ANDALSO: Difference between revisions

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File:Osx.png|'''yes'''
File:Osx.png|'''yes'''
</gallery>
</gallery>
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{{Cl|NEXT}} index
{{Cl|NEXT}} index


{{Text|<nowiki>' value of index is now > 10</nowiki>|#919191}}
{{Text|<nowiki>' value of index is now &gt; 10</nowiki>|#919191}}


{{Cl|PRINT}} {{Text|<nowiki>"Trying _ANDALSO"</nowiki>|#FFB100}}
{{Cl|PRINT}} {{Text|<nowiki>"Trying _ANDALSO"</nowiki>|#FFB100}}


{{Text|<nowiki>' _ANDALSO performs short-circuiting logical conjunction and hence the GetArrayValue check is completely bypassed</nowiki>|#919191}}
{{Text|<nowiki>' _ANDALSO performs short-circuiting logical conjunction and hence the GetArrayValue check is completely bypassed</nowiki>|#919191}}
{{Cl|IF}} index >= {{Text|1|#F580B1}} {{Cl|_ANDALSO}} index <= {{Text|10|#F580B1}} {{Cl|_ANDALSO}} {{Text|GetArrayValue|#55FF55}}(values(), index, v) {{Cl|THEN}}
{{Cl|IF}} index &gt;= {{Text|1|#F580B1}} {{Cl|_ANDALSO}} index &lt;= {{Text|10|#F580B1}} {{Cl|_ANDALSO}} {{Text|GetArrayValue|#55FF55}}(values(), index, v) {{Cl|THEN}}
     {{Cl|PRINT}} {{Text|<nowiki>"_ANDALSO: Value ="</nowiki>|#FFB100}}; v
     {{Cl|PRINT}} {{Text|<nowiki>"_ANDALSO: Value ="</nowiki>|#FFB100}}; v
{{Cl|ELSE}}
{{Cl|ELSE}}
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{{Text|<nowiki>' AND does not performs short-circuiting logical conjunction and hence QB64-PE will throw a runtime error: Subscript out of range</nowiki>|#919191}}
{{Text|<nowiki>' AND does not performs short-circuiting logical conjunction and hence QB64-PE will throw a runtime error: Subscript out of range</nowiki>|#919191}}
{{Cl|IF}} index >= {{Text|1|#F580B1}} {{Cl|AND (boolean)|AND}} index <= {{Text|10|#F580B1}} {{Cl|AND (boolean)|AND}} {{Text|GetArrayValue|#55FF55}}(values(), index, v) {{Cl|THEN}}
{{Cl|IF}} index &gt;= {{Text|1|#F580B1}} {{Cl|AND (boolean)|AND}} index &lt;= {{Text|10|#F580B1}} {{Cl|AND (boolean)|AND}} {{Text|GetArrayValue|#55FF55}}(values(), index, v) {{Cl|THEN}}
     {{Cl|PRINT}} {{Text|<nowiki>"AND: Value ="</nowiki>|#FFB100}}; v
     {{Cl|PRINT}} {{Text|<nowiki>"AND: Value ="</nowiki>|#FFB100}}; v
{{Cl|ELSE}}
{{Cl|ELSE}}

Revision as of 12:09, 8 December 2024

_ANDALSO is a boolean logical operator that performs short-circuiting logical conjunction on two expressions.


Syntax

result = firstvalue _ANDALSO secondvalue


Description

  • A logical operation is said to be short-circuiting if the compiled code can bypass the evaluation of one expression depending on the result of another expression.
  • If the result of the first expression evaluated determines the final result of the operation, there is no need to evaluate the second expression, because it cannot change the final result.
  • Short-circuiting can improve performance if the bypassed expression is complex, or if it involves procedure calls.
  • If both expressions evaluate to true, result is true.


Availability

  • none

    none

  • v3.13.0

    v3.13.0

  • Apix.png
  • yes

    yes

  • yes

    yes

  • yes

    yes


Examples

Example: AND versus _ANDALSO 

DIM AS LONG index, values(1 TO 10), v

FOR index = 1 TO 10
    values(index) = RND * 255
NEXT index

' value of index is now > 10

PRINT "Trying _ANDALSO"

' _ANDALSO performs short-circuiting logical conjunction and hence the GetArrayValue check is completely bypassed
IF index >= 1 _ANDALSO index <= 10 _ANDALSO GetArrayValue(values(), index, v) THEN
    PRINT "_ANDALSO: Value ="; v
ELSE
    PRINT "_ANDALSO: Outside range."
END IF

PRINT
PRINT "Trying AND"

' AND does not performs short-circuiting logical conjunction and hence QB64-PE will throw a runtime error: Subscript out of range
IF index >= 1 AND index <= 10 AND GetArrayValue(values(), index, v) THEN
    PRINT "AND: Value ="; v
ELSE
    PRINT "AND: Outside range."
END IF

END

FUNCTION GetArrayValue%% (arr() AS LONG, idx AS LONG, value AS LONG)
    value = arr(idx)
    GetArrayValue = -1 ' return true
END FUNCTION


See also


Navigation:
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Keyword Reference - Alphabetical
Keyword Reference - By usage
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