foo.cc: In function ‘int main()’:
foo.cc:19:25: warning: ‘zhongjiancha’ may be used uninitialized [-Wmaybe-uninitialized]
   19 |             zhongjiancha+=a[i];
      |             ~~~~~~~~~~~~^~~~~~
foo.cc:6:19: note: ‘zhongjiancha’ was declared here
    6 |     int month,day,zhongjiancha,cha;cin>>month>>day;
      |                   ^~~~~~~~~~~~