Object-oriented Software in Ada 95

276 Input and output
The following program appends instances of Number, one of the integer types to the end of the file
file.txt:
with Text_Io;
use Text_Io;
procedure Main is
type Number is range 1 .. 10;
Fd : Text_Io.File_Type; --File descriptor
File_Name: constant String:= "file.txt";--Name
package Pack_Number_Io is new Text_Io.Integer_Io( Number );
begin
Open( File=>Fd, Mode=>Append_File, Name=>File_Name );
for I in Number loop
Pack_Number_Io.Put( Fd, I ); New_Line( Fd );
end loop;
Close(Fd);
exception
when Name_Error =>
Put("Cannot append to " & File_Name ); New_Line;
end Main;
18.3 Reading and writing binary data
Any instance of a type may be read and written to a file using the package Ada.Sequential_io. By using this
package, binary images of objects may be read and written. For example, the following code writes instances of
the data structure Person to the file people.txt. Firstly the Package_Types defines the data structure
Person used to represent an individual person.
package Pack_Types is
Max_Chs : constant := 10;
type Gender is ( Female, Male );
type Height_Cm is range 0 .. 300;
type Person is record
Name : String( 1 .. Max_Chs ); --Name as a String
Height : Height_Cm := 0; --Height in cm.
Sex : Gender; --Gender of person
end record;
type Person_Index is range 1 .. 3;
subtype Person_Range is Person_Index;
type Person_Array is array ( Person_Range ) of Person;
end Pack_Types;
© M A Smith - May not be reproduced without permission