Re: st: binary format type str question

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

At 08:35 PM 3/12/2007, Mark Fisher wrote:
> Hi. I'm writing a Mathematica program to read stata "dta" files. I 
> have the "Stata help for dta" page, which is quite useful. 
> Everything seems to work fine as long as the data types are in the 
> range 251 to 255 (byte, int, long, float, or double). But I can't 
> figure out how to properly read the data when the data types are in 
> the range 1 to 244 (str1, str2, ... str244). BTW, I have no trouble 
> reading the "char" strings for the data_label and the time_stamp; I 
> just read them in as a list of bytes, discard the bytes starting 
> with the first zero, and convert the remaining bytes to ascii. But 
> the str types don't seem be the same sort of beast. Any guidance 
> would be appreciated. Thanks.
>
> --Mark.
I'm not looking at the documentation for this, and I've never done 
any work like that, but I do recall reading that the string types are 
stored such that...
 they have a 0-byte terminator if they are shorter than the maximal 
length of the type;
 they have no terminator otherwise -- if they fill up the maximal length.

Thus, you need the type's nominal (maximal) length as a factor in 
reading the values.

For example, if the type is str20, then the values have a 0-byte 
terminator if they are shorter than 20, and no terminator if they are 
20 characters long.

I hope this is correct and that it helps.  Good luck.
--David

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