Sometimes a programmer would like a statement, or group of statements to execute only if certain conditions are true. There may be a different statement, or group of statements that are to be executed when the condition is false. An expression that can be evaluated to true or false is called a Boolean expression. (Named after a mathematician named Boole.)
Examples of Boolean Expressions: (X and Y are variables)
| X = 5 | (True if X has a value equal to 5) |
| X > Y | (True if X is greater than Y; example X is 7, Y is 3) |
| X < Y | (True if X is less than Y; example X is 2, Y is 2.5) |
| X <> Y | (True if X is not equal to Y; example X is 5, Y is 6) |
| X >= Y | (X is greater than or equal to Y; example X is 4, Y is 3 or 4) |
| X <= Y | (X is less than or equal to Y; example X is 4, Y is 4 or 5) |
If you want to execute one or more statements when a Boolean expression is true use the format shown below:
If Boolean exp. Then
statement 1 statement ... Else false statement 1 false statement ... End If
The Else section is optional;. If there are no statements to execute when the Boolean expression is false, you may leave out the else section.