How to correct this sas function in order to have the jaccard distance?

Question

I created a SAS function using fcmp to calculate the jaccard distance between two strings. I do not want to use macros, as I'm going to use it through a large dataset for multiples variables. the substrings I have are missing others.

proc fcmp outlib=work.functions.func;
function distance_jaccard(string1 $, string2 $);
n = length(string1);
m = length(string2);
ngrams1 = "";


    do i = 1 to (n-1);
    ngrams1 = cats(ngrams1, substr(string1, i, 2) || '*');
    end;

    /*ngrams1= ngrams1||'*';*/

    put ngrams1=;

    ngrams2 = "";

    do j = 1 to (m-1);
        ngrams2 = cats(ngrams2, substr(string2, j, 2) || '*');
    end;
endsub;

options cmplib=(work.functions);


data test;
  string1 = "joubrel";
  string2 = "farjoubrel";
  jaccard_distance = distance_jaccard(string1, string2);
run;

I expected ngrams1 and ngrams2 to contain all the substrings of length 2 instead I got this

ngrams1=jo*ou*ub
ngrams2=fa*ar*rj

Answer 1

If you want real help with your algorithm you need to explain in words what you want to do.

I suspect your problem is that you never defined how long you new character variables NGRAM1 and NGRAM2 should be. From the output you show it appears that FCMP defaulted them to length $8.

To define a variable you need use a LENGTH statement (or an ATTRIB statement with the LENGTH= option) before you start referencing the variable.