Thread: appending output file...

Hi, I'm wondering if someone can help get me started on this. I sat down to do it and realized I couldn't. lol
This is what I'm trying to do:
I have an output file that I want to append. The tricky part is I want to scan in the last number listed in the file, add to it another number, then print the sum onto the next line. Then do it again, so scan in the sum I just printed (now the last number listed), add a number, and print the new sum on the next line.

Just in case that was confusing this is what I mean.
In the file I have

1

So I take 1 and add 2 so I have

1
2

Then I take 2 and add 3 so I have

1
2
5

etc.

I was using "a+" to open the file... I didn't get very far.
Any suggestions appreciated.
Thanks.

Well, if you could tell me a better way to update the scan to that value, I'd be fine with that. But I'm doing this with a huge list, so it's not like I can just type it in each time like in my little example.
I can do this with an array, but like I said, it's huge and my compiler was freaking out because I had a lot of huge arrays, so I wanted to just output everything instead.

There has to be some fairly simple way of doing this. :S

I was trying something along these lines...
It would maybe do the first number correctly, but then I'm not sure what it was doing. I really didn't get that far.

(This is simplified, delta is defined and things.)

Code:

     fx=fopen("x.txt", "a+");
     for(i=0; i<10; i++){
              fscanf(fx, "&#37;lf\n", &previous);
              fprintf(fx, "%e", previous+delta);
              }
              
     fclose(fx);

Any comments on that?

I was hoping that each time previous would switch to the number that had just been printed and it would move down the line, but it doesn't seem to be happening.