OR (boolean): Difference between revisions

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{{PageExamples}}
''Example:''  
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a% = 100
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{{PageSeeAlso}}
{{PageSeeAlso}}
* [[AND]], [[OR]] {{text|(logical operators)}}
* [[AND]], [[OR]]
* [[AND (boolean)]], [[XOR (boolean)]]
* [[AND (boolean)]], [[XOR (boolean)]]
* [[IF...THEN]]
* [[IF...THEN]]

Latest revision as of 21:23, 2 February 2023

The OR conditional operator evaluates an expression to true (-1) if any of the arguments is also true.


Syntax

IF expression1 OR expression2 THEN {code}


Description

  • OR adds an alternative to another conditional evaluation. If either element in the evaluation is true then the evaluation is true.
  • Parenthesis may be used to clarify the order of comparisons in an evaluation.
  • Not to be confused with the AND and OR numerical operations.


         Table 3: The relational operations for condition checking.

 In this table, A and B are the Expressions to compare. Both must represent
 the same general type, i.e. they must result into either numerical values
 or STRING values. If a test succeeds, then true (-1) is returned, false (0)
     if it fails, which both can be used in further Boolean evaluations.
 ┌─────────────────────────────────────────────────────────────────────────┐
 │                          Relational Operations                          │
 ├────────────┬───────────────────────────────────────────┬────────────────┤
 │ OperationDescriptionExample usage  │
 ├────────────┼───────────────────────────────────────────┼────────────────┤
 │   A = B    │ Tests if A is equal to B.                 │ IF A = B THEN  │
 ├────────────┼───────────────────────────────────────────┼────────────────┤
 │   A <> B   │ Tests if A is not equal to B.             │ IF A <> B THEN │
 ├────────────┼───────────────────────────────────────────┼────────────────┤
 │   A < B    │ Tests if A is less than B.                │ IF A < B THEN  │
 ├────────────┼───────────────────────────────────────────┼────────────────┤
 │   A > B    │ Tests if A is greater than B.             │ IF A > B THEN  │
 ├────────────┼───────────────────────────────────────────┼────────────────┤
 │   A <= B   │ Tests if A is less than or equal to B.    │ IF A <= B THEN │
 ├────────────┼───────────────────────────────────────────┼────────────────┤
 │   A >= B   │ Tests if A is greater than or equal to B. │ IF A >= B THEN │
 └────────────┴───────────────────────────────────────────┴────────────────┘
   The operations should be very obvious for numerical values. For strings
   be aware that all checks are done case sensitive (i.e. "Foo" <> "foo").
   The equal/not equal check is pretty much straight forward, but for the
   less/greater checks the ASCII value of the first different character is
                          used for decision making:

   E.g. "abc" is less than "abd", because in the first difference (the 3rd
        character) the "c" has a lower ASCII value than the "d".

   This behavior may give you some subtle results, if you are not aware of
                   the ASCII values and the written case:

   E.g. "abc" is greater than "abD", because the small letters have higher
        ASCII values than the capital letters, hence "c" > "D". You may use
        LCASE$ or UCASE$ to make sure both strings have the same case.


Examples

Example:

a% = 100
b% = 50

IF (a% > b% AND a% < 100) OR b% = 50 THEN PRINT "True"
True
Explanation: The first evaluation was False, but the OR evaluation made the statement true and the code was executed.


See also



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