根据用户输入寻找数组中的最大值（C＃）

Question

这里的学生。

目前正在一个项目中寻找基于用户输入的数组中的最高值。

我正在使用的当前foreach循环获取用户输入，然后只找到匹配第二个数组的第一个实例，而不是继续循环。

我试过两种方法。两者都以相同的结果结束。

首先，我尝试创建一个列表，然后排序和反转。这样我可以拿0指数，它是最高

static void Main(string[] args) 
    { 
     string[] fishColors = new string[15] { "pink", "purple", "red", "orange", "blue", "green", "pink", "green", "blue", "red", "orange", "purple", "green", "red", "purple" }; 
     int[] fishLengths = new int[15] { 49, 5, 45, 10, 14, 1, 44, 17, 48, 11, 13, 17, 20, 15, 37 }; 

     List<int> userFishLengths = new List<int>(); 

     int userChoice = 0; 
     string input = null; 
     int longestFish = 0; 

     do { 
      Console.WriteLine("Please select the number from the list below for the color of fish you would like to choose:\r\n0. Pink\r\n1. Purple\r\n2. Red\r\n3. Orange\r\n4. Blue\r\n5. Green"); 
      input = Console.ReadLine(); 
     } while (Int32.TryParse(input, out userChoice) == false) ; 

     string userColor = fishColors[userChoice]; 

     foreach (string fish in fishColors) 
     { 
      if (userColor == fish) 
      { 
       int indexID = Array.IndexOf(fishColors, fish); 
       int fishLength = fishLengths[indexID]; 
       userFishLengths.Add(fishLength); 
      } 
     } 

     userFishLengths.Sort(); 
     userFishLengths.Reverse(); 

     Console.WriteLine("The longest fish in the tank with the color you chose (" + userColor + ") is " + userFishLengths[0]+" inches."); 

    } 

其次，我试图创建一个值，它需要每次都在，并覆盖变量，如果是较大的。

static void Main(string[] args) 
    { 
     string[] fishColors = new string[15] { "pink", "purple", "red", "orange", "blue", "green", "pink", "green", "blue", "red", "orange", "purple", "green", "red", "purple" }; 
     int[] fishLengths = new int[15] { 49, 5, 45, 10, 14, 1, 44, 17, 48, 11, 13, 17, 20, 15, 37 }; 

     int userChoice = 0; 
     string input = null; 
     int longestFish = 0; 

     do { 
      Console.WriteLine("Please select the number from the list below for the color of fish you would like to choose:\r\n0. Pink\r\n1. Purple\r\n2. Red\r\n3. Orange\r\n4. Blue\r\n5. Green"); 
      input = Console.ReadLine(); 
     } while (Int32.TryParse(input, out userChoice) == false) ; 

     string userColor = fishColors[userChoice]; 

     foreach (string fish in fishColors) 
     { 
      if (userColor == fish) 
      { 
       int indexID = Array.IndexOf(fishColors, fish); 
       int fishLength = fishLengths[indexID]; 

       if (fishLength > longestFish) 
       { 
        longestFish = fishLength; 
       } 
      } 
     } 

     Console.WriteLine("The longest fish in the tank with the color you chose (" + userColor + ") is " + longestFish + " inches."); 

    } 

任何帮助/建议，将不胜感激。谢谢！

Answer 1

问题在于你的Array.IndexOf()调用。

int indexID = Array.IndexOf(fishColors, fish); 

您fishColors数组的内容不是唯一的，并且因此Array.IndexOf(fishColors, fish)呼叫被简单地返回第一匹配元素的索引。 （"pink" = 0例如，"red" = 2）

---

你会使用不同的数据结构来存储这些值更适合。使用Dictionary<TKey,TValue>进行研究，例如

var fish = new Dictionary<string, int[]>() 
{ 
    { "pink", new[] { 49, 44 } }, 
    { "purple", new[] { 5, 17, 37 } } 
}; 

这会让你更容易查找与颜色相关的长度。

---

或者，如果你一定要保留使用两个数组，你可以用一个简单的for循环，而不是一个foreach做到这一点。

for (int i = 0; i < fishColors.Length; i++) 
{ 
    if (userColor == fishColors[i]) 
    { 
     int fishLength = fishLengths[i]; 

     if (fishLength > longestFish) 
     { 
      longestFish = fishLength; 
     } 
    } 
} 

Answer 2

脚本没有工作，因为你使用：

int indexID = Array.IndexOf(fishColors, fish); 

总是给你的第一场比赛，而不是目前的对。

例如： 您正在搜索“purple”，并始终输入条目5。

如果我不想改变你的代码了，那么这将改变版本：

 static void Main(string[] args) 
     { 
      string[] fishColors = new string[15] { "pink", "purple", "red", "orange", "blue", "green", "pink", "green", "blue", "red", "orange", "purple", "green", "red", "purple" }; 
      int[] fishLengths = new int[15] { 49, 5, 45, 10, 14, 1, 44, 17, 48, 11, 13, 17, 20, 15, 37 }; 

      int userChoice = 0; 
      string input = null; 
      int longestFish = 0; 

      do 
      { 
       Console.WriteLine("Please select the number from the list below for the color of fish you would like to choose:\r\n0. Pink\r\n1. Purple\r\n2. Red\r\n3. Orange\r\n4. Blue\r\n5. Green"); 
       input = Console.ReadLine(); 
      } while (Int32.TryParse(input, out userChoice) == false); 

      string userColor = fishColors[userChoice]; 

      int indexID = 0; 
      foreach (string fish in fishColors) 
      { 
       if (userColor == fish) 
       { 
        int fishLength = fishLengths[indexID]; 

        if (fishLength > longestFish) 
        { 
         longestFish = fishLength; 
        } 
       } 
       indexID++; 
      } 

      Console.WriteLine("The longest fish in the tank with the color you chose (" + userColor + ") is " + longestFish + " inches."); 
      Console.ReadKey(); 
     } 

但随着LINQ，你可以使它更简单：

 static void Main(string[] args) 
     { 
      string[] fishColors = new string[15] { "pink", "purple", "red", "orange", "blue", "green", "pink", "green", "blue", "red", "orange", "purple", "green", "red", "purple" }; 
      int[] fishLengths = new int[15] { 49, 5, 45, 10, 14, 1, 44, 17, 48, 11, 13, 17, 20, 15, 37 }; 

      int userChoice = 0; 
      string input = null; 
      int longestFish = 0; 

      do 
      { 
       Console.WriteLine("Please select the number from the list below for the color of fish you would like to choose:\r\n0. Pink\r\n1. Purple\r\n2. Red\r\n3. Orange\r\n4. Blue\r\n5. Green"); 
       input = Console.ReadLine(); 
      } while (Int32.TryParse(input, out userChoice) == false); 

      string userColor = fishColors[userChoice]; 
      longestFish = fishColors 
       .Zip(fishLengths, (color, length) => new { color, length }) 
       .Where(s => s.color.Equals(userColor)).Max(x => x.length); 

      Console.WriteLine("The longest fish in the tank with the color you chose (" + userColor + ") is " + longestFish + " inches."); 
      Console.ReadKey(); 
     } 

Answer 3

我知道，这是学生项目;但问题是非常一个的LINQ已被设计为

string[] fishColors = new string[] //DONE: you have no need in specifing magic number "15" 
    { "pink", "purple", "red", "orange", "blue", "green", "pink", "green", "blue", 
     "red", "orange", "purple", "green", "red", "purple" }; 

    int[] fishLengths = new int[] //DONE: you have no need in specifing magic number "15" 
    { 49, 5, 45, 10, 14, 1, 44, 17, 48, 11, 13, 17, 20, 15, 37 }; 

    // Color/its index correspondence: 
    // Key - index: 1, 2, 3, ... 
    // Value - color: pink, purple, red, ... 
    var colors = fishColors 
    .Distinct() 
    .Select((color, index) => new { 
     color = color, 
     index = index + 1, }) 
    .ToDictionary(item => item.index, item => item.color); 

    string userColor = null; 

    while (true) { 
    Console.WriteLine("Please select the number from the list below for the color of fish you would like to choose:"); 

    //DONE: instead of hardcoding, build the string 
    Console.WriteLine(string.Join(Environment.NewLine, colors 
     .OrderBy(pair => pair.Key) 
     .Select(pair => $"{pair.Key}. {pair.Value}"))); 

    //DONE: input is valid if and only iff it's integer and it corresponds to color 
    if (int.TryParse(Console.ReadLine(), out var code) && // <- out var - C# 7.0 Syntax 
     colors.TryGetValue(code, out userColor)) 
     break; 
    } 

    //DONE: zip colors and lengths, filter out userColor fish only, get maximum 
    var result = fishColors 
    .Zip(fishLengths, (color, length) => new { color = color, length = length }) 
    .Where(item => item.color == userColor) 
    .Max(item => item.length); 

    //DONE: do not concat string, but use string interpolation (or formatting) 
    Console.WriteLine($"The longest fish in the tank with the color you chose ({userColor}) is {result} inches.");