C#使用迭代计算二维数组中的最小值

Question

我刚开始我的第一个 C# 编程课（完全没有编程经验），我必须要求用户输入 5 天内以及每一天的降雨量，并将数据存储在二维字符串数组中命名为雨量数据。然后我需要找到所有使用迭代输入的总和、平均值、最低和最高值。我已经算出总和和平均值，但我不知道如何找到最低值和值。我知道如何找到一维数组中的最小值和最大值，但无法计算出在多维数组中找到它所需的迭代。

string[,] rainfallData = new string[5, 2];

Console.Write("\nPlease enter a day of the week: ");
rainfallData[0, 0] = Console.ReadLine();

Console.Write("\nHow many inches of rain did you get on {0}: ", rainfallData[0, 0]);
rainfallData[0, 1] = Console.ReadLine();

Console.Write("\n\nPlease enter the next day of the week: ");
rainfallData[1, 0] = Console.ReadLine();

Console.Write("\nHow many inches of rain did you get on {0}: ", rainfallData[1, 0]);
rainfallData[1, 1] = Console.ReadLine();

Console.Write("\n\nPlease enter the next day of the week: ");
rainfallData[2, 0] = Console.ReadLine();

Console.Write("\nHow many inches of rain did you get on {0}: ", rainfallData[2, 0]);
rainfallData[2, 1] = Console.ReadLine();

Console.Write("\n\nPlease enter the next day of the week: ");
rainfallData[3, 0] = Console.ReadLine();

Console.Write("\nHow many inches of rain did you get on {0}: ", rainfallData[3, 0]);
rainfallData[3, 1] = Console.ReadLine();

Console.Write("\n\nPlease enter the next day of the week: ");
rainfallData[4, 0] = Console.ReadLine();

Console.Write("\nHow many inches of rain did you get on {0}: ", rainfallData[4, 0]);
rainfallData[4, 1] = Console.ReadLine();

double myMin2 = Convert.ToDouble(rainfallData[0, 1]);
for (int i = 0; i < rainfallData.GetLength(0); i++)
{
   foreach (double element in rainfallData[i, 1])
     {
     if (element < myMin2)
     {
       myMin2 = element;
     }
     }
}
Console.WriteLine("The day with the lowest amount of rainfall received {0}\" of rain.\n", myMin2);

无论为雨量输入什么值，myMin2 始终是雨量数据[0,1] 的值。我知道这是因为我设置了 myMin2 = Convert.ToDouble(rainfallData[0, 1] 但是在代码前面找到一维数组的最小值时，这种相同的格式有效。循环让我陷入循环和我已经在这一节卡了3个小时了。我想自己找到答案，但我怕此时见林不见林，浪费了宝贵的时间，我现在已经不在了.

PS - 我已尽力正确发布所有内容，但这是我第一次在此网站上发布，我还不知道所有规则。如果我做错了，我很抱歉。

Answer 1

问题是你把所有的数据都存储为String，然后又想以Double的方式操作

这不是最有效的代码，但它与你的接近，所以我想你会理解它：

            string[,] rainfallData = new string[5, 2];

            // Load data for 5 days. All the data is stored as string
            for (int dayOfWeek = 0; dayOfWeek < 5; dayOfWeek++)
            {
                Console.WriteLine("Please enter a day of the week: ");
                rainfallData[dayOfWeek, 0] = Console.ReadLine();

                Console.WriteLine($"How many inches of rain did you get on {rainfallData[dayOfWeek, 0]}");
                rainfallData[dayOfWeek, 1] = Console.ReadLine();
            }


            // Now let's find the minimum.
            double minRain = Double.Parse(rainfallData[0, 1]);
            for (int dayOfWeek = 1; dayOfWeek < rainfallData.GetLength(0); dayOfWeek++)
            {
                // you need to convert to double, and then compare.
                double rainOnDayOfWeek = Double.Parse(rainfallData[dayOfWeek, 1]);
                if (rainOnDayOfWeek < minRain)
                {
                    minRain = rainOnDayOfWeek;
                }
            }
            Console.WriteLine($"The day with the lowest amount of rainfall received {minRain} of rain.");

如果你不明白，请告诉我

----编辑----

仅仅写下为什么你的代码不起作用并不容易解释，我在这里尝试：

                // Here a lot of very confusing things are happening:
                // 1. All Strings are an array of characters, so here you are doing: "foreach character in rainfallData[i, 1]"
                // 2. In all programming languages, every character is also a code (number). That is called ASCII code. 
                // because you do "double element" you are asking C# to convert that character into it's code
                // for example, 'a' = 97, 'b' = 98, 'A' = 65, 'B' = 66, '1' = 49, '2' = 50
                foreach (double element in rainfallData[i, 1])
                {
                    if (element < myMin2)
                    {
                        myMin2 = element;
                    }
                }

                // This code is exactly the same as the previous one.
                // Maybe here you understand better what is going on
                foreach (char element in rainfallData[i, 1])
                {
                    // This is not the same as Convert.ToDouble, here you are getting the ASCII code of the char
                    double elementCode = (double)element; 
                    if (element < myMin2)
                    {
                        myMin2 = element;
                    }
                }

----编辑 2---- 尝试将此行添加到您的代码中，然后执行它。也许你能明白我的意思：

Console.WriteLine($"Element = '{element}'. In ASCII, '{element}' == '{(char)element}' and myMin2 = '{myMin2}'");

            double myMin2 = Convert.ToDouble(rainfallData[0, 1]);
            for (int i = 0; i < rainfallData.GetLength(0); i++)
            {
                foreach (double element in rainfallData[i, 1])
                {
                    Console.WriteLine($"Element = '{element}'. In ASCII, '{element}' == '{(char)element}' and myMin2 = '{myMin2}'");
                    if (element < myMin2)
                    {
                        myMin2 = element;
                    }
                }

Answer 2

string[,] rainfallData = new string[5, 2];
        int b = 0;
        int lowest = 99,highest=0;
        for (int i = 0; i <rainfallData.Length-5; i++)
        {

            for (b = 0; b < 1; b++)
            {

                if (i != rainfallData.Length)
                {
                    Console.Write("Please enter a day of the week: ");
                    rainfallData[i, b] = Console.ReadLine();
                    Console.Write("How many inches of rain did you get on {0}: ", rainfallData[i, b]);
                    rainfallData[i, b] = Console.ReadLine();
                }
                else
                    break;

            }

        }
        for (int i = 0; i < rainfallData.Length-5; i++)
        {
            for (b = 0; b<1; b++)
            {
                lowest = Math.Min(lowest, Convert.ToInt32(rainfallData[i, b]));
                highest = Math.Max(highest, Convert.ToInt32(rainfallData[i, b]));

            }

        }

        Console.WriteLine("The day with the lowest amount of rainfall received {0}\" of rain.", lowest);
        Console.WriteLine("The day with the highest amount of rainfall received {0}\" of rain.", highest);