Word Document Properties

Part II: Learning the Ropes 
09_046500 ch04.qxp 12/5/06 5:54 PM Page 84

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In most cases it doesn’t matter whether you use the 
+
or the 
&
. The 
&
is the
traditional symbol, so you’ll see it used most often. However, it’s important to
realize that the 
+
and 
&
aren’t precisely the same, even though they normally
work the same. When in doubt, use the 
&
.
The 
+
is actually a math operation; it adds two items together. When you add
two strings, VBA concatenates them as long as there are actually two values
to add. Using the 
+
symbol can help you achieve a performance benefit, espe-
cially when you need to add many strings together. The performance benefit
occurs because VBA performs fewer checks.
The 
&
is the safer symbol and the one you should use in situations where the
+
doesn’t work. For example, when you try to add a string that contains infor-
mation to a string that doesn’t contain anything (a null string), the result is a
null string. (You must use the 
Variant
data type to create a null string; dis-
cover more about this data type in the “Working with variant data” section of
the chapter.) However, when you concatenate the two strings by using the 
&
,
the result is a string with a blank (for the null) attached.
You must also use the 
&
when you want to place text within an Excel or other
application calculation. Using 
= “Hello” + “Goodbye”
results in an error,
but using 
= “Hello” & “Goodbye”
concatenates the two strings.
Use of the 
+
assumes that the two data types are the same or that you’re adding
a string to a 
Variant
that contains a string. The 
Variant
data type can contain
anything or nothing (null). You must use 
&
to concatenate dissimilar data types,
such as a string to a number.
Sometimes you’ll use the 
&
and the 
+
together to achieve a particular result. For
example, you might experience a situation where you don’t know in advance
whether a particular variable will contain a null or a string. An address might
contain a second address line, or it might contain a null value. If you use 
&
for
all of the concatenation tasks, the output will contain a blank line. However,
using the 
+
correctly displays the data without a blank line. Listing 4-2 shows
an example of how to use 
&
and 
+
together.