C++ learning notes II

01	Calculate square root using binary search method	02	Simple banking system without using class
03	Alibaba banking system with multiple users(still no class)	4.1	Alibaba banking system with multiple users II(main.CPP)
4.2	Alibaba banking system with multiple users II(Bank.CPP)	4.3	Alibaba banking system with multiple users II(Bank.h)
4.4	Alibaba banking system with multiple users II(Transaction.CPP)	4.5	Alibaba banking system with multiple users II(Account.CPP)