BMI 输出始终为 0,0 - C#

Question

我对 C# 和一般编程还很陌生，但每天都在尝试和学习！

我做了一个应用程序，正在尝试输出用户输入的 BMI，您可以选择英制和公制。

我会在这里粘贴我的代码，但我尝试了多种不同的方法，但似乎只能从我的“bmi”值中得到 0,0。我认为数学应该是正确的，但无论我将什么粘贴到身高和体重中，我总是得到 0,0。

namespace Assignment3
{
    public partial class Form1 : Form
    {
        private string name = "No name";
        private BMICalculator2 bmiCalc = new BMICalculator2();


        public Form1()
        {
            InitializeComponent();
            InitializeGUI();
        }


        private void InitializeGUI()
        {
            this.Text = "The Body Mass Calculator"; //  this = me --> Mainform

            //input controls

            lblHeight.Text = "Height (feet)";
            lblWeight.Text = "Weight (lbs)";

            //output controls
            txtHeight.Text = string.Empty;
            txtWeight.Text = string.Empty;
            rbtnImperial.Checked = true;

        }

        private void UpdateHeightText()
        {
            if (rbtnMetric.Checked)
                lblHeight.Text = "Height (cm)";
            else
                lblHeight.Text = "Height (ft, in)";


            if (rbtnImperial.Checked)
                lblWeight.Text = "Weight (lbs)";
            else
                lblWeight.Text = "Weight (kg)";
        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }

        private void textBox1_TextChanged(object sender, EventArgs e)
        {
            
        }

        private void label1_Click(object sender, EventArgs e)
        {

        }

        private void groupBox1_Enter(object sender, EventArgs e)
        {

        }

        private void groupBox2_Enter(object sender, EventArgs e)
        {

        }


        private void ReadInputBMI_Click(object sender, EventArgs e)
        {
            bool ok = ReadInputBMI(); // Calling the method checking BMI imputs

            if (ok)
            {
                CalculateAndDisplayResults();
            }

            groupBoxResult.Text = "Results for " + name; // changing the text to user's name
        }

        private void ReadName()
        {
            // reading & storing the name of user
            if (string.IsNullOrEmpty(name))
            {
                name = "NO NAME";
            }
            else
            {
                name = txtName.Text.Trim();
            }

        }

        private bool ReadHeightAndWeight()
        {
            double height = 0.0;
            double weight = 0.0;
            double inch = 0.0;

            // checking so the height and weight is a valid input

            bool ok = double.TryParse(txtHeight.Text, out height);
            if (!ok)
            {
                MessageBox.Show("The height value is invalid", "Error");
            }

             ok = ok && double.TryParse(txtWeight.Text, out weight); // only returns the ok value if both the values are valid! 

            if (!ok)
            {
                MessageBox.Show("The weight value is invalid", "Error");
            }

            // cm --> m, ft --> in

            if (bmiCalc.GetUnit() == UnitTypes.Metric)
                height = height / 100.0; // cm --> m
            else if (bmiCalc.GetUnit() == UnitTypes.American)
                height = height * 12.0 + inch; //ft --> in

            bmiCalc.SetHeight(height);
            bmiCalc.SetWeight(weight);


            return ok; // only returns the ok value if both the values are valid! 
        }

        private bool ReadInputBMI() // Reads all the imputs
        {
            ReadName();
            bool heightAndWeightOK = ReadHeightAndWeight();
            ReadUnit();

            return heightAndWeightOK;
        }

        private void ReadUnit()
        {
            if (rbtnMetric.Checked)
                bmiCalc.SetUnit(UnitTypes.Metric);
            else if (rbtnImperial.Checked)
                bmiCalc.SetUnit(UnitTypes.American);
            
           
        }

        private void CalculateAndDisplayResults()
        {
            bool inputOK = ReadInputBMI(); // read the input values
            if (inputOK)
            {
                double bmi = bmiCalc.CalculateBMI(bmiCalc.GetHeight(), bmiCalc.GetWeight(), bmiCalc.GetUnit());
                resultBMIOutput.Text = bmi.ToString("f2");
            }
        }





    private void ReadInputBMI_TextChanged(object sender, EventArgs e)
    {

    }

    private void rbtnMetric_CheckedChanged(object sender, EventArgs e)
    {
        UpdateHeightText(); // runs the checking method
    }
}

}

BMICalculator2.cs
    using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Assignment3
{
    class BMICalculator2
    {
        private string name = "No Name";
        private double height = 0;
        private double weight = 0;
        private UnitTypes unit;

        public double CalculateBMI(double height, double weight, UnitTypes unitTypes)
        {
            double bmi = 0;

            if (unitTypes == UnitTypes.Metric)
            {
                // Calculate BMI using metric values
                bmi = weight / Math.Pow(height / 100, 2);
            }
            else if (unitTypes == UnitTypes.American)
            {
                // Calculate BMI using imperial values
                bmi = (weight * 703) / Math.Pow(height, 2);
            }

            return bmi;
        }

        public string BMIWeightCategory() // BMI Values taken from Who website
        {
            double bmi = CalculateBMI(height, weight, unit);
            string stringout = string.Empty;
            if (bmi > 40)
                stringout = "Overweight (Obesity Class III)";
            else if (bmi >= 35 && bmi <= 39.9)
                stringout = "Overweight (Obesity Class II)";
            else if (bmi >= 30 && bmi <= 34.9)
                stringout = "Overweight (Obesity Class I)";
            else if (bmi >= 25 && bmi <= 29.9)
                stringout = "Overweight (Pre-obese)";
            else if (bmi >= 18.5 && bmi <= 24.9)
                stringout = "Normal weight";
            else if (bmi < 18.5)
                stringout = "Underweight";
            return stringout;
        }


        internal UnitTypes GetUnit()
        {
            return unit;
        }

        public double GetHeight()
        {
            return height;
        }

        public double GetWeight()
        {
            return weight;
        }

        // setters
        public void SetHeight(double height)
        {
        }

        public void SetUnit(UnitTypes unit)
        {
        }

        public void SetWeight(double value)
        {
            if (value >= 0)
                height = value;
        }
    }
}




UnitTypes
            enum UnitTypes
        {
            Metric,
            American
        }
    }

Answer 1

好吧，至少有一个问题是相当明显的：

        public void SetHeight(double height)
        {
        }

        public void SetUnit(UnitTypes unit)
        {
        }

        public void SetWeight(double value)
        {
            if (value >= 0)
                height = value;
        }

SetHeight

和

SetUnit

做nothing，

SetWeight

做错事。

这些类型的错误在开始编程时很容易犯。出于这个原因，学习如何使用 debugger 是必不可少的。这使您可以单步执行程序，并在执行时检查字段和变量。这使您可以验证您的假设。为什么BMI为零？因为权重为零。为什么权重为零？等等等等

另见 Eric Lippert 的文章如何调试小程序