Chris,
Brevity is important, especially since it is the stated goal of the challenge. But there's another aspect. Golf is little fun if you have to crawl from hole to hole, even if you end up well under par. Here, too, it matters how fast different approaches get there. In this respect, not only FreelanceReinhard's method is the tersest but it outperforms any other technique hands down. I had suspected it was the case because SAS string search functions are based on an extremely rapid underlying algorithm - but didn't know by how much before testing it. The step below tests the FINDC approach, the APP approach, and the loop approach.
The result is that the run times for the four methods (in the order listed above) are related as 1:10:15. Ten times is a pretty astounding difference between FINDC and the next fastest method, the APP. The latter would probably fare faster if it didn't have to do the implicit character-to-numeric type conversions. It also shows how relatively slow the combination of looping and the CHAR function is.
On a different note, I see nothing inherently "dangerous" in CALL POKE(LONG) and have used it to speed things up (including in production under W, U/L, and z/OS) since at least 1998 (and even penned a few papers on the subject). At any rate, it's totally safe to write to an address already occupied by an element of a temp array - which also guarantees that address-wise, adjacent elements abut each other in physical memory. (Note how this circumstance is exploited below to populate all bytes of N L-long elements of a temp array with random digits without a need to loop through the array itself.)
Best regards
Paul D.
%let N = 100 ; /* Number of random strings to test */
%let L = 32 ; /* Length of each string */
%let R = 10000 ; /* Number of test repetitions */
data _null_ ;
array ss [&N] $ &L _temporary_ ;
/* Populate each L-long string with random digits from 0 to 9 */
call streaminit (7) ;
x = addrlong (ss[1]) ;
do j = 1 to &N * &L ;
call pokelong (put (rand ("uniform", 0, 9), 1.), ptrlongadd (x, j - 1), 1) ;
end ;
/* FINDC approach */
t = time() ;
do r = 1 to &R ;
do j = 1 to &N ;
max = findc ("123456789", ss[j], -9) ;
end ;
end ;
t1 = time() - t ;
/* APP approach - note implicit type conversions */
t = time() ;
array cc [&L] $ 1 _temporary_ ;
do r = 1 to &R ;
do j = 1 to &N ;
call pokelong (ss[j], addrlong (cc[1]), &L) ;
max = max (of cc[*]) ;
end ;
end ;
t2 = time() - t ;
/* Loop approach - $1-to-$1 comparison with conversion */
t = time() ;
do r = 1 to &R ;
do j = 1 to &N ;
cm = "0" ;
do i = 1 to &L ;
cm = cm <> char (ss[j], i) ;
end ;
max = input (cm, 1.) ;
end ;
end ;
t3 = time() - t ;
rel_time = catx (":", 1, round (t2/t1), round (t3/t1)) ;
put rel_time ;
run ;
