Logical Operators

Table of Contents

Logical operations work with Boolean expressions to yield an answer for expressions. Individually they are quite straightforward but can be combined to create complex expressions.

Logical Operators

And Operator

The And operator requires 2 Boolean values, gives a True answer when both sides of the argument are also True, otherwise False. A logic table demonstrates this more clearly.

For the expression:

Z And X

Sub andOperator()

     Dim X As Boolean, Z As Boolean

     X = True: Z = True: Debug.Print CStr(X) & " and " & CStr(Z) & " evaluate to " & CStr(X And Z)
     X = True: Z = False: Debug.Print CStr(X) & " and " & CStr(Z) & " evaluate to " & CStr(X And Z)
     X = False: Z = True: Debug.Print CStr(X) & " and " & CStr(Z) & " evaluate to " & CStr(X And Z)
     X = False: Z = False: Debug.Print CStr(X) & " and " & CStr(Z) & " evaluate to " & CStr(X And Z)

End Sub

Running the code above produces this result in the immediate window:

True and True evaluate to True
True and False evaluate to False
False and True evaluate to False
False and False evaluate to False

Or Operator

The Or operator requires 2 Boolean values, gives a value of True when either side of the argument is True. A logic table demonstrates this more clearly.

For the expression:

Z Or X

Sub orOperator()

    Dim X As Boolean, Z As Boolean

    X = True: Z = True: Debug.Print CStr(X) & " or " & CStr(Z) & " evaluate to " & CStr(X Or Z)
    X = True: Z = False: Debug.Print CStr(X) & " or " & CStr(Z) & " evaluate to " & CStr(X Or Z)
    X = False: Z = True: Debug.Print CStr(X) & " or " & CStr(Z) & " evaluate to " & CStr(X Or Z)
    X = False: Z = False: Debug.Print CStr(X) & " or " & CStr(Z) & " evaluate to " & CStr(X Or Z)
    
End Sub

Running the code above produces this result in the immediate window:

True or True evaluate to True
True or False evaluate to True
False or True evaluate to True
False or False evaluate to False

Not Operator

The Not operator requires 1 Boolean value, gives a value of True when the argument is False, and False when the argument is True. A logic table demonstrates this more clearly.

For the expression:

Not X

Sub notOperator()

    Dim X As Boolean
    
    X = True: Debug.Print "Not " & CStr(X) & " evaluates to " & CStr(Not X)
    X = False: Debug.Print "Not " & CStr(X) & " evaluates to " & CStr(Not X)

End Sub

Running the code above produces this result in the immediate window:

Not True evaluates to False
Not False evaluates to True

A Slightly More Practical Example

Public Sub testOperator()
    Dim x As Integer
    Dim y As Integer
    Dim z As Boolean
    
    x = 1
    y = 2
    z = False
    
    'And operator
    If (x = 1) And (y = 1) Then
        Debug.Print "The AND expression has evaluated to true!"
    Else
        Debug.Print "The AND expression has evaluated to false!"
    End If
    
    'Or operator
    If (x = 1) Or (y = 1) Then
        Debug.Print "The OR expression has evaluated to true!"
    Else
        Debug.Print "The OR expression has evaluated to false!"
    End If
    
    'Not operator
    If Not z Then
        'z = false so Not z evaluates to true!!!
        Debug.Print "The NOT expression has evaluated to true!"
    Else
        Debug.Print "The NOT expression has evaluated to false!"
    End If
    
End Sub

Running the code above produces this result in the immediate window:

The AND expression has evaluated to false!
The OR expression has evaluated to true!
The NOT expression has evaluated to true!

Logical Operators