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74 Saturday Morning

Table 5-3 Continued

Pattern Matches Does Not Match
c?d cad, cod, cud, c!d cook, dad, cd
#####-#### Any “ZIP plus 4” ZIP code Anything else
[!5]#### Any five-digit number not starting with 5 Anything else

The final comparison operator is used to compare object references. The Is operator
returns True if two references refer to the same object:
ObjectRef1 Is ObjectRef2
You can also use Is to determine if an object reference does not reference anything (con-
tains the value Nothing):
ObjectRef Is Nothing

Operator Precedence

With some expressions, there is no doubt as to how it will be evaluated. Other more complex
expressions, however, can be ambiguous. Look at this expression:

12 * 3 + 5
If the multiplication is done first, you have 36 + 5 resulting in 41. If the addition is per-
formed first, you have 12 * 8 resulting in 96. VBA’s rules of operator precedence resolve this
sort of situation by specifying the order in which operations are carried out. In highest to
lowest precedence order, they are:

Exponentiation (^)
Multiplication (*) and division (/)
Integer division (\)
Modulus (mod)
Addition (+) and subtraction (-)
String concatenation (&)

In the previous example 12 * 3 + 5, the multiplication is performed first and the result
is 41.

When the order of execution is not modified by operator precedence or
parentheses, it always proceeds from left to right in the expression.
Tip
You can modify the order of execution in an expression by using parentheses. Anything
within parentheses is evaluated first, regardless of operator precedence. Thus,