.cc:16:14: error: request for member 'x' in 'a', which is of non-class type 'int'
   16 |   s.x=(2.0*a.x+1.0*b.x)/3;
      |              ^
a.cc:16:22: error: request for member 'x' in 'b', which is of non-class type 'int'
   16 |   s.x=(2.0*a.x+1.0*b.x)/3;
      |                      ^
a.cc:17:14: error: request for member 'y' in 'a', which is of non-class type 'int'
   17 |   s.y=(2.0*a.y+1.0*b.y)/3;
      |              ^
a.cc:17:22: error: request for member 'y' in 'b', which is of non-class type 'int'
   17 |   s.y=(2.0*a.y+1.0*b.y)/3;
      |                      ^
a.cc:18:14: error: request for member 'x' in 'a', which is of non-class type 'int'
   18 |   t.x=(1.0*a.x+2.0*b.x)/3;
      |              ^
a.cc:18:22: error: request for member 'x' in 'b', which is of non-class type 'int'
   18 |   t.x=(1.0*a.x+2.0*b.x)/3;
      |                      ^
a.cc:19:14: error: request for member 'x' in 'a', which is of non-class type 'int'
   19 |   t.y=(1.0*a.x+2.0*b.x)/3;
      |              ^
a.cc:19:22: error: request for member 'x' in 'b', which is of non-class type 'int'
   19 |   t.y=(1.0*a.x+2.0*b.x)/3;
      |                      ^
a.cc:22:14: error: cannot convert 'Point' to 'int'
   22 |   koch(n-1,a,s);
      |              ^
      |              |
      |              Point
a.cc:10:27: note:   initializing argument 3 of 'void koch(int, int, int)'
   10 | void koch(int n,int a,int b) {
      |                       ~~~~^
a.cc:24:12: error: cannot convert 'Point' to 'int'
   24 |   koch(n-1,s,u);
      |            ^
      |            |
      |            Point
a.cc:10:21: note:   initializing argument 2 of 'void koch(int, int, int)'
   10 | void koch(int n,int a,int b) {
      |                 ~~~~^
a.cc:25:41: error: no match for 'operator<' (operand types are 'std::basic_ostream<char>::__ostream_type' {aka 'std::basic_ostream<char>'} and '<unresolved overloaded function type>')
   25 |   cout<<fixed<<setprecision(8)<<u.x<<u.y<flush;
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~
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:1:
/usr/include/c++/14/bits/stl_iterator.h:448:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator<(const reverse_iterator<_Iterator>&, const reverse_iterator<_Iterator>&)'
  448 |     operator<(const reverse_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:448:5: note:   template argument deduction/substitution failed:
a.cc:25:42: note:   'std::basic_ostream<char>::__ostream_type' {aka 'std::basic_ostream<char>'} is not derived from 'const std::reverse_iterator<_Iterator>'
   25 |   cout<<fixed<<setprecision(8)<<u.x<<u.y<flush;
      |                                          ^~~~~
/usr/include/c++/14/bits/stl_iterator.h:493:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator<(const reverse_iterator<_Iterator>&, const reverse_iterator<_IteratorR>&)'
  493 |     operator<(const reverse_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:493:5: note:   template argument deduction/substitution failed:
a.cc:25:42: note:   'std::basic_ostream<char>::__ostream_type' {aka 'std::basic_ostream<char>'} is not derived from 'const std::reverse_iterator<_Iterator>'
   25 |   cout<<fixed<<setprecision(8)<<u.x<<u.y<flush;
      |                                          ^~~~~
/usr/include/c++/14/bits/stl_iterator.h:1694:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator<(const move_iterator<_IteratorL>&, const move_iterator<_IteratorR>&)'
 1694 |     operator<(const move_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1694:5: note:   template argument deduction/substitution failed:
a.cc:25:42: note:   'std::basic_ostream<char>::__ostream_type' {aka 'std::basic_ostream<char>'} is not derived from 'const std::move_iterator<_IteratorL>'
   25 |   cout<<fixed<<setprecision(8)<<u.x<<u.y<flush;
      |                                          ^~~~~
/usr/include/c++/14/bits/stl_iterator.h:1760:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator<(const move_iterator<_IteratorL>&, const move_iterator<_IteratorL>&)'
 1760 |     operator<(const move_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1760:5: note:   template argument deduction/substitution failed:
a.cc:25:42: note:   'std::basic_ostream<char>::__ostream_type' {aka 'std::basic_ostream<char>'} is not derived from 'const std::move_iterator<_IteratorL>'
   25 |   cout<<fixed<<setprecision(8)<<u.x<<u.y<flush;
      |                                          ^~~~~
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:1045:5: note: candidate: 'template<class _T1, class _T2> constexpr bool std::operator<(const pair<_T1, _T2>&, const pair<_T1, _T2>&)'
 1045 |     operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:1045:5: note:   template argument deduction/substitution failed:
a.cc:25:42: note:   'std::basic_ostream<char>::__ostream_type' {aka 'std::basic_ostream<char>'} is not derived from 'const std::pair<_T1, _T2>'
   25 |   cout<<fixed<<setprecision(8)<<u.x<<u.y<flush;
      |                                          ^~~~~
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:673:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator<(basic_string_view<_CharT, _Traits>, basic_string_view<_CharT, _Traits>)'
  673 |     operator< (basic_string_view<_CharT, _Traits> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:673:5: note:   template argument deduction/substitution failed:
a.cc:25:42: note:   'std::basic_ostream<char>' is not derived from 'std::basic_string_view<_CharT, _Traits>'
   25 |   cout<<fixed<<setprecision(8)<<u.x<<u.y<flush;
      |                                          ^~~~~
/usr/include/c++/14/string_view:680:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator<(basic_string_view<_CharT, _Traits>, __type_identity_t<basic_string_view<_CharT, _Traits> >)'
  680 |     operator< (basic_string_view<_CharT, _Traits> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:680:5: note:   template argument deduction/substitution failed:
a.cc:25:42: note:   'std::basic_ostream<char>' is not derived from 'std::basic_string_view<_CharT, _Traits>'
   25 |   cout<<fixed<<setprecision(8)<<u.x<<u.y<flush;
      |                                          ^~~~~
/usr/include/c++/14/string_view:688:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator<(__type_identity_t<basic_string_view<_CharT, _Traits> >, basic_string_view<_CharT, _Traits>)'
  688 |     operator< (__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:688:5: note:   template argument deduction/substitution failed:
a.cc:25:42: note:   couldn't deduce template parameter '_CharT'
   25 |   cout<<fixed<<setprecision(8)<<u.x<<u.y<flush;
      |                                          ^~~~~
/usr/include/c++/14/bits/basic_string.h:3874:5: 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>&)'
 3874 |     operator<(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3874:5: note:   template argument deduction/substitution failed:
a.cc:25:42: note:   'std::basic_ostream<char>::__ostream_type' {aka 'std::basic_ostream<char>'} is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   25 |   cout<<fixed<<setprecision(8)<<u.x<<u.y<flush;
      |                                          ^~~~~
/usr/include/c++/14/bits/basic_string.h:3888:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> bool std::operator<(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const _CharT*)'
 3888 |     operator<(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3888:5: note:   template argument deduction/substitution failed:
a.cc:25:42: note:   'std::basic_ostream<char>::__ostream_type' {aka 'std::basic_ostream<char>'} is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   25 |   cout<<fixed<<setprecision(8)<<u.x<<u.y<flush;
      |                                          ^~~~~
/usr/include/c++/14/bits/basic_string.h:3901:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> bool std::operator<(const _CharT*, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3901 |     operator<(const _CharT* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3901:5: note:   template argument deduction/substitution failed:
a.cc:25:42: note:   mismatched types 'const _CharT*' and 'std::basic_ostream<char>'
   25 |   cout<<fixed<<setprecision(8)<<u.x<<u.y<flush;
      |                                          ^~~~~
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:2600:5: note: candidate: 'template<class ... _TElements, class ... _UElements> constexpr bool std::operator<(const tuple<_UTypes ...>&, const tuple<_Elements ...>&)'
 2600 |     operator<(const tuple<_TElements...>& __t,
      |     ^~~~~~~~
/usr/include/c++/14/tuple:2600:5: note:   template argument deduction/sub