nth occurrence substring in a string

[BrahmanandaRao]

data nth_occurence;
string="abc12abc56abc" ;
run;

how to find nth abc (nth occurence) substring in a string without regex

[Ksharp]

It looks like a student homework or a interview question?

%let n=3;

data nth_occurence;
string="abc12abc56abc" ;
p=0;
do n=1 to &n.;
 p=find(string,'abc','i',p+1);
end;
drop n;
run;