/in/foo.cc: In member function 'bool DateTime::isLeapyear()':
/in/foo.cc:18:28: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   if(year%400==0||year%4==0&&year%100!=0)
                   ~~~~~~~~~^~~~~~~~~~~~~
/in/foo.cc:21:9: warning: statement has no effect [-Wunused-value]
    false;      
         ^
/in/foo.cc: In function 'void count(DateTime&, int)':
/in/foo.cc:31:6: warning: unused variable 'flag' [-Wunused-variable]
  int flag;
      ^~~~
/in/foo.cc: In member function 'bool DateTime::isLeapyear()':
/in/foo.cc:22:2: warning: control reaches end of non-void function [-Wreturn-type]
  }
  ^