ZIP Code and City Finder Sample

Article
06/30/2006

Microsoft Corporation

July 2004

Applies to:
Microsoft MapPoint 2002
Microsoft MapPoint 2004

Summary: Learn how to create a simple Microsoft Visual Basic 6.0 application that takes a ZIP Code as input and returns a city. (3 printed pages)

Introduction
Creating the Application

Introduction

This article describes how to build a simple Microsoft Visual Basic 6.0 application that takes a United States ZIP Code as input, returns the city that the ZIP Code is in, and centers the Microsoft MapPoint map on that ZIP Code. This sample was written for MapPoint North America and will not work with MapPoint Europe without modifications.

When you run the application, be aware of the following limitations:

Because ZIP Code boundaries do not always follow city boundaries, you might get mixed results in some cases.
Some ZIP Codes are not located in areas that MapPoint defines as a city; for these ZIP Codes, you can instead return the county that the ZIP Code is located in by using the geoShowByRegion2 constant (county) instead of geoShowByCity (city).
MapPoint might not contain ZIP Codes that have been recently added by the U.S. Postal service.

Creating the Application

To create the application

In Visual Basic, open a new Standard EXE project.
On the Project menu, click References, and then select Microsoft MapPoint 9.0 Object Library (North America).
Add a TextBox control to Form1, and in the Properties window, set the Text property to nothing (empty).
Add a CommandButton control to Form1, and in the Properties Window, change the Caption property of the Command1 control to Find city.

Double-click the CommandButton control and add the following code to the Command1_Click() subroutine:

Private Sub Command1_Click()
        Dim oCityLoc As MapPoint.Location
        Dim oMap As MapPoint.Map
        Set oMap = CreateObject("MapPoint.Application").ActiveMap
        oMap.Application.Visible=True
        oMap.Application.UserControl=True


        Dim zipCode As String
        zipCode = Text1.Text

        Set oCityLoc = FindCityForZipCode(zipCode, oMap)
        If Not (Nothing Is oCityLoc) Then
            MsgBox "ZIP Code " & zipCode & " is in " & oCityLoc.Name & "."
        Else
            MsgBox "Couldn't find city for this ZIP Code."
        End If

End Sub

' Returns the city at the center of the ZIP Code
Function FindCityForZipCode(strZip As String, oMap As MapPoint.Map) As MapPoint.Location
    Dim oZipLoc As MapPoint.Location

    Dim oZipResults As MapPoint.FindResults

    Set oZipResults = oMap.FindAddressResults(, , , , strZip, "USA")

    ' If it's not a good match, then don't accept it
    If geoFirstResultGood = oZipResults.ResultsQuality Then
        Set oZipLoc = oZipResults(1)
    Else
        Exit Function
    End If

    '  Must be a match to a Post Code (US ZIP Code)
    If Not (geoShowByPostal1 = oZipLoc.Type) Then
        Exit Function
    End If

    ' Go to the ZIP Code location on the map to hit test    
    oZipLoc.GoTo    
    Dim x As Integer
    Dim y As Integer
    x = oMap.LocationToX(oZipLoc)
    y = oMap.LocationToY(oZipLoc)

    ' Find all geographic entities at that point
    Dim oContext As MapPoint.FindResults
    Set oContext = oMap.ObjectsFromPoint(x, y)

    ' Return the city at that point (if any)    
    For Each obj In oContext
        If geoShowByCity = obj.Type Then
            Set FindCityForZipCode = obj
            Exit Function
        End If
    Next obj

End Function

Run the Visual Basic project. Type any U.S. ZIP Code in the text box. A pop-up message appears indicating the city to which the ZIP Code belongs. The MapPoint map also centers itself on that ZIP Code.

ZIP Code and City Finder Sample

Contents

Introduction

Creating the Application

Additional resources