How to find the number of alphabet and non-alphabet letters in a string?

[Reeza · Accepted solution]

n_alpha = length(compress(string, , 'ka'));
n_non_alpha = length(compress(string, , 'a'));

Probably need to test if that accounts for spaces correctly. 

Compress function is documented here

[Rick_SAS]

Assuming that non-letters include spaces, punctuation, numbers, etc, you can use the ANYALPHA function to  differentiate letters from nonletters:

data Have;
length s $72;
input s 1-72;
/* number of letters and non-letters */
L = length(s);
nLetters = 0;
nNonLetters = 0;
do i = 1 to L;
isLetter = anyalpha(substr(s, i, 1));
nLetters + isLetter;
nNonLetters + ^isLetter;
end;
output;
drop i isLetter;
datalines;
In 28 days, the Anglo-Saxon lord ate 134 carrots. He had 20/20 vision!
e^{i*pi} + 1 = 0
ABCDEFG 123 HIJK 456 LMNOP 789 QRSTUV 0 WXYZ
;

proc print; run;