Template:LogicalTruthPlugin: Difference between revisions

From QB64 Phoenix Edition Wiki
Jump to navigation Jump to search
No edit summary
No edit summary
Line 2: Line 2:
               Table 4: The logical operations and its results.
               Table 4: The logical operations and its results.


   The results of the logical operations, where '''A''' and '''B''' are the [[Expressions]]
   The results of the logical operations, where '''A''' and '''B''' are the [[Expression|Expressions]]
   to invert or combine. Both may be results of former [[Boolean]] evaluations.
   to invert or combine. Both may be results of former [[Boolean]] evaluations.
   ┌────────────────────────────────────────────────────────────────────────┐
   ┌────────────────────────────────────────────────────────────────────────┐
   │                          '''[[Logical operations]]'''                          │
   │                          '''[[Boolean|Logical Operations]]'''                          │
   ├───────┬───────┬───────┬─────────┬────────┬─────────┬─────────┬─────────┤
   ├───────┬───────┬───────┬─────────┬────────┬─────────┬─────────┬─────────┤
   │  A  │  B  │ [[NOT]] B │ A [[AND]] B │ A [[OR]] B │ A [[XOR]] B │ A [[EQV]] B │ A [[IMP]] B │
   │  A  │  B  │ [[NOT]] B │ A [[AND]] B │ A [[OR]] B │ A [[XOR]] B │ A [[EQV]] B │ A [[IMP]] B │

Revision as of 00:01, 15 December 2022

               Table 4: The logical operations and its results.

  The results of the logical operations, where A and B are the Expressions
  to invert or combine. Both may be results of former Boolean evaluations.
  ┌────────────────────────────────────────────────────────────────────────┐
  │                           Logical Operations                           │
  ├───────┬───────┬───────┬─────────┬────────┬─────────┬─────────┬─────────┤
  │   A   │   B   │ NOT B │ A AND B │ A OR B │ A XOR B │ A EQV B │ A IMP B │
  ├───────┼───────┼───────┼─────────┼────────┼─────────┼─────────┼─────────┤
  │ truetrue  │ false │  true   │ true   │  false  │  true   │  true   │
  ├───────┼───────┼───────┼─────────┼────────┼─────────┼─────────┼─────────┤
  │ truefalse │ true  │  false  │ true   │  true   │  false  │  false  │
  ├───────┼───────┼───────┼─────────┼────────┼─────────┼─────────┼─────────┤
  │ falsetrue  │ false │  false  │ true   │  true   │  false  │  true   │
  ├───────┼───────┼───────┼─────────┼────────┼─────────┼─────────┼─────────┤
  │ falsefalse │ true  │  false  │ false  │  false  │  true   │  true   │
  └───────┴───────┴───────┴─────────┴────────┴─────────┴─────────┴─────────┘
  Note: In most BASIC languages incl. QB64 these are bitwise operations,
        hence the logic is performed for each corresponding bit in both
        operators, where true or false indicates whether a bit is set or
        not set. The outcome of each bit is then placed into the respective
        position to build the bit pattern of the final result value.

   As all Relational Operations return negative one (-1, all bits set) for
    true and zero (0, no bits set) for false, this allows us to use these
    bitwise logical operations to invert or combine any relational checks,
    as the outcome is the same for each bit and so always results into a
            true (-1) or false (0) again for further evaluations.