Replacement of names of variables

Question

First of all, I know replace or plugging input of given function through command Replace[] or /.{x->1} etc.

Here I want to focus not just on plugging or replacing variables into numbers but just replacing some of the variable's names or deleting unnecessary operations to another.

First of all suppose I have sequences aa1,aa2,aa3,aa4, bb1,bb2,bb3,bb4, cc1,cc2,cc3,cc4, etc. and I have a function whose expression is some combination of particular sequences.

I want to replace the name of all my sequences i.e., aa1-> ab1, cc1-> cb1, etc

So for a given input $aa1bb1+aa2cc1$, after this replacement, this produces $ab1bb1+ ab2cb1$.

Using some editor like notepad, I can do this by find and research easily but have wonder whether a similar thing can do on Mathematica itself.

Answer 1

If you are trying to do replacement in the front end, you can try something like

ac = Cells[CellStyle -> {"Input"}];
content = NotebookRead /@ ac;
newContent = content /. {"aa1" -> "ab1", "cc1" -> "cb1"};
Scan[NotebookWrite[ac[[#]], newContent[[#]]] &, Range@Length@newContent];

Answer 2

Clear["Global`*"]

rules = {aa1 -> ab1, aa2 -> ab2, cc1 -> cb1};

convert[x_] := ToExpression@StringJoin[
   StringReplace[ToString[x],
    Map[ToString, rules, {2}]]]

expr = aa1bb1 + aa2cc1;

convert@expr

(* ab1bb1 + ab2cb1 *)