%SYSFUNC( DATA-STEP-FUNC(_null_string_) ) behavior seems inconsistent to me.   Any explanation?   Useful References: %SYSFUNC() doc - Note the note that "an empty argument position will not generate a NULL argument, but a zero length argument." This prior (but 2010!) detailed explanation of %SYSFUNC() More below, after demo code   Demo code: %macro test_null_string_handling(str); %if %length(%sysfunc(TRIMN(&str))) > 0 %then %put TRIMN() TEST - NON-ZERO STRING LENGTH. String is [&str]; %else %put TRIMN() TEST - ZERO STRING LENGTH. String is [&str]; %if %length(%sysfunc(STRIP(&str))) > 0 %then %put STRIP() TEST - NON-ZERO STRING LENGTH. String is [&str]; %else %put STRIP() TEST - ZERO STRING LENGTH. String is [&str]; %if %length(%sysfunc(COMPRESS(&str,,s))) > 0 %then %put COMPRESS() TEST - NON-ZERO STRING LENGTH. String is [&str]; %else %put COMPRESS() TEST - ZERO STRING LENGTH. String is [&str]; %if %sysfunc(PRXMATCH(m/\S/i,&str)) > 0 %then %put PRXMATCH() TEST - NON-ZERO STRING LENGTH. String is [&str]; %else %put PRXMATCH() TEST - ZERO STRING LENGTH. String is [&str]; %mend test_null_string_handling; %test_null_string_handling(%str()) %test_null_string_handling(%str( )) %test_null_string_handling(one) %test_null_string_handling( ) Log result: TRIMN() TEST - ZERO STRING LENGTH. String is [] STRIP() TEST - ZERO STRING LENGTH. String is [] COMPRESS() TEST - ZERO STRING LENGTH. String is [] PRXMATCH() TEST - ZERO STRING LENGTH. String is [] 319 %test_null_string_handling(%str( )) TRIMN() TEST - ZERO STRING LENGTH. String is [ ] STRIP() TEST - ZERO STRING LENGTH. String is [ ] COMPRESS() TEST - ZERO STRING LENGTH. String is [ ] PRXMATCH() TEST - ZERO STRING LENGTH. String is [ ] 320 %test_null_string_handling(one) TRIMN() TEST - NON-ZERO STRING LENGTH. String is [one] STRIP() TEST - NON-ZERO STRING LENGTH. String is [one] COMPRESS() TEST - NON-ZERO STRING LENGTH. String is [one] PRXMATCH() TEST - NON-ZERO STRING LENGTH. String is [one] 321 %test_null_string_handling( ) ERROR: The function TRIMN referenced by the %SYSFUNC or %QSYSFUNC macro function has too few arguments. TRIMN() TEST - ZERO STRING LENGTH. String is [] ERROR: The function STRIP referenced by the %SYSFUNC or %QSYSFUNC macro function has too few arguments. STRIP() TEST - ZERO STRING LENGTH. String is [] COMPRESS() TEST - ZERO STRING LENGTH. String is [] PRXMATCH() TEST - ZERO STRING LENGTH. String is []   QUESTION: Why do TRIMN() and STRIP() choke on a null string and throw an ERROR, but COMPRESS() and PRXMATCH() do not? How should we know whether a DATA STEP function in %SYSFUNC() handles null strings, and for which arguments? I'm missing something fundamental. Thanks for any help figuring out what that is 🙂   A few further details from the doc pages of these 4 functions: TRIMN: "TRIMN returns a string with a length of zero for a blank string." STRIP: "For strings that are blank, the STRIP and TRIMN functions return a string with a length of zero" - Note that in the test, above, TRIM() also throws the ERROR. COMPRESS: "COMPRESS function allows null arguments." PRXMATCH: No mention of null or blank arguments. But it does not choke on them. Thanks! ... View more

I've searched to communities for solutions to this, or at least explanations, but find none. Any insights would be helpful.   Here is example code, to illustrate the problems.   Objective: Read a UTF-8 encoded page; parse it to sas variables; and store as sas7bdat ... without corrupting UTF-8 chars.   Example code. %let w_encoding = UTF-8; %let r_encoding = UTF-8; filename WRITE './unitslab_conversions.txt' encoding="&W_ENCODING"; filename READ './unitslab_conversions.txt' encoding="&R_ENCODING"; libname data './data' inencoding="&R_ENCODING" outencoding="&W_ENCODING"; proc http method="GET" url="https://unitslab.com/" out=WRITE ; run; data data.lbtests; infile READ length=len lrecl=32767; input line $varying32767. len; line = strip(line); if prxmatch('/^<li>.+\/node/i', line); if prxmatch('/(microglobulin|cancer|beta|kappa|mass|mullerian)/i', line); lbtest = strip(scan(line,5,'<>')); node = strip(scan(line,2,'"')); *--- Paste in strings from the UTF-8 page NB - NONE OF THESE MATCH ; if index(lbtest, 'anti-Mullerian') or index(lbtest, 'Beta 2-microglobulin (ß2-M)') or index(lbtest, 'Free ß-subunit of human chorionic gonadotropin (free ßhCG)') or index(lbtest, 'Kappa (κ)') then putlog 'INFO: FOUND EXPECTED string match: ' lbtest=; *--- https://www.w3schools.com/charsets/ref_html_utf8.asp NB - LIMITED CHAR RANGE ALSO MATCH TRANSCODE (CORRUPTED) chars above \x{2000} ; if prxmatch('/[\x{03b2}\x{052f}]/', line) then putlog 'INFO: FOUND EXPECTED HTML5 UTF-8 char: ' lbtest=; keep lbtest node; run;   Problems with results:   1 - SAS log - Notice the corrupted UTF-8 chars - I've bolded some UTF-8 hyphens and greek chars:   lbtest=alpha-1‑microglobulin node=/node/89 lbtest=anti‐Mullerian hormone (AMH) node=/node/155 lbtest=beta - CrossLaps - Degradation products of type I collagen node=/node/164 lbtest=Beta 2‐microglobulin (β2‐M) node=/node/145 lbtest=beta-Hydroxybutyric acid node=/node/225 lbtest=CA 125 (Cancer Antigen 125) node=/node/104 lbtest=CA 15-3 (Cancer Antigen 15-3) node=/node/105 lbtest=CA 72-4 (Antigène de cancer 72-4) node=/node/107 lbtest=CK‐MB mass - the MB isoenzyme of creatine kinase (quantitative determination) node=/node/157 lbtest=Kappa (κ) light chain node=/node/150   2 - Similar in the resulting SAS7BDAT, despite encoding being UTF-8, but different corruption, appearing to eat up more char bytes:       3 - Similar result viewing SAS7BDAT outside a SAS session - UNIVERSAL VIEWER, but still different corruption of UTF-8 chars:     Thanks for any insights, tips or fixes to this code that can avoid this UTF-8 character corruption. GG ... View more