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Listing 4-2
Adding versus Concatenating Strings
Public Sub AddVersusConcatenate()
‘ Create three strings for testing.
Dim Address1 As String
Dim Address2 As Variant
Dim OtherInfo As String
‘ Place a value into the strings.
Address1 = “123 First Street”
OtherInfo = “Somewhere, NV 12345”
(continued)
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Chapter 4: Storing and Modifying Information
09_046500 ch04.qxp 12/5/06 5:54 PM Page 85

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Listing 4-2 
(continued)
‘ Place a Null value into the second address line.
Address2 = Null
‘ Concatenate the string to a null.
Dim ConString As String
ConString = Address1 & vbCrLf & _
Address2 & vbCrLf & _
OtherInfo
‘ Display the result. You see a blank line for the 
‘ null.
MsgBox ConString
‘ Add the string to a null.
Dim AddString As String
AddString = Address1 & vbCrLf & _
(Address2 + vbCrLf) & _
OtherInfo
‘ Display the result. You see no blank line.
MsgBox AddString
‘ Show that the results are correct when Address2
‘ contains a value.
Address2 = “Apt 3G”
AddString = Address1 & vbCrLf & _
(Address2 + vbCrLf) & _
OtherInfo
MsgBox AddString
End Sub
When you run this code, the first 
MsgBox
call displays the output with a
blank line between 
Address1
and 
OtherInfo
because 
Address2
is 
Null
.
However, the second 
MsgBox
call displays the data correctly because it relies
on 
+
for concatenation.
Now that you’ve seen the first two cases showing a 
Null
value, it’s time to
see what happens when 
Address2
contains a string. The code places a value
into 
Address2
, re-creates the 
AddString
value, and displays the message
box again. This time, the 
Address2
value appears between 
Address1
and
OtherInfo
, just as it should.
The 
+
can improve performance in other ways. For example, when you need to
check for a null in a variable, you can use the 
+
instead of the 
&
to improve per-
formance. Because of the way 
+
works, you don’t need to use the 
IsNull()
function to verify that a variant contains a null value before you process it.
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