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Q38299: How CodeView Interprets Values (octal, decimal, hexadecimal)

Article: Q38299
Product(s): See article
Version(s): 1.x 2.00 2.10 2.20 | 2.20
Operating System(s): MS-DOS | OS/2
Keyword(s): ENDUSER | | mspl13_basic
Last Modified: 23-NOV-1988

Problem:

When trying to watch a portion of memory, I have a problem with
the following command at the dialog prompt:

   WW DS:0050 L 4.

I thought this should have created a watch on the four words starting
at offset 0x50. It actually set the watch starting at 0x28, CodeView
interpreted the number as if it had been in base 8. Using the N
command to change the radix doesn't make any difference.

Response:

In this case, the 0's before the offset cause CodeView to evaluate the
expression in octal. CodeView provides three different prefixes for
numbers to use an explicit base: 0 signifies octal, 0n signifies
decimal, and 0x signifies hexadecimal. The current radix setting will
have no bearing on numbers entered with these prefixes; however, it
will affect those without prefixes.

The lines below have different meanings when setting watches.
The left column is the command, while the right column is an example
of the display produced in the watch window. Radix is assumed to be 10.

The following is an example:

1. ww 50               50    :  0067:0032  6942

2. ww 050              050   :  0067:0028  6328

3. ww 0n50             0n50  :  0067:0032  6942

4. ww 0x50             0x50  :  0067:0050  6163

The first command sets the watch at the address specified using the
current radix. This address will change when you use the N command to
change the radix; the 50 on the left of the watch remains the same;
however, the offset in the address will change to watch 50 in the new
base. This address will always be displayed in hexadecimal, but 50
will be evaluated differently.

Examples 2 through 4 show watches being set in octal, decimal, and
hexadecimal modes, respectively. These addresses will never change
with a change of radix.

Notice that watches 1 and 3 match. This is because by default CodeView
is in base 10, so 50 and 0n50 evaluate to the same thing. Using N 8 will
cause watches 1 and 2 to match, and N 16 will match 1 and 4.

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