Difference between revisions of "$DYNAMIC"

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The '''$DYNAMIC''' Metacommand allows the creation of dynamic(changeable) array sizes.
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The [[$DYNAMIC]] [[Metacommand|metacommand]] allows the creation of dynamic (resizable) arrays.
  
  
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{{PageSyntax}}
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:{[[REM]] | [[apostrophe|']] } [[$DYNAMIC]]
  
{{PageSyntax}} REM $DYNAMIC
 
  
 
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{{PageDescription}}
* Metacommands require a [[REM]] or apostrophy ( ' ) before them.
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* QBasic [[Metacommand|metacommands]] require [[REM]] or [[Apostrophe|apostrophe]] (') before them and are normally placed at the start of the main module.
* Metacommands should be placed at the program start in the main module.
 
 
* Dynamic arrays can be resized using [[REDIM]]. The array's type cannot be changed.
 
* Dynamic arrays can be resized using [[REDIM]]. The array's type cannot be changed.
* All data in the array will be lost when redimensioned in QBasic.
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* All data in the array will be lost when [[REDIM]]ensioned except when [[_PRESERVE]] is used.
* In '''QB64''', REDIM [[_PRESERVE]] can preserve and move the previous array data when the array boundaries change.
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* [[REDIM]] [[_PRESERVE]] can preserve and may move the previous array data when the array boundaries change.
* [[_PRESERVE]] allows the [[UBOUND|upper]] and [[LBOUND|lower]] boundaries of an array to be changed.
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* [[_PRESERVE]] allows the [[UBOUND|upper]] and [[LBOUND|lower]] boundaries of an array to be changed. The number of dimensions cannot change.
* Dynamic arrays can also be resized by the program user's input if desired.
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* [[$DYNAMIC]] arrays must be [[REDIM]]ensioned if [[ERASE]] or [[CLEAR]] are used as the arrays are removed completely.
* [[$DYNAMIC|Dynamic]] arrays MUST be [[REDIM]]ensioned if [[ERASE]] or [[CLEAR]] are used to clear the array values.  
 
  
  
''Example:'' Re-dimensioning a $DYNAMIC array using [[_PRESERVE]].
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{{PageExamples}}
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''Example:'' [[REDIM]]ing a $DYNAMIC array using [[_PRESERVE]] to retain previous array values.
 
{{CodeStart}} '' ''
 
{{CodeStart}} '' ''
 
{{Cl|REM}} {{Cl|$DYNAMIC}}            'create dynamic arrays only
 
{{Cl|REM}} {{Cl|$DYNAMIC}}            'create dynamic arrays only
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{{Cl|END}} '' ''
 
{{Cl|END}} '' ''
 
{{CodeEnd}}
 
{{CodeEnd}}
{{OutputStart}}
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{{OutputStart}}0  1  2  3  4  5  6  7  8  9  10
0  1  2  3  4  5  6  7  8  9  10
 
  
 
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''See also:''
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{{PageSeeAlso}}
* [[$STATIC]], [[$INCLUDE]], [[Metacommand]]
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* [[$STATIC]], [[$INCLUDE]]
* [[DIM]], [[REDIM]], [[Arrays]]
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* [[DIM]], [[REDIM]], [[_DEFINE]]
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* [[STATIC]]
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* [[ERASE]], [[CLEAR]]
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* [[Arrays]], [[Metacommand]]
  
  
 
{{PageNavigation}}
 
{{PageNavigation}}

Latest revision as of 15:36, 17 February 2021

The $DYNAMIC metacommand allows the creation of dynamic (resizable) arrays.


Syntax

{REM | ' } $DYNAMIC


Description

  • QBasic metacommands require REM or apostrophe (') before them and are normally placed at the start of the main module.
  • Dynamic arrays can be resized using REDIM. The array's type cannot be changed.
  • All data in the array will be lost when REDIMensioned except when _PRESERVE is used.
  • REDIM _PRESERVE can preserve and may move the previous array data when the array boundaries change.
  • _PRESERVE allows the upper and lower boundaries of an array to be changed. The number of dimensions cannot change.
  • $DYNAMIC arrays must be REDIMensioned if ERASE or CLEAR are used as the arrays are removed completely.


Examples

Example: REDIMing a $DYNAMIC array using _PRESERVE to retain previous array values.

REM $DYNAMIC 'create dynamic arrays only DIM array(10) 'create array with 11 elements FOR i = 0 TO 10 array(i) = i: PRINT array(i); 'set and display element values NEXT PRINT REDIM _PRESERVE array(10 TO 20) FOR i = 10 TO 20 PRINT array(i); NEXT END

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See also



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