/in/foo.c:1:1: error: unknown type name 'using'
 using namespace std;
 ^~~~~
/in/foo.c:1:17: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'std'
 using namespace std;
                 ^~~
/in/foo.c:2:6: warning: character constant too long for its type
 cout('Hello World!');
      ^~~~~~~~~~~~~~
/in/foo.c:2:6: error: expected declaration specifiers or '...' before '\x726c6421'