Transfer statement [Revelation On-Line Wiki]

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====== Transfer statement  ======


 
==== Description ====
 
Moves the contents of one variable into another variable, and clears the original variable.
 
==== Syntax ====
 
**Transfer** //variable1// To //variable2//
 
==== Parameters ====
 
The Transfer statement accepts arguments for the following parameters.

^Parameter^Description^
|//variable1//|The source variable. After the execution of a Transfer statement, //variable1// is null.|
|//variable2//|The target. After a transfer, //variable2// contains the data originally represented by //variable1//. It is not necessary to initialize the target variable before transferring to it.\\ ||

 
==== Remarks ====
 
The Transfer statement moves the value of a variable by reference. Instead of copying the data represented by a variable, Transfer copies the pointer to that data. The effect is a very quick reassignment, with no loss of memory.

If the contents of a variable are copied using an assignment operator (for example,
A = B), BASIC+ makes a copy of the value in the source variable (B), and loads it into the location represented by the target variable (A). The assignment operator is a transfer by value. This consumes both time and memory, and thus direct assignment is less efficient than using the Transfer statement.
 
==== Example ====
 
<code>
/* The program processes each record in the CUSTOMER file. After calling the external program RECORD_STATS,

the program restores the values of @RECORD and @ID by transferring them from temporary variables. The local subroutine FURTHER_PROCESSING is not shown.*/

Open "TEST" To CUSTOMER_TABLE Else
  status = Set_FSError()
  Return
End
Select CUSTOMER_TABLE
Done = 0
Loop
  ReadNext @ID Else Done = 1
Until Done
  Read @RECORD From CUSTOMER_TABLE, @ID Then
    * save contents before calling routine
    * in case RECORD_STATS changes values
    SAVE_RECORD = @RECORD
    SAVE_ID = @ID
    Call RECORD_STATS
    * restore contents
    Transfer SAVE_RECORD To @RECORD
    Transfer SAVE_ID To @ID
    GoSub Further_Processing
  End
Repeat
</code>