/in/foo.cc: In member function 'int Date1::day(int, int)':
/in/foo.cc:32:30: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   32 |                 if(nian%4==0 && nian%100!=0||nian%400==0)
      |                    ~~~~~~~~~~^~~~~~~~~~~~~~
/in/foo.cc:31:15: warning: suggest explicit braces to avoid ambiguous 'else' [-Wdangling-else]
   31 |             if(yue==2)
      |               ^
/in/foo.cc: In member function 'int Date1::year()':
/in/foo.cc:40:26: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   40 |             if(nian%4==0 && nian%100!=0||nian%400==0)
      |                ~~~~~~~~~~^~~~~~~~~~~~~~
/in/foo.cc: In member function 'void Date1::at()':
/in/foo.cc:53:15: warning: unused variable 'd' [-Wunused-variable]
   53 |           int d=0;
      |               ^
/in/foo.cc: In member function 'int Date1::day(int, int)':
/in/foo.cc:36:9: warning: control reaches end of non-void function [-Wreturn-type]
   36 |         }
      |         ^