topic Re: How can i read a number with Least significant byte first in New SAS User

How can i read a number with Least significant byte first ?

cperichon_macif — Fri, 28 Sep 2018 08:47:52 GMT

Hi,

I have to read a dbf (version 7) file from sas.

As a result, i started to create a program .

However, i need to read three fields with LSB in file header like this :

4-7 32-bit number Number of records in the table. (Least significant byte first.)
8-9 16-bit number Number of bytes in the header. (Least significant byte first.)
10-11 16-bit number Number of bytes in the record. (Least significant byte first.)

How can i do ?

Thanks for your reply.

%Let NBRECORD=520400E5;

%let nbrecord=%sysfunc(inputn(&nbrecord.,hex.));

/* with lsb */
%let nbrecord=%sysfunc(inputn(&nbrecord.,????.));

Best regards.

Re: How can i read a number with Least significant byte first ?

Kurt_Bremser — Fri, 28 Sep 2018 08:52:16 GMT

SAS provides direct access with SAS/ACCESS to PC Files. Do you have that licensed?

Re: How can i read a number with Least significant byte first ?

Kurt_Bremser — Fri, 28 Sep 2018 08:53:48 GMT

PS which number would you expect to get from

520400E5

Re: How can i read a number with Least significant byte first ?

cperichon_macif — Fri, 28 Sep 2018 08:54:17 GMT

Yes i have

Re: How can i read a number with Least significant byte first ?

Kurt_Bremser — Fri, 28 Sep 2018 08:55:08 GMT

Then use proc import with dbms=dbf.

Re: How can i read a number with Least significant byte first

cperichon_macif — Fri, 28 Sep 2018 09:02:13 GMT

Unfortunately i can't .

The dbf file is Dbase version 7 !

The number (32bits) i want to read is 520400E5 (hex) .

Re: How can i read a number with Least significant byte first

Kurt_Bremser — Fri, 28 Sep 2018 09:20:23 GMT

I asked which decimal number you want to get out of 520400E5.

Re: How can i read a number with Least significant byte first

cperichon_macif — Fri, 28 Sep 2018 09:26:07 GMT

Sorry, this one : 283333 (the number of rows or records table).

Re: How can i read a number with Least significant byte first

Kurt_Bremser — Fri, 28 Sep 2018 10:24:25 GMT

@cperichon_macif wrote:

Sorry, this one : 283333 (the number of rows or records table).

That doesn't match at all. The hex representation of this number is 000452c5. With no method of reordering can I get the hex you posted.

Could you please post a hex dump of the first 16 bytes of the file?

Note that in SAS, the first position in a string is 1, not 0. So if you read the first 16 bytes into a string, the number of records is substr(string,5,4)

Re: How can i read a number with Least significant byte first

Kurt_Bremser — Fri, 28 Sep 2018 10:32:33 GMT

I see. You started 1 position too late. Look for hex C5520400. Once you convert that with informat ibr4., you'll get your count.

Re: How can i read a number with Least significant byte first

cperichon_macif — Fri, 28 Sep 2018 12:50:05 GMT

thank you so much, you were right !

Do you agree with this code , if i only want to read the first 12 bytes ?.

data header;
	infile dbf recfm=n;
	informat version $char1.;
	informat year $char1.;
	informat month $char1.;
	informat day $char1.;
	format version $hex.;
	format year $hex.;
	format month $hex.;
	format day $hex.;
	input version 
		@2 year   
		@3 month 
		@4 day 
		@5 nbrecord ibr4. 
		@9 nbbyteh ibr2. 
		@11 nbbyter ibr2.  

	;

	if _n_=2 then
		stop;
run;

Here is the link of dbf file structure : http://www.dbase.com/KnowledgeBase/int/db7_file_fmt.htm

My goal is to read the file, create a sas table and apply some updates or add new records .

Then, i put down the sas table in the dbf file.

Best regards.

Re: How can i read a number with Least significant byte first

Kurt_Bremser — Fri, 28 Sep 2018 13:05:49 GMT

Looks right to me. Personally, I'd use formatted input all the way throgh, and convert to a SAS date:

data header;
infile dbf recfm=n;
input
  version $char1.
  _year $char1.
  _month $char1.
  _day $char1.
  nbrecord ibr4. 
  nbbyteh ibr2. 
  nbbyter ibr2.  
;
format
  version $hex2.
  date yymmddd10.
;
date = input(put(_year,$hex2.) !! put(_month,$hex2.) !! put(day,$hex2.),yymmdd6.);
output;
stop;
drop _year _month _day;
run;

Take care that a suitable yearcutoff= option has been set.

I see no mention in the SAS documentation about dBase versions being supported or not. What happens when you try to use proc import with dbms=dbf?

Re: How can i read a number with Least significant byte first

cperichon_macif — Fri, 28 Sep 2018 13:19:57 GMT

Here is the log when i use the proc import :

24         proc import dbms=dbf file="&racjob.\macif.dbf" replace out=macif;
24       !                                                                   run;

NOTE: Imported 1 columns and 283333 rows of data from the dBase table file.
NOTE: WORK.MACIF data set was successfully created.
NOTE: PROCEDURE IMPORT used (Total process time):
      real time           13.37 seconds
      cpu time            2.14 seconds

The number of rows is good but only one column with no data !

Nom   Type   Longueur   Format   Informat   Libellé
DBWINUS0   Alphanumérique   0   $.   $.   DBWINUS0

Re: How can i read a number with Least significant byte first

Kurt_Bremser — Fri, 28 Sep 2018 13:44:03 GMT

Nice. One character column of length zero. So there's something that breaks SAS's dbf engine.

I'd put it to SAS technical support, just to see what they have to say.

Could you try to use dbfExport to create a csv file, and read that with a data step? The downside would be that you need to know the structure beforehand.