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Tip of the Day
Language: Visual Basic
Expertise: Intermediate
Aug 20, 1997

Toggle Boolean Values Using Not

To toggle a variable between True and False, use the Not operator instead of an If statement. Use the Not operator on those variables you have explicitly set with the True or False keyword. Option 1 runs slower than Option 2. Option 1:
 If bPerform Then 
bPerform = False 
Else 
bPerform = True 
End If 
Option 2:
 bPerform = Not bPerform 
Be careful when using the Not operator on integers that are a number other than True or False (-1 and 0 respectively):
 Sub cmdBool_Click () 
Dim iBool As Integer 
Dim iTemp As Integer 

iBool = True 
Print iBool ' Prints -1 
Print Not iBool ' Prints 0 

iTemp = 5 
Print iTemp ' Prints 5 
Print Not iTemp ' Prints -6 
If iTemp Then 
Print "iTemp is True" ' Prints Here 
Else 
Print "iTemp is False" 
End If 
End Sub 
The Not operator does bitwise manipulation, so manipulating the 5 actually makes it a negative 6.
Paul D. Sheriff
 
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