Question

这是代码

Public Partial Class MainForm
Public Sub New()
    ' The Me.InitializeComponent call is required for Windows Forms designer support.
    Me.InitializeComponent()

    '
    ' TODO : Add constructor code after InitializeComponents
    '
End Sub

Sub Label4Click(sender As Object, e As EventArgs)

End Sub

Sub Button2Click(sender As Object, e As EventArgs)
    Dim poundInAKg As Double = 2.20462
    Dim KGInAPound As Double = 0.453592
    If pound.Text = " " Then
        MessageBox.Show("Please fill atleast one value Kilo or Pound : ")
    End If

    kilo.Text = Val(pound.Text) * 0.453592
    'pound.Text = Val(kilo.Text / 2.20462 )


End Sub

Sub MainFormLoad(sender As Object, e As EventArgs)

End Sub
End Class

错误是来自＆＃39; Double＆＃39;的隐式转换。 to＆＃39; String＆＃39;。（BC42016）请帮忙

Answer 1

您应该使用double.TryParse方法尝试将用户输入（字符串）转换为double值，然后，如果转换成功，执行moltiplication并将所有内容重新转换回字符串

Dim poundInAKg As Double = 2.20462
Dim KGInAPound As Double = 0.453592
Dim poundVal As Double
if double.TryParse(pound.Text, poundVal) Then
    kilo.Text = (poundVal * 0.453592).ToString()
else
    MessageBox.Show("Please fill atleast one value Kilo or Pound : ")
End If

如何在不使用VB.net窗体应用程序中的“”将文本框值设置为double并且make为空？

1 个答案: