给出一百分制成绩，要求输出成绩等级

if (a<=100 || a>=0) d=10;
这里应该是 d=a/10;
不然的话 d一直是10 当然是A了

#include <iostream>
using namespace std;
int main()
{char d,c,c1,c2,c3,c4,c5;
float a;
cout<<"please enter a";
cin>>a;
c1='A';
c2='B';
c3='C';
c4='D';
c5='E';
if (a<=100 || a>=0) d=a/10;
else d=0;
switch(d)
{case 10:
case 9:c=c1;break;
case 8:c=c2;break;
case 7:c=c3;break;
case 5:c=c4;break;
case 6:
case 4:
case 3:
case 2:
case 1:c=c5;break;
}
cout<<c<<endl;
return 0;
}

#include <iostream>
using namespace std;
int main()
{char d,c,c1,c2,c3,c4,c5;
float a;
cout<<"please enter a."<<endl;
cin>>a;
c1='A';
c2='B';
c3='C';
c4='D';