Question

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

这个问题让我烦恼了好几天，当你运行它说转换无效的代码时。

Answer 1

更改此声明：

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

进入这个：

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

基本上，Or子句期望双方都有布尔结果。在左侧，您已经正确地使用布尔结果（RadioButton3.Text = RadioButton1.Text）放置了一个逻辑语句，但是在它的右侧，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。

你的下一个if语句有同样的问题，需要以同样的方式修复。

System.InvalidCastException：＆＃39; from string＆＃34; United States of America（USA）＆＃34;输入＆＃39;布尔＆＃39;无效。＆＃39;

1 个答案: