Language: C++

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

int main(){
	char c;
	cin >> c;
	bloo flag = false;
	
	if(c == 'a'){
		flag = true;
	}
	else if(c == 'i'){
		flag = true;
	}
	else if(c == 'u'){
		flag = true;
	}
	else if(c == 'e'){
		flag = true;
	}
	else if(c == 'o'){
		flag = true;
	}
	else{
		flag = false;
	}
	
	if(flag == true){
		cout << "vowel" <<endl;
	}
	else{
		cout << "consonant" << endl;
	}
}

Compiler output:
a.cc:2:16: error: expected identifier before '.' token
    2 | using namespace.std;
      |                ^
a.cc:2:16: error: expected ';' before '.' token
    2 | using namespace.std;
      |                ^
      |                ;
a.cc:2:16: error: expected unqualified-id before '.' token
a.cc: In function 'int main()':
a.cc:6:9: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
    6 |         cin >> c;
      |         ^~~
      |         std::cin
In file included from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:146,
                 from a.cc:1:
/usr/include/c++/14/iostream:62:18: note: 'std::cin' declared here
   62 |   extern istream cin;           ///< Linked to standard input
      |                  ^~~
a.cc:7:9: error: 'bloo' was not declared in this scope
    7 |         bloo flag = false;
      |         ^~~~
a.cc:10:17: error: 'flag' was not declared in this scope
   10 |                 flag = true;
      |                 ^~~~
a.cc:13:17: error: 'flag' was not declared in this scope
   13 |                 flag = true;
      |                 ^~~~
a.cc:16:17: error: 'flag' was not declared in this scope
   16 |                 flag = true;
      |                 ^~~~
a.cc:19:17: error: 'flag' was not declared in this scope
   19 |                 flag = true;
      |                 ^~~~
a.cc:22:17: error: 'flag' was not declared in this scope
   22 |                 flag = true;
      |                 ^~~~
a.cc:25:17: error: 'flag' was not declared in this scope
   25 |                 flag = false;
      |                 ^~~~
a.cc:28:12: error: 'flag' was not declared in this scope
   28 |         if(flag == true){
      |            ^~~~
a.cc:29:17: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   29 |                 cout << "vowel" <<endl;
      |                 ^~~~
      |                 std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:29:35: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   29 |                 cout << "vowel" <<endl;
      |                                   ^~~~
      |                                   std::endl
In file included from /usr/include/c++/14/istream:41,
                 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/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
a.cc:32:17: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   32 |                 cout << "consonant" << endl;
      |                 ^~~~
      |                 std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:32:40: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   32 |                 cout << "consonant" << endl;
      |                                        ^~~~
      |                                        std::endl
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~