How to debug a macro that calculates distances between two points? - vba

Question

I have a macro that calculates distances between two points. I am unable to get it to work, and would like some help debugging it.
I have created a Google API key, and have incorporated that in as well, but for some reason the macro doesn't work
Public Function
GetDT(origin_city As String, _
origin_state As String, origin_country As String, _
destination_city As String, _
destination_state As String, destination_country As String _
)
Dim surl As String
Dim oXH As Object
Dim bodytxt As String
Dim distanc_e As String
surl = "http://maps.googleapis.com/maps/api/distancematrix/xml?origins="
& _
Replace(origin_city, " ", "+") & "+" & Replace(origin_state, " ", "+") &
"+" & Replace(origin_country, " ", "+") & _
"&destinations=" & _
Replace(destination_city, " ", "+") & "+" & Replace(destination_state, "
", "+") & "+" & Replace(destination_country, " ", "+") & _
"&mode=driving&units=metric&key=MY_KEY"
Set oXH = CreateObject("msxml2.xmlhttp")
With oXH
.Open "get", surl, False
.send
bodytxt = .responseText
End With
bodytxt = Right(bodytxt, Len(bodytxt) - InStr(1, bodytxt, "<text>") - 5)
tim_e = Left(bodytxt, InStr(1, bodytxt, "</text>") - 1)
bodytxt = Right(bodytxt, Len(bodytxt) - InStr(1, bodytxt, "<text>") - 5)
distanc_e = Left(bodytxt, InStr(1, bodytxt, "</text>") - 1)
GetDT = distanc_e
Set oXH = Nothing
End Function

Answer 1

There is no way to confidently answer this question with the information provided. Writing a separate function to create the url will make your code more testable. Using Option Explicit to force all variables to be declared will detect any typos.
If MY_KEY is a variable then the url should look like this "..metric&key=" & MY_KEY.
surl = GetDTURL(origin_city, origin_state, origin_country, destination_city, destination_state, destination_country)
Function GetDTURL(origin_city As String, origin_state As String, origin_country As String, destination_city As String, destination_state As String, destination_country As String)
Dim surl As String
Const BaseURl As String = "http://maps.googleapis.com/maps/api/distancematrix/xml?origins=#origin_city+#origin_state+#origin_country&destinations=#destination_city+#destination_state+#destination_country&mode=driving&units=metric&key=MY_KEY"
surl = BaseURl
surl = Replace(surl, "#origin_city", origin_city)
surl = Replace(surl, "#origin_state", origin_state)
surl = Replace(surl, "#origin_country", origin_country)
surl = Replace(surl, "#destination_city", destination_city)
surl = Replace(surl, "#destination_state", destination_state)
surl = Replace(surl, "#destination_country", destination_country)
surl = Replace(surl, " ", "+")
GetDTURL = surl
End Function