inserting data in a file

[Paul Rice]

Is it possible to use fstream to insert data in the middle of file? Do I need to rewrite the file each time? What if I want to remove data from the middle of a file?

I have a bunch of lists I'd like to save to the HD but the only thing that works is rewriting the whole list. Does this become a problem as the lists get larger?

Paul

[dcjr84]

You can position the read and write cursor for your output stream anywhere you want I believe.

Go to this website and have a look at seekg and seekp.

I don't have much experience with these and haven't used them in quite a few years, so I am not entirely sure they will do what you want.

You can also checkout this website which gives quite a bit of info on C++ I/O and streams.

Not sure if this helps, but you can open an existing file that is already on the hard disk for output in append mode. Meaning anything dumped to it will be tacked on the end of it, and won't overwrite anything existing.

ofstream myFile("myFile.txt", ios::app );

Here is a link to all the fstream modes.

Hope this helps

[Paul Rice]

It seems seekp will position anywhere in the file for writing but overwrites the data already at that position. At least that's the behavior I'm getting right now.

[dcjr84]

Did you try opening the file in append mode, and then using seekp?

Perhaps that will not overwrite your data.

I have always found in my experience that writing data to anywhere other than the beginning or end of a file is a real pain.