VBA Data Types and Limits
Boolean
Dim Value As BooleanA Boolean is used to store values that can be represented as either True or False. Internally, the data type is stored as a 16 bit value with 0 representing False and any other value representing True.
It should be noted that when a Boolean is cast to a numeric type, all of the bits are set to 1. This results in an internal representation of -1 for signed types and the maximum value for an unsigned type (Byte).
Dim Example As Boolean
Example = True
Debug.Print CInt(Example) 'Prints -1
Debug.Print CBool(42) 'Prints True
Debug.Print CByte(True) 'Prints 255The casting function to convert to a Boolean is CBool(). Even though it is represented internally as a 16 bit number,
casting to a Boolean from values outside of that range is safe from overflow, although it sets all 16 bits to 1:
Dim Example As Boolean
Example = CBool(2 ^ 17)
Debug.Print CInt(Example) 'Prints -1
Debug.Print CByte(Example) 'Prints 255