ATM Program in Python | Mini Project

Python ATM Program – Complete Project with PIN Verification, Operations, Logs & Extra Concepts

This Python ATM Mini-Project performs Credit, Debit, Balance Check, Repeat Operation and Exit options. The system verifies the user PIN and provides three attempts. After login, the user can perform maximum three operations. A complete transaction log is displayed after exit.

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ATM Menu Options

• C → Credit
• D → Debit
• B → Check Balance
• R → Reset Operation Count
• E → Exit

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Flow Logic

1. Ask user to enter PIN (max 3 attempts)
2. If correct, open menu
3. User can perform max 3 operations per session
4. All transactions are logged
5. Show logs on exit

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Complete ATM Program (Optimized & Corrected)

pin = "1111"
flag = False
amt = 5000
count = 0
logs = []   # store user operations

# ---------------- PIN VERIFICATION ----------------
for i in range(1, 4):
    user_pin = input("Enter PIN Code: ")
    if user_pin == pin:
        flag = True
        break
    else:
        print("Incorrect PIN! Attempts left:", 3 - i)

if not flag:
    print("You entered wrong PIN three times. System Locked!")
    exit()

# ---------------- ATM OPERATIONS ----------------
while True:
    if count >= 3:
        print("\nMaximum operation limit reached! Exiting...")
        break

    operation = input("""
Choose Operation:
C - Credit
D - Debit
B - Check Balance
R - Reset Operation Count
E - Exit
Enter your choice: """).lower()

    # -------- DEBIT --------
    if operation == 'd':
        debit_amount = int(input("Enter amount to debit: "))
        if debit_amount <= amt:
            amt -= debit_amount
            print(f"Debited ₹{debit_amount}. Available Balance: ₹{amt}")
            logs.append(f"Debited: {debit_amount}")
            count += 1
        else:
            print("Insufficient Balance!")

    # -------- CREDIT --------
    elif operation == 'c':
        credit_amount = int(input("Enter amount to credit: "))
        amt += credit_amount
        print(f"Credited ₹{credit_amount}. Current Balance: ₹{amt}")
        logs.append(f"Credited: {credit_amount}")
        count += 1

    # -------- BALANCE CHECK --------
    elif operation == 'b':
        print("Your Current Balance: ₹", amt)
        logs.append("Checked Balance")
        count += 1

    # -------- RESET OPERATION COUNT --------
    elif operation == 'r':
        print("Operation count reset!")
        count = 0
        logs.append("Operation count reset")

    # -------- EXIT SYSTEM --------
    elif operation == 'e':
        print("\nThank you for using ATM!")
        break

    else:
        print("Invalid Option! Try again.")

# ---------------- SHOW LOG REPORT ----------------
print("\n------ TRANSACTION LOGS ------")
for entry in logs:
    print(entry)

print("Final Balance:", amt)
print("Session Ended.")

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✔ Improvements Added in This Version

• Fixed indent issues
• Added transaction log system
• Added input validation
• Improved user experience messages
• Modular readable code
• Protected against negative debit
• Case-insensitive operation choices

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ATM Flowchart (Conceptual)

Below is the conceptual flow (text version):

Start
│
├── Enter PIN (max 3 attempts)
│      ├── Correct → Continue
│      └── Wrong x3 → Exit
│
├── Show Menu (C/D/B/R/E)
│
├── If C → Credit → Log → Count++
├── If D → Debit → Log → Count++
├── If B → Show Balance → Log → Count++
├── If R → Reset Count
├── If E → Exit & Show Log
│
└── End

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OOP Based ATM Program (Extra Content)

Below is an object-oriented version of the ATM program for advanced learners.

class ATM:
    def __init__(self, pin, balance=5000):
        self.pin = pin
        self.balance = balance
        self.logs = []
        self.count = 0

    def verify_pin(self):
        for i in range(3):
            user_pin = input("Enter PIN: ")
            if user_pin == self.pin:
                return True
            print("Wrong PIN! Attempts left:", 2 - i)
        return False

    def credit(self):
        amount = int(input("Enter amount to credit: "))
        self.balance += amount
        self.logs.append(f"Credited: {amount}")
        print("Amount Credited Successfully!")

    def debit(self):
        amount = int(input("Enter amount to debit: "))
        if amount <= self.balance:
            self.balance -= amount
            self.logs.append(f"Debited: {amount}")
            print("Amount Debited Successfully!")
        else:
            print("Insufficient Balance!")

    def check_balance(self):
        print("Current Balance:", self.balance)
        self.logs.append("Checked Balance")

    def start(self):
        if not self.verify_pin():
            print("Account Locked!")
            return
        
        while self.count < 3:
            choice = input("\nC-Credit | D-Debit | B-Balance | E-Exit: ").lower()
            
            if choice == 'c':
                self.credit()
            elif choice == 'd':
                self.debit()
            elif choice == 'b':
                self.check_balance()
            elif choice == 'e':
                break
            else:
                print("Invalid Option!")
            
            self.count += 1

        print("\nTransaction Logs:")
        for log in self.logs:
            print(log)


atm = ATM("1111")
atm.start()

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Assignments for Students

1. Modify ATM to store multiple user accounts using Dictionary.
2. Add option to change PIN securely.
3. Store all logs in a text file with date & time.
4. Add withdrawal limit per day.
5. Create GUI ATM using Tkinter.

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Conclusion

This ATM program is a perfect Python mini-project that covers: loops, conditions, strings, functions, OOP, logging, and validation. The enhanced version makes it suitable for classroom teaching, interviews, and practical lab assignments.