C# 读取文本文件查找最小最大平均值

Question

我正在 TAFE 学习，但类(class)和我自己都没有从我的讲师那里得到任何帮助。

我需要从一个 txt 文件中读取并从中找到最小最大值和平均值并将其打印到控制台。

之前的练习是从一个数组中获取最小最大平均值，我已经写了这个并且它工作正常。我正在使用 VS2012。

我已经编写了读取文本文件并将其打印到控制台的代码 - 但我找不到最小最大值和平均值。我得到“对象引用未设置到对象的实例”。当我运行程序时。

请注意，我使用相同的代码从数组中查找最小最大平均值...我觉得这可能是问题所在，但我无法解决!!

这是我的数组代码...

        static void Main(string[] args)
        {
            int[] hoursArray = { 1, 24, 9, 7, 6, 12, 10, 11, 23, 8, 2, 9, 8, 8, 9, 7, 9, 15, 6, 1, 7, 6, 12, 10, 11, 23, 1, 2, 9, 8 };
            for (int i = 0; i < hoursArray.Length; i++)
            {
                Console.WriteLine(hoursArray[i].ToString());
            }

            {

                {
                    int low = hoursArray[0];
                    for (int index = 1; index > hoursArray.Length; index++)
                    {
                        if (hoursArray[index] < low)
                        {
                            low = hoursArray[index];
                        }
                    }

                    Console.WriteLine("Lowest Hours Parked = " + low);

                int high = hoursArray[0];
                for (int index = 1; index < hoursArray.Length; index++)
                {
                    if (hoursArray[index] > high)
                    {
                        high = hoursArray[index];
                    }
                }

                Console.WriteLine("Highest Hours Parked = " + high);

                    int total = 0;
                    double average = 0;
                    for (int index = 0; index < hoursArray.Length; index++)
                    {
                        total = total + hoursArray[index];
                    }

                    average = (double)total / hoursArray.Length;
                    Console.WriteLine("Average Hours Parked =" + average.ToString("N"));

                    Console.ReadLine();
                }
            }
        }
    }
}

如前所述，这工作正常。现在我的问题...我已经编写了代码来显示文本文件中的数据，如下所示以及我的评论...

        static void Main(string[] args)
    {
        StreamReader hours = new StreamReader("hours.txt");
        string number = "";

        while (number != null)
        {
            number = hours.ReadLine();
            if (number != null)
                Console.WriteLine(number);
        }
        //list of numbers above is all ok when running program

        int total = 0;
        double average = 0;
        for (int index = 0; index < number.Length; index++)
        {
            total = total + number[index];
        }
        average = (double)total / number.Length;
        Console.WriteLine("Average = " + average.ToString("N2"));

        int high = number[0];

        for (int index = 0; index < number.Length; index++)
        {
            if (number[index] > high)
            {
                high = number[index];
            }
        }

        Console.WriteLine("Highest number = " + high);

        int low = number[0];

        for (int index = 0; index > number.Length; index++)
        {
            if (number[index] < low)
            {
                low = number[index];
            }
        }
        Console.WriteLine("Lowest number = " + low);
        hours.Close();
                Console.ReadLine();
        }
    }
}

Answer 1

我建议使用 Linq:

// First of all define the source - it can be an array, file - whatever:
// var source = hoursArray; // e.g. source for the array
var source = File
  .ReadLines(@"C:\MyFile.txt")         //TODO: put actual file here
  .SelectMany(line => line.Split(',')) //TODO: put actual separator here
  .Select(item => int.Parse(item));

// having got source (IEnumerable<int>) let's compute min, max, average

int max = 0;
int min = 0;
double sum = 0.0; // to prevent integer division: 7/2 = 3 when 7.0 / 2 = 3.5
int count = 0;
boolean firstItem = true;

foreach (item in source) {
  sum += item; 
  count += 1;

  if (firstItem) {
    firstItem = false;
    max = item;
    min = item;
  } 
  else if (item > max)
    max = item;
  else if (item < min)
    min = item;
}

// Finally, formatted output
Console.Write("Min = {0}; Max = {1}; Average = {2}", min, max, sum / count);