How do I seek and delete in a file ?
I need to find a number in a file, and delete it.
seekfile = fopen("seeknr.dat","a+");
What shall I use to open the file with.
a+ is only to append some data....
w+ will overwrite the data in the file, when it opens it.
r+ will only read.
I need to both read, write and delete...
Any good ideas...
Hope to get help
Gugge
Last edited by Gugge; 07-04-2002 at 03:48 AM.
!G!
isn't write also read and delete ?
i think only read is not able to write...
there is no extra delete function afaik
>isn't write also read and delete ?
No. "w" is ONLY to write data. Delete? Never.
>i think only read is not able to write...
Right. With "r" mode, you can only read data.
>there is no extra delete function afaik
Right.
Gugge, the best bet for you would be to:
1.) Create another temporary file ("w" mode)
2.) Write in all the data you want (read from the original file)
3.) Ignore all that you don't want
4.) Remove the original file
5.) Rename this temporary filename to the original filename
Search the forums, you'll get many more ideas on this.
[QUOTE]Originally posted by shaik786
[B]>isn't write also read and delete ?
No. "w" is ONLY to write data. Delete? Never.
Requesting a clarifiecation , oh wise shaik.....
Doesn't "w" overwrite a file if it exists...
so you could skip the step of removing the original file by just overwriting it with the new data? (this may not be a good idea for other reasons)
if so....
maybe that's what the earlier post meant by "w" being delete
if not....
I need to throw away some of these damn books
thanks,
Regis
>No. "w" is ONLY to write data. Delete? Never.
That's "a", "w" will remove all previous data in the file before writing if possible, "a" leaves everything intact and sets the file pointer to the end of the file.
>a+ is only to append some data....
>w+ will overwrite the data in the file, when it opens it.
>r+ will only read.
a+ will append to the file, but you can also read.
w+ will set the file to zero length if possible and you can also read
r+ will both read and write, the file pointer is set to offset 0 and all data remains intact.
-Prelude
My best code is written with the delete key.
How are you going to do this system-independently?1.) Create another temporary file ("w" mode)
2.) Write in all the data you want (read from the original file)
3.) Ignore all that you don't want
4.) Remove the original file
5.) Rename this temporary filename to the original filename
Why not just read the file in buffer, edit buffer, and write the buffer to disk.
