foo.c: In function ‘main’:
foo.c:38:22: warning: ‘iday’ may be used uninitialized [-Wmaybe-uninitialized]
   38 |                 total=total+iday;
      |                 ~~~~~^~~~~~~~~~~
foo.c:5:26: note: ‘iday’ was declared here
    5 |     int year,month,day,i,iday;
      |                          ^~~~