read and write text file

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9 total messages Started by didan Tue, 22 Mar 2005 16:33

Author: didan
Date: Tue, 22 Mar 2005 16:33

3 lines
848 bytes

For a 30M data file, what is the fast way to read and write it?
Thanks

Re: read and write text file

Author: Hans Galema
Date: Tue, 22 Mar 2005 17:26

8 lines
1104 bytes

didan wrote:
> For a 30M data file, what is the fast way to read and write it?

Probably fopen(), fread(), fwrite(), ftell() ...

Do you want to do specific actions ?

Hans.

Re: read and write text file

Author: didan
Date: Tue, 22 Mar 2005 18:50

12 lines
1206 bytes

Seems the file is too big. I didn't get any error, but I couldn't read anything. Do you have any experience on reading big files? Thanks

Hans Galema <notused@notused.nl> wrote:
>didan wrote:
>> For a 30M data file, what is the fast way to read and write it?
>
>Probably fopen(), fread(), fwrite(), ftell() ...
>
>Do you want to do specific actions ?
>
>Hans.

Re: read and write text file

Author: Hans Galema
Date: Tue, 22 Mar 2005 19:14

7 lines
1313 bytes

didan wrote:
> Seems the file is too big. I didn't get any error, but I couldn't read anything. Do you have any experience on reading big files? Thanks

Why does it seem to big ? Yes I regularly read such bigs files.
What is the problem ?

Hans.

Re: read and write text file

Author: didan
Date: Tue, 22 Mar 2005 21:37

11 lines
1335 bytes

I don't know why. It works now. but it takes about 10 second to read it. How to speed up?

Hans Galema <notused@notused.nl> wrote:
>didan wrote:
>> Seems the file is too big. I didn't get any error, but I couldn't read anything. Do you have any experience on reading big files? Thanks
>
>Why does it seem to big ? Yes I regularly read such bigs files.
>What is the problem ?
>
>Hans.

Re: read and write text file

Author: Thomas Maeder [TeamB]
Date: Tue, 22 Mar 2005 21:51

9 lines
1447 bytes

"didan" <relaxandfree@yahoo.com> writes:

> I don't know why. It works now. but it takes about 10 second to read
> it. How to speed up?

You post a lot of questions and very little information.

Please show us the (*minimal*) slow code. We can then try to improve
on it.

Re: read and write text file

Author: didan
Date: Wed, 23 Mar 2005 21:45

17 lines
1488 bytes

here is the code
fPtr = fopen(fileName,"r")
fscanf(fPtr,"%f", &data)

is there any better way to read a file?
 
maeder@glue.ch (Thomas Maeder [TeamB]) wrote:
>"didan" <relaxandfree@yahoo.com> writes:
>
>> I don't know why. It works now. but it takes about 10 second to read
>> it. How to speed up?
>
>You post a lot of questions and very little information.
>
>Please show us the (*minimal*) slow code. We can then try to improve
>on it.

Re: read and write text file

#10

Author: Hans Galema
Date: Wed, 23 Mar 2005 22:15

14 lines
1369 bytes

didan wrote:
> here is the code
> fPtr = fopen(fileName,"r")
> fscanf(fPtr,"%f", &data)

With one fscanf you will not read 30 MB.

You should show a complete loop.

And all the types of the variables.

You should also tell of course how the datafile is build up.

Hans.

Re: read and write text file

#11

Author: Ed Mulroy [TeamB]
Date: Thu, 24 Mar 2005 03:32

15 lines
1333 bytes

FYI:

That code does not have anything to check if the returned FILE * value 
is NULL.  You really should test it before using it.

.  Ed

> didan wrote in message
> news:4241e36f$1@newsgroups.borland.com...
>
> here is the code
> fPtr = fopen(fileName,"r")
> fscanf(fPtr,"%f", &data)
>
> is there any better way to read a file?

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