Introduction - If you have any usage issues, please Google them yourself
Declare a bank account class BankAccount, member variables for account number, head of a household name, head of the household id number, account balance, the three construction method, respectively BankAccount (), BankAccount (account number, head of a household name, id number) (account balance the default is 0), BankAccount (account number, head of a household name, id number, account balance). Separately using three structure function to establish three object, and print output three account information.