vb.net - Windows 窗体中的数字 CAPTCHA 验证

Question

我正在创建一个程序，该程序在两个单独的标签上显示两个随机数，然后我必须添加/减去它们，并且应该在文本框中输入答案

如何添加或减去数字并在文本框中输入答案？

我在 Visual Basic Windows 窗体应用程序中创建它

Answer 1

I think you are trying to do some security technique. what ever it may i appreciate your try. based on the question and what am understand, i will give the following code as suggestion for you.

Code to generate random numbers and random operators in label

Dim op As Integer ' to represent the operator
Private Sub Generate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Generate.Click
    Dim Rand As New System.Random
    op = Rand.Next(0, 3)'randomly select operator 
    lblfirst.Text = Rand.Next(0, 10)'first random number
    lblsecond.Text = Rand.Next(0, 10)'second random number
    If op = 0 Then ' choosing operator based on op
        lblop.Text = "+"
    ElseIf op = 1 Then
        lblop.Text = "-"
    ElseIf op = 2 Then
        lblop.Text = "*"
    End If
End Sub

Following is the check button's click event that will evaluate the expression in label and check with the answer in the text box: display the message as result

 Private Sub check_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles check.Click
        Dim result As Double = 0.0
        If op = 0 Then
            result = CDbl(lblfirst.Text) + CDbl(lblsecond.Text)
        ElseIf op = 1 Then
            result = CDbl(lblfirst.Text) - CDbl(lblsecond.Text)
        ElseIf op = 2 Then
            result = CDbl(lblfirst.Text) * CDbl(lblsecond.Text)
        End If
        If result = CDbl(TextBox1.Text) Then
            MsgBox("Correct")
        Else
            MsgBox("Wrong")
        End If
    End Sub

Answer 2

这将在 0-10 之间添加两个随机数：

        Dim Rand As New System.Random
        Dim Rand1 as integer = Rand.Next(0, 10)
        Dim Rand2 as integer = Rand.Next(0, 10)
        YourLabel1.Text = Rand1.toString()
        YourLabel2.Text = Rand2.toString()
        YourAnswerLabel.Text = Rand1 + Rand2