如何从另一个类C＃调用一个类

Question

我正在使用4种方法来计算BMI。我如何从主体中调用方法。该代码可以编译，但不能提供所需的输出。我应该添加方法而不是类吗？输出仅要求我输入内容并终止。任何帮助都会帮助

class Program
{
    static void Main(string[] args)
    {       
        LbToKg Kgs = new LbToKg();
        InchesToMeters Mts = new InchesToMeters();
        BMIMetric BMiMet = new BMIMetric();
        BMICategory BMICat = new BMICategory();
        Console.ReadLine();
    }
    class LbToKg
    {
        public double LbsToKg(double lbs)
        {
            lbs = Convert.ToDouble(Console.ReadLine());
            double kilograms = lbs * 0.45359237;
            Console.WriteLine(lbs + " pounds is " + kilograms + " kilograms");
            Console.ReadLine();
            return kilograms;
        }
    }
    class InchesToMeters
    {
        public double InchToMeters(double inches)
        {
            inches = Convert.ToDouble(Console.ReadLine());
            double meters = inches / 39.37;
            Console.WriteLine(inches + " inches is " + meters + " meters");
            return meters;

        }
    }
    class BMIMetric
    {
        public double BMIMetrics(double kilograms, double meters)
        {
            double bmi = kilograms / (meters * meters);
            Console.WriteLine("Your BMI is:{0}", Math.Round(bmi, 4));
            return bmi;
        }
    }
    class BMICategory
    {
        public static void BMICategories(double bmi)
        {
            if (bmi < 18.5)
                Console.WriteLine("You are underweight.");
            else if (bmi > 18.5 && bmi < 24.9)
                Console.WriteLine("You're normal weight.");
            else if (bmi > 25.0 && bmi < 29.9)
                Console.WriteLine("You're Overweight.");
            else if (bmi > 30.0)
                Console.WriteLine("You are Obese"); 
        }
    }
}

Answer 1

您有点偏离轨道：您使用方法定义类，并且仅使用这些类的构造函数，该类不执行任何操作，而是要调用您定义的方法。因此，它们不应包装在任何类中，而只能包装在Program类上的方法。而且，它们应该是静态的，就像您想在static Main方法中调用它们一样。因此，您的代码应为：

class Program
{
    static void Main(string[] args)
    {       
        double kgs = LbsToKg();
        double mts = InchToMeters();
        double bmiMet = BMIMetrics(kgs, mts);
        BMICategories(bmiMet);
        Console.ReadLine();
    }
    // you don't need paramteter - you collect it from the user
    public static  double LbsToKg()
    {
        double lbs = Convert.ToDouble(Console.ReadLine());
        double kilograms = lbs * 0.45359237;
        Console.WriteLine(lbs + " pounds is " + kilograms + " kilograms");
        Console.ReadLine();
        return kilograms;
    }
    // you don't need paramteter - you collect it from the user
    public static double InchToMeters()
    {
        double inches = Convert.ToDouble(Console.ReadLine());
        double meters = inches / 39.37;
        Console.WriteLine(inches + " inches is " + meters + " meters");
        return meters;

    }

    public static double BMIMetrics(double kilograms, double meters)
    {
        double bmi = kilograms / (meters * meters);
        Console.WriteLine("Your BMI is:{0}", Math.Round(bmi, 4));
        return bmi;
    }

    public static void BMICategories(double bmi)
    {
        if (bmi < 18.5)
            Console.WriteLine("You are underweight.");
        else if (bmi > 18.5 && bmi < 24.9)
            Console.WriteLine("You're normal weight.");
        else if (bmi > 25.0 && bmi < 29.9)
            Console.WriteLine("You're Overweight.");
        else if (bmi > 30.0)
            Console.WriteLine("You are Obese"); 
    }

}

Answer 2

我建议在单个类中实现业务逻辑：

public class Bmi {
  public Bmi(double inches, double lbs) {
    if (inches <= 0.0)
      throw new ArgumentOutOfRangeException(nameof(inches));
    else if (lbs <= 0.0)
      throw new ArgumentOutOfRangeException(nameof(lbs));

    Inches = inches;
    Lbs = lbs;
  }

  public double Lbs    {get;}
  public double Kg     => Lbs * 0.45359237;
  public double Inches {get;}
  public double Meters => Inches / 39.37;
  public double Index  => Kg / (Meters * Meters);

  public string Description {
    get {
      double bmi = Index;

      if (bmi < 18.5) 
        return "underweight";
      else if (bmi < 24.9) 
        return "normal weight"; 
      else if (bmi < 29.9) 
        return "overweight";
      else 
        return "obese";
    }
  }

  public override string ToString() => Description;
}

我们也提取ReadDouble：

public static double ReadDouble(string title) {
  Console.WriteLine(title);

  while (true) {
    if (double.TryParse(Console.ReadLine(), out double result))
      return result;

    Console.WriteLine("Sorry, invalid syntax. Please, provide floating point value.");
  }
}

然后您可以使用它：

   static void Main(string[] args) {
     Bmi bmi = new Bmi(
       ReadDouble("Please, enter your height in inches:"),
       ReadDouble("Please, enter your weight in lbs:")
     );

     Console.WriteLine($"You are {bmi.Description}");

     Console.ReadKey();
   }  

请注意，您可以轻松提供更多信息，例如

   Console.WriteLine($"You are {bmi.Description} with BMI index {bmi.Index:f2}");

Answer 3

您没有调用任何方法，请尝试如下操作：

public static void Main(string[] args) {
    var bmi = BMIMetric.BMIMetrics(70, 170);
    BMICategory.BMICategories(bmi);
}

Answer 4

这应该对您有用。

static void Main(string[] args)
{
    double kilograms = ConsoleConvertors.LbsToKg();
    double Mts = ConsoleConvertors.InchToMeters();
    double BMiMet = ConsoleConvertors.BMIMetrics();
    double BMICat = ConsoleConvertors.BMICategories();
}

public static class  ConsoleConvertors
{
    public static double LbsToKg()
    {
        Console.WriteLine("LbsToKg - Enter lsb:");
        var lbs = Convert.ToDouble(Console.ReadLine());
        double kilograms = lbs * 0.45359237;
        Console.WriteLine(lbs + " pounds is " + kilograms + " kilograms");
        return kilograms;
    }
    public static double InchToMeters()
    {
        Console.WriteLine("InchToMeters - Enter inch:");
        var inches = Convert.ToDouble(Console.ReadLine());
        double meters = inches / 39.37;
        Console.WriteLine(inches + " inches is " + meters + " meters");
        return meters;
    }
    public static double BMIMetrics( )
    {
        Console.WriteLine("BMIMetrics - Enter kilograms :");
        var kilograms = Convert.ToDouble(Console.ReadLine());
        Console.WriteLine("BMIMetrics - Enter meters :");
        var metter = Convert.ToDouble(Console.ReadLine());
        double bmi = kilograms / (metter * metter);
        Console.WriteLine("Your BMI is:{0}", Math.Round(bmi, 4));
        return bmi;
    }
    public static double BMICategories()
    {
        Console.WriteLine("BMICategories - Enter bmi :");
        var bmi = Convert.ToDouble(Console.ReadLine());
        if (bmi < 18.5)
            Console.WriteLine("You are underweight.");
        else if (bmi > 18.5 && bmi < 24.9)
            Console.WriteLine("You're normal weight.");
        else if (bmi > 25.0 && bmi < 29.9)
            Console.WriteLine("You're Overweight.");
        else if (bmi > 30.0)
            Console.WriteLine("You are Obese");

        return bmi;
    }
}

Answer 5

这里发生的事情是您正在创建对象Kgs，Mts等，但从未调用方法LbsToKg，InchToMeters等。要调用它们，您将使用Kgs.LbsToKgs();和Mts.InchToMeters();。

通常，对于此类程序，您将使用不带单独类的方法。这是编写程序时更改最少的一种方法：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace bmiCalculator
{
    class Program
    {
        static void Main(string[] args)
        {
            double kg = LbsToKg();
            double m = InchToMeters();
            double bmi = BMIMetrics(kg, m);

            BMICategories(bmi); 

            Console.ReadLine();
        }

        public static double LbsToKg()
        {
            Console.Write("Weight in lbs: ");
            double lbs = Convert.ToDouble(Console.ReadLine());
            double kilograms = lbs * 0.45359237;
            Console.WriteLine(lbs + " pounds is " + kilograms + " kilograms");
            return kilograms;
        }

        public static double InchToMeters()
        {
            Console.Write("Height in inches: ");
            double inches = Convert.ToDouble(Console.ReadLine());
            double meters = inches / 39.37;
            Console.WriteLine(inches + " inches is " + meters + " meters");
            return meters;
        }

        public static double BMIMetrics(double kilograms, double meters)
        {
            double bmi = kilograms / (meters * meters);
            Console.WriteLine("Your BMI is:{0}", Math.Round(bmi, 4));
            return bmi;
        }

        public static void BMICategories(double bmi)
        {
            if (bmi < 18.5)
                Console.WriteLine("You are underweight.");
            else if (bmi > 18.5 && bmi < 24.9)
                Console.WriteLine("You're normal weight.");
            else if (bmi > 25.0 && bmi < 29.9)
                Console.WriteLine("You're Overweight.");
            else if (bmi > 30.0)
                Console.WriteLine("You are Obese"); 
        }
    }
}