Q66424: LSET Can Assign One TYPE Variable to a Different TYPE

Article: Q66424
Product(s): See article
Version(s): 4.00 4.00b 4.50
Operating System(s): MS-DOS
Keyword(s): ENDUSER | SR# S901017-34 B_BasicCom | mspl13_basic
Last Modified: 12-NOV-1990

The LSET statement can assign a variable dimensioned as one
user-defined TYPE to a variable dimensioned as a different
user-defined TYPE. This can be useful in assigning string TYPEs that
differ in length.

This information applies to Microsoft QuickBASIC versions 4.00, 4.00b,
4.50 for MS-DOS, to Microsoft BASIC Compiler versions 6.00 and 6.00b
for MS-DOS and MS OS/2, and to Microsoft BASIC Professional
Development System (PDS) versions 7.00 and 7.10 for MS-DOS and MS
OS/2.

Direct (or LET) assignment of differing TYPEs correctly gives a "Type
Mismatch" error, because direct assignment requires identical TYPEs.

LSET allows you to assign any user-defined TYPE variable to any other
user-defined TYPE variable. However, you must be cautious not to
mismatch numeric elements (INTEGER, LONG, SINGLE, or DOUBLE) (or
CURRENCY in BASIC PDS only) when using LSET assignment of record TYPE
variables, or else you will assign spurious values.

Note: If the user-defined TYPEs are of different lengths, LSET copies
only the number of bytes in the shorter of the two variables. For
example, if you LSET a 10-byte variable into a 2-byte variable, LSET
will copy only 2 bytes of the larger variable into the smaller
variable. If you LSET the 2-byte variable into the larger one, it will
copy only the first 2 bytes of the larger variable.

In the following code example, LSET assigns a variable of one TYPE to
a variable of another TYPE.

Code Example
------------

   TYPE Type1
      FirstName AS STRING * 10
      LastName AS STRING * 12
   END TYPE
   TYPE Type2
      FullName AS STRING * 22
   END TYPE
   DIM Var1 AS Type1
   DIM Var2 AS Type2

   Var1.FirstName = "John"
   Var1.LastName = "Smith"
   LSET Var2 = Var1   ' Assigns record variables of differing TYPEs
   PRINT Var2.FullName
   END

The output is as follows:

   John      Smith

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