GET: Difference between revisions

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(Created page with "The GET # statement reads data from a file or port device by bytes or record positions. {{PageSyntax}} : GET #{{Parameter|fileNumber&}}, [{{Parameter|position}}][, {{{Parameter|targetVariable}}|{{Parameter|targetArray()}}}] {{PageDescription}} * {{Parameter|fileNumber&}} is the file or port number used in the OPEN AS BINARY or RANDOM statement. * The INTEGER or LONG byte {{Parameter|position}} in a BINARY file or the record {{Paramete...")
 
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{{PageDescription}}
{{PageDescription}}
* {{Parameter|fileNumber&}} is the file or port number used in the [[OPEN]] AS [[BINARY]] or [[RANDOM]] statement.  
* {{Parameter|fileNumber&}} is the file or port number used in the [[OPEN]] AS [[BINARY]] or [[RANDOM]] statement.
* The [[INTEGER]] or [[LONG]] byte {{Parameter|position}} in a [[BINARY]] file or the record {{Parameter|position}} in a [[RANDOM]] file '''must be greater than zero'''.
* The [[INTEGER]] or [[LONG]] byte {{Parameter|position}} in a [[BINARY]] file or the record {{Parameter|position}} in a [[RANDOM]] file '''must be greater than zero'''.
* The {{Parameter|position}} can be omitted if the GET operations are consecutive based on the {{Parameter|targetVariable}} [[TYPE]] byte size.
* The {{Parameter|position}} can be omitted if the GET operations are consecutive based on the {{Parameter|targetVariable}} [[TYPE]] byte size.
* The {{Parameter|targetVariable}} [[Data types|type]] or [[FIELD]] ''variable'' size determines the byte size and the next {{Parameter|position}} in the file.
* The {{Parameter|targetVariable}} [[Data types|type]] or [[FIELD]] ''variable'' size determines the byte size and the next {{Parameter|position}} in the file.
* The first byte position in a file is 1. <!-- giving the previous information is enough: This may require adding one to an offset value when documentation uses that position as 0. -->
* The first byte position in a file is 1.
* GET does not require a byte or record {{Parameter|position}} or {{Parameter|targetVariable}} (or comma) when using a [[FIELD]] statement.
* GET does not require a byte or record {{Parameter|position}} or {{Parameter|targetVariable}} (or comma) when using a [[FIELD]] statement.
* '''QB64''' can [[PUT]] the entire contents of an array to a file and later GET those contents to a {{Parameter|targetArray()}} (include brackets).
* '''QB64''' can [[PUT]] the entire contents of an array to a file and later GET those contents to a {{Parameter|targetArray()}} (include brackets).
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{{PageExamples}}
{{PageExamples}}
''Example 1:'' Opening a RANDOM file using LEN to calculate and LEN = to designate the file record size.
''Example 1:'' Opening a RANDOM file using LEN to calculate and LEN = to designate the file record size.
{{CodeStart}} '' ''
{{CodeStart}}
{{Cl|TYPE}} variabletype
{{Cl|TYPE}} variabletype
   x {{Cl|AS}} {{Cl|INTEGER}}'      '2 bytes
   x {{Cl|AS}} {{Cl|INTEGER}}'      '2 bytes
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{{Cl|PRINT}} newrec.x, newrec.y, newrec.z
{{Cl|PRINT}} newrec.x, newrec.y, newrec.z


{{Cl|END}} '' ''
{{Cl|END}}
{{CodeEnd}}
{{CodeEnd}}
{{OutputStart}} 16 bytes
{{OutputStart}} 16 bytes
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''Example 2:'' Placing the contents of a numerical array into a [[BINARY]] file. You may want to put the array size at the beginning too.
''Example 2:'' Placing the contents of a numerical array into a [[BINARY]] file. You may want to put the array size at the beginning too.
{{CodeStart}} '' ''
{{CodeStart}}
{{Cl|DIM}} {{Cl|SHARED}} array(100) {{Cl|AS}} {{Cl|INTEGER}}
{{Cl|DIM}} {{Cl|SHARED}} array(100) {{Cl|AS}} {{Cl|INTEGER}}


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{{Cl|NEXT}}
{{Cl|NEXT}}
{{Cl|PRINT}} "done"
{{Cl|PRINT}} "done"
{{Cl|END SUB}} '' ''
{{Cl|END SUB}}
{{CodeEnd}}
{{CodeEnd}}
: ''Note:'' Use empty brackets in QB64 when using [[GET]] to create an array or [[PUT]] to create a [[BINARY]] data file.
: ''Note:'' Use empty brackets in QB64 when using [[GET]] to create an array or [[PUT]] to create a [[BINARY]] data file.
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{{PageSeeAlso}}
{{PageSeeAlso}}
* [[PUT|PUT #]], [[SEEK]], [[SEEK (statement)]]  
* [[PUT|PUT #]], [[SEEK]], [[SEEK (function)]]
* [[INPUT (file statement)|INPUT #]], [[GET (TCP/IP statement)]]
* [[INPUT (file statement)|INPUT #]], [[GET (TCP/IP statement)]]
* [[FIELD]], [[RANDOM]], [[BINARY]]
* [[FIELD]], [[RANDOM]], [[BINARY]]

Latest revision as of 23:51, 24 February 2023

The GET # statement reads data from a file or port device by bytes or record positions.


Syntax

GET #fileNumber&, [position][, {targetVariable|targetArray()}]


Description

  • fileNumber& is the file or port number used in the OPEN AS BINARY or RANDOM statement.
  • The INTEGER or LONG byte position in a BINARY file or the record position in a RANDOM file must be greater than zero.
  • The position can be omitted if the GET operations are consecutive based on the targetVariable TYPE byte size.
  • The targetVariable type or FIELD variable size determines the byte size and the next position in the file.
  • The first byte position in a file is 1.
  • GET does not require a byte or record position or targetVariable (or comma) when using a FIELD statement.
  • QB64 can PUT the entire contents of an array to a file and later GET those contents to a targetArray() (include brackets).
  • GET may ignore the end of a file and return bad data. If the EOF function returns -1 after a GET operation, it indicates that the data has ended.
 DO UNTIL EOF(1)
   GET #1, , value%
   IF NOT(EOF(1)) THEN PUT #2, , value%
 LOOP


Examples

Example 1: Opening a RANDOM file using LEN to calculate and LEN = to designate the file record size. 

TYPE variabletype
  x AS INTEGER'       '2 bytes
  y AS STRING * 10'  '10 bytes
  z AS LONG'          '4 bytes
END TYPE'            '16 bytes total
DIM record AS variabletype
DIM newrec AS variabletype

file$ = "testrand.inf" '<<<< filename may overwrite existing file
number% = 1 '<<<<<<<<<< record number to write cannot be zero
RecordLEN% = LEN(record)
PRINT RecordLEN%; "bytes"
record.x = 255
record.y = "Hello world!"
record.z = 65535
PRINT record.x, record.y, record.z

OPEN file$ FOR RANDOM AS #1 LEN = RecordLEN%
PUT #1, number% , record 'change record position number to add records
CLOSE #1

OPEN file$ FOR RANDOM AS #2 LEN = RecordLEN%
NumRecords% = LOF(2) \ RecordLEN%
PRINT NumRecords%; "records"

GET #2, NumRecords% , newrec 'GET last record available
CLOSE #2
PRINT newrec.x, newrec.y, newrec.z

END

 16 bytes
 255        Hello worl       65535
 1 records
 255        Hello worl       65535
Explanation: The byte size of the record TYPE determines the LOF byte size of the file and can determine the number of records.
To read the last record GET the number of records. To add a record, use the number of records + 1 to PUT new record data.


Example 2: Placing the contents of a numerical array into a BINARY file. You may want to put the array size at the beginning too. 

DIM SHARED array(100) AS INTEGER

FOR i = 1 TO 100
  array(i) = i
NEXT
showme  'display array contents

OPEN "BINFILE.BIN" FOR BINARY AS #1

PUT #1, , array()

ERASE array 'clear element values from array and display empty
showme
CLOSE #1

OPEN "BINFILE.BIN" FOR BINARY AS #2
GET #2, , array()
CLOSE #2
showme  'display array after transfer from file

END

SUB showme
FOR i = 1 TO 100
  PRINT array(i);
NEXT
PRINT "done"
END SUB
Note: Use empty brackets in QB64 when using GET to create an array or PUT to create a BINARY data file.


See also


Navigation:
Main Page with Articles and Tutorials
Keyword Reference - Alphabetical
Keyword Reference - By usage
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