How do i found out the number of lines in a file

[Vasilis Serghi]

Presently I define the number of lines to be expected in a file when
defining the array size and the initialisation of this array. This works
fine for now, but i'm sure that in the future this could change. So rather
than explicitly define the number expected, the file is read and the number
defined that way.

So I have a csv file that I can read in, how can I work out the number of
lines in the file? Is there a function that can do this, or do I need to
code this myself?

Vas.

[Stefano Ghirlanda]

"Vasilis Serghi" <vs*****@jaguar .com> writes:

So I have a csv file that I can read in, how can I work out the
number of lines in the file? Is there a function that can do this,
or do I need to code this myself?

Just count the number of \n characters in the file (or whatever
character combination the system uses for "end of line").

From what you say it seems you already know the maximum length of a
line. If not, you can add a counter to keep track of how long the
longest line is, to be sure to allocate enough memory.

--
Stefano | Department of Psychology, University of Bologna
Ghirlanda | Interdisciplina ry cultural research, Stockholm University
http://www.intercult.su.se/~stefano

[Flash Gordon]

On Thu, 19 Feb 2004 10:24:55 -0000
"Vasilis Serghi" <vs*****@jaguar .com> wrote:

Presently I define the number of lines to be expected in a file when
defining the array size and the initialisation of this array. This
works fine for now, but i'm sure that in the future this could change.
If you were sure that it would not change then you can be certain some
abstrad would change it :-)
So rather
than explicitly define the number expected, the file is read and the
number defined that way.

So I have a csv file that I can read in, how can I work out the number
of lines in the file? Is there a function that can do this, or do I
need to code this myself?

You will have to work it out yourself by counting the lines as you read
them in. If you are trying to load all of the data in to memory then you
will need to malloc the space then realloc as necessary.
--
Flash Gordon
Paid to be a Geek & a Senior Software Developer
Although my email address says spam, it is real and I read it.

[Christopher Benson-Manica]

Stefano Ghirlanda <st************ ***@unibo.it> spoke thus:

From what you say it seems you already know the maximum length of a
line. If not, you can add a counter to keep track of how long the
longest line is, to be sure to allocate enough memory.

Who needs to allocate memory? fgetc() can handle this job quite well.

--
Christopher Benson-Manica | I *should* know what I'm talking about - if I
ataru(at)cybers pace.org | don't, I need to know. Flames welcome.

[Lewis Bowers]

Vasilis Serghi wrote:

Presently I define the number of lines to be expected in a file when
defining the array size and the initialisation of this array. This works
fine for now, but i'm sure that in the future this could change. So rather
than explicitly define the number expected, the file is read and the number
defined that way.

So I have a csv file that I can read in, how can I work out the number of
lines in the file? Is there a function that can do this, or do I need to
code this myself?

You would code it yourself using some functions from the Standard C library.

You could experiment with dynamically allocated storage for the array as you
read the data file. And, as you do this keep track of the number of elements
allocated. How this is done depends on the array data type and the file format.

You could put this all in a struct data type.
For example, if the data was type int:

typedef struct DATA
{
int *array; /* holds the data */
size_t size; /* keep track of the number of elements */
}DATA;

Write a function to add data to the array.

int *AddDATA(DATA *p, int data)
{
int *tmp;
size_t cnt = p->size;

if((tmp = realloc(p->array, (cnt+1)*sizeof *tmp)) == NULL) return NULL;
p->array = tmp;
p->array[p->size++] = data;
return &p->array[cnt];
}

In main you would declare the struct:
DATA myData = {NULL};

open the file and as you read an item of data, call the function and store the
data dyamically in
the array.

Beware that even dynamic allocations are not limitless. Available memory space
may be
exhausted to the point where no more storage can be made available for the
array.The
function return of NULL would indicated the failure of allocation.

[Dan Pop]

In <87************ @jesus.intercul t.su.se> Stefano Ghirlanda <st************ ***@unibo.it> writes:

"Vasilis Serghi" <vs*****@jaguar .com> writes:

So I have a csv file that I can read in, how can I work out the
number of lines in the file? Is there a function that can do this,
or do I need to code this myself?

Just count the number of \n characters in the file (or whatever
character combination the system uses for "end of line").

If he opens the file in text mode, as he is supposed to do, it's '\n'
*regardless* of the local system conventions. It's the job of the C
runtime support to transparently handle the conversions between '\n'
and whatever the local system uses, on text streams (but not on binary
streams).

Dan
--
Dan Pop
DESY Zeuthen, RZ group
Email: Da*****@ifh.de

[Stefano Ghirlanda]

Da*****@cern.ch (Dan Pop) writes:

If he opens the file in text mode, as he is supposed to do, it's
'\n' *regardless* of the local system conventions. It's the job of
the C runtime support to transparently handle the conversions
between '\n' and whatever the local system uses, on text streams
(but not on binary streams).

Even better. I was uncertain whether this was the case, so I threw in
a warning.

--
Stefano | Department of Psychology, University of Bologna
Ghirlanda | Interdisciplina ry cultural research, Stockholm University
http://www.intercult.su.se/~stefano

[Rouben Rostamian]

In article <87************ @jesus.intercul t.su.se>,
Stefano Ghirlanda <st************ ***@unibo.it> wrote:

"Vasilis Serghi" <vs*****@jaguar .com> writes:

So I have a csv file that I can read in, how can I work out the
number of lines in the file? Is there a function that can do this,
or do I need to code this myself?

Just count the number of \n characters in the file (or whatever
character combination the system uses for "end of line").

But beware that the number lines may be 1 more than the number
of \n characters if the file does not end in \n.

The C standard assumes that a text stream is terminated by a
newline. Your CSV file, however, may have been created by
a utility which may not have heard of the C standard.

--
Rouben Rostamian

[Default User]

Lewis Bowers wrote:

You could experiment with dynamically allocated storage for the array as you
read the data file. And, as you do this keep track of the number of elements
allocated. How this is done depends on the array data type and the file format.

I would also strongly consider a linked list for storing the strings. If
your access to the strings once loaded is essentially sequential, then
that's a viable solution.
Brian Rodenborn

[Dan Pop]

In <c1**********@p c18.math.umbc.e du> ro****@pc18.mat h.umbc.edu (Rouben Rostamian) writes:

In article <87************ @jesus.intercul t.su.se>,
Stefano Ghirlanda <st************ ***@unibo.it> wrote:

"Vasilis Serghi" <vs*****@jaguar .com> writes:

So I have a csv file that I can read in, how can I work out the
number of lines in the file? Is there a function that can do this,
or do I need to code this myself?

Just count the number of \n characters in the file (or whatever
character combination the system uses for "end of line").

But beware that the number lines may be 1 more than the number
of \n characters if the file does not end in \n.

Does that extra bunch of characters after the last newline qualify as a
line?

Dan
--
Dan Pop
DESY Zeuthen, RZ group
Email: Da*****@ifh.de