novinosrin has provided the idea and I build further on his.
hhchenfx is in looking for a SAS function to provide the position and order of occurrence of 'a' in a string. I don't find a readymade SAS function for his desire. However, we can build a function using the SAS function compiler (FCMP). Here is a function:
proc fcmp outlib = work.cmput.str;
function findpatnext(str $, pat $);
file log;
static lastpos 1;
pos = findc(str, pat, 'it', lastpos); /* edit: added semicolon */
lastpos = pos + 1;
return(pos);
endsub;
quit;
In a Data Step we can call the function as:
options cmplib = work.cmput;
data want;
length str $26;
str = '098ab-c1za3-8a1-8a-1a01212';
loc = 1;
do order = 1 by 1 while(loc);
loc = findpatnext(str, 'a');
if loc then output;
end;
run;
The output Data Set, WANT:
Obs
str
loc
order
1
098ab-c1za3-8a1-8a-1a01212
4
1
2
098ab-c1za3-8a1-8a-1a01212
10
2
3
098ab-c1za3-8a1-8a-1a01212
14
3
4
098ab-c1za3-8a1-8a-1a01212
18
4
5
098ab-c1za3-8a1-8a-1a01212
21
5
We repeat the Data Step using NAME in SASHELP.CLASS as:
data want;
set sashelp.class(keep = name);
loc = 1;
do order = 1 by 1 while(loc);
loc = findpatnext(name, 'a');
if loc then output;
end;
run;
The output Data Set is:
Obs Name loc order
1 Alfred 1 1
2 Alice 1 1
3 Barbara 2 1
4 Barbara 5 2
5 Barbara 7 3
6 Carol 2 1
7 James 2 1
8 Jane 2 1
9 Janet 2 1
10 Mary 2 1
11 Ronald 4 1
12 Thomas 5 1
13 William 6 1
Edited:
In case, the n-th occurrence of 'a' is needed, the do-loop in the Data Step can be modified. Suppose the 3-rd occurrence is needed then the following Data Step can be used:
data want;
length str $26;
str = '098ab-c1za3-8a1-8a-1a01212';
loc = 1;
do order = 1 by 1 while(loc);
loc = findpatnext(str, 'a');
if order = 3 then do; output; leave; end;
end;
run;
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