Language: C++

#include<iostream>
#include<string>
int main()
{
  std::string src;
  std::cin>>src;
  int count=0;
  for(std::string *itr=src.begin(),std::string *itr2=src.end();itr!=src.end();++itr,--itr2)
  {
    if(*itr!=*itr2)
      ++count;
  }
  std::cout<<count/2;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:8:33: error: cannot convert 'std::__cxx11::basic_string<char>::iterator' to 'std::string*' {aka 'std::__cxx11::basic_string<char>*'} in initialization
    8 |   for(std::string *itr=src.begin(),std::string *itr2=src.end();itr!=src.end();++itr,--itr2)
      |                        ~~~~~~~~~^~
      |                                 |
      |                                 std::__cxx11::basic_string<char>::iterator
a.cc:8:48: error: qualified-id in declaration before '*' token
    8 |   for(std::string *itr=src.begin(),std::string *itr2=src.end();itr!=src.end();++itr,--itr2)
      |                                                ^
a.cc:8:47: error: expected ';' before '*' token
    8 |   for(std::string *itr=src.begin(),std::string *itr2=src.end();itr!=src.end();++itr,--itr2)
      |                                               ^~
      |                                               ;
a.cc:8:49: error: 'itr2' was not declared in this scope; did you mean 'itr'?
    8 |   for(std::string *itr=src.begin(),std::string *itr2=src.end();itr!=src.end();++itr,--itr2)
      |                                                 ^~~~
      |                                                 itr
a.cc:8:67: error: no match for 'operator!=' (operand types are 'std::string*' {aka 'std::__cxx11::basic_string<char>*'} and 'std::__cxx11::basic_string<char>::iterator')
    8 |   for(std::string *itr=src.begin(),std::string *itr2=src.end();itr!=src.end();++itr,--itr2)
      |                                                                ~~~^~~~~~~~~~~
      |                                                                |           |
      |                                                                |           std::__cxx11::basic_string<char>::iterator
      |                                                                std::string* {aka std::__cxx11::basic_string<char>*}
In file included from /usr/include/x86_64-linux-gnu/c++/14/bits/c++allocator.h:33,
                 from /usr/include/c++/14/bits/allocator.h:46,
                 from /usr/include/c++/14/string:43,
                 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/new_allocator.h:222:9: note: candidate: 'template<class _Up> bool std::operator!=(const __new_allocator<char>&, const __new_allocator<_Tp>&)'
  222 |         operator!=(const __new_allocator&, const __new_allocator<_Up>&)
      |         ^~~~~~~~
/usr/include/c++/14/bits/new_allocator.h:222:9: note:   template argument deduction/substitution failed:
a.cc:8:77: note:   'std::__cxx11::basic_string<char>::iterator' is not derived from 'const std::__new_allocator<_Tp>'
    8 |   for(std::string *itr=src.begin(),std::string *itr2=src.end();itr!=src.end();++itr,--itr2)
      |                                                                             ^
In file included from /usr/include/c++/14/iosfwd:42,
                 from /usr/include/c++/14/ios:40:
/usr/include/c++/14/bits/postypes.h:197:5: note: candidate: 'template<class _StateT> bool std::operator!=(const fpos<_StateT>&, const fpos<_StateT>&)'
  197 |     operator!=(const fpos<_StateT>& __lhs, const fpos<_StateT>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/postypes.h:197:5: note:   template argument deduction/substitution failed:
a.cc:8:77: note:   mismatched types 'const std::fpos<_StateT>' and 'std::string*' {aka 'std::__cxx11::basic_string<char>*'}
    8 |   for(std::string *itr=src.begin(),std::string *itr2=src.end();itr!=src.end();++itr,--itr2)
      |                                                                             ^
/usr/include/c++/14/bits/allocator.h:243:5: note: candidate: 'template<class _T1, class _T2> bool std::operator!=(const allocator<_CharT>&, const allocator<_T2>&)'
  243 |     operator!=(const allocator<_T1>&, const allocator<_T2>&)
      |     ^~~~~~~~
/usr/include/c++/14/bits/allocator.h:243:5: note:   template argument deduction/substitution failed:
a.cc:8:77: note:   mismatched types 'const std::allocator<_CharT>' and 'std::string*' {aka 'std::__cxx11::basic_string<char>*'}
    8 |   for(std::string *itr=src.begin(),std::string *itr2=src.end();itr!=src.end();++itr,--itr2)
      |                                                                             ^
In file included from /usr/include/c++/14/string:48:
/usr/include/c++/14/bits/stl_iterator.h:455:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator!=(const reverse_iterator<_Iterator>&, const reverse_iterator<_Iterator>&)'
  455 |     operator!=(const reverse_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:455:5: note:   template argument deduction/substitution failed:
a.cc:8:77: note:   mismatched types 'const std::reverse_iterator<_Iterator>' and 'std::string*' {aka 'std::__cxx11::basic_string<char>*'}
    8 |   for(std::string *itr=src.begin(),std::string *itr2=src.end();itr!=src.end();++itr,--itr2)
      |                                                                             ^
/usr/include/c++/14/bits/stl_iterator.h:500:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator!=(const reverse_iterator<_Iterator>&, const reverse_iterator<_IteratorR>&)'
  500 |     operator!=(const reverse_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:500:5: note:   template argument deduction/substitution failed:
a.cc:8:77: note:   mismatched types 'const std::reverse_iterator<_Iterator>' and 'std::string*' {aka 'std::__cxx11::basic_string<char>*'}
    8 |   for(std::string *itr=src.begin(),std::string *itr2=src.end();itr!=src.end();++itr,--itr2)
      |                                                                             ^
/usr/include/c++/14/bits/stl_iterator.h:1686:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator!=(const move_iterator<_IteratorL>&, const move_iterator<_IteratorR>&)'
 1686 |     operator!=(const move_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1686:5: note:   template argument deduction/substitution failed:
a.cc:8:77: note:   mismatched types 'const std::move_iterator<_IteratorL>' and 'std::string*' {aka 'std::__cxx11::basic_string<char>*'}
    8 |   for(std::string *itr=src.begin(),std::string *itr2=src.end();itr!=src.end();++itr,--itr2)
      |                                                                             ^
/usr/include/c++/14/bits/stl_iterator.h:1753:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator!=(const move_iterator<_IteratorL>&, const move_iterator<_IteratorL>&)'
 1753 |     operator!=(const move_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1753:5: note:   template argument deduction/substitution failed:
a.cc:8:77: note:   mismatched types 'const std::move_iterator<_IteratorL>' and 'std::string*' {aka 'std::__cxx11::basic_string<char>*'}
    8 |   for(std::string *itr=src.begin(),std::string *itr2=src.end();itr!=src.end();++itr,--itr2)
      |                                                                             ^
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:1052:5: note: candidate: 'template<class _T1, class _T2> constexpr bool std::operator!=(const pair<_T1, _T2>&, const pair<_T1, _T2>&)'
 1052 |     operator!=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:1052:5: note:   template argument deduction/substitution failed:
a.cc:8:77: note:   mismatched types 'const std::pair<_T1, _T2>' and 'std::string*' {aka 'std::__cxx11::basic_string<char>*'}
    8 |   for(std::string *itr=src.begin(),std::string *itr2=src.end();itr!=src.end();++itr,--itr2)
      |                                                                             ^
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:651:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator!=(basic_string_view<_CharT, _Traits>, basic_string_view<_CharT, _Traits>)'
  651 |     operator!=(basic_string_view<_CharT, _Traits> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:651:5: note:   template argument deduction/substitution failed:
a.cc:8:77: note:   mismatched types 'std::basic_string_view<_CharT, _Traits>' and 'std::string*' {aka 'std::__cxx11::basic_string<char>*'}
    8 |   for(std::string *itr=src.begin(),std::string *itr2=src.end();itr!=src.end();++itr,--itr2)
      |                                                                             ^
/usr/include/c++/14/string_view:658:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator!=(basic_string_view<_CharT, _Traits>, __type_identity_t<basic_string_view<_CharT, _Traits> >)'
  658 |     operator!=(basic_string_view<_CharT, _Traits> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:658:5: note:   template argument deduction/substitution failed:
a.cc:8:77: note:   mismatched types 'std::basic_string_view<_CharT, _Traits>' and 'std::string*' {aka 'std::__cxx11::basic_string<char>*'}
    8 |   for(std::string *itr=src.begin(),std::string *itr2=src.end();itr!=src.end();++itr,--itr2)
      |                                                                             ^
/usr/include/c++/14/string_view:666:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator!=(__type_identity_t<basic_string_view<_CharT, _Traits> >, basic_string_view<_CharT, _Traits>)'
  666 |     operator!=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:666:5: note:   template argument deduction/substitution failed:
a.cc:8:77: