About Brandon Drake Expertise I can answer questions regarding the Graphics object, file access, general optimization, printing (on paper), user controls, program mathematics, the registry, creating macros, processes, and fundamental or basic questions. I have made a few asp.net pages but I do not know the language extensively. I have not done much work with databases but I have created my own database systems.
Experience I have been programming with visual basic for 6 years. In all I have written programs in about 8 programming languages, although, I only know about 3 well. I have written a few applications but mainly I like to write programs for fun.
Expert: Brandon Drake Date: 5/19/2006 Subject: boolean function
Question Dear Sir,
Need your explaination to understand the following Boolean function. Thanks in advance.
*********************************************************
Private Sub btnHire_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnHire.Click
If Not ValidateData() Then
Return
End If
Select Case cboEmployeeType.SelectedIndex
Case -1
Exit Sub
Case 0
HireFullTimeEmployee()
End Select
End Sub
Private Function ValidateData() As Boolean
Dim dataInValid As Boolean = True
If Not IsDate(txtHireDate.Text) Then
MsgBox("Hire Date must be a date in the format MM/DD/YY.", _
MsgBoxStyle.Exclamation, Me.Text)
dataInValid = False
End If
Return (dataInValid)
End Function
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Let say I hit the btnHire, it will execute the first line - If Not ValidateData() Then.
Afterthat it will go to ValidateData function.
Let say the txtHireDate.Text is in invalid format, so a message prompt and dataInValid=False.
Finally Return(dataInValid) which is False and again back to btnHire.
So what I don't understand is :
Once back to first line - If Not ValidateData() Then , what is the actual return value of this ValidateData()? This line means what ?
Answer Callisto.
1) You may be confused by this variable name "DataInValid". The variable is set to True when data is Valid and false when data is invalid.
2) When you are back in the first function, the return value of ValidateData is false. However, the word "not" reverses this--so "ValidateData"=False but "Not ValidateData()"=True. Therefore the "Return" inside the if statement will execute.
If you have any more questions or if something above is not clear you can always send me another question.
