1.2.2　實現1：不使用函數的單個賬戶

在代碼清單1-2顯示的最初版本中，只有一個賬戶。

代碼清單1-2：只包含一個賬戶的銀行模擬程序（文件: Bank1_OneAccount.py）

   # Non-OOP
   # Bank Version 1
   # Single account
　
? accountName = ‘Joe’
   accountBalance = 100
   accountPassword = ‘soup’
　
   while True:
     ? print()
       print(‘Press b to get the balance’)
       print(‘Press d to make a deposit’)
       print(‘Press w to make a withdrawal’)
       print(‘Press s to show the account’)
       print(‘Press q to quit’)
       print()
　
       action = input(‘What do you want to do? ‘)
       action = action.lower() # force lowercase
       action = action[0] # just use first letter
       print()
　
       if action == ‘b’:
           print(‘Get Balance:’)
           userPassword = input(‘Please enter the password: ‘)
           if userPassword != accountPassword:
               print(‘Incorrect password’)
           else:
               print(‘Your balance is:’, accountBalance)
　
       elif action == ‘d’:
           print(‘Deposit:’)
           userDepositAmount = input(‘Please enter amount to deposit: ‘)
           userDepositAmount = int(userDepositAmount)
           userPassword = input(‘Please enter the password: ‘)
　
           if userDepositAmount < 0:
                print(‘You cannot deposit a negative amount!’)
　
           elif userPassword != accountPassword:
               print(‘Incorrect password’)
　
           else: # OK
               accountBalance = accountBalance + userDepositAmount
               print(‘Your new balance is:’, accountBalance)
　
       elif action == ‘s’: # show
           print(‘Show:’)
           print(‘       Name’, accountName)
           print(‘       Balance:’, accountBalance)
           print(‘       Password:’, accountPassword)
           print()
　
       elif action == ‘q’:
           break
　
       elif action == ‘w’:
           print(‘Withdraw:’)
　
           userWithdrawAmount = input(‘Please enter the amount to withdraw: ‘)
           userWithdrawAmount = int(userWithdrawAmount)
           userPassword = input(‘Please enter the password: ‘)
　
           if userWithdrawAmount < 0:
               print(‘You cannot withdraw a negative amount’)
　
           elif userPassword != accountPassword:
               print(‘Incorrect password for this account’)
　
           elif userWithdrawAmount > accountBalance:
               print(‘You cannot withdraw more than you have in your account’)
　
           else: #OK
               accountBalance = accountBalance - userWithdrawAmount
               print(‘Your new balance is:’, accountBalance)
　
   print(‘Done’)

程序首先初始化了3個變量，用于代表一個賬戶的數據（?）。然后，顯示了一個菜單，用于選擇操作（?）。程序的主代碼直接操作全局賬戶變量。

在本例中，所有操作都在主代碼級別；代碼中沒有使用函數。程序可以正確運行，但看起來有點長。為了使很長的程序變得更加清晰，通常采用的方法是將相關代碼放到函數中，然后調用那些函數。我們在銀行程序的下一個實現中將探討這種方法。