Language: C++

#include <bits/stdc++.h>
using namespace std;

int main() {
	int N,L;
    cin >> N >> L;
    vector<char> a(N);
    for(int i=0;i<N;i++){
      getline(cin,a.at(i));
    }
    sort(a.begin(),a.end());
    string s;
    for(int i=0;i<N;i++){
      s.push_back(a.at(i));
    }
    cout << s << endl;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:9:14: error: no matching function for call to 'getline(std::istream&, __gnu_cxx::__alloc_traits<std::allocator<char>, char>::value_type&)'
    9 |       getline(cin,a.at(i));
      |       ~~~~~~~^~~~~~~~~~~~~
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:9:14: note:   mismatched types 'std::__cxx11::basic_string<_CharT, _Traits, _Allocator>' and '__gnu_cxx::__alloc_traits<std::allocator<char>, char>::value_type' {aka 'char'}
    9 |       getline(cin,a.at(i));
      |       ~~~~~~~^~~~~~~~~~~~~
/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:9:14: note:   mismatched types 'std::__cxx11::basic_string<_CharT, _Traits, _Allocator>' and '__gnu_cxx::__alloc_traits<std::allocator<char>, char>::value_type' {aka 'char'}
    9 |       getline(cin,a.at(i));
      |       ~~~~~~~^~~~~~~~~~~~~
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