I've started with a assignment for a ATM code, I'm supposed to use text file in some way or another. so far I've got this:
print("Hello, and welcome to the ATM machine!\n")
a_pin = {1111, 2222, 3333, 4444}
def process():
pin = int(input("\nplease enter below your 4-digit pin number: "))
if pin in a_pin:
if pin == (1111):
f = open("a.txt", "r")
elif pin == (2222):
f = open("b.txt", "r")
elif pin == (3333):
f = open("c.txt", "r")
elif pin == (4444):
f = open("d.txt", "r")
print(
"""
MENU:
1: view your current balance
2: make a withdraw
3: make a deposit
4: exit
""")
option = input("\nwhat would you like to do? ")
if option == "1":
print(f.read())
elif option == "2":
y = str(input("\nHow much would you like you like to withdraw? "))
f.write(y)
print("Excellent, your transaction is complete!")
elif option == "3":
z = str(input("\nHow much would you like to deposit? "))
f.write(z)
print("Excellent, your transaction is complete!")
elif option == "4":
input("Please press the enter key to exit.")
else:
print("\nthat was a wrong pin number!")
x = input("\nwould you like to try again? '(y/n)' ")
if x == "y":
process()
else:
input("\npress the enter key to exit.")
process()
The code works as of now, but I want to save some time by asking how to most effectively overwrite content on the text files when withdrawing/depositing. I was thinking of pickled files... but will be very happy for any suggestions, since normal commands like write dont really work for this task, if i want to display the new ammount to user after a withdraw/deposit. Many thanks!
The key point is to consider the necessary "mode" to open the file so that it can be not only be read (r) but also modified (r+):
if pin == (1111):
f = open("a.txt", "r+")
elif pin == (2222):
f = open("b.txt", "r+")
elif pin == (3333):
f = open("c.txt", "r+")
elif pin == (4444):
f = open("d.txt", "r+")
Then store the current balance in the file, and update it after each transaction.
# read current balance from file and save its value
bal = float(f.read().strip('\n')) # or replace float() with int()
# reset file pointer to beginning of file before updating contents
f.seek(0)
if option == '1':
print(f.read()) # or simply, print(bal)
elif option == '2':
y = str(input("\nHow much would you like you like to withdraw? "))
bal -= int(y) # calculate new balance
f.write(str(bal)+'\n') # write new balance to file as a string
print("Excellent, your transaction is complete!")
elif option == '3':
z = str(input("\nHow much would you like to deposit? "))
bal += int(z)
f.write(str(bal)+'\n')
print("Excellent, your transaction is complete!")