I've a programming project in my college.
Using a File type for storing data is allowed, and I did exactly like this one: pascal-programming
And, here's what I achieved so far:
I tried to write the Records data into Untyped files instead and it worked
I want to override a function with dynamic parameter (e.g: I can switch which Record I want to process, in this case there's 2 different "Records").
Open(var f: File; var data)
data = represent can receive "anything". cmiiw
The reason why I did this, I don't think it's a good idea to recreate the same function over and over, e.g: when using 3 or more different "Records"
I also encountered a problem that the files can't store or backup the actual binary files to the temporary "Records" variable, it always give the 0 values.
my solution here doesn't provide any generic related procedures (check the last sentences):
program test_untyped;
{ A crude database recording }
uses crt;
type
Temployee = record
name : string[20];
address : string[40];
phone : string[15];
age : byte;
salary : longint;
end;
arr_employee = array[1..100] of Temployee;
var
F : File;
c : char;
// r : Temployee;
r, realR : arr_employee;
s : string;
i, j, n : integer;
procedure fRead;
begin
seek(F, 0);
i := 0;
repeat
clrscr;
inc(i);
writeln('increment: ', i); readln;
writeln('File position : ',filepos(F));
blockRead(F, r[i], sizeOf(Temployee));
writeln('Name = ', r[i].name); { Input data }
writeln('Address = ', r[i].address);
writeln('Phone = ', r[i].phone);
writeln('Age = ', r[i].age);
writeln('Salary = ', r[i].salary);
write('Show data again (Y/N) ?');
repeat
c:=upcase(readkey); { Ask user : Input again or not }
until c in ['Y','N'];
writeln(c);
// realR[i] := r[i]; // backup, to show later
until c='N';
end; // end fRead
procedure fWrite;
begin
seek(F, filesize(F));
repeat
clrscr;
inc(i);
writeln('berapa nilai i: ', i);
writeln('File position : ',filepos(F));
write('Name = '); readln(r[i].name); { Input data }
write('Address = '); readln(r[i].address);
write('Phone = '); readln(r[i].phone);
write('Age = '); readln(r[i].age);
write('Salary = '); readln(r[i].salary);
blockWrite(F, r[i], sizeOf(Temployee)); { Write data to file }
write('Input data again (Y/N) ?');
repeat
c:=upcase(readkey); { Ask user : Input again or not }
until c in ['Y','N'];
writeln(c);
until c='N';
end;
// procedure fDelete;
// var
// nama: string;
// delElement: integer;
// tempR: Temployee;
// begin
// seek(F, 0);
// write('search your data by name: '); readln(nama);
// while not eof(F) do
// begin
// writeln('file position: ', filePos(F));
// blockRead(F, tempR, sizeOf(Temployee));
// if (nama = tempR.name) then
// begin
// delElement := filePos(F);
// end else
// begin
// // seek(F, )
// blockWrite(F, tempR, sizeOf(Temployee));
// end;
// end;
// end; // end fDelete
procedure fDisplay;
begin
writeln('nilai i saat ini: ', i); readln;
for j := 1 to i do
begin
clrscr;
writeln('Name = ', r[j].name); { Input data }
writeln('Address = ', r[j].address);
writeln('Phone = ', r[j].phone);
writeln('Age = ', r[j].age);
writeln('Salary = ', r[j].salary);
readln;
end;
end;
begin
clrscr;
// write('Input file name to record databases : '); readln(s);
s := 'coba1.dat';
assign(F,s); { Associate it }
{$I-}
reset(F, sizeOf(Temployee)); { First, open it }
{$I+}
n:=IOResult;
if n<>0 then { If it's doesn't exist then }
begin
{$I-}
rewrite(F, sizeOf(Temployee)); { Create it }
{$I+}
n:=IOResult;
if n<>0 then
begin
writeln('Error creating file !'); halt;
end;
end
else
begin { If it exists then }
n:=filesize(F); { Calculate total record }
// seek(F,n); { Move file pointer PAST the last record }
end;
fileMode := 2;
reset(F, sizeOf(Temployee));
fRead;
fWrite;
// fDelete;
fDisplay;
close(F);
end.
I'm wondering is the Pascal can be any good to use a generic programming? at least for this semester using Pascal in my college XD
Thank you and Best Regards,
EDIT: Pascal still doesn't support Generic Programming 'till the day I posted this question. So sad, really. You might wanna consider read this references instead.
I don't understand the main issue here, but would suggest using a typed file instead of an untyped one. An untyped file is much harder to maintain, and provides (in my eyes) no benefits.
Consider the code:
type
Temployee = record
name : string[20];
address : string[40];
phone : string[15];
age : byte;
salary : longint;
end;
VAR
fEmployee : File Of Temployee;
Employees : ARRAY[0..100] Of Temployee;
Employee : Temployee;
PROCEDURE OpenEmployeeFile(CONST TheFileName:AnsiString);
BEGIN
AssignFile(fEmployee,TheFileName);
IF FileExistsUTF8(TheFileName) { *Converted from FileExists* }
THEN Reset(fEmployee)
ELSE Rewrite(fEmployee);
END;
PROCEDURE CloseEmployeeFile;
BEGIN
Close(fEmployee);
END;
FUNCTION ReadEmployee(Position:WORD): Temployee;
BEGIN
Seek(fEmployee,Position);
Read(fEmployee,Result);
END;
PROCEDURE WriteEmployee(CONST Employee:Temployee; Position:WORD);
BEGIN
Seek(fEmployee,Position);
Write(fEmployee,Employee);
END;
Error handling not implemented. Code samples as a guideline, not complete. It provides a basic skeleton for opening and closing the employee-file, as well as reading and writing at specific positions (specific records) in the file.
Or.