Checking person age

[BloodySandwich]

Hello, I'm working on the form where I want the user to enter their date of birth and if is under 18 they will see the message box. The form consist of 2 textboxes: Day, Year and one combobox with list of Months. At the moment no matter what year I enter everything is passing through.

Code:

Private Sub btnContinue_Click(sender As Object, e As EventArgs) Handles btnContinue.Click

        Dim currentYear As Integer = Today.Year
        Dim CURRENTmONTH As Integer = Today.Month
        Dim CurrentDay As Integer = Today.Day

        Dim birthYear As Integer = Integer.TryParse(txtYear.Text, birthYear)
        Dim birthMonth As Integer = Integer.TryParse(cboMonths.SelectedIndex - 1, birthMonth)
        Dim birthDay As Integer = Integer.TryParse(txtDay.Text, birthDay)

        Dim Age As Integer = currentYear - birthYear

        If CURRENTmONTH = birthMonth Then

            If CurrentDay < birthDay Then
                Age -= 1
            End If
        ElseIf CURRENTmONTH < birthMonth Then
            Age -= 1
        ElseIf Age < 18 Then
            MessageBox.Show("You're not old enough to register. Use guest Account")
        Else
            MessageBox.Show("You're good to go")
        End If


    End Sub

[Shaggy Hiker]

Welcome to the forums. I edited your post to add [CODE][/CODE] tags which you can do by pressing the # button and pasting the code between the resulting tags.


As for the question, you'd be better off using a DateTimePicker to get the birthday than using a trio of textboxes, but that's up to you. In any case, TryParse doesn't return an integer, it returns a Boolean, so for the code to even compile, you must have Option Strict OFF. If you turn Option Strict ON, you'll probably find several problems, and they are all worth fixing.

If you stick with the integers, you might as well just turn them into a date:

dim birthDate = new Date(birthYear,birthMonth,birthDay)

at which point you can do something like this:

If (date.Today-birthDate).TotalYears<18 Then

However, if you want to go the way you are, then fix the problem with TryParse, then put a breakpoint on the first If statement and step through the code to see what is happening. This is an excellent place to learn breakpoints and code stepping. If the code isn't doing what you expect, don't guess at why not. With a breakpoint, you can pause the code at any line and see what all the variables hold, then step forwards line by line (F11) and watch the variables change, see which branches are taken at any If statement, and so on.

[ChrisE]

Hi,

use Dtp like Shaggy said, or I would just use a Textbox

 Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
        Dim Birth As Date = TextBox4.Text
        If Date.TryParse(Birth, TextBox4.Text) = False Then
            MessageBox.Show("wrong Date !")
        End If
        Dim year, month, day As Integer
        While year <= (Now.Year - Birth.Year)
            While month <= (Now.Month - Birth.Month)
                While day <= (Now.Day - Birth.Day)
                    day += 1
                End While
                month += 1
            End While
            year += 1
        End While
        year -= 1 : month -= 1 : day -= 1
        If year < 18 Then
            MessageBox.Show("You're not old enough to register. Use guest Account")
        End If
        Label1.Text = (year & " year(s) " & month & " month(s) " & day & " day(s)")
    End Sub

regards
Chris

[BloodySandwich]

Hi Shaggy and ChrisE, thanks for helping me out. I have tried use breakpoint, and I notice that since that line the value is set to -1 for some reason and is using -1 for all calculations. I wonder why is increasing year to 2018 instead of 2016, since is suppose to calculate 2017-1? Is it because of 2017-(-1)=2018? Thanks. PS: Iam not quick at learning. Thank you for patience.
Code:

Dim birthYear As Integer = Integer.TryParse(txtYear.Text, birthYear)
        Dim birthMonth As Integer = Integer.TryParse(cboMonths.SelectedIndex - 1, birthMonth)
        Dim birthDay As Integer = Integer.TryParse(txtDay.Text, birthDay)

[techgnome]

You're using TryParse wrong... TryParse returns a BOOLEAN VALUE ... indicating if the conversion was successful or not. The numerical conversion is returned through the second parameter. So it returns the value through the output parameter, but then you immediately overwrite it by stuffing the true/false return value into the integer value. The code should look likle this:

Dim birthYear As Integer = 0
Dim birthMonth As Integer = 0
Dim birthDay As Integer = 0

If Integer.TryParse(txtYear.Text, birthYear) andalso Integer.TryParse(cboMonths.SelectedIndex - 1, birthMonth) andalso Integer.TryParse(txtDay.Text, birthDay) Then 
... work with the values here
else
.. one or more of the conversions was bad
end if

-tg

[BloodySandwich]

Is working now, thank you, guys. I really appreciate you took your time to help me. Thanks again

[Shaggy Hiker]

As I said earlier, if you turn Option Strict ON, it would have shown this problem. Option Strict is off by default, but that allows you to do unsafe conversions, so it's best to set Option Strict ON in either the project or for ALL projects using Options (Under Projects and Solutions on the VB Defaults tab).

[BloodySandwich]

Thanks for the tip I'll enable from now on.Is there any way to compare two strings from two textboxes.
Textbox1.Text = TextBox2.Text doesn't work.

[Shaggy Hiker]

In what way does it not work, cause that should work...fairly well. There are ways it can fail if you do it that way. For one thing, the capitalization has to be the same. If you don't want to care about that you can use String.Equals, which has several overloads. One of the overloads takes a third argument, which you would set to CurrentCultureIgnoreCase (or whatever option like that Intellisense gives you).

That won't take care of hidden spaces, though. A leading or trailing space would be invisible, and darn hard to see unless you are using a font that has all characters taking up the same width (TrueType fonts, I think). You can use String.Trim() to get rid of any leading or trailing spaces, but that still leaves the case where somebody put two spaces between words. There are two spaces between two of the words in the last sentence, but you may not see which two. Similarly, that can be hard to see in a textbox, and I don't know any good way to catch that.

For strings to be equal, they really have to be equal, including in their hidden characters. Trim takes care of leading and trailing characters...beyond that you're a bit hosed.

[BloodySandwich]

Well I make mistake now I know why wasn't working. I have came up with something like this? Is working well. My programming level is just beginner do you think I could improve som
Do you think is appropriate to use textchanged event for txtConfPass? Thanks
Code:

Private Sub txtPassword_KeyPress(sender As Object, e As KeyPressEventArgs) Handles txtPassword.KeyPress
        If Char.IsLetterOrDigit(e.KeyChar) And txtPassword.Text.Length < 7 or e.KeyChar= ControlsChars.Back Then
            e.Handled = False
        Else
            e.Handled = True
            lblErrPass.Visible = True
            lblErrPass.Text = "Password can consit of letters, numbers and up to 7 characters"

        End If
End Sub

 Private Sub txtConfPass_TextChanged(sender As Object, e As EventArgs) Handles txtConfPass.TextChanged
        If (txtConfPass.Text <> txtPassword.Text) Then
            lblPassCheck.Visible = True
            lblPassCheck.Text = "Password don't match."
        ElseIf (txtConfPass.Text = txtPassword.Text) Then
            lblPassCheck.Visible = True
            lblPassCheck.Text = "Correct."
        End If
End Sub