hide credit card numbers
// cc = "12345678901123456"
// hide_card_number(cc)
// [ "************3456" ]
def hide_card_number(card_number) size = card_number.to_s.size - 1 cc = "" i = 0 0.upto(size) do if( i > size - 4 ) else cc += "*" end i += 1 end cc = cc + card_number[size-3, size].to_s return cc end