Object-oriented Software in Ada 95

Input and output 277
Then the following example program writes instance of Person to the file people.txt.
with Text_Io, Pack_Types, Sequential_Io;
use Text_Io, Pack_Types;
procedure Main is
File_Name: constant String:= "people.txt";--Name
People : Person_Array;
package Io is new Sequential_Io( Person );
begin
declare
Fd : Io.File_Type; --File descriptor
begin
People(1) := (Name=>"Mike ", Sex=>Male, Height=>183);
People(2) := (Name=>"Corinna ", Sex=>Female, Height=>171);
People(3) := (Name=>"Miranda ", Sex=>Female, Height=> 74);
Io.Create( File=>Fd, Mode=>Io.Out_File, Name=>File_Name );
for I in Person_Range loop
Io.Write( Fd, People(I) );
end loop;
Io.Close(Fd);
exception
when Name_Error =>
Put("Cannot create " & File_Name ); New_Line;
end;
end Main;
Note:
The package Ada.Text_Io is used to provide the definition of the exception Name_Error.
When using the generic package Ada.Sequential_Io, the procedures read and write are used
to perform the input and output operations.
To read back the data written to the file people.txt the following example program is used:
with Text_Io, Pack_Types, Sequential_Io;
use Text_Io, Pack_Types;
procedure Main7 is
File_Name: constant String:= "people.txt";--Name
People : Person_Array;
package Io is new Sequential_Io( Person );
begin
declare
Fd : Io.File_Type; --File descriptor
begin
Io.Open( File=>Fd, Mode=>Io.In_File, Name=>File_Name );
for I in Person_Range loop
Io.Read( Fd, People(I) );
Put( People(I).Name );
Put( Height_Cm'Image( People(I).Height ) );
if People(I).Sex = Male then
Put(" Male");
else
Put(" Female");
end if;
New_Line;
end loop;
Io.Close(Fd);
exception
when Name_Error =>
Put("Cannot open " & File_Name ); New_Line;
end;
end Main7;
© M A Smith - May not be reproduced without permission