Solved

Boolean Logic using VB functions

Posted on 2004-04-21
8
459 Views
Last Modified: 2012-06-27
I need to get visual basic to do boolean algebra so it can act like a combinational logic circuit.
I programmed it to give an output with a boolean equation but it has been returning decimal values. Why is this? This is the code I used :

Gout = ((NOT B) OR ((NOT A) AND (NOT D)) OR ((NOT A) AND (NOT C) AND (NOT F)) OR ((NOT A) AND (NOT C) AND (NOT E) AND (NOT H))

Please note also that the variables A,B,C,D,E,F,H all represent smaller formula's. These formula's use binary inputs from text boxes. The smaller formula's are all written before the Gout output in the program.
  Can you please help me with this its very urgent.
0
Comment
Question by:junebrady
8 Comments
 
LVL 5

Expert Comment

by:ennixo
ID: 10877259
you must define variables' types


Dim A As Boolean, B As Boolean, C As Boolean, D As Boolean, E As Boolean, F As Boolean, H As Boolean, Gout As Boolean
0
 
LVL 6

Expert Comment

by:PhilAI
ID: 10877425
Or use the CBool function to convert each variable to Boolean
0
 
LVL 19

Expert Comment

by:RanjeetRain
ID: 10877458
>> Please note also that the variables A,B,C,D,E,F,H all represent smaller formula's

Your formulaes must return Boolean values. For testing purpose do this.

MsgBox A
MsgBox B
MsgBox C
MsgBox D
MsgBox E
MsgBox F
MsgBox G
MsgBox H

If any of them display any values other than a "True" or a "False", then you know where to check!
0
DevOps Toolchain Recommendations

Read this Gartner Research Note and discover how your IT organization can automate and optimize DevOps processes using a toolchain architecture.

 
LVL 76

Expert Comment

by:David Lee
ID: 10877483
I don't think you HAVE to define the variables types, although it certainly makes sense to do so.  Consider the online help text for the Boolean data type:

----

Boolean variables are stored as 16-bit (2-byte) numbers, but they can only be True or False. Boolean variables display as either True or False (when Print is used) or #TRUE# or #FALSE# (when Write # is used). Use thekeywords True and False to assign one of the two states to Boolean variables.

When other numeric types are converted to Boolean values, 0 becomes False and all other values become True. When Boolean values are converted to other data types, False becomes 0 and True becomes -1.

----

If the values coming back are 0 and/or -1, then you are getting the numeric representation of a True/False result.  If the values are something other than 0 and -1, then as the help text states "all other values become true".  Declaring the variables as type Boolean will make interpreting the results easier and will preclude a varibale from having a value other than true or false, but it's not absolutely essential so long as you understand the rules the system uses to determine true and false values in non-Boolean data.
0
 
LVL 6

Expert Comment

by:___XXX_X_XXX___
ID: 10890787
I think that the author meant something different.

Suggestion:
These variables A,B,C,D,E,F,G and H are 8 bit numbers from 0 to 255.
So he want to make some bitwise operations like AND:
01110100
AND
00110010
________
00110000

This is "boolean algebra" for me.

junebrady: How many states (different values) your variables from A to H can have ? Is your A-H variables can contain only 0 and 1 (1 bit) or they can contain 8 bit values ?

"I programmed it to give an output with a boolean equation but it has been returning decimal values. Why is this" - Because these AND , NOT , OR operates over bits in bytes. So as above AND example, this is equivalent to
116  (Decimal)
AND
50    (Decimal)
______________

48   (Decimal)


For example try this:

MsgBox 116 And 50 ' Returns 48 as above
MsgBox 255 And 47 ' Returns 47
MsgBox 1 Or 2 ' Returns 3
MsgBox 1 Or 3 ' Returns 3
MsgBox 2 Or 3 ' Returns 3
MsgBox Not 255 ' Returns 0

You can "feel" boolean algebra logic in last 4 MsgBox examples.
Is that you need ?
0
 
LVL 5

Accepted Solution

by:
Netminder earned 0 total points
ID: 11447807
PAQed - no points refunded (of 125)

Netminder
Site Admin
0

Featured Post

ScreenConnect 6.0 Free Trial

Explore all the enhancements in one game-changing release, ScreenConnect 6.0, based on partner feedback. New features include a redesigned UI, app configurations and chat acknowledgement to improve customer engagement!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Article by: Martin
Here are a few simple, working, games that you can use as-is or as the basis for your own games. Tic-Tac-Toe This is one of the simplest of all games.   The game allows for a choice of who goes first and keeps track of the number of wins for…
You can of course define an array to hold data that is of a particular type like an array of Strings to hold customer names or an array of Doubles to hold customer sales, but what do you do if you want to coordinate that data? This article describes…
Get people started with the process of using Access VBA to control Excel using automation, Microsoft Access can control other applications. An example is the ability to programmatically talk to Excel. Using automation, an Access application can laun…
This lesson covers basic error handling code in Microsoft Excel using VBA. This is the first lesson in a 3-part series that uses code to loop through an Excel spreadsheet in VBA and then fix errors, taking advantage of error handling code. This l…

778 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question