Chapter
11
I
Technical Information
How
Variables are Stored
BASIC stores variables in its data segment
as
follows:
Byte
Byte
0
Bytes
1
and
2
Byte
3
Byte
4
+
integer stored
in Byte
3
Byte
4
+
length
Contents Description
Type
Identifies the type
of
vari-
able stored
at
this location:
2
integer
3
string
4
single precision
8
double precision
Name The first 2 characters
of
the
variable name.
Integer Integer is the number
of
ad-
3
-
38
ditional characters in the
variable name.
Name The remainder
of
the vari-
able name is stored at bytes
4
+
the integer stored in
Byte
3.
The contents
of
the variable
are stored in the bytes im-
mediately following the vari-
able name. The data can be
2,
3,
4,
or
8
bytes in length,
depending
on
the type
of
data.
Data
At
least
3
bytes are required
to
store any variable name.
A
1-
or
2-character variable name occupies exactly
3
bytes. Bytes
1
and
2
for
the
first
2 characters and Byte
3
to contain a zero to indi-
cate that there are no additional characters in the variable
name. If the variable name only contains
1
or
2 characters, the
data is stored beginning at Byte
4.
As you can see, the location
of
the first actual byte
of
data depends on the length
of
the vari-
able name. VARPTR returns the offset
of
the first actual byte
of
data, not the offset
of
the beginning
of
the storage area.
357
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