/in/foo.cc: In function 'int main()':
/in/foo.cc:9:9: error: expression '(a = 0)' is not a constant-expression
   case a=0 : cout<<"Sunday";
        ~^~
/in/foo.cc:9:10: error: modification of 'a' is not a constant-expression
   case a=0 : cout<<"Sunday";
          ^
/in/foo.cc:10:9: error: expression '(a = 1)' is not a constant-expression
   case a=1 : cout<<"Monday";
        ~^~
/in/foo.cc:10:10: error: modification of 'a' is not a constant-expression
   case a=1 : cout<<"Monday";
          ^
/in/foo.cc:11:9: error: expression '(a = 2)' is not a constant-expression
   case a=2 : cout<<"Tuesday";
        ~^~
/in/foo.cc:11:10: error: modification of 'a' is not a constant-expression
   case a=2 : cout<<"Tuesday";
          ^
/in/foo.cc:12:9: error: expression '(a = 3)' is not a constant-expression
   case a=3 : cout<<"Wednesday";
        ~^~
/in/foo.cc:12:10: error: modification of 'a' is not a constant-expression
   case a=3 : cout<<"Wednesday";
          ^
/in/foo.cc:13:9: error: expression '(a = 4)' is not a constant-expression
   case a=4 : cout<<"Thursday";
        ~^~
/in/foo.cc:13:10: error: modification of 'a' is not a constant-expression
   case a=4 : cout<<"Thursday";
          ^
/in/foo.cc:14:9: error: expression '(a = 5)' is not a constant-expression
   case a=5 : cout<<"Friday";
        ~^~
/in/foo.cc:14:10: error: modification of 'a' is not a constant-expression
   case a=5 : cout<<"Friday";
          ^
/in/foo.cc:15:9: error: expression '(a = 6)' is not a constant-expression
   case a=6 : cout<<"Sunday";
        ~^~
/in/foo.cc:15:10: error: modification of 'a' is not a constant-expression
   case a=6 : cout<<"Sunday";
          ^