We are running a survey to help us improve the experience for all of our members. If you see the survey appear, please take the time to tell us about your experience if you can.
i didn't know the meaning of this (P0=~(row[f][i]))
Look up the assignment operator, complement operator, subscript operator, and parenthesized expression in your C reference.
K&R has entries for all of them (except the parentheses and brackets) in the index. If your 'C' textbook doesn't have this (or a similar reference), then get a better one!
www.amazon.co.uk/.../ref=sr_1_1