C# c如何在代码中添加约束

我编写了以下代码，根据用户的年龄计算公园的总入场费。代码运行良好。我想再增加一个功能，如果用户输入年龄<0的值；再给用户两次机会输入正确的年龄值。年龄值必须大于等于0。尝试3次后，将出现一条错误消息，无效…，程序将打印感谢并终止。我不需要有人写代码，我需要一个想法，我可以在哪里和如何实现我的代码这个功能

静态环[]args {

        string username;
        int password, count=0 , num_guest , age;
        for (int i = 0; i < 3; i++)
        {
            Console.Write("Username : ");
            username = Console.ReadLine().ToString();
            Console.Write("Password : ");
             password = Convert.ToInt32(Console.ReadLine());

             if (password.Equals(63100))
             {
                 Console.Clear();
                 Console.WriteLine("Welcome " + username);
                 Console.Write("Enter number of guests : ");
                 num_guest = Convert.ToInt32(Console.ReadLine());

                 if (num_guest <= 0)
                 {
                     Console.Clear();
                     Console.WriteLine("Thank You");
                     Environment.Exit(0);
                 }
                     else
                 {

                     for (int j = 1; j <num_guest+1; j++)
                     {
                         Console.Write("Enter age of "+j+" guest : ");
                         age = Convert.ToInt32(Console.ReadLine());

                             if (age >= 0)
                             {
                                 if (age == 0 && age == 1)
                                 {
                                     count = count + 0;
                                 }
                                 else if (age >= 2 && age <= 17)
                                 {
                                     count = count + 60;
                                 }

                                 else if (age >= 18 && age <= 59)
                                 {
                                     count = count + 35;
                                 }

                                 else if (age > 60)
                                 {
                                     count = count + 30;
                                 }
                               }

                     }

                     Console.WriteLine(count);
                     Console.ReadLine();

                 }

                 break;
             }
             else
             {
                 Console.WriteLine("Incorrect Password!");
             }
        }

        Console.Clear();
        Console.WriteLine("Bye..." );
        Environment.Exit(0);

    }

---

使用带计数器的while循环，当它达到0时，当用户输入有效年龄时终止或中断

您应该将循环与计数器一起使用，每次年龄递增计数器读取和解析年龄输入后，您可以使用while循环验证它，如果无效，请再次请求它

Console.Write("Enter age of "+j+" guest : ");
age = Convert.ToInt32(Console.ReadLine());
int tries = 0;
while (age < 0)
{
    if (tries >= MAX_TRIES)
       return;
    else
       ++tries;

    Console.WriteLine("Age must be zero or a positive number");
    age = Convert.ToInt32(Console.ReadLine());
}

---

首先，您应该开始将代码分成不同的方法以提高可读性。如果用户在3次尝试中未输入有效年龄，则可以将其中一个方法命名为ReadValidAge并返回-1。类似于：

 private static int ReadValidAge(int guestNumber)
 {
      int result;
      for(int i = 3; i > 0;)
      {
          Console.Write("Enter Age of guest {0}: ", guestNumber);
          if(int.TryParse(Console.ReadLine(),out result) && result > 0)
          {
              return result;
          }
          else
          {
               Console.WriteLine("Invalid Age entered ... {0} Tries left!", --i); 
          }
      }
      return -1;
 }

然后调用它并使用if语句从程序中分支：

  for (int j = 1; j <num_guest+1; j++)
  {
      age = ReadValidAge(j);
      if(age == -1)
      {
          //Say byebye here

          return;
      }
      // your orignal code

 private static int ReadValidAge(int guestNumber)
 {
      int result;
      for(int i = 3; i > 0;)
      {
          Console.Write("Enter Age of guest {0}: ", guestNumber);
          if(int.TryParse(Console.ReadLine(),out result) && result > 0)
          {
              return result;
          }
          else
          {
               Console.WriteLine("Invalid Age entered ... {0} Tries left!", --i); 
          }
      }
      return -1;
 }

  for (int j = 1; j <num_guest+1; j++)
  {
      age = ReadValidAge(j);
      if(age == -1)
      {
          //Say byebye here

          return;
      }
      // your orignal code