How to define a function with varying amount parameters?

Question

I am new to proc fcmp and I want to know how to write a user-defined function with varying amount parameters, which like whichc() or coalesce(), in SAS.

I will be grateful if anybody could give me some hints.

Answer 1

It's not possible, although you can pass arrays as described here (reproduced below):

function sas_summation (b[*]) varargs;
   total = 0;
   do i = 1 to dim(b);
       total = total + b[i];
   end;
return(total);
endsub;
run;
quit;

options cmplib=work.functions;

data one;
  input x1-x5;
datalines;
1 2 3 4 5
2 3 4 5 6
4 5 6 7 8
;
run;

data two;
set one;
array temp (5) _temporary_;
array perm2 (*) x1-x5;
do i=1 to dim(temp);
  temp(i)=perm2(i);
end;
drop i;
x=sas_summation(temp);
run;