ReadAndSum

Program ReadAndSum;
{ This program extends the program SumThem by reading
  the five values to sum from a file using another procedure
  called ReadFive()

  IMPORTANT: The file 'rs_data.txt' MUST EXIST on the a: drive.
  See procedure ReadFive for file data format details.
}

{ set up a type that defines an array of 5 elements each of 
  type real. This way we don't have to repeatedly type 
   array[1..5] of real.
}
type
   tp_Array5 = array[1..5] of real;

var
   infile  : text;
   nums    : tp_Array5;
   the_sum : real;


{ ----------------------------------------------------------------
  ReadFive
  Read five numbers (of type real) into num_list[] from the
  file assigned to in_file.
  Note we assume each number is on a separate line.
  ---------------------------------------------------------------- }

procedure ReadFive(var in_file : text; var num_list : tp_Array5);
var
   i : integer;    { i is a local variable of ReadFive }

begin
   i := 1;
   while (i <= 5) do
   begin
      readln(in_file, num_list[i]);
      i := i + 1;
   end; { while }

end; { ReadFive }


{ ----------------------------------------------------------------
  CalcSum
  Calculate the sum of the numbers in num_list[]
  ---------------------------------------------------------------- }

procedure CalcSum(num_list : tp_Array5; var sum : real);
var
   i : integer;    { i is a local variable of CalcSum }

begin
   sum := 0.0;   { initialize sum to be zero }

   i := 1;
   while (i <= 5) do
   begin
      sum := sum + num_list[i];
      i := i + 1;
   end; { while }

end; { CalcSum }


{ ----------------------------------------------------------------
  main program begins
  ---------------------------------------------------------------- }

begin
   { First we must open the file for reading }
   assign(infile, 'a:rs_data.txt');
   reset(infile);

   ReadFive(infile, nums);

   CalcSum(nums, the_sum);

   writeln('The sum of the numbers is: ', the_sum:0:3);

   { always be sure to close the file }
   close(infile);

end. { main program }