From:	"David Lee" <keeyu AT poetic DOT com>
Newsgroups:	comp.os.msdos.djgpp
Subject:	seekg() bug
Date:	Sat, 5 Aug 2000 13:43:33 +0800
Organization:	IMS Netvigator
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To:	djgpp AT delorie DOT com
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Reply-To:	djgpp AT delorie DOT com

I opened a fstream object and tried to position the file pointer with seekg
().

I found that seekg () always worked as long as eof () was not encountered.
Once eof () holds, it would appear to work as usual, but subsequent reading
from the fstream object were wrong.

Any idea?

Here is what I mean:

#include <fstream>

void
main ()
{
    fstream f ("dummy", ios::out | ios::bin);
    f.write ("0123456789", 10);
    f.close ();

    f.open ("dummy", ios::in | ios::bin);

    f.seekg (4, ios::beg);
    char x;
    f.read (&x, 1);
    cout << x << endl;        // print 4, as expected

    while (!f.eof ())            // goto end of file
        f.read (&x,1);

    // now f.eof () holds.
    f.seekg (7, ios::beg);
    f.read (&x, 1);
    cout << x << endl;        // does **NOT** print 7 (in fact, it prints 4,
the previous input).

    f.close ();
}

- Raw text -