Question

我很难弄清楚我的BMI计算器出了什么问题。当我进入体重指数小于10时，他们会显示为肥胖。如果我输入10以上的任何东西，它会显示为体重不足。任何帮助将不胜感激。

这张照片是我的问题的一个例子：

以下是我的计算代码：

Protected Sub btnCalc_Click(sender As Object, e As EventArgs) Handles btnCalc.Click

    Dim bmi As Double
    Dim bmiRounded As Double

    bmi = (txtWeight.Text * 703) / (txtHeight.Text * txtHeight.Text)

    bmiRounded = Math.Round(bmi, 1)
    lblBMI.Text = bmiRounded
    Select Case lblBMI.Text
        Case 0.0 To 18.5
            lblBMIResult.Text = "Underweight"
        Case 18.6 To 24.9
            lblBMIResult.Text = "Normal"
        Case 25.0 To 29.9
            lblBMIResult.Text = "Overweight"
        Case Is >= 30.0
            lblBMIResult.Text = "Obese"
    End Select
End Sub

Answer 1

您的代码存在一些问题：

最好在开始计算之前将txtWeight.Text和txtHeight.Text中的值转换为数字，而不是依靠编译器为您隐式转换它们。
您可以使用height ^ 2。
使用计算出的bmiRounded代替lblBMI.Text中的Select Case。
第一种情况可以写成Case Is <= 18.5，就像你对最后一种情况所做的那样。

以下是包含以上所有建议的更新版本：

Private Sub btnCalc_Click(sender As Object, e As EventArgs) Handles btnCalc.Click
    Dim bmi As Double
    Dim bmiRounded As Double

    Dim height As Integer = Integer.Parse(txtHeight.Text)
    Dim weight As Integer = Integer.Parse(txtWeight.Text)

    bmi = (weight * 703) / (height ^ 2)
    bmiRounded = Math.Round(bmi, 1)
    lblBMI.Text = bmiRounded

    Select Case bmiRounded
        Case Is <= 18.5
            lblBMIResult.Text = "Underweight"
        Case 18.6 To 24.9
            lblBMIResult.Text = "Normal"
        Case 25.0 To 29.9
            lblBMIResult.Text = "Overweight"
        Case Is >= 30.0
            lblBMIResult.Text = "Obese"
    End Select
End Sub

注意：我假设您将以整数形式输入身高和体重，但如果您想以小数点输入它们，请转换为Double而不是Integer：

Dim height As Double = Double.Parse(txtHeight.Text)
Dim weight As Double = Double.Parse(txtWeight.Text)

Answer 2

对数字使用数字变量。不要使用字符串参数尝试数学。将Option Strict On放在代码文件的顶部。

Option Strict On

Public Class Form1

    Private Sub btnCalc_Click(sender As Object, e As EventArgs) Handles btnCalc.Click
        Dim height As Double = Double.Parse(txtHeight.Text)
        Dim weight As Double = Double.Parse(txtWeight.Text)

        Dim bmi As Double = (weight * 703) / (height * height)
        Dim bmiRounded As Double = Math.Round(bmi, 1)

        lblBMI.Text = bmiRounded.ToString()

        Select Case bmiRounded
            Case 0.0 To 18.5
                lblBMIResult.Text = "Underweight"
            Case 18.6 To 24.9
                lblBMIResult.Text = "Normal"
            Case 25.0 To 29.9
                lblBMIResult.Text = "Overweight"
            Case Is >= 30.0
                lblBMIResult.Text = "Obese"
        End Select
    End Sub

End Class

VB错误与BMI计算

2 个答案: