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Q31172: Use ERASE to Reinitialize Array of User-Defined TYPE Records

Article: Q31172
Product(s): See article
Version(s): 4.00 4.00b 4.50
Operating System(s): MS-DOS
Keyword(s): ENDUSER | B_BasicCom | mspl13_basic
Last Modified: 28-DEC-1989

To reinitialize a user-defined record TYPE, each element has to be
reinitialized independently. Reinitializing each element is a lengthy
task if the record has hundreds of fields (for example, an application
using user-defined record TYPEs with GET# and PUT# with random access
files).

To quickly reinitialize a record of a user-defined TYPE, make it an
array and ERASE it when desired.

This information also applies to Microsoft BASIC Compiler Versions
6.00 and 6.00b for MS-DOS and OS/2 and to Microsoft BASIC PDS Version
7.00 for MS-DOS and MS OS/2.

If a variable is DIMmed as an array of user-defined TYPEs with one or
more elements, it can be ERASEd.

ERASE reinitializes all elements to null (zero). Remember that if an
ERASEd array was declared as $DYNAMIC, it must be REDIMmed or DIMmed
to redeclare it as an array.

The following code demonstrates reinitialization for $STATIC and
$DYNAMIC arrays:

TYPE FileType
Client AS STRING * 20
Age AS INTEGER
Sex AS STRING * 1
END TYPE

REM ********* If $STATIC:       **********
DIM DataStatic(1) AS FileType
REM  Assign and use user-defined TYPE elements as needed in this part of
REM program:
Datastatic(1).Client="Client Name"
Datastatic(1).Age=33
Datastatic(1).Sex="M"
ERASE DataStatic  ' Sets Client, Age, and Sex elements back to null.

REM ********* If $DYNAMIC:   **********
REM $DYNAMIC
DIM DataDynamic(1) AS FileType
REM  Assign and use user-defined TYPE elements as needed in this part of
REM program:
Datadynamic(1).Client="Client Name"
Datadynamic(1).Age=33
Datadynamic(1).Sex="M"
ERASE DataDynamic    ' Erases array.
DIM DataDynamic(1) AS FileType    ' Dimensions array again.

Note that adding the OPTION BASE 1 statement to the above program
makes the arrays start at element 1 instead of element 0. This will
save memory if you do not intend to use element 0 of the array.

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