Language: C++

#include <bits/stdc++.h>
using namespace std;
int main() {
  string s;
  sin >> s;
  vector<string> omoji;
  omoji = {'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'};
  vector<string> komoji;
  komoji = {'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'};
  for (int i = 0;i < 26;i++) {
    if (s = omoji.at(i)){
      cout << "A" << endl;
    }
    else if (s = komoji.at(i)){
      cout << "a" << endl;
    }
  }
} 

Compiler output:
a.cc: In function 'int main()':
a.cc:5:7: error: no match for 'operator>>' (operand types are '<unresolved overloaded function type>' and 'std::string' {aka 'std::__cxx11::basic_string<char>'})
    5 |   sin >> s;
      |   ~~~~^~~~
In file included from /usr/include/c++/14/string:54,
                 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.h:4064:5: note: candidate: 'std::basic_istream<_CharT, _Traits>& std::operator>>(basic_istream<_CharT, _Traits>&, __cxx11::basic_string<_CharT, _Traits, _Allocator>&) [with _CharT = char; _Traits = char_traits<char>; _Alloc = allocator<char>]'
 4064 |     operator>>(basic_istream<char>& __is, basic_string<char>& __str);
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:4059:48: note:   no known conversion for argument 1 from '<unresolved overloaded function type>' to 'std::basic_istream<char>&'
 4059 |     operator>>(basic_istream<_CharT, _Traits>& __is,
      |                ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~
In file included from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:41:
/usr/include/c++/14/cstddef:131:5: note: candidate: 'template<class _IntegerType> constexpr std::__byte_op_t<_IntegerType> std::operator>>(byte, _IntegerType)'
  131 |     operator>>(byte __b, _IntegerType __shift) noexcept
      |     ^~~~~~~~
/usr/include/c++/14/cstddef:131:5: note:   template argument deduction/substitution failed:
a.cc:5:10: note:   cannot convert 'std::sin' (type '<unresolved overloaded function type>') to type 'std::byte'
    5 |   sin >> s;
      |          ^
/usr/include/c++/14/bitset:1597:5: note: candidate: 'template<class _CharT, class _Traits, long unsigned int _Nb> std::basic_istream<_CharT, _Traits>& std::operator>>(basic_istream<_CharT, _Traits>&, bitset<_Nb>&)'
 1597 |     operator>>(std::basic_istream<_CharT, _Traits>& __is, bitset<_Nb>& __x)
      |     ^~~~~~~~
/usr/include/c++/14/bitset:1597:5: note:   template argument deduction/substitution failed:
a.cc:5:10: note:   mismatched types 'std::basic_istream<_CharT, _Traits>' and 'float(float)'
    5 |   sin >> s;
      |          ^
a.cc:5:10: note:   mismatched types 'std::basic_istream<_CharT, _Traits>' and 'long double(long double)'
a.cc:5:10: note:   mismatched types 'std::basic_istream<_CharT, _Traits>' and 'double(double) noexcept'
a.cc:5:10: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'std::bitset<_Nb>'
In file included from /usr/include/c++/14/istream:1109,
                 from /usr/include/c++/14/sstream:40,
                 from /usr/include/c++/14/complex:45,
                 from /usr/include/c++/14/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:127:
/usr/include/c++/14/bits/istream.tcc:978:5: note: candidate: 'template<class _CharT, class _Traits> std::basic_istream<_CharT, _Traits>& std::operator>>(basic_istream<_CharT, _Traits>&, _CharT&)'
  978 |     operator>>(basic_istream<_CharT, _Traits>& __in, _CharT& __c)
      |     ^~~~~~~~
/usr/include/c++/14/bits/istream.tcc:978:5: note:   template argument deduction/substitution failed:
a.cc:5:10: note:   mismatched types 'std::basic_istream<_CharT, _Traits>' and 'float(float)'
    5 |   sin >> s;
      |          ^
a.cc:5:10: note:   mismatched types 'std::basic_istream<_CharT, _Traits>' and 'long double(long double)'
a.cc:5:10: note:   mismatched types 'std::basic_istream<_CharT, _Traits>' and 'double(double) noexcept'
a.cc:5:10: note:   couldn't deduce template parameter '_Traits'
/usr/include/c++/14/istream:849:5: note: candidate: 'template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(basic_istream<char, _Traits>&, unsigned char&)'
  849 |     operator>>(basic_istream<char, _Traits>& __in, unsigned char& __c)
      |     ^~~~~~~~
/usr/include/c++/14/istream:849:5: note:   template argument deduction/substitution failed:
a.cc:5:10: note:   mismatched types 'std::basic_istream<char, _Traits>' and 'float(float)'
    5 |   sin >> s;
      |          ^
a.cc:5:10: note:   mismatched types 'std::basic_istream<char, _Traits>' and 'long double(long double)'
a.cc:5:10: note:   mismatched types 'std::basic_istream<char, _Traits>' and 'double(double) noexcept'
a.cc:5:10: note:   couldn't deduce template parameter '_Traits'
/usr/include/c++/14/istream:854:5: note: candidate: 'template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(basic_istream<char, _Traits>&, signed char&)'
  854 |     operator>>(basic_istream<char, _Traits>& __in, signed char& __c)
      |     ^~~~~~~~
/usr/include/c++/14/istream:854:5: note:   template argument deduction/substitution failed:
a.cc:5:10: note:   mismatched types 'std::basic_istream<char, _Traits>' and 'float(float)'
    5 |   sin >> s;
      |          ^
a.cc:5:10: note:   mismatched types 'std::basic_istream<char, _Traits>' and 'long double(long double)'
a.cc:5:10: note:   mismatched types 'std::basic_istream<char, _Traits>' and 'double(double) noexcept'
a.cc:5:10: note:   couldn't deduce template parameter '_Traits'
/usr/include/c++/14/istream:896:5: note: candidate: 'template<class _CharT, class _Traits> std::basic_istream<_CharT, _Traits>& std::operator>>(basic_istream<_CharT, _Traits>&, _CharT*)'
  896 |     operator>>(basic_istream<_CharT, _Traits>& __in, _CharT* __s)
      |     ^~~~~~~~
/usr/include/c++/14/istream:896:5: note:   template argument deduction/substitution failed:
a.cc:5:10: note:   mismatched types 'std::basic_istream<_CharT, _Traits>' and 'float(float)'
    5 |   sin >> s;
      |          ^
a.cc:5:10: note:   mismatched types 'std::basic_istream<_CharT, _Traits>' and 'long double(long double)'
a.cc:5:10: note:   mismatched types 'std::basic_istream<_CharT, _Traits>' and 'double(double) noexcept'
a.cc:5:10: note:   mismatched types '_CharT*' and 'std::__cxx11::basic_string<char>'
/usr/include/c++/14/istream:939:5: note: candidate: 'template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(basic_istream<char, _Traits>&, unsigned char*)'
  939 |     operator>>(basic_istream<char, _Traits>& __in, unsigned char* __s)
      |     ^~~~~~~~
/usr/include/c++/14/istream:939:5: note:   template argument deduction/substitution failed:
a.cc:5:10: note:   mismatched types 'std::basic_istream<char, _Traits>' and 'float(float)'
    5 |   sin >> s;
      |          ^
a.cc:5:10: note:   mismatched types 'std::basic_istream<char, _Traits>' and 'long double(long double)'
a.cc:5:10: note:   mismatched types 'std::basic_istream<char, _Traits>' and 'double(double) noexcept'
a.cc:5:10: note:   couldn't deduce template parameter '_Traits'
/usr/include/c++/14/istream:945:5: note: candidate: 'template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(basic_istream<char, _Traits>&, signed char*)'
  945 |     operator>>(basic_istream<char, _Traits>& __in, signed char* __s)
      |     ^~~~~~~~
/usr/include/c++/14/istream:945:5: note:   template argument deduction/substitution failed:
a.cc:5:10: note:   mismatched types 'std::basic_istream<char, _Traits>' and 'float(float)'
    5 |   sin >> s;
      |          ^
a.cc:5:10: note:   mismatched types 'std::basic_istream<char, _Traits>' and 'long double(long double)'
a.cc:5:10: note:   mismatched types 'std::basic_istream<char, _Traits>' and 'double(double) noexcept'
a.cc:5:10: note:   couldn't deduce template parameter '_Traits'
/usr/include/c++/14/istream:1099:5: note: candidate: 'template<class _Istream, class _Tp> _Istream&& std::operator>>(_Istream&&, _Tp&&)'
 1099 |     operator>>(_Istream&& __is, _Tp&& __x)
      |     ^~~~~~~~
/usr/include/c++/14/istream:1099:5: note:   template argument deduction/substitution failed:
a.cc:5:10: note:   couldn't deduce template parameter '_Istream'
    5 |   sin >> s;
      |          ^
/usr/include/c++/14/complex:509:5: note: candidate: 'template<class _Tp, class _CharT, class _Traits> std::basic_istream<_CharT, _Traits>& std::operator>>(basic_istream<_CharT, _Traits>&, complex<_Tp>&)'
  509 |     operator>>(basic_istream<_CharT, _Traits>& __is, complex<_Tp>& __x)
      |     ^~~~~~~~
/usr/include/c++/14/complex:509:5: note:   template argument deduction/substitution failed:
a.cc:5:10: note:   mismatched types 'std::basic_istream<_CharT, _Traits>' and 'float(float)'
    5 |   sin >> s;
      |          ^
a.cc:5:10: note:   mismatched types 'std::basic_istream<_CharT, _Traits>' and 'long double(long double)'
a.cc:5:10: note:   mismatched types 'std::basic_istream<_CharT, _Traits>' and 'double(double) noexcept'
a.cc:5:10: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'std::complex<_Tp>'
In file included from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:143:
/usr/include/c++/14/iomanip:76:5: note: candidate: 'template<class _CharT, class _Traits> std::basic_istream<_CharT, _Traits>& std::operator>>(basic_istream<_CharT, _Traits>&, _Resetiosflags)'
   76 |     operator>>(basic_istream<_CharT, _Traits>& __is, _Resetiosflags __f)
      |     ^~~~~~~~
/usr/include/c++/14/iomanip:76:5: note:   template argument deduction/substitution failed:
a.cc:5:10: note:   mismatched types 'std::basic_istream<_CharT, _Traits>' and 'float(float)'
    5 |   sin >> s;
      |          ^
a.cc:5:10: note:   mismatched types 'std::basic_istream<_CharT, _Traits>' and 'long double(long double)'
a.cc:5:10: note:   mismatched types 'std::basic_istream<_CharT, _Traits>' and 'double(double) noexcept'
a.cc:5:10: note:   couldn't deduce template parameter '_CharT'
/usr/include/c++/14/iomanip:106:5: note: candidate: 'template<class _CharT, class _Traits> std::basic_istream<_CharT, _Traits>& std::operator>>(basic_istream<_CharT, _Traits>&, _Setiosflags)'
  106 |     operator>>(basic_istream<_CharT, _Traits>& __is, _Setiosflags __f)
      |     ^~~~~~~~
/usr/include/c++/14/iomanip:106:5: note:   template argument deduction/substitution failed:
a.cc:5:10: note:   mismatched types 'std::basic_istream<_CharT, _Traits>' and 'float(float)'
    5 |   sin >> s;
      |          ^
a.cc:5:10: note:   mismatched types 'std::basic_istream<_CharT, _Traits>' and 'long double(long do