Article ID: 11910
Article Last Modified on 2/11/2004
APPLIES TO
- Microsoft Macro Assembler 4.0
- Microsoft Macro Assembler 5.0
- Microsoft Macro Assembler 5.1 Standard Edition
- Microsoft Macro Assembler 6.0 Standard Edition
This article was previously published under Q11910
SYMPTOMS
When trying to get the length of a text string, using the SIZE operator can
produce undesired results. In the example below, MSG_LEN is set to a value
of 1, but it seems it should be set to a value of 11:
MSG DB 'Darth Vader'
MSG_LEN EQU SIZE MSG
CAUSE
The value of MSG_LEN should be 1. The SIZE operator is defined to be the
LENGTH * TYPE as stated in the documentation. The expression, LENGTH MSG,
will be equal to 1 (when applied to a data label, the LENGTH operator
returns the number of elements created by the DUP operator; otherwise it
returns 1) and the expression, TYPE MSG, will be equal to 1. Therefore, the
variable MSG_LEN will be equal to 1.
RESOLUTION
In Macro Assembler version 6.0, the SIZEOF operator can be used to calulate
the total number of bytes allocated to a data item. In versions prior to
6.0, a simple way to calculate the value you want is as follows:
MSG DB 'Darth Vader'
MSG_LEN EQU $-MSG
Additional query words: 4.00 5.00 5.10 6.00
Keywords: KB11910