Difference between revisions of "GET"

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The '''GET #''' file or port device statement reads data by bytes or record positions.
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The [[GET #]] statement reads data from a file or port device by bytes or record positions.
 
 
  
  
 
{{PageSyntax}}
 
{{PageSyntax}}
:: '''GET #''filenumber&'',''' [''position''][, {''holdingvariable''|''holdingarray()''}]
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: [[GET #]]{{Parameter|fileNumber&}}, [{{Parameter|position}}][, {{{Parameter|targetVariable}}|{{Parameter|targetArray()}}}]
 
 
  
  
* File/port number is the file number used in the [[OPEN]] AS [[BINARY]] or [[RANDOM]] statement.  
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{{PageDescription}}
* The [[INTEGER]] or [[LONG]] byte ''position'' in a [[BINARY]] file or the record ''position'' in a [[RANDOM]] file '''must be greater than zero'''.
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* {{Parameter|fileNumber&}} is the file or port number used in the [[OPEN]] AS [[BINARY]] or [[RANDOM]] statement.  
* The ''position'' can be omitted if the GETs are consecutive based on the ''holding variable'' [[TYPE]] byte size.
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* 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 ''holding variable'' [[TYPE]] or [[FIELD]] ''variable'' size determines the byte size and the next ''position'' in the file.
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* The {{Parameter|position}} can be omitted if the GET operations are consecutive based on the {{Parameter|targetVariable}} [[TYPE]] byte size.
* The first file position is 1. This may require adding one to an offset value when documentation uses that position as 0.
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* The {{Parameter|targetVariable}} [[Data types|type]] or [[FIELD]] ''variable'' size determines the byte size and the next {{Parameter|position}} in the file.
* GET does NOT require a byte or record ''position'' or ''holding variable''(or comma) when using a [[FIELD]] statement!
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* 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. -->
* '''QB64''' can [[PUT]] the entire contents of an array to a file and later GET those contents to a ''holding array''(include brackets).
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* GET does not require a byte or record {{Parameter|position}} or {{Parameter|targetVariable}} (or comma) when using a [[FIELD]] statement.
* '''GET can ignore an [[EOF]] statement and return bad data! [[EOF]] after a GET denotes that the data has ended!'''
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* '''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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* '''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.'''
 
{{TextStart}} DO UNTIL {{Cb|EOF}}(1)
 
{{TextStart}} DO UNTIL {{Cb|EOF}}(1)
 
   {{Cb|GET}} #1, , value%
 
   {{Cb|GET}} #1, , value%
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{{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}} '' ''
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''See also:''
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{{PageSeeAlso}}
 
* [[PUT|PUT #]], [[SEEK]], [[SEEK (statement)]]  
 
* [[PUT|PUT #]], [[SEEK]], [[SEEK (statement)]]  
 
* [[INPUT (file statement)|INPUT #]], [[GET (TCP/IP statement)]]
 
* [[INPUT (file statement)|INPUT #]], [[GET (TCP/IP statement)]]

Latest revision as of 02:42, 20 September 2017

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



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