plc

procedure StrPlace(s: string; var str: string; position: Integer);
var
  d, i, p, c, l, z: Integer;
begin
  z := Length(s);
  if (z > 0) then
  begin
    l := Length(str);
    if ((l > 0) and not (position > l)) then
    begin
      p := position;
      case (p > 0) of
        True:
        begin
          case ((p + z) > l) of
            True: c := ((l - p) + 1);
            False: c := z;
          end;
          for i := 1 to c do
            str[((i + p) - 1)] := s[i];
        end;
        False:
        begin
          d := (1 - p);
          if (d < z) then
          begin
            c := (z - d);
            p := (p + d);
            if ((p + c) > l) then
              c := ((l - p) + 1);
            for i := 1 to c do
              str[((p + i) - 1)] := s[(i + d)];
          end;
        end;
      end;
    end;
  end;
end;

var
  str: string;
  i, l, x, y, z: Integer;

const
  TEXT1 = 'Testing this StrPlace() function';
  TEXT2 = '                                  ';
  BACKWARDS = False;
  ITERATIONS = 3;
  DELAY = 25;

begin
  l := Length(TEXT2);
  x := -(l - 1);
  y := (l + 1);
  case BACKWARDS of
    True:
    for z := 1 to ITERATIONS do
      for i := y downto x do
      begin
        ClearDebug;
        str := TEXT2;
        StrPlace(TEXT1, str, i);
        WriteLn('"' + str + '" [' + IntToStr(i) + ']');
        Wait(DELAY);
      end;
    False:
    for z := 1 to ITERATIONS do
      for i := x to y do
      begin
        ClearDebug;
        str := TEXT2;
        StrPlace(TEXT1, str, i);
        WriteLn('"' + str + '" [' + IntToStr(i) + ']');
        Wait(DELAY);
      end;
  end;
end.