Here, for completeness without further comment, is the code for RTrim, LTrim and Trim which are included in the unit Tools.

      Function RTrim (Var S : String) : String ;
      {
         RTrim -- remove trailing blanks
      }
      Var
         i : Byte ;
      begin { RTrim }
         for i := Length(S) downto 1 do
            if S[i] > BLANK then begin
               S     := Copy(S,1,i) ;
               RTrim := S ;
               Exit
            end ;
         {
               if we reach this point then S contains only BLANKS
            so we return a null string
         }
         S     := '' ;
         RTrim := S
      end ; { RTrim }

      Function LTrim (Var S : String) : String ;
      {
         LTrim -- remove leading blanks
      }
      Var
         i : Byte ;
      begin { LTrim }
         for i := 1 to Length(S) do
            if S[i] > BLANK then begin
               S     := Copy(S,i,MAXSTR) ;
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DeTab is the inverse of EnTab. Here is the specification:

{
PROGRAM
      DeTab    -- convert tabs to blanks
USAGE
      DeTab
FUNCTION
      DeTab copies its input to its output, expanding horizontal tabs to 
      blanks along the way, so that the output is visually the same as the        
      input, but contains no tab chars.  Tab stops are assumed to be set
      every three columns (i.e., 1, 4, 7, 10, ...), so that each tab char
      is replaced by from one to three blanks.
BUGS
      1. DeTab is naive about backspace, vertical motions, and
         non-printing chars.
      2. Each line of output will be truncated at MAXSTR chars.
      3. Trailing BLANKS will be trimmed from each line of output.
}

DeTab's main routine echos EnTab's, reducing the problem to one of detabbing a single string. To detab the string we could try to simply apply EnTab's strategy in reverse, however, this is another chance to apply the "how would a human do it?" approach.

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