QB64-PE/internal/help/RANDOM.txt

'''RANDOM''' is used in an [[OPEN]] statement to read([[GET]]) from or write([[PUT]]) to a file. 



{{PageSyntax}}
:: OPEN Filename$ FOR RANDOM AS #1 [LEN = ''recordlength%'']


* RANDOM is the Default mode if no mode is given in the OPEN statement.
* It creates the file if the legal file name given does NOT exist.
* As a RANDOM file, it can read or write any record using [[GET]] and/or [[PUT]] statements. 
* ''Recordlength%'' is determined by getting the LEN of a [[TYPE]] variable or a [[FIELD]] statement.
* If no record length is used in the [[OPEN]] statement, the default record size is 128 bytes except for the last record.
* A record length cannot exceed 32767 or an [[ERROR Codes|error]] will occur!
* To determine the number of records in a file the records% = [[LOF]] \ recordlength%. 
* A serial communication port can also be opened for RANDOM in an [[OPEN COM]] statement.


''Example:'' Function that finds a RANDOM file's record number for a string value such as a phone number.
{{CodeStart}} '' ''
{{Cl|TYPE}} customer
  age {{Cl|AS}} {{Cl|INTEGER}}
  phone {{Cl|AS}} {{Cl|STRING}} * 10
{{Cl|END}} {{Cl|TYPE}}

{{Cl|DIM}} {{Cl|SHARED}} cust {{Cl|AS}} customer, recLEN
recLEN = {{Cl|LEN}}(cust)            'get the length of the record type
{{Cl|PRINT}} "Rec{{Cl|LEN}}:"; recLEN

{{Cl|OPEN}} "randfile.rec" {{Cl|FOR...NEXT|FOR}} {{Cl|RANDOM}} {{Cl|AS}} #1 {{Cl|LEN}} = recLEN
{{Cl|FOR...NEXT|FOR}} i = 1 {{Cl|TO}} 4
  {{Cl|READ}} cust.age, cust.phone
  {{Cl|PUT}} #1, , cust
{{Cl|NEXT}}
{{Cl|CLOSE}} #1

RP = RecordPos("randfile.rec", "2223456789")  'returns 0 if record not found!

{{Cl|PRINT}} RP  

{{Cl|IF...THEN|IF}} RP {{Cl|THEN}}
  {{Cl|OPEN}} "randfile.rec" {{Cl|FOR...NEXT|FOR}} {{Cl|RANDOM}} {{Cl|AS}} #2 {{Cl|LEN}} = recLEN
  {{Cl|GET}} #2, RP, cust
  {{Cl|CLOSE}} #2
{{Cl|PRINT}} cust.age, cust.phone
{{Cl|END IF}}

{{Cl|END}}

{{Cl|DATA}} 59,2223456789,62,4122776477,32,3335551212,49,1234567890

{{Cl|FUNCTION}} RecordPos (file$, search$)
f = {{Cl|FREEFILE}}
{{Cl|OPEN}} file$ {{Cl|FOR (file statement)|FOR}} {{Cl|INPUT (file mode)|INPUT}} {{Cl|AS}} #f
FL = {{Cl|LOF}}(f)
dat$ = {{Cl|INPUT$}}(FL, f)
{{Cl|CLOSE}} f
recpos = {{Cl|INSTR}}(dat$, search$)
{{Cl|IF...THEN|IF}} recpos {{Cl|THEN}} RecordPos = recpos \ recLEN + 1 {{Cl|ELSE}} RecordPos = 0
{{Cl|END FUNCTION}} '' ''
{{CodeEnd}}
:''Note:'' Random files can store records holding various variable types using a [[TYPE]] definition or a [[FIELD]] statement.


''See also:'' 
* [[GET]], [[PUT]], [[FIELD]]
* [[BINARY]] 
* [[SEEK]], [[SEEK (statement)]]


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