Vb.net System.InvalidCastException:&x27；从字符串“转换”；美利坚合众国（美国）“；输入'；布尔值'；无效；

这个问题困扰了我好几天，当您运行代码时，它说转换无效。

更改此语句：

Partial Class Default2
    Inherits System.Web.UI.Page

    Private Sub form1_Load(sender As Object, e As EventArgs) Handles form1.Load

        Dim Flagimageurl(6) As String ' creating the flag image url array'
        Flagimageurl(0) = "https://www.cia.gov/library/publications/the-world-factbook/graphics/flags/large/uk-lgflag.gif"
        Flagimageurl(1) = "https://upload.wikimedia.org/wikipedia/en/thumb/c/c3/Flag_of_France.svg/800px-Flag_of_France.svg.png"
        Flagimageurl(2) = "https://upload.wikimedia.org/wikipedia/en/thumb/0/05/Flag_of_Brazil.svg/720px-Flag_of_Brazil.svg.png"
        Flagimageurl(3) = "https://upload.wikimedia.org/wikipedia/en/thumb/9/9a/Flag_of_Spain.svg/750px-Flag_of_Spain.svg.png"
        Flagimageurl(4) = "https://upload.wikimedia.org/wikipedia/en/thumb/a/a4/Flag_of_the_United_States.svg/1235px-Flag_of_the_United_States.svg.png"
        Flagimageurl(5) = "https://upload.wikimedia.org/wikipedia/commons/thumb/a/a2/Flag_of_Russia_%28Kremlin.ru%29.svg/1024px-Flag_of_Russia_%28Kremlin.ru%29.svg.png"


        Dim CountryNames(6) As String 'creating the country names array'
        CountryNames(0) = "United Kingdom"
        CountryNames(1) = "France"
        CountryNames(2) = "Brazil"
        CountryNames(3) = "Spain"
        CountryNames(4) = "United States of America (USA)"
        CountryNames(5) = "Russia"

        flag.ImageUrl = Flagimageurl(6 * Rnd()) 'Choosing a random flag'
        RadioButton1.Text = CountryNames(5 * Rnd()) 'Randomly picks the country according to the CountryNames array'
        RadioButton2.Text = CountryNames(5 * Rnd())  ' with random * 6 you get blanks so you need to use random * 5'
        RadioButton3.Text = CountryNames(5 * Rnd())
        RadioButton4.Text = CountryNames(5 * Rnd())

        If RadioButton1.Text = RadioButton2.Text Then 'Makes sure that the radiobuttons don't show duplicate answers'
            RadioButton2.Text = CountryNames(5 * Rnd())
        End If

        If RadioButton2.Text = RadioButton1.Text Then
            RadioButton1.Text = CountryNames(5 * Rnd())
        End If

        If RadioButton3.Text = RadioButton1.Text Or RadioButton2.Text Then
            RadioButton3.Text = CountryNames(5 * Rnd())
        End If

        If RadioButton4.Text = RadioButton1.Text Or RadioButton2.Text Or RadioButton3.Text Then
            RadioButton4.Text = CountryNames(5 * Rnd())
        End If

    End Sub
End Class

为此：

If RadioButton3.Text = RadioButton1.Text Or RadioButton2.Text Then

基本上，

或

子句要求两边都有布尔结果。在它的左侧，您已经正确地放置了一个带有布尔结果的逻辑语句（

RadioButton3.Text=RadioButton1.Text

），但在它的右侧，您只有一个字符串类型（

RadioButton2.Text

只是一个字符串）。这就是OR语句抛出错误的原因

---

您的下一个if语句有相同的问题，需要以相同的方式修复。

是的，谢谢您的工作，但现在如果您运行代码2，则4个选项中的2个是相同的。

If RadioButton3.Text = RadioButton1.Text Or RadioButton3.Text = RadioButton2.Text Then