PROGRAM BlockReadDemo;
TYPE ProductT = RECORD
                  Part_Number : Integer;
                  Stock : Integer;
                  Price : Real;
                  Description : STRING[20];
 (* ...
 Other fields here ...
 *)
                END;
VAR
  Product : ProductT;
  Product_File : FILE OF ProductT;
  APrice : Real;
  FUNCTION Standard_Inventory_Value : Real;
    (* File must be RESET before calling this function *)
  VAR
    Value : Real;
  BEGIN
    Seek(Product_File, 0); Value := 0.0;
    WHILE NOT Eof(Product_File) DO
      BEGIN
        Read(Product_File, Product);
        Value := Value+Product.Price*Product.Stock;
      END;
    Standard_Inventory_Value := Value;
  END;

  FUNCTION My_Inventory_Value : Real;
  CONST BufferSize = 500;
  VAR
    Buffer : ARRAY[1..BufferSize] OF ProductT;
    F : FILE ABSOLUTE Product_File;
    Value : Real;
    i, RecsInBuffer : Integer;

  BEGIN
    Seek(F, 0); Value := 0.0;
    WHILE NOT Eof(F) DO
      BEGIN
        BlockRead(F, Buffer, BufferSize, RecsInBuffer);
        FOR i := 1 TO RecsInBuffer DO
          Value := Value+Buffer[i].Price*Buffer[i].Stock;
      END;
    My_Inventory_Value := Value;
  END;

BEGIN
  WriteLn('This program is strictly a demonstration.');
  WriteLn('It does nothing useful of itself.');
  Assign(Product_File, 'TEMP.$$$');
  ReWrite(Product_File);
  APrice := 1.0;
  FillChar(product, SizeOf(Product), 0);
  Product.Stock := 1;
  (*You may replace 100.0 with a larger number if you wish.*)
  WHILE APrice <= 100.0 DO
    BEGIN
      Product.Price := APrice;
      Write(Product_File, Product);
      APrice := APrice + 1;
    END;
  WriteLn('Typed-file function gives result ',Standard_Inventory_Value:1:4);
  WriteLn('UNtyped-file function gives result ',My_Inventory_Value:1:4);
  Close(Product_File);
  Erase(Product_File);
END.