Getting Zip+4 from USPS.com

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Introduction

I must start by stressing that this is for educational purposes only!! Ok, now that I got that out of the way.

The purpose of this project is to demostrate how to extract data from a website.

Lets get right to the good stuff.....the code!

The Code

The first step is to format the url with all the required information.

Function ReplaceSpaceWithPlusSign(ByVal vStr As String) As String
    Dim strTemp As String
    Try
        strTemp = Replace(vStr, vbTab, " ")
        strTemp = Replace(strTemp, vbCr, " ")
        strTemp = Replace(strTemp, vbLf, " ")
        strTemp = Replace(strTemp, " ", "+")
        ' Remove leading and trailing spaces
        strTemp = Trim(strTemp)
        Return strTemp
    Catch ex As Exception
        MsgBox("Function: ReplaceSpaceWithPlusSign" + vbCrLf + "Message: " + ex.Message, MsgBoxStyle.Critical, "Error")
    End Try
End Function

strAdd = ReplaceSpaceWithPlusSign(txtAddress.Text)
strCity = ReplaceSpaceWithPlusSign(Trim(txtCity.Text))
strState = ReplaceSpaceWithPlusSign(cmbState.Text)
'USPS web address
urlStr = "http://zip4.usps.com/zip4/zcl_0_results.jsp?visited=1&pagenumber=0&firmname=&address2=" _
           + strAdd + "&address1=&city=" + strCity + "&state=" + strState + "&urbanization=&zip5=&submit.x=6&submit.y=15"

Now that you have the correcly formatted URL pass it to a function to read the websites source code.

Public Function ReadWebSite(ByVal URL As String) As String
    Dim req As HttpWebRequest
    Dim res As HttpWebResponse
    Dim strContents As String
    Dim StrStream As Stream
    Dim Cok As Cookie
    Dim oWebResponse As WebResponse
    Dim oReturnStream As Stream
    Dim oReturnStreamReader As StreamReader
    Dim myReq As HttpWebRequest
    Dim myResponse As HttpWebResponse
    
    req = Nothing
    res = Nothing
    strContents = Nothing
    StrStream = Nothing
    Cok = Nothing
    oWebResponse = Nothing
    oReturnStream = Nothing
    oReturnStreamReader = Nothing
    myReq = Nothing
    myResponse = Nothing
Try
'***********************************************************************************************
' Connects to web site and gets cookie
'*********************************************************************************************** 
    myReq = DirectCast(WebRequest.Create(URL), HttpWebRequest)
    myReq.CookieContainer = New CookieContainer
    myResponse = DirectCast(myReq.GetResponse, HttpWebResponse)
    myResponse.Cookies = myReq.CookieContainer.GetCookies(myReq.RequestUri)
 
    If myResponse.Cookies.Count > 0 Then
        Cok = myResponse.Cookies(0)
    Else
        Cok = Nothing
    End If
'***********************************************************************************************
'***********************************************************************************************
' Constucts html request
'*********************************************************************************************** 
    req = DirectCast(WebRequest.Create(URL), HttpWebRequest)
    req.Accept = "*/*"
    req.ContentType = "application/x-www-form-urlencoded"
    req.AllowAutoRedirect = True
    req.UserAgent = "Mozilla/4.0 (compatible;" + " MSIE 6.0; Windows NT 5.0; .NET CLR 1.0.3705)"
    req.ContentType = "application/x-www-form-urlencoded" '"text/html"
    If Not Cok Is Nothing Then
        req.CookieContainer = New CookieContainer
        req.CookieContainer.Add(Cok)
    End If
'***********************************************************************************************
'***********************************************************************************************
' Retrieves HTML Response
'*********************************************************************************************** 
    oWebResponse = req.GetResponse()
    oReturnStream = oWebResponse.GetResponseStream()
    oReturnStreamReader = New StreamReader(oReturnStream)
    strContents = oReturnStreamReader.ReadToEnd().Trim()
    oReturnStreamReader.Close()
    myResponse.Close()
    Return strContents
Catch ex As Exception
    If UCase(ex.Message) = UCase("The operation has timed-out.") Then
        MsgBox("Please try again" + vbCrLf + "Postal service website timed-out.", MsgBoxStyle.Information, "Website timed-out")
        Return ""
    ElseIf UCase(ex.Message) = UCase("The remote server returned an error: (500) Internal Server Error.") Then
        MsgBox("Please try again" + vbCrLf + "Postal service website returned an Internal Error.", MsgBoxStyle.Information, "Internal Error")
        Return ""
    ElseIf UCase(ex.Message) = UCase("Thread was being aborted.") Or UCase(ex.Message) = UCase("Thread was being aborted") Then
    'Do nothing
    Else
        MsgBox("Function: ReadWebSite" + vbCrLf + "Message: " + ex.Message, MsgBoxStyle.Critical, "Error")
        Return ""
    End If
End Try
'***********************************************************************************************
End Function

Now that you have the source code pass it to another function that uses regular expressions to find the zip code.

Public Function GetZipCodeFromWeb(ByVal str As String) As String
    Dim RemoveNonDigits As String
    'Removes all none digits
    Dim r1 As Regex = New Regex("[^\d]")
    'String format on usps.com's web site
    Dim r12 As Regex = New Regex("(\d{5})-(\d{4})")
    'Finds all digits
    Dim r13 As Regex = New Regex("\d\d\d\d\d\d\d\d\d")
    If str <> "" Then
        Dim m14 As MatchCollection = r12.Matches(str)
        Dim lstr As String
    Try
        If m14(1).Success Then
            RemoveNonDigits = r1.Replace(m14(1).ToString, "")
            If RemoveNonDigits <> "" Then
                Dim m15 As Match = r13.Match(RemoveNonDigits)
                If m15.Success Then
                    Return Convert.ToString(Regex.Replace(m15.ToString, "(\d{5})(\d{4})", "$1-$2"))
                Else
                    Return "1"
                End If
            Else
                Return "1"
            End If
        Else
            Return "1"
        End If
    Catch ex As Exception
        If ex.TargetSite Is Nothing Then
            'Do nothing
            Return "1"
        Else
            MsgBox("Function: GetZipCodeFromWeb" + vbCrLf + "Message: " + ex.Message, MsgBoxStyle.Critical, "Error")
            Return "1"
        End If
    End Try
      Else
   Return "1"
End If
End Function

Thats it!!