想问下这段代码为什么会编译错误

我是个初学者自己怎么想都想不出问题出在哪想请大家指点下
#include<iostream>
const int Max = 10;

int main()
{
  using namespace std;
  double donation[Max];
  double sum = 0;
  double ave = 0;
  int count = 0;
  int i = 0;

  cout << "请输入最多10个donation值(输入非数字时将结束输入)\n";
  cout << "donation#1: ";
  while (i < Max && cin >> donation[i])
  {
    sum += donation[i];
    if (++i < Max)
      cout << "donation#" << i + 1 << ": ";
   }
  if (0 == i)
    cout << "没有donation.\n";
  ave = sum / i;
  for (int j = 0; j < i;j++)
  {
    if (donation[j] > ave)
      ++count;
   }
  cout << "平均值: " << ave << " "
       << count << " 个数字超过平均值.";
  cin.get();
  cin.get();
  return 0;
}
为什么编译时一直提示:'ave' is a assigned a value that is never used in function main()