Some languages have special semantics for obtaining a known line number from a file.



Task

Demonstrate how to obtain the contents of a specific line within a file.

For the purpose of this task demonstrate how the contents of the seventh line of a file can be obtained,   and store it in a variable or in memory   (for potential future use within the program if the code were to become embedded).

If the file does not contain seven lines,   or the seventh line is empty,   or too big to be retrieved,   output an appropriate message.

If no special semantics are available for obtaining the required line,   it is permissible to read line by line.

Note that empty lines are considered and should still be counted.

Also note that for functional languages or languages without variables or storage,   it is permissible to output the extracted data to standard output.




with Ada.Text_IO;  use Ada.Text_IO;
 
procedure Rosetta_Read is
   File : File_Type;
begin
   Open (File => File,
         Mode => In_File,
         Name => "rosetta_read.adb");
   Set_Line (File, To => 7);
 
   declare
      Line_7 : constant String := Get_Line (File);
   begin
      if Line_7'Length = 0 then
         Put_Line ("Line 7 is empty.");
      else
         Put_Line (Line_7);
      end if;
   end;
 
   Close (File);
exception
   when End_Error =>
      Put_Line ("The file contains fewer than 7 lines.");
      Close (File);
   when Storage_Error =>
      Put_Line ("Line 7 is too long to load.");
      Close (File);
end Rosetta_Read;