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Q74924: A Structure Template Can Be Referenced in a MASM Program

Article: Q74924
Product(s): Microsoft Macro Assembler
Version(s): MS-DOS:5.10,5.10a,6.0
Operating System(s): 
Keyword(s): 
Last Modified: 04-MAY-2001

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The information in this article applies to:

- Microsoft Macro Assembler (MASM), versions 5.10, 5.10a, 6.0 
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SUMMARY
=======

With the Microsoft Macro Assembler (MASM), if a structure type is declared but
no instance of the structure is ever defined, the assembler will still permit
access to the structure.

This is expected behavior for the assembler. A reference to a structure field in
this manner is equivalent to taking the offset of the field from the beginning
of the structure.

MORE INFORMATION
================

The sample code below illustrates this situation. The example declares an
"animal" structure type, but does not define an instance of the structure. A
reference to this structure type is then made in the following line:

     mov ax, animal.dog

As described above, the reference to animal.dog just generates the offset of the
field, dog, from the beginning of the structure; therefore, this line is
effectively the same as the statement "mov ax, 2".

Sample Code
-----------

  ; Assemble options needed: none

          .MODEL SMALL

          animal   struc
          cat     dw  11
          dog     dw  12
          animal   ends

          .CODE
  start:  mov ax, @data
          mov ds, ax
          mov ax, animal.dog
          END start

Additional query words: kbinf 5.10 5.10a 6.00 6.00a 6.00b

======================================================================
Keywords          :  
Technology        : kbMASMsearch kbAudDeveloper kbMASM600
Version           : MS-DOS:5.10,5.10a,6.0

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