/in/foo.cc: In function 'int main()':
/in/foo.cc:8:8: error: 'positive' was not declared in this scope
  cout<<positive;
        ^~~~~~~~
/in/foo.cc:9:8: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
  if(n=0)
        ^
/in/foo.cc:10:8: error: 'zero' was not declared in this scope
  cout<<zero;
        ^~~~
/in/foo.cc:12:8: error: 'negative' was not declared in this scope
  cout<<negative;
        ^~~~~~~~