Why are you returning the 6th lottery number (again, out of range) in getLottery()? You are using arrays incorrectly. Each entry in the array needs to be accessed seperately. And what's with this line?
lottery_numbers[i] = i * i; //store lottery numbers in the
???
This program is pretty erronous and confusing. Fix up your syntax issues with your class methods, array passing, and loop techniques. Use google for syntax issues.