Thread: Reading from file

Hello!
I have a reading from file inside my program.
My problem is I'm not sure how to make the program to check if there are either 2 or 4 elements to read in line.
Basically, it should read from textfile like this:
A 1 2 (if there are 2 numbers and no more, read them and go to the next line)
or
A 1 2 3 4 (if there are 4 numbers read all of them and go to next line)
so basically the textfile would look for example like
A 1 2
A 3 4
A 7 8 9 10
(it seperates every element to different variable).

My program works that in case of 'A' it reads 2 numbers:
fscanf(file,"%d %d",&i1, &i2);
But how to make it read 2 numbers if there are 2 numbers, and 4 if there are 4?

Hope u understood what I meant, thanks for help in advance!

The "scanf" family of functions returns the number of items successfully read. Think about how you can use this to your advantage.

Adding to Matt's advice, consider using fgets to read the entire line into a buffer and then sscanf on the buffer.

Originally Posted by Matticus

The "scanf" family of functions returns the number of items successfully read. Think about how you can use this to your advantage.

Yeah, I made a lot of attempts already but every time I fail something.
In my mind it looks like
if fscanf returns 2 (values), then read 2 more values and go further
if fscanf returns 4 (values), then go further
Should it look like that in theory? If yes then I must mess up something in code

Assuming there can either be two or four numbers per line, I would approach it as: Attempt to read the maximum (i.e. four) values. If only two are read, you know you have two. If four are read, you know you have four. Otherwise, an error has occurred.

If there can theoretically be any number of values on a given line, I would look into solutions other than "scanf" - but your original question implied that it was either two or four values per line only. (If this is not the case, clearly explain the possible inputs so we can offer potentially better methods).

Originally Posted by Matticus

Assuming there can either be two or four numbers per line, I would approach it as: Attempt to read the maximum (i.e. four) values. If only two are read, you know you have two. If four are read, you know you have four. Otherwise, an error has occurred.

If there can theoretically be any number of values on a given line, I would look into solutions other than "scanf" - but your original question implied that it was either two or four values per line only. (If this is not the case, clearly explain the possible inputs so we can offer potentially better methods).

Yeah, I meant 2 or 4 values, but actually I'd like also to try to make it for example max 10 numbers. I think scanf will not be enough anymore?

"scanf" will work fine for this.

someone help me with this please!! i have an exam tomorrow!! plsss help

Originally Posted by maslayer

someone help me with this please!! i have an exam tomorrow!! plsss help

Please stop spamming the board with your begging. You've already received a response in your thread after only ten minutes, which is very good for free help. Don't be selfish.

Oh, I forgot to mention important thing.
I said it looks for example
A 1 2
A 3 4
A 7 8 9 10
But I forgot to say that every line has a number before it.
So it looks like
1 A 1 2
2 A 3 4
3 A 7 8 9 10
4 ...
5 ...

And that's where my problem comes from. It reads the number from next line and I want to avoid that.

#EDIT: That maslayer post isn't mine. I don't know him.

If you don't want that first number, you can tell "scanf" to ignore it using an asterisk thusly: "%*d"

Originally Posted by Pinkysuavo

#EDIT: That maslayer post isn't mine. I don't know him.

Yes, I know. My response was directed at them, for posting their nonsense in your thread.

@UP
That helped, thanks!