Programming Excel with VBA and .NET

Expressions

In programming languages, expressions are anything that produces a result. You use expressions to evaluate something, such as a math calculation or a true/false condition. In Visual Basic, the Immediate window functions as an expression evaluator, so it’s a good place to try out different expressions, as shown in Figure 2-13.

Figure 2-13. Use the Immediate window to quickly evaluate expressions

Expressions can return values of any type, including arrays or references to objects. The Immediate window can’t display those types, however. Within a program, expressions are usually found to the right of the equals sign:

    res = CubeRoot(42)

But they can also be used as part of any statement that takes a value:

    If IsArray(Selection) Then MsgBox("You selected multiple cells.")

Simple expressions can be combined to form complex ones using operators . Visual Basic provides different sets of operators depending on the type of the expression, as listed in Table 2-9.

Table 2-9. Visual Basic operators

Numeric operators	Comparison operators (return Boolean values)	Logical operators	String operators	Object operators
^	=	And	&	Is
−	<>	Eqv	Like	Set (assign)
*	<	Imp	= (assign)
/	>	Not
\	<=	Or
Mod	>=	Xor
+
= (assign)

The Like and Is operators in Table 2-9 return Boolean values, but I group them with ...