Manipulation of text files in C++

Hady · 05-30-2005, 12:49 AM

Hi!

Could anyone tell me how I can add one line to the beginning of a text file using C++?
I know how to open/close/read from a text file, I just want adding one line without affecting any other content in the file..

Thank you for your time.

enemorales · 05-30-2005, 04:24 AM

I don't know if it can be done in other way, but one possibility is:

1.- open file.txt for reading and file.txt.bak for writing
2.- write a "\n" to file.txt.bak
3.- copy the content
4.- close the files
5.- remove file.txgt
6.- rename file.txt.bak to file.txt

step 5 shouldn't be very difficult. you only have to read from one file (which you know how to do) and write to the other, while the first file still has something inside.

jonaskoelker · 05-30-2005, 03:03 PM

I think he meant `one line', not `one newline', but that's a minor issue.

you could also do something along the lines of (pseudo-code):

Code:

stringbuffer b;
b.append("myline\n")
for char in filestream('file.txt'): b.append(char);
f = filestream('file.txt', 'w');
for char in b: f.write(char);
f.close();

Hady · 05-31-2005, 02:00 AM

OK!
Thank you guys for your help!

enemorales · 05-31-2005, 07:51 AM

Your pseudo-code looks a lot like python ;-)

jonaskoelker · 05-31-2005, 08:24 AM

Quote:

Your pseudo-code looks a lot like python ;-)

That's because python is runnable pseudo-code ;-)