给出一个百分制的成绩，要求输出等级'A',B'','C','D','E'。90分以上为'A'.80~89为'B',70~79为‘C’,

#include<iostream>
using namespace std;
int main()
{  float score;
   char grade;
   cout<<"please enter score of student:";
   cin>>score;
   while(score>100&&score<0)
   {cout<<"date error,enter date again:";
   cin>>score;
   }
   switch(int(score/10))
   { 
   case 10:
   case 9:grade='A';break;
   case 8:grade='B';break;
   case 7:grade='C';break;
   case 6:grade='D';break;
   default:grade='E';
   }
   cout<<"score is "<<score<<",grade is "<<grade<<endl;
   return 0;
}