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Re: st: binary format type str question
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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