Re: st: binary format type str question

[David Kantor <kantor.d@att.net>]

I'm not sure how you are determining the end of the data segment. I 
always understood that the allocation for string data (and all data) 
is in fixed-length chunks. So I expect 641 bytes per record (if I 
added correctly), for a total of 32691 bytes.

If your str98 value is only, say, 70 characters long, then character 
71 is a null character (zero). Characters 72 - 98 are irrelevant, but 
probably filled with nulls as well. I would not interpret consecutive 
nulls as signifying empty values (for other variables).

One can imagine other ways of storing string data, but Stata uses 
fixed-length, fixed_position allocation.

Again, I would look into how you decided where the end of the data segment is.
Also see - help dta-.  (I am looking at the Stata 8 on-screen 
help.  It says in one place that the allocated length of each var 
label is 33; later it says 81.  I think 81 is correct.)

HTH
--David

At 05:48 AM 3/13/2007, you wrote:

> Thanks David. That's what I think I'm doing and it works for 
> data_label and time_stamp, but it doesn't seem to work for the str types.
>
> Here's an example. There are 6 variables with types 98, 136, 102, 
> 105, 102, and 98. I read that as 6 str types with maximum lengths 98 
> bytes, 136 bytes, etc. There are 51 observations. But the remaining 
> number of bytes is 1071. This means there are 3.5 bytes per datum. 
> There aren't enough bytes to go around if I assume fixed lengths! 
> One the other hand, if I try to start another variable as soon as I 
> hit a zero, I find there are multiple zeros in a row, which would 
> seem to indicate no data for some variables. Hmm. Clearly I'm 
> missing something.
>
> --Mark.
> [...]
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