%SYSFUNC is not as smart as DATA step

Basically %SYSFUNC is for string manipulation. It is difficult for %SYSFUNC to know what argument is numeric or character. Take FINDW as example, if we do not specify character argument clearly, it will try converting the string to numeric using %SYSEVALF. Although it may give out correct value, it still give out ERROR message.

data _null_;
   source = "word1 word2 word3";
   pos = findw(source, 'word1', ' ', 'i');
   put "SUCCESS: " pos=;
run;

SUCCESS: pos=1
NOTE: DATA statement used (Total process time):
      real time           0.00 seconds
      cpu time            0.00 seconds
      

ERROR: %SYSEVALF function has no expression to evaluate.
%put FAIL: %sysfunc(findw(%str(word1 word2 word3), word1, %str( ), i));
FAIL: 1

%put SUCCESS: %sysfunc(findw(%str(word1 word2 word3), word1, ' ', i));
SUCCESS: 1