topic Re: Determine the logical record length of a text file in SAS Programming

Determine the logical record length of a text file

MichaelvanStraten — Sun, 23 Aug 2020 11:54:57 GMT

Dear community members,

Hope you are healthy and feeling well these days.

I am not a programmer, so please forgive me for my unprofessional language. This is my problem:

I import into SAS a text file with no delimiters; variables are defined by fixed spaces. I am now getting this file in an old version (LRECL=316) and a new version (LRECL=322) with some changes in certain fields. I need to differentiate between the two based on this difference alone. Is there a function in SAS or SAS/SQL that will return the LRECL of a text file?

TIA,

Michael

Re: Determine the logical record length of a text file

Kurt_Bremser — Sun, 23 Aug 2020 12:14:42 GMT

Do this first:

data _null_;
infile "yourfile" lrecl=350 length=rlen obs=1;
input;
call symputx('rlen',rlen);
run;

This will store the observed length of the first line into &rlen, so you can run the following code conditionally.

PS if you read the file with RECFM=F or RECFM=N, which means that no line separators are present in the file, you will need a more complicated trick.

Re: Determine the logical record length of a text file

Ksharp — Sun, 23 Aug 2020 12:14:19 GMT

data _null_;
 infile 'c:\temp\have.csv' end=last;
 input;
 retain lrecl ;
 lrecl=max(lrecl,length(_infile_));
 if last then putlog 'max lrecl is ' lrecl;
 run;

NOTE: The infile 'c:\temp\have.csv' is:
      File Name=c:\temp\have.csv,
      RECFM=V,LRECL=256

max lrecl is 74
NOTE: 148 records were read from the infile 'c:\temp\have.csv'.
      The minimum record length was 0.
      The maximum record length was 74.
NOTE: DATA statement used (Total process time):
      real time           0.01 seconds
      cpu time            0.01 seconds

Re: Determine the logical record length of a text file

RichardDeVen — Sun, 23 Aug 2020 13:09:55 GMT

Text file with fixed record layout and also HAS line termination characters

Use @Kurt_Bremser example utilizing INFILE LENGTH=<variable> option to retrieve data record length from 1st line of file.

Text file with fixed record layout and has NO line termination characters

The MOD function can be useful

Determine filesize
Compute
- R1 = mod (filesize,316)
- R2 = mod (filesize,322)
if R1 = 0 and R2 ^= 0 presume record length 316; else
if R1 ^= 0 and R2 = 0 presume record length 322; else
filesize is k x LCM(316,322). Perform test inputs and your understanding of expected values to determine which record length (i.e. record type) you have.
Note: LCM(316,322) is filesize 32,232

Example code for determining file size (in Windows)

filename au 'autoexec.sas';

data _null_;
  fid = fopen ('au');

  filesize = finfo(fid,'file size (bytes)');
  put 'NOTE: ' filesize=;

  rc = fclose (fid);
run;

Re: Determine the logical record length of a text file

Kurt_Bremser — Sun, 23 Aug 2020 12:16:34 GMT

@RichardDeVen's method is the "trick" I was referring to in my PS.

Re: Determine the logical record length of a text file

MichaelvanStraten — Sun, 23 Aug 2020 13:07:06 GMT

Dear KurtBremser, Ksharp and RichardADeVenezia,

Thank you all for your helpful solutions.

Michael