I thank all those that helped me with the file problem. But it seems problems won't just stop turning up. I don't know how to use arrow keys to move from one field to another. The thing is that i am asked to move through the fields to fix the data in the records if necessary but i have no idea of how the code to move between fields is. All i need is to move through the following fields:
Student name
Student surname
Subjects

(I only need to use up and down arrow keys)

Here's my code

Procedure Amend;
var
i, ts : integer;
choice : char;

begin
clrscr;
ts := 1;
assign(mainfile, 'C:\main.dat');
reset(mainfile);
for i := 1 to filesize(mainfile) do
begin
ts := 1;
reset(mainfile);
seek(mainfile, filesize(mainfile) - i);
read(mainfile, onestud);
gotoxy(20, 12);
Writeln('Student Name : ', onestud.name);
gotoxy(20, 13);
Writeln('Student Surname : ', onestud.surname);
gotoxy(20, 14);
Write('Subjects : ');
while onestud.subs <> [] do
begin
if ts in onestud.subs then
begin
write(subject_array[ts], ' ');
onestud.subs := onestud.subs - [ts];
end;
inc(ts);
end;
choice := Readkey;
case choice of
#0: Begin
Case choice Of
#72: begin
gotoxy(20, 28);
writeln(newname);
end;

#80:
end;
end;
end;

readln;
close(mainfile);
end;
end;

(I tried doing something but i didn't manage)
Thanks

: I thank all those that helped me with the file problem. But it seems problems won't just stop turning up. I don't know how to use arrow keys to move from one field to another. The thing is that i am asked to move through the fields to fix the data in the records if necessary but i have no idea of how the code to move between fields is. All i need is to move through the following fields:
: Student name
: Student surname
: Subjects
:
: (I only need to use up and down arrow keys)
:
: Here's my code
:
: Procedure Amend;
: var
: i, ts : integer;
: choice : char;
:
: begin
: clrscr;
: ts := 1;
: assign(mainfile, 'C:\main.dat');
: reset(mainfile);
: for i := 1 to filesize(mainfile) do
: begin
: ts := 1;
: reset(mainfile);
: seek(mainfile, filesize(mainfile) - i);
: read(mainfile, onestud);
: gotoxy(20, 12);
: Writeln('Student Name : ', onestud.name);
: gotoxy(20, 13);
: Writeln('Student Surname : ', onestud.surname);
: gotoxy(20, 14);
: Write('Subjects : ');
: while onestud.subs <> [] do
: begin
: if ts in onestud.subs then
: begin
: write(subject_array[ts], ' ');
: onestud.subs := onestud.subs - [ts];
: end;
: inc(ts);
: end;
: choice := Readkey;
: case choice of
: #0: Begin
: Case choice Of
: #72: begin
: gotoxy(20, 28);
: writeln(newname);
: end;
:
: #80:
: end;
: end;
: end;
:
: readln;
: close(mainfile);
: end;
: end;
:
: (I tried doing something but i didn't manage)
: Thanks

To use the arrow keys, you need to do a dual key read. If the first key = char(0) then you need to read the keystroke again. The second character will be the value that you want to compare. For the arrows, the characters that define them are UP=char(72) and DOWN=char(80).

As for moving through fields, the easiest way is to just keep re-writing the data onto the screen and when the selected line is being written to the screen, change the background to a different color.

USES Crt, Dos;
VAR
   Selection : ShortInt;
   Key : Char;

Begin
     Repeat
           If Selection = 0 Then TextBackground(1) ELSE TextBackground(0);
           WriteLn('Choice #1');
           If Selection = 1 Then TextBackground(1) ELSE TextBackground(0);
           WriteLn('Choice #2');
           If Selection = 2 Then TextBackground(1) ELSE TextBackground(0);
           WriteLn('Choice #3');
           Key := Readkey;
           If Key = #0 Then
           Begin
                Key := Readkey;
                Case Key Of
                 #72 : Dec(Selection);
                 #80 : Inc(Selection);
                End;
           End;
     Until Key = #27;
End.

This is the basic idea. This doesn't check to see if Selection is within 1-3 and this writing method makes the code a little bit long, but it should get you started.

Phat Nat

I tried your program but it doesn't seem to work well. I tried fixing it up but i didn't manage

: I tried your program but it doesn't seem to work well. I tried fixing it up but i didn't manage
:
Sorry my fault, it works fine. I wanted to ask, let's sa i have an index file and i list all the student's according to their name and surname. How can i use the left and right keys and home and end keys in addition to the up and down keys?

: : I tried your program but it doesn't seem to work well. I tried fixing it up but i didn't manage
: :
: Sorry my fault, it works fine. I wanted to ask, let's sa i have an index file and i list all the student's according to their name and surname. How can i use the left and right keys and home and end keys in addition to the up and down keys?

Note the addition to the following code:

USES Crt, Dos;
VAR
   Selection : ShortInt;
   Key : Char;

Begin
     Repeat
           If Selection = 0 Then TextBackground(1) ELSE TextBackground(0);
           WriteLn('Choice #1');
           If Selection = 1 Then TextBackground(1) ELSE TextBackground(0);
           WriteLn('Choice #2');
           If Selection = 2 Then TextBackground(1) ELSE TextBackground(0);
           WriteLn('Choice #3');
           Key := Readkey;
           If Key = #0 Then
           Begin
                Key := Readkey;
                Case Key Of
                 #72 : Dec(Selection);
                 #80 : Inc(Selection);
                 ELSE WriteLn(Ord(Key));
                End;
           End;
     Until Key = #27;
End.

If the key you press isn't listed (up & down in this case) it will display the ordinal value of that key (75=LEFT, 77=RIGHT). I don't have Home/End/PageUp/PageDown/etc memorized, but it will tell you their values when you press the key.

Phat Nat