从txt文件中汇总,然后平均每10行

int i;
while (average.good()) // only while we are good
{
  sum = 0; // you need to clean it
  for(i = 0; i < 10; i++)
  {   
    average >> number;

    if (!average.good()) break; // if number of lines is not mod10

    sum = sum + number;
    // i++; you already do that in for loop
  }
  if (i)
  {
    cout << sum / i << endl; // only print after each 10 or less
  }
}

或使用单回路:

sum = 0;
int i = 0;

while (average >> number) {
  sum = sum + number;
  ++i;

  if (i == 10) {
    cout << sum / i << endl;
    sum = i = 0;
  }
}
if (i) {
  cout << sum / i << endl;
}

你可以用一个 std::deque

#include <fstream>
#include <deque>
#include <numeric>

int main()
{
    std::ifstream read("average.txt");

    constexpr unsigned linesToAverage = 10;
    std::deque<double> numbers;
    double currentNumber = 0.0;

    while (read >> currentNumber) {
        if (numbers.size() == linesToAverage) {
            std::cout << std::accumulate(std::begin(numbers), std::end(numbers), 0.0) / linesToAverage << std::endl;
            numbers.pop_back();
        }

        numbers.push_front(currentNumber);
    }

    return 0;
}