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DavidB
DavidB

Reputation: 2596

How is this boolean value being set

I have come across the following code and don't understand it.

Dim bTemp as boolean = False
Dim License as integer = 2066350014
bTemp = aAreaLicence(1) And License

If aAreaLicence(1) = 64 then the boolean is set to false

If aAreaLicence(1) = 16 then the boolean is set to true

I have no idea what is happening here, can someone explain it please?

Upvotes: 2

Views: 62

Answers (3)

Matt Wilko
Matt Wilko

Reputation: 27322

From the Docs

And Operator

Performs a logical conjunction on two Boolean expressions, or a bitwise conjunction on two numeric expressions.

So in your case you are having a bitwise conjunction.

64 And 2066350014

evaluates to 0 which is False when converted to a Boolean value because it is Zero

16 And 2066350014

evaluates to 16 which is True when converted to a Boolean value because it is Non-Zero

Upvotes: 2

Iryna
Iryna

Reputation: 335

Numbers Licences and aAreaLicence(1) are converted to binary and then operation "and" is executed on every bit. So:

2066350014 (10) = 1111011001010011111111110111110 (2)
        64 (10) = 0000000000000000000000001000000 (2)
        16 (10) = 0000000000000000000000000010000 (2)

If we execute "and" operation:

1111011001010011111111110111110 
And
0000000000000000000000001000000 
=
0000000000000000000000000000000 - that means 2066350014 And 64 = false

1111011001010011111111110111110
And
0000000000000000000000000010000
=
0000000000000000000000000010000 - that means 2066350014 And 16 = true

Upvotes: 4

Dunken
Dunken

Reputation: 8681

Decimal to Binary:

2066350014 = 1111011001010011111111110111110

64 = 1000000

16 = 10000

Then use Boolean algebra: 

bTemp = aAreaLicence(1) And Licences = 64 AND 2066350014 = 0  = false

bTemp = aAreaLicence(1) And Licences = 16 AND 2066350014 = 16 = true

Upvotes: 1

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