Pascal - not writing to file

Question

Howdy, Pascal masters! I've got a file type of custom records:

DBCell = record
    Name: string[10];
    Surname: string[15];
    Balance:integer;
    OpenDate: record
        year: integer;
        month: 1..12;
        day:1..31
    end;
    AccountN: string[10];
end;
DBFile = file of DBCell;

And functions, that open and add new element to file:

procedure Fopenf(var F:DBFile; var FName:string; var FOpened:boolean);
begin
    Assign(F,FName);

    rewrite(F);

    FOpened:=true;
end;

procedure InsN(var F:DBFile;var cell:DBCell;var FOpened:boolean);
begin
        Write(F,cell);
        Close(F);
        Rewrite(F);
        Writeln('Added');
        FOpened:=false;
end;

Problem is, nothing is actually written to file. What am I doing wrong?

ninjalj · Answer 1 · 2011-05-11T06:39:36.027

2

It's been a long time since I've done any Pascal, but IIRC Rewrite truncates the file. You should use Append.

You don't need the Rewrite() after inserting a record in the file:

procedure InsN(var F:DBFile;var cell:DBCell;var FOpened:boolean);
begin
    Write(F,cell);
    Close(F);
    Writeln('Added');
    FOpened:=false;
end;

If you don't want to truncate the file every time you open it:

procedure Fopenf(var F:DBFile; var FName:string; var FOpened:boolean);
begin
    Assign(F,FName);

    append(F);

    FOpened:=true;
end;

edited May 11 '11 at 06:39

answered May 11 '11 at 00:34

ninjalj

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2

You can't append() to file of custom records. You can reset() file and change pointer to the end of it, though. Anyway, problem's solved, thanks for help. – Arnthor May 11 '11 at 10:12
@Nordvind since your problem is solved, it would be polite to select some of the answers as the correct one by clicking on the big "V" at left :) – brandizzi Jul 25 '11 at 13:05

score 1 · Accepted Answer · answered Jul 25 '11 at 12:43

1

The problem is the 'rewrite' call in InsN. 'Rewrite' creates a new file, so by calling it at the end of your program, you are creating a new, empty file!

answered Jul 25 '11 at 12:43

No'am Newman

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Pascal - not writing to file

2 Answers2