Recursion Output Problem

Hi All,

I am writing a recursion problem to do some string manipulation. Seems like I am almost there. However, my function operates perfectly and does perform the manipulation I want. But, during exit condition, it performs one more recursion, and somehow it screws up the output, at the very end. It is as following: I would sincerely appreciate your help/inputs.

function strnew = stringop1rec(strogi, str1, str2,rtflag, ltflag)
lnstr = lenfunc(strogi); lnstr1 = lenfunc(str1); lnstr2 = lenfunc(str2); dff = lnstr1 - lnstr2;

      if rem(lnstr,2)~=0
          disp('The String is Length is Odd Numbers.  The Function ignored the Middle Character.')
      end
  %Depending upon number of arguments passed into Function Starting Position
  %are initialized
      if nargin == 3
          rtflag=1; ltflag=lnstr;
      elseif nargin == 4
          disp('Please enter the starting position for Other half Character C2 :')
      else
          rtflag = rtflag+1; ltflag = ltflag-1;
      end

ii=0; jj=0;

%Calculates the occurence of Character C1 in first half of string
    for i=rtflag:floor(lnstr/2)
            if strogi(i:i+lnstr1-1) == str1;
                ii=i;
                break;
            end
    end

%Calculates the occurence of Character C2 in second half of string
    for j=ltflag:-1:ceil(lnstr/2+1)
            if strogi(j-lnstr2+1:j) == str2;
                jj = j;
                break;
            end
    end
s1 = 0; s2=0;
strnew=strogi;    

%The Following Loops are written to avoid using Concatenante Function.
if ii~=0 && jj~=0
        for rti=rtflag:floor(lnstr/2)
            if rti< ii
                strnew(rti)=strogi(rti);
            elseif rti>=ii && rti<ii+lnstr2
                s2 = s2+1;
                strnew(rti)=str2(s2);
            else
                strnew(rti)=strogi(rti+dff);
            end
        end
        for lti=ltflag:-1:floor(lnstr/2)
            if lti> jj
                strnew(lti)=strogi(lti);
            elseif lti<=jj && lti>jj-lnstr1
                s1 = s1+1;
                strnew(lti)=str1(lnstr1-s1+1);
            else
                strnew(lti)=strogi(lti+dff);
            end
        end

      stringop1rec(strnew,str1,str2,ii,jj);  %If Code finds a pair of substrings, performs Recursion
  end