我想知道如何縮短此代碼中if陳述句的重復使用-有解無憂

我重復了一系列 if 陳述句 3 次，我想知道如何解決這個問題。我嘗試制作一種更新價格的方法，但它并沒有讓我呼叫它。有沒有辦法只撰寫一次價格 if 陳述句系列，并在大小 if 陳述句中呼叫它？

我對 C# 很陌生，所以任何幫助將不勝感激。

        Console.WriteLine("What size pizza would you like?\nSmall, Medium, or Large? (S, M, L)");
        string size = Console.ReadLine();

        if(size == "S" || size =="s")
        {
            decimal price = 5.00M;
            Console.WriteLine("How many toppings would you like?\n0, 1, or 2?");
            int topping = Convert.ToInt32(Console.ReadLine());
            if (topping == 0)
            {
                price = price   0.00M;

            }
            else if (topping == 1)
            {
                price = price   1.00M;
            }
            else if (topping == 2)
            {
                price = price   1.50M;
            }
            price = Math.Round(price   (price * 0.10m), 2);
            Console.WriteLine("Including 10% tax, you total bill is ${0}", price);
        }
        else if(size == "M" || size == "m")
        {
            decimal price = 7.00M;
            Console.WriteLine("How many toppings would you like?\n0, 1, or 2?");
            int topping = Convert.ToInt32(Console.ReadLine());
            if (topping == 0)
            {
                price = price   0.00M;

            }
            else if (topping == 1)
            {
                price = price   1.00M;
            }
            else if (topping == 2)
            {
                price = price   1.50M;
            }
            price = Math.Round(price   (price * 0.10m), 2);
            Console.WriteLine("Including 10% tax, you total bill is ${0}", price);
        }
        else if (size == "L" || size == "l")
        {
            decimal price = 9.00M;
            Console.WriteLine("How many toppings would you like?\n0, 1, or 2?");
            int topping = Convert.ToInt32(Console.ReadLine());
            if (topping == 0)
            {
                price = price   0.00M;

            }
            else if (topping == 1)
            {
                price = price   1.00M;
            }
            else if (topping == 2)
            {
                price = price   1.50M;
            }


            // price = Math.Round(price   (price * 0.10m), 2);
            price = price   (price * 0.10m);

             Console.WriteLine("Including 10% tax, you total bill is ${0}", price);

        }

uj5u.com熱心網友回復：

據我所見，代碼相同，但價格不同，所以這樣做

   void GetOrder(decimal price){
      Console.WriteLine("How many toppings would you like?\n0, 1, or 2?");
      int topping = Convert.ToInt32(Console.ReadLine());
      if (topping == 0)
      {
           price = price   0.00M;

      }
      else if (topping == 1)
      {
          price = price   1.00M;
      }
      else if (topping == 2)
      {
            price = price   1.50M;
      }
      price = Math.Round(price   (price * 0.10m), 2);
      Console.WriteLine("Including 10% tax, you total bill is ${0}", price);
 }

然后做

if(size == "S" || size =="s"){
   GetOrder(5.0m);
else if(size == "M" || size == "m")        
   GetOrder(7.0m)
 ....

uj5u.com熱心網友回復：

您可以更改方法并在大約 5 行代碼中完成整個操作。這種方法更像是在現實世界中的實作方式，其中價格將存盤在一些可配置的資料存盤中，而不是嵌入到程式的代碼中：

var basePrices = new Dictionary<string, decimal>(){
  ["S"] = 5,
  ["M"] = 7,
  ["L"] = 9
};

string size = Console.ReadLine().ToUpper();
int topping = Convert.ToInt32(Console.ReadLine());

var price = (basePrices[size]   (topping > 0 ? topping * 0.5m   0.5m : 0)) * 1.1m

Console.WriteLine("Including 10% tax, you total bill is ${0:0.00}", price);

這里沒有任何錯誤檢查，為簡潔起見，我省略了 WriteLines；練習讓讀者恢復它們并進行錯誤檢查，但傳達的概念是：

您可以使用字典將一個值映射到另一個值，在這種情況下 S => 5 等
字典是區分大小寫的，所以我們 ToUpper 輸入
如果您的厚臉皮用戶將放入 S、M 或 L 以外的其他內容，您可以使用basePrices.TryGetValue(size, out var basePrice)- 如果未找到大小，則 TryGet Value 回傳 false，因此您可以使用它來給他們一個錯誤訊息而不是價格。同樣對于澆頭，如果他們鍵入 alpha chars Convert.ToInt32 將引發例外，因此您可以查看int.TryParse；與 TryGetValue 的想法相同，它回傳一個表示成功的布林值。
你的澆頭是數學的；它們看起來像每個澆頭的成本為 0.5，如果用戶想要它們，再加上 0.5 - 這test?true value:false value就是topping>0 ? ... : 0
計算澆頭價格意味著它們可以以一百萬個澆頭報價。您可以進行上限檢查
您也可以對澆頭價格使用相同的字典概念

    var toppingPrices = new Dictionary<int, decimal>(){
      [0] = 0,
      [1] = 1,
      [2] = 1.5
    }

您可以獲得字串格式化程序來進行四舍五入：格式化{0:0.00}并在其中拋出任何舊小數

uj5u.com熱心網友回復：

如果在 C# 8 或更高版本上使用帶有模式匹配的switch 運算式：

using static System.Console;

WriteLine(@"What size pizza would you like?
Small, Medium, or Large? (S, M, L)");
var price = ReadLine() switch
{
    "S" or "s" => 5.00M,
    "M" or "m" => 7.00M,
    "L" or "l" => 9.00M,
    var invalid => throw new ($"Invalid pizza size: {invalid}")
};

WriteLine(@"How many toppings would you like?
0, 1, or 2?");
price  = ReadLine() switch
{
    "0" => 0.00M,
    "1" => 1.00M,
    "2" => 1.50M,
    var invalid => throw new ($"Invalid number of toppings: {invalid}")
};
price *= 1.10M;

WriteLine($"Including 10% tax, you total bill is {price:C2}");

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標籤：C＃ if 语句

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