SAS code, loop index and more, how to simplify - loops

Question

I have SAS code below and then can run. The challenge is I have to repeat them so many times and it looks really awkward. I need Trans1-Tran2, TransOut1-TransOut100, and the BBB, AAA, VCS are user defined and no trend to follow.
%transform(Trans1,BBB,TransOut1);
%transform(Trans2,AAA,TransOut2);
%transform(Trans3,VCS,TransOut3);
%transform(Trans4,REM,TransOut4);
I am thinking combine do loop and Scan in my code but I do not know how to use index in the variable name so I cannot test my idea. Sample code that cannot run.
%let second= BBB, AAA, VCS,REM;
%macro trans;
%do i=1 %to 4;
%transform(Trans(i)?,%scan(&second.,&i),TransOut(i);
%end;
%mend;
I post some testing code below:
%macro test(data, var);
Data &data.;
Fname= "John";
Phone= 123;
City="Chicago";
Zip=65456;
keep &var.;
Run;
%mend;
%test(test1, Phone);
%test(test2, Fname);
%test(test3, City);
%test(test4, Zip);

Answer 1

You got it almost right already.
(Best leave out the comma in your list).
%let second= BBB AAA VCS REM;
%macro trans;
%do i=1 %to 4;
%transform(Trans&i,%scan(&second.,&i),TransOut&i);
%end;
%mend;
If you are dealing with a long list, you should consider using call execute:
data init;
input index userDef $;
datalines;
1 AAA
2 BBB
3 VCS
4 REM
;
run;
data _null_;
set init;
call execute(
cats(
'%transform(Trans', index, ',', userDef, ',TransOut', index,')'
)
);
run;
edit: using cats now, as suggested by Joe

Answer 2

In addition to Jetzler's answer, note that depending on the situation, it may be easier to include the loops in your macro:
%let trans = trans1 trans2 trans3 trans4;
%let trips = aaa bbb rem vcs;
%let outs = transout1 transout2 transout3 transout4;
%macro transform;
%do i = 1 %to %sysfunc(countw(&trans.));
%do j = 1 %to %sysfunc(countw(&trips.));
%do k = 1 %to %sysfunc(countw(&outs.));
/*your code here*/
%end;
%end;
%end;
%mend transform;
%transform;