VARPTR: Difference between revisions

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The '''VARPTR''' function returns an [[INTEGER]] value that is the offset part of the variable or array memory address within it's segment.  
The '''VARPTR''' function returns an [[INTEGER]] value that is the offset part of the variable or array memory address within it's segment.




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* Because many QBasic statements change the locations of variables in memory, use the values returned by VARPTR and VARSEG immediately after the functions are used!
* Because many QBasic statements change the locations of variables in memory, use the values returned by VARPTR and VARSEG immediately after the functions are used!
* Integer array sizes are limited to 32767 elements when using [[VARPTR]] in QB and '''QB64'''!. Create a larger array using [[_BYTE]]. Example: [[DIM]] [[SHARED]] Memory (65535) AS [[_UNSIGNED]] [[_BYTE]]
* Integer array sizes are limited to 32767 elements when using [[VARPTR]] in QB and '''QB64'''!. Create a larger array using [[_BYTE]]. Example: [[DIM]] [[SHARED]] Memory (65535) AS [[_UNSIGNED]] [[_BYTE]]
* '''Warning: DEF SEG, VARSEG , VARPTR, PEEK or POKE access QB64's emulated 16 bit conventional memory block!'''  
* '''Warning: DEF SEG, VARSEG , VARPTR, PEEK or POKE access QB64's emulated 16 bit conventional memory block!'''
: '''It is highly recommended that QB64's [[_MEM]] memory system be used to avoid running out of memory.'''
: '''It is highly recommended that QB64's [[_MEM]] memory system be used to avoid running out of memory.'''




''See also:''  
''See also:''
* [[BSAVE]], [[BLOAD]]
* [[BSAVE]], [[BLOAD]]
* [[SADD]],  [[DEF SEG]]
* [[SADD]],  [[DEF SEG]]

Revision as of 02:56, 23 January 2023

The VARPTR function returns an INTEGER value that is the offset part of the variable or array memory address within it's segment.


Syntax

offset% = VARPTR(variable_name[(reference_index%)])


  • If variablename is not defined before VARPTR or VARSEG is called, the variable is created and it's address is returned.
  • Reference index is used to set the offset address of an array index, not necessarily the lowest index.
  • When a string variable, VARPTR returns the offset address location of the first byte of the string.
  • Because many QBasic statements change the locations of variables in memory, use the values returned by VARPTR and VARSEG immediately after the functions are used!
  • Integer array sizes are limited to 32767 elements when using VARPTR in QB and QB64!. Create a larger array using _BYTE. Example: DIM SHARED Memory (65535) AS _UNSIGNED _BYTE
  • Warning: DEF SEG, VARSEG , VARPTR, PEEK or POKE access QB64's emulated 16 bit conventional memory block!
It is highly recommended that QB64's _MEM memory system be used to avoid running out of memory.


See also:



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