Language: C++

#include<iostream>
#include<string>
#include<algorithm>
#define lp(i,n) for(int i=0;i<n;i++)
using namespace std;
int main(){
	int n,a,b;
	string row,com;
	cin>>row>>n;
	lp(i,n){
		cin>>com>>a>>b;
		if(com=="replace"){
			string in;
			cin>>in;
			int k=0;
			for(int i=a;i<=b;i++){
				row[i]=in[k];
				k++;
			}
		}
		else if(com=="reverse"){
			row=reverse(row[a],row[b]);
		}
		else {
			for(int i=a;i<=b;i++){
				cout<<row[i];
			}
			cout<<endl;
		}
	}
	return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:22:50: error: no match for 'operator=' (operand types are 'std::string' {aka 'std::__cxx11::basic_string<char>'} and 'void')
   22 |                         row=reverse(row[a],row[b]);
      |                                                  ^
In file included from /usr/include/c++/14/string:54,
                 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/basic_string.h:941:8: note: candidate: 'template<class _Tp> std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::_If_sv<_Tp, std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&> std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::operator=(const _Tp&) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]'
  941 |        operator=(const _Tp& __svt)
      |        ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:941:8: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/basic_string.h: In substitution of 'template<class _CharT, class _Traits, class _Alloc> template<class _Tp, class _Res> using std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::_If_sv = std::enable_if_t<((bool)std::__and_<std::is_convertible<const _Tp&, std::basic_string_view<_CharT, _Traits> >, std::__not_<std::is_convertible<const _Tp*, const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>*> >, std::__not_<std::is_convertible<const _Tp&, const _CharT*> > >::value), _Res> [with _Tp = void; _Res = std::__cxx11::basic_string<char>&; _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]':
/usr/include/c++/14/bits/basic_string.h:941:8:   required by substitution of 'template<class _Tp> std::__cxx11::basic_string<char>::_If_sv<_Tp, std::__cxx11::basic_string<char>&> std::__cxx11::basic_string<char>::operator=(const _Tp&) [with _Tp = void]'
a.cc:22:29:   required from here
   22 |                         row=reverse(row[a],row[b]);
      |                                                  ^
/usr/include/c++/14/bits/basic_string.h:152:70: error: forming reference to void
  152 |                  __not_<is_convertible<const _Tp&, const _CharT*>>>::value,
      |                                                                      ^~~~~
/usr/include/c++/14/bits/basic_string.h:817:7: note: candidate: 'std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::operator=(const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]'
  817 |       operator=(const basic_string& __str)
      |       ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:817:37: note:   no known conversion for argument 1 from 'void' to 'const std::__cxx11::basic_string<char>&'
  817 |       operator=(const basic_string& __str)
      |                 ~~~~~~~~~~~~~~~~~~~~^~~~~
/usr/include/c++/14/bits/basic_string.h:828:7: note: candidate: 'std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::operator=(const _CharT*) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]'
  828 |       operator=(const _CharT* __s)
      |       ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:828:31: note:   no known conversion for argument 1 from 'void' to 'const char*'
  828 |       operator=(const _CharT* __s)
      |                 ~~~~~~~~~~~~~~^~~
/usr/include/c++/14/bits/basic_string.h:840:7: note: candidate: 'std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::operator=(_CharT) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]'
  840 |       operator=(_CharT __c)
      |       ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:840:24: note:   no known conversion for argument 1 from 'void' to 'char'
  840 |       operator=(_CharT __c)
      |                 ~~~~~~~^~~
/usr/include/c++/14/bits/basic_string.h:858:7: note: candidate: 'std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::operator=(std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&&) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]'
  858 |       operator=(basic_string&& __str)
      |       ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:858:32: note:   no known conversion for argument 1 from 'void' to 'std::__cxx11::basic_string<char>&&'
  858 |       operator=(basic_string&& __str)
      |                 ~~~~~~~~~~~~~~~^~~~~
/usr/include/c++/14/bits/basic_string.h:926:7: note: candidate: 'std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::operator=(std::initializer_list<_Tp>) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]'
  926 |       operator=(initializer_list<_CharT> __l)
      |       ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:926:42: note:   no known conversion for argument 1 from 'void' to 'std::initializer_list<char>'
  926 |       operator=(initializer_list<_CharT> __l)
      |                 ~~~~~~~~~~~~~~~~~~~~~~~~~^~~
In file included from /usr/include/c++/14/algorithm:61,
                 from a.cc:3:
/usr/include/c++/14/bits/stl_algo.h: In instantiation of 'void std::reverse(_BIter, _BIter) [with _BIter = char]':
a.cc:22:15:   required from here
   22 |                         row=reverse(row[a],row[b]);
      |                             ~~~~~~~^~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:1089:63: error: no matching function for call to '__iterator_category(char&)'
 1089 |       std::__reverse(__first, __last, std::__iterator_category(__first));
      |                                       ~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~
In file included from /usr/include/c++/14/bits/stl_iterator_base_funcs.h:66,
                 from /usr/include/c++/14/string:47:
/usr/include/c++/14/bits/stl_iterator_base_types.h:239:5: note: candidate: 'template<class _Iter> constexpr typename std::iterator_traits< <template-parameter-1-1> >::iterator_category std::__iterator_category(const _Iter&)'
  239 |     __iterator_category(const _Iter&)
      |     ^~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_iterator_base_types.h:239:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/stl_iterator_base_types.h: In substitution of 'template<class _Iter> constexpr typename std::iterator_traits< <template-parameter-1-1> >::iterator_category std::__iterator_category(const _Iter&) [with _Iter = char]':
/usr/include/c++/14/bits/stl_algo.h:1089:63:   required from 'void std::reverse(_BIter, _BIter) [with _BIter = char]'
 1089 |       std::__reverse(__first, __last, std::__iterator_category(__first));
      |                                       ~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~
a.cc:22:15:   required from here
   22 |                         row=reverse(row[a],row[b]);
      |                             ~~~~~~~^~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_iterator_base_types.h:239:5: error: no type named 'iterator_category' in 'struct std::iterator_traits<char>'
  239 |     __iterator_category(const _Iter&)
      |     ^~~~~~~~~~~~~~~~~~~