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delete procedure Posted by sexyderry on 30 Apr 2003 at 11:16 AM

can any one help with a delete procedure please. it is AS coursework and i cant get it to work it compiles but gives a run time error.

begin
clrscr;
assign (pupilfile,'n:pupil.dat');
reset (pupilfile);
writeln ('existing file');
writeln;writeln;writeln;
writeln ('name':15,' Candidate':9,'year':6,'mark':5);
writeln (' ':15,' number ':9,' ':6,' ':5);

writeln;
writeln;
readln;
while not eof (pupilfile) do
begin
read (pupilfile,temp);
writeln (temp.name:15,temp.cand_no:9,temp.year:6,temp.mark:5);
end;

reset (pupilfile);
writeln ('enter candidate number to be deleted');
readln (n);
position:=0;
while not eof (pupilfile) do
begin
read (pupilfile,temp);
position:=(position+1);
if (temp.cand_no=n) then begin
clrscr;
writeln (temp.name:15,temp.cand_no:9,temp.year:6,temp.mark:5);
writeln;writeln;
writeln ('is this the record to be deleted: ');
readln (ans);
if (ans='y') or (ans='Y') then begin
seek (pupilfile,filesize(pupilfile)-1);
truncate (pupilfile);
end;
reset (pupilfile);
clrscr;
writeln ('name':15,'year':10,'mark':10);
writeln;

while not eof (pupilfile) do
begin
read (pupilfile,temp);
writeln (temp.name:15,temp.cand_no:8,temp.year:6,temp.mark:5);
end;
close (pupilfile);

end;
end;

??????????????????????????????? thanks for your help...

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Re: delete procedure Posted by roland48 on 2 May 2003 at 2:46 PM

: can any one help with a delete procedure please. it is AS coursework and i cant get it to work it compiles but gives a run time error.
:
: begin
: clrscr;
: assign (pupilfile,'n:pupil.dat');
: reset (pupilfile);
: writeln ('existing file');
: writeln;writeln;writeln;
: writeln ('name':15,' Candidate':9,'year':6,'mark':5);
: writeln (' ':15,' number ':9,' ':6,' ':5);
:
: writeln;
: writeln;
: readln;
: while not eof (pupilfile) do
: begin
: read (pupilfile,temp);
: writeln (temp.name:15,temp.cand_no:9,temp.year:6,temp.mark:5);
: end;
:
: reset (pupilfile);
: writeln ('enter candidate number to be deleted');
: readln (n);
: position:=0;
: while not eof (pupilfile) do
: begin
: read (pupilfile,temp);
: position:=(position+1);
: if (temp.cand_no=n) then begin
: clrscr;
: writeln (temp.name:15,temp.cand_no:9,temp.year:6,temp.mark:5);
: writeln;writeln;
: writeln ('is this the record to be deleted: ');
: readln (ans);
: if (ans='y') or (ans='Y') then begin
: seek (pupilfile,filesize(pupilfile)-1);
: truncate (pupilfile);
: end;
: reset (pupilfile);
: clrscr;
: writeln ('name':15,'year':10,'mark':10);
: writeln;
:
: while not eof (pupilfile) do
: begin
: read (pupilfile,temp);
: writeln (temp.name:15,temp.cand_no:8,temp.year:6,temp.mark:5);
: end;
: close (pupilfile);
:
: end;
: end;
:
: ??????????????????????????????? thanks for your help...
:
:
:

Take a look in your help-file to get the sense of your runtime-error!
I gues there is an IO-Error . You are not shure, if the requested file
exists and you make a reset on an file just opend.
Use the local compiler-switch {$I-)... Code ...{SI+} to trap your
error and get the meaning of IOResult!

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Re: delete procedure Posted by Phat Nat on 3 May 2003 at 7:51 AM

: can any one help with a delete procedure please. it is AS coursework and i cant get it to work it compiles but gives a run time error.
:
: begin
: clrscr;
: assign (pupilfile,'n:pupil.dat');
: reset (pupilfile);
: writeln ('existing file');
: writeln;writeln;writeln;
: writeln ('name':15,' Candidate':9,'year':6,'mark':5);
: writeln (' ':15,' number ':9,' ':6,' ':5);
:
: writeln;
: writeln;
: readln;
: while not eof (pupilfile) do
: begin
: read (pupilfile,temp);
: writeln (temp.name:15,temp.cand_no:9,temp.year:6,temp.mark:5);
: end;
:
: reset (pupilfile);
: writeln ('enter candidate number to be deleted');
: readln (n);
: position:=0;
: while not eof (pupilfile) do
: begin
: read (pupilfile,temp);
: position:=(position+1);
: if (temp.cand_no=n) then begin
: clrscr;
: writeln (temp.name:15,temp.cand_no:9,temp.year:6,temp.mark:5);
: writeln;writeln;
: writeln ('is this the record to be deleted: ');
: readln (ans);
: if (ans='y') or (ans='Y') then begin
: seek (pupilfile,filesize(pupilfile)-1);
: truncate (pupilfile);
: end;
: reset (pupilfile);
: clrscr;
: writeln ('name':15,'year':10,'mark':10);
: writeln;
:
: while not eof (pupilfile) do
: begin
: read (pupilfile,temp);
: writeln (temp.name:15,temp.cand_no:8,temp.year:6,temp.mark:5);
: end;
: close (pupilfile);
:
: end;
: end;
:
: ??????????????????????????????? thanks for your help...

What are all your variables (mainly the TEMP variable) declared as ?

Phat Nat

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Re: delete procedure Posted by sexyderry on 3 May 2003 at 1:28 PM

: : can any one help with a delete procedure please. it is AS coursework and i cant get it to work it compiles but gives a run time error.
: :
: : begin
: : clrscr;
: : assign (pupilfile,'n:pupil.dat');
: : reset (pupilfile);
: : writeln ('existing file');
: : writeln;writeln;writeln;
: : writeln ('name':15,' Candidate':9,'year':6,'mark':5);
: : writeln (' ':15,' number ':9,' ':6,' ':5);
: :
: : writeln;
: : writeln;
: : readln;
: : while not eof (pupilfile) do
: : begin
: : read (pupilfile,temp);
: : writeln (temp.name:15,temp.cand_no:9,temp.year:6,temp.mark:5);
: : end;
: :
: : reset (pupilfile);
: : writeln ('enter candidate number to be deleted');
: : readln (n);
: : position:=0;
: : while not eof (pupilfile) do
: : begin
: : read (pupilfile,temp);
: : position:=(position+1);
: : if (temp.cand_no=n) then begin
: : clrscr;
: : writeln (temp.name:15,temp.cand_no:9,temp.year:6,temp.mark:5);
: : writeln;writeln;
: : writeln ('is this the record to be deleted: ');
: : readln (ans);
: : if (ans='y') or (ans='Y') then begin
: : seek (pupilfile,filesize(pupilfile)-1);
: : truncate (pupilfile);
: : end;
: : reset (pupilfile);
: : clrscr;
: : writeln ('name':15,'year':10,'mark':10);
: : writeln;
: :
: : while not eof (pupilfile) do
: : begin
: : read (pupilfile,temp);
: : writeln (temp.name:15,temp.cand_no:8,temp.year:6,temp.mark:5);
: : end;
: : close (pupilfile);
: :
: : end;
: : end;
: :
: : ??????????????????????????????? thanks for your help...
:
:
: What are all your variables (mainly the TEMP variable) declared as ?
:
: Phat Nat
:
:
:
they are all in the glabal variable box.

all the candidates profiles are read into a record, and pupilfile is read into temp.

type a=record
name_address:string[15];
candno_address: integer;
addressline:string[20];
town:string[10];
postcode:string[6];
end;

type p=record
name : string[15];
cand_no:integer;
year : integer;
mark : integer;
new_grade:char;
sub_ref_code:string[5];

var temp : p;
pupilfile : file of p;
end;

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Re: delete procedure Posted by Phat Nat on 3 May 2003 at 5:12 PM

This message was edited by Phat Nat at 2003-5-3 17:13:40

: can any one help with a delete procedure please. it is AS coursework and i cant get it to work it compiles but gives a run time error.
:

begin
clrscr;
assign (pupilfile,'n:pupil.dat');
reset (pupilfile);
writeln ('existing file');
writeln;writeln;writeln;
writeln ('name':15,' Candidate':9,'year':6,'mark':5);
writeln ('    ':15,' number   ':9,'    ':6,'    ':5);

writeln;
writeln;
readln;
while not eof (pupilfile) do
      begin
      read (pupilfile,temp);
      writeln (temp.name:15,temp.cand_no:9,temp.year:6,temp.mark:5);
      end;

reset (pupilfile);
writeln ('enter candidate number to be deleted');
readln (n);
position:=0;

while not eof (pupilfile) do
begin
     read (pupilfile,temp);
     position:=(position+1);
     if (temp.cand_no=n) then
     begin
          clrscr;
          writeln (temp.name:15,temp.cand_no:9,temp.year:6,temp.mark:5);
          writeln;writeln;
          writeln ('is this the record to be deleted: ');
          readln (ans);
          if (ans='y') or (ans='Y') then
          begin
               seek (pupilfile,filesize(pupilfile)-1);
               truncate (pupilfile);
          end;
          reset (pupilfile);
          clrscr;
          writeln ('name':15,'year':10,'mark':10);
          writeln;

          while not eof (pupilfile) do
          begin
               read (pupilfile,temp);
               writeln (temp.name:15,temp.cand_no:8,temp.year:6,temp.mark:5);
          end;
          close (pupilfile);
     end; 
end;   { before it can exit here, it checks again up above }

Your problem is that you are closing your file and then it checks it again. Since the file is closed, it gives a runtime error when it checks for the end of the file.

          {...}
          while not eof (pupilfile) do
          begin
               read (pupilfile,temp);
               writeln (temp.name:15,temp.cand_no:8,temp.year:6,temp.mark:5);
          end;
     end; 
     close (pupilfile);     { Move the close call here }
end;

This should do it.

Phat Nat

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Re: delete procedure Posted by sexyderry on 4 May 2003 at 6:49 AM

: This message was edited by Phat Nat at 2003-5-3 17:13:40

: : can any one help with a delete procedure please. it is AS coursework and i cant get it to work it compiles but gives a run time error.
: :
:

: begin
: clrscr;
: assign (pupilfile,'n:pupil.dat');
: reset (pupilfile);
: writeln ('existing file');
: writeln;writeln;writeln;
: writeln ('name':15,' Candidate':9,'year':6,'mark':5);
: writeln ('    ':15,' number   ':9,'    ':6,'    ':5);
: 
: writeln;
: writeln;
: readln;
: while not eof (pupilfile) do
:       begin
:       read (pupilfile,temp);
:       writeln (temp.name:15,temp.cand_no:9,temp.year:6,temp.mark:5);
:       end;
: 
: reset (pupilfile);
: writeln ('enter candidate number to be deleted');
: readln (n);
: position:=0;
: 
: while not eof (pupilfile) do
: begin
:      read (pupilfile,temp);
:      position:=(position+1);
:      if (temp.cand_no=n) then
:      begin
:           clrscr;
:           writeln (temp.name:15,temp.cand_no:9,temp.year:6,temp.mark:5);
:           writeln;writeln;
:           writeln ('is this the record to be deleted: ');
:           readln (ans);
:           if (ans='y') or (ans='Y') then
:           begin
:                seek (pupilfile,filesize(pupilfile)-1);
:                truncate (pupilfile);
:           end;
:           reset (pupilfile);
:           clrscr;
:           writeln ('name':15,'year':10,'mark':10);
:           writeln;
: 
:           while not eof (pupilfile) do
:           begin
:                read (pupilfile,temp);
:                writeln (temp.name:15,temp.cand_no:8,temp.year:6,temp.mark:5);
:           end;
:           close (pupilfile);
:      end; 
: end;   { before it can exit here, it checks again up above }
:

:
: Your problem is that you are closing your file and then it checks it again. Since the file is closed, it gives a runtime error when it checks for the end of the file.
:
:

:           {...}
:           while not eof (pupilfile) do
:           begin
:                read (pupilfile,temp);
:                writeln (temp.name:15,temp.cand_no:8,temp.year:6,temp.mark:5);
:           end;
:      end; 
:      close (pupilfile);     { Move the close call here }
: end;
:

:
: This should do it.
:
: Phat Nat
:
:
:
:
I CANNOT BELIEVE I DIDNT SEE THAT!! THANKS ALOT NAT. YOU HERO!! LOL!! CHEERS FOR THAT.

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