Files:
1.main.cpp
2.Bank_account.cpp
3.Bank_account.h
Initial 2 entries are already created- 1. UserId - 1, Password - pass123, Balance - 1000
2.UserId - 2, Password - 123pass, Balance - 1500
Then, if user wants to create his own account he is asked to enter 1, else 0, then he is assigned with Id 3
and is asked to create password, and initial balance is 500 and then function is called where one has to enter
id and then password and if it matches then again user is asked if he wants to withdraw(press 1), deposit(press 2),
request balance(press 3) or exit, and hence required changes in balance are made as per users chosen option
and if password doesnt match or id doesnt exist program returns to initial stage where user has to reenter id and password.