请各位大神赐教 百分制转化五分制

我想实现百分制到五分制的转换，我这个总是有错误
#include <iostream.h>
using namespace std;
void main()
{    int old_grade[10]=100,92,72,83,49,71;
int i
for(i=0;i<10;i++)
cout<<TranGrade(grade[i])<<endl;
}
int TranGrade(int old_grade)
{int new_grade;
switch(old_grade/10)
{
case 10:
case 9:
    new_grade=1;
    break;
case 8:
    new_grade=2;
    break;
case 7:
    new_grade=3;
    break;
case 6:
    new_grade=4;
        break;
default:
    new_grade=5;