Count columns in TXT with C++?

I have these types of data in txt files.

1   3   4   5
2   4   5   2
3   5   7   8
2   5   7   8

or even

1 3 4 5
2 4 5 2
3 5 7 8
2 5 7 8

Separated with TABs, with one space or exported from excel. I need a function to count columns, that returns an int, how can I do this?

Thanks!