EOF (end of file) problem

Hi!
I hope I'm asking the right question in the right group.
I have a problem with a piece of C++ code that runs well under Linux
(gcc 2.96) but doesn't run as expected in Windows (Borland C++ 5.5.1):
Here's the code:
**********
int num;
ifstream in_file;
in_file.open("whatever.txt");
while (!in_file.eof())
cin >> num;
**********
Example input:
1 2 3 4 5 6 7EOF -> Linux OK; Windows not
1 2 3 4 5 6 7
EOF -> Linux & Windows OK
In Linux it reads right to the end of the file. But in Windows it misses
the last number (7) unless there's a newline character at the end of the
last line to be read. If I replace "int num" with "char num" the it
works as it should. What am I missing here?
Thanks in advance,
Karlo.

re: EOF (end of file) problem

Hi,

This is the way I read files (both linux and windows).

ifstream Input( 'whatever.txt' );
if( Input.is_open() )
{
string Line;
while( Input )
{
getline( Input, Line );
if( Input )
{
cout << "Read <" << Line << ">" << endl;
}
}

}

Note the extra check after reading!

Regards, Ron AF Greve.


"Karlo Basic" <karlman@email.si> wrote in message
news:bo059c$14rabn$1@ID-212926.news.uni-berlin.de...[color=blue]
> Hi!
> I hope I'm asking the right question in the right group.
> I have a problem with a piece of C++ code that runs well under Linux
> (gcc 2.96) but doesn't run as expected in Windows (Borland C++ 5.5.1):
> Here's the code:
> **********
> int num;
> ifstream in_file;
> in_file.open("whatever.txt");
> while (!in_file.eof())
> cin >> num;
> **********
> Example input:
> 1 2 3 4 5 6 7EOF -> Linux OK; Windows not
> 1 2 3 4 5 6 7
> EOF -> Linux & Windows OK
> In Linux it reads right to the end of the file. But in Windows it misses
> the last number (7) unless there's a newline character at the end of the
> last line to be read. If I replace "int num" with "char num" the it
> works as it should. What am I missing here?
> Thanks in advance,
> Karlo.
>[/color]

re: EOF (end of file) problem

On Sat, 01 Nov 2003 13:03:21 +0100, Moonlit wrote:
[color=blue]
> Hi,
>
> This is the way I read files (both linux and windows).
>
> ifstream Input( 'whatever.txt' );
> if( Input.is_open() )
> {
> string Line;
> while( Input )
> {
> getline( Input, Line );
> if( Input )
> {
> cout << "Read <" << Line << ">" << endl;
> }
> }
>
> }
>
> Note the extra check after reading!
>
> Regards, Ron AF Greve.
>[/color]

This is a little neater (avoids your extra check):

while (getline(Input, Line))
{
cout << "Read <" << Line << ">" << endl;
}

re: EOF (end of file) problem

Hi,

"Simon Saunders" <simon.saunders@net.ntl.com> wrote in message
news:pan.2003.11.01.12.14.02.612951@net.ntl.com...[color=blue]
> On Sat, 01 Nov 2003 13:03:21 +0100, Moonlit wrote:
>[color=green]
> > Hi,
> >
> > This is the way I read files (both linux and windows).
> >
> > ifstream Input( 'whatever.txt' );
> > if( Input.is_open() )
> > {
> > string Line;
> > while( Input )
> > {
> > getline( Input, Line );
> > if( Input )
> > {
> > cout << "Read <" << Line << ">" << endl;
> > }
> > }
> >
> > }
> >
> > Note the extra check after reading!
> >
> > Regards, Ron AF Greve.
> >[/color]
>
> This is a little neater (avoids your extra check):
>
> while (getline(Input, Line))
> {
> cout << "Read <" << Line << ">" << endl;
> }
>[/color]
Oops, you are right, never noticed the fact that getline actually returns
the stream (stupid me :-( ).

Thanks for the tip.

Regards, Ron AF Greve

re: EOF (end of file) problem

Well when reading in a file C++ Has no way of telling if it will read
in a char, int, ect... So it will return in char because this type of
variable can hold any letter, number, or symbol. So when reading in a
file read it into a char variable. This is why when you read in the
file using a char variable it works correctly.

BTW: Many people think that there is really a EOF symbol in a file..
This is NOT true. C++ Will return -1 when the file is complete read
in... EOF is a Marco declared in iostream.h for -1.

Andrew

re: EOF (end of file) problem

On 1 Nov 2003 07:58:03 -0800, ComputerNerd8888@cox.net (Andrew EMA
Free!) wrote in comp.lang.c++:
[color=blue]
> Well when reading in a file C++ Has no way of telling if it will read
> in a char, int, ect... So it will return in char because this type of
> variable can hold any letter, number, or symbol. So when reading in a
> file read it into a char variable. This is why when you read in the
> file using a char variable it works correctly.
>
> BTW: Many people think that there is really a EOF symbol in a file..
> This is NOT true. C++ Will return -1 when the file is complete read
> in... EOF is a Marco declared in iostream.h for -1.
>
> Andrew[/color]

The C++ standard inherits the macro EOF from the C language standard,
and does not specify or require that the value of this macro be -1,
although that is very common.

The only requirement is that EOF have type int and a value less than
0. It could be any value from -1 through INT_MIN inclusive.

--
Jack Klein
Home: http://JK-Technology.Com
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