/in/foo.c: In function 'main':
/in/foo.c:5:5: error: 'a' undeclared (first use in this function)
     a=2,b=5,c=3;
     ^
/in/foo.c:5:5: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:5:9: error: 'b' undeclared (first use in this function)
     a=2,b=5,c=3;
         ^
/in/foo.c:5:8: warning: left-hand operand of comma expression has no effect [-Wunused-value]
     a=2,b=5,c=3;
        ^
/in/foo.c:5:13: error: 'c' undeclared (first use in this function)
     a=2,b=5,c=3;
             ^
/in/foo.c:5:12: warning: left-hand operand of comma expression has no effect [-Wunused-value]
     a=2,b=5,c=3;
            ^
/in/foo.c:6:2: error: 'cout' undeclared (first use in this function)
  cout<<a<<" "<<b<<" "<<c<<endl;
  ^~~~
/in/foo.c:6:27: error: 'endl' undeclared (first use in this function)
  cout<<a<<" "<<b<<" "<<c<<endl;
                           ^~~~