Language: C++

#include<bits/stdc++.h>
using namespace std;
int main()
{
  char s;
  getline(cin, s);
  if(s=="ABC")
    cout<<ARC;
  else 
    cout<<ABC;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:6:10: error: no matching function for call to 'getline(std::istream&, char&)'
    6 |   getline(cin, s);
      |   ~~~~~~~^~~~~~~~
In file included from /usr/include/c++/14/string:55,
                 from /usr/include/c++/14/bitset:52,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:52,
                 from a.cc:1:
/usr/include/c++/14/bits/basic_string.tcc:907:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::basic_istream<_CharT, _Traits>& std::getline(basic_istream<_CharT, _Traits>&, __cxx11::basic_string<_CharT, _Traits, _Allocator>&, _CharT)'
  907 |     getline(basic_istream<_CharT, _Traits>& __in,
      |     ^~~~~~~
/usr/include/c++/14/bits/basic_string.tcc:907:5: note:   candidate expects 3 arguments, 2 provided
In file included from /usr/include/c++/14/string:54:
/usr/include/c++/14/bits/basic_string.h:4117:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::basic_istream<_CharT, _Traits>& std::getline(basic_istream<_CharT, _Traits>&, __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 4117 |     getline(basic_istream<_CharT, _Traits>& __is,
      |     ^~~~~~~
/usr/include/c++/14/bits/basic_string.h:4117:5: note:   template argument deduction/substitution failed:
a.cc:6:10: note:   mismatched types 'std::__cxx11::basic_string<_CharT, _Traits, _Allocator>' and 'char'
    6 |   getline(cin, s);
      |   ~~~~~~~^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:4125:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::basic_istream<_CharT, _Traits>& std::getline(basic_istream<_CharT, _Traits>&&, __cxx11::basic_string<_CharT, _Traits, _Allocator>&, _CharT)'
 4125 |     getline(basic_istream<_CharT, _Traits>&& __is,
      |     ^~~~~~~
/usr/include/c++/14/bits/basic_string.h:4125:5: note:   candidate expects 3 arguments, 2 provided
/usr/include/c++/14/bits/basic_string.h:4132:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::basic_istream<_CharT, _Traits>& std::getline(basic_istream<_CharT, _Traits>&&, __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 4132 |     getline(basic_istream<_CharT, _Traits>&& __is,
      |     ^~~~~~~
/usr/include/c++/14/bits/basic_string.h:4132:5: note:   template argument deduction/substitution failed:
a.cc:6:10: note:   mismatched types 'std::__cxx11::basic_string<_CharT, _Traits, _Allocator>' and 'char'
    6 |   getline(cin, s);
      |   ~~~~~~~^~~~~~~~
In file included from /usr/include/c++/14/cstdio:42,
                 from /usr/include/c++/14/ext/string_conversions.h:45,
                 from /usr/include/c++/14/bits/basic_string.h:4154:
/usr/include/stdio.h:697:18: note: candidate: '__ssize_t getline(char**, size_t*, FILE*)'
  697 | extern __ssize_t getline (char **__restrict __lineptr,
      |                  ^~~~~~~
/usr/include/stdio.h:697:18: note:   candidate expects 3 arguments, 2 provided
a.cc:7:7: error: ISO C++ forbids comparison between pointer and integer [-fpermissive]
    7 |   if(s=="ABC")
      |      ~^~~~~~~
a.cc:8:11: error: 'ARC' was not declared in this scope
    8 |     cout<<ARC;
      |           ^~~
a.cc:10:11: error: 'ABC' was not declared in this scope
   10 |     cout<<ABC;
      |           ^~~