/in/foo.cc: In function 'int main()':
/in/foo.cc:37:8: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
  if(n=2)
        ^
/in/foo.cc: In function 'int gongyue(int, int)':
/in/foo.cc:19:9: warning: 'yue' may be used uninitialized in this function [-Wmaybe-uninitialized]
  return yue;
         ^~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:49:18: warning: 'yue' may be used uninitialized in this function [-Wmaybe-uninitialized]
  printf("%d",yue);
                  ^