The macro checks determine if the external file is empty in SAS. An error message is written to the log if it doesn’t exist. SAS attempts to read the data from the file if the file exists.
Data access functions like FOPEN, FREAD, and FGET are used to retrieve the data. The message is written to the log if there is no data to be read from the file.
%macro check_empty(outfile); %let filrf=myfile; %if %sysfunc(fileexist(&outfile)) %then %do; %let rc=%sysfunc(filename(filrf,&outfile)); %let fid=%sysfunc(fopen(&filrf)); %if &fid > 0 %then %do; %let rc=%sysfunc(fread(&fid)); %let rc=%sysfunc(fget(&fid,mystring)); %if &rc = 0 %then %put &mystring; %else %put file is empty; %let rc=%sysfunc(fclose(&fid)); %end; %let rc=%sysfunc(filename(filrf)); %end; %else %put file does not exist; %mend check_empty; %check_empty(/home/9to5sas/demo.txt)
The %LET statement is used to create a macro variable named &filrf that will contain the fileref name.
The %IF statement with the FILEEXIST function verifies that the file passed to the macro exists.
The FILENAME function associates a fileref with the file passed into the macro named &outfile.
We Use the FOPEN function to open that file and assign a file identifier value to the macro variable &fid.
To ensure that the FGET function was successful, we use the %IF statement. If the operation were successful, FGET would return 0, and we use a %PUT statement to write the contents of the variable named &mystring to the log.
The %PUT statement will write an empty message to the log if the %IF condition is false.