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Simple Banking System in C#

Last Updated : 29 Sep, 2025
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The Simple Banking System is a console application that demonstrates fundamental C# concepts including Object-Oriented Programming (OOP), methods, arrays and string manipulation. This project allows users to create accounts, deposit money, withdraw money, check balances and view account details.

How the System Works

The banking system manages multiple customer accounts with basic operations:

  • Account Creation: Create new bank accounts with customer details
  • Deposit: Add money to an existing account
  • Withdraw: Remove money from an account (with balance validation)
  • Balance Inquiry: Check current account balance
  • Account Details: View complete account information
  • Account Listing: Display all existing accounts

The system uses arrays to store account data and demonstrates core OOP principles through a BankAccount class.

Algorithm

  1. Define BankAccount class with properties and methods
  2. Initialize arrays to store multiple accounts
  3. Display menu system and get user input
  4. Process user operations based on choice
  5. Repeat until user exits

Step 1: Class Definition and Properties

C# 
using System; namespace SimpleBankingSystem {  // BankAccount class demonstrating OOP concepts  public class BankAccount  {  // Private fields (Encapsulation)  private int accountNumber;  private string accountHolderName;  private double balance;  private string accountType;  // Constructor  public BankAccount(int accNum, string name, double initialBalance, string type)  {  accountNumber = accNum;  accountHolderName = name;  balance = initialBalance;  accountType = type;  }  // Public properties (Encapsulation)  public int AccountNumber   {   get { return accountNumber; }   }  public string AccountHolderName   {   get { return accountHolderName; }   set { accountHolderName = value; }  }  public double Balance   {   get { return balance; }   }  public string AccountType   {   get { return accountType; }   }  } }

Explanation

Namespace: Groups related classes together and prevents naming conflicts.

Class Definition: The BankAccount class represents a real-world bank account using OOP principles.

Private Fields: Data members are kept private to ensure encapsulation - external code cannot directly access or modify them.

  • accountNumber: Unique identifier for each account
  • accountHolderName: Customer's name as a string
  • balance: Current account balance as double for decimal values
  • accountType: Type of account (Savings/Checking)

Constructor: Special method that initializes new objects with required data when creating an account.

Properties: Provide controlled access to private fields:

  • get accessor retrieves the value
  • set accessor allows modification (only for AccountHolderName)
  • Read-only properties (AccountNumber, Balance, AccountType) only have get accessors

Step 2: Account Methods (Deposit and Withdraw)

C# 
// Method to deposit money  public void Deposit(double amount)  {  if (amount > 0)  {  balance += amount;  Console.WriteLine($"Successfully deposited ${amount:F2}");  Console.WriteLine($"New balance: ${balance:F2}");  }  else  {  Console.WriteLine("Deposit amount must be positive!");  }  }  // Method to withdraw money  public bool Withdraw(double amount)  {  if (amount <= 0)  {  Console.WriteLine("Withdrawal amount must be positive!");  return false;  }  else if (amount > balance)  {  Console.WriteLine("Insufficient funds!");  Console.WriteLine($"Current balance: ${balance:F2}");  return false;  }  else  {  balance -= amount;  Console.WriteLine($"Successfully withdrew ${amount:F2}");  Console.WriteLine($"New balance: ${balance:F2}");  return true;  }  }  // Method to display account details  public void DisplayAccountDetails()  {  Console.WriteLine("\n--- Account Details ---");  Console.WriteLine($"Account Number: {accountNumber}");  Console.WriteLine($"Account Holder: {accountHolderName}");  Console.WriteLine($"Account Type: {accountType}");  Console.WriteLine($"Current Balance: ${balance:F2}");  Console.WriteLine("------------------------");  }

Explanation

Deposit Method:

  • Takes double amount parameter
  • Validates input (must be positive)
  • Updates balance and displays confirmation
  • Uses string interpolation ($"") and format specifier (:F2) for currency display

Withdraw Method:

  • Returns bool to indicate success/failure
  • Multiple validation checks using if-else statements
  • Checks for positive amount and sufficient funds
  • Updates balance only if all validations pass

DisplayAccountDetails Method:

  • void return type (no return value)
  • Uses formatted console output for clean display
  • Demonstrates string formatting and layout techniques

Step 3: Main Program Structure and Arrays

C# 
class Program  {  // Array to store bank accounts  static BankAccount[] accounts = new BankAccount[100];  static int accountCount = 0;  static void Main(string[] args)  {  Console.WriteLine("=================================");  Console.WriteLine(" Welcome to Simple Bank System ");  Console.WriteLine("=================================");  // Main program loop  while (true)  {  DisplayMenu();  int choice = GetUserChoice();  switch (choice)  {  case 1:  CreateAccount();  break;  case 2:  DepositMoney();  break;  case 3:  WithdrawMoney();  break;  case 4:  CheckBalance();  break;  case 5:  ViewAccountDetails();  break;  case 6:  ListAllAccounts();  break;  case 7:  Console.WriteLine("Thank you for using Simple Bank System!");  return;  default:  Console.WriteLine("Invalid choice! Please try again.");  break;  }  Console.WriteLine("\nPress any key to continue...");  Console.ReadKey();  Console.Clear();  }  }  }

Explanation

Static Array:

  • BankAccount[] accounts stores up to 100 account objects
  • static keyword allows access without creating Program instance
  • accountCount tracks how many accounts are currently stored

Main Method:

  • Entry point of the program
  • Contains infinite loop (while(true)) for continuous operation
  • Uses switch statement for menu navigation
  • Console.ReadKey() pauses execution
  • Console.Clear() clears screen for better user experience

Program Flow:

  • Display welcome message
  • Show menu and get user choice
  • Execute corresponding method based on choice
  • Repeat until user chooses to exit

Step 4: Menu System and User Input Validation

C# 
// Method to display menu  static void DisplayMenu()  {  Console.WriteLine("\n--- Bank Menu ---");  Console.WriteLine("1. Create Account");  Console.WriteLine("2. Deposit Money");  Console.WriteLine("3. Withdraw Money");  Console.WriteLine("4. Check Balance");  Console.WriteLine("5. View Account Details");  Console.WriteLine("6. List All Accounts");  Console.WriteLine("7. Exit");  Console.Write("Enter your choice (1-7): ");  }  // Method to get user choice with validation  static int GetUserChoice()  {  string input = Console.ReadLine();  if (int.TryParse(input, out int choice))  {  return choice;  }  return -1; // Invalid input  }  // Method to find account by account number  static BankAccount FindAccount(int accountNumber)  {  for (int i = 0; i < accountCount; i++)  {  if (accounts[i].AccountNumber == accountNumber)  {  return accounts[i];  }  }  return null;  }

Explanation

DisplayMenu Method:

  • static method accessible without object instance
  • Uses Console.WriteLine() for menu options
  • Console.Write() for input prompt (no newline)

GetUserChoice Method:

  • Demonstrates input validation using int.TryParse()
  • Returns -1 for invalid input (error handling)
  • Converts string input to integer safely

FindAccount Method:

  • Linear search through accounts array
  • Uses for loop to iterate through stored accounts
  • Returns BankAccount object if found, null if not found
  • Demonstrates array traversal and object comparison

Step 5: Account Creation and String Validation

C# 
// Method to create new account  static void CreateAccount()  {  if (accountCount >= accounts.Length)  {  Console.WriteLine("Maximum number of accounts reached!");  return;  }  Console.WriteLine("\n--- Create New Account ---");    Console.Write("Enter account holder name: ");  string name = Console.ReadLine();  // Validate name input  if (string.IsNullOrWhiteSpace(name))  {  Console.WriteLine("Invalid name! Account creation failed.");  return;  }  Console.Write("Enter account type (Savings/Checking): ");  string type = Console.ReadLine();  Console.Write("Enter initial deposit amount: $");  string balanceInput = Console.ReadLine();  if (double.TryParse(balanceInput, out double initialBalance) && initialBalance >= 0)  {  // Generate account number  int accountNumber = 1000 + accountCount + 1;  // Create new account object  BankAccount newAccount = new BankAccount(accountNumber, name, initialBalance, type);    // Add to array  accounts[accountCount] = newAccount;  accountCount++;  Console.WriteLine($"\nAccount created successfully!");  Console.WriteLine($"Account Number: {accountNumber}");  Console.WriteLine($"Account Holder: {name}");  Console.WriteLine($"Initial Balance: ${initialBalance:F2}");  }  else  {  Console.WriteLine("Invalid amount! Account creation failed.");  }  }

Explanation

Array Bounds Checking:

  • Prevents array overflow by checking accountCount >= accounts.Length
  • Graceful error handling with informative messages

String Validation:

  • string.IsNullOrWhiteSpace() checks for empty or whitespace-only input
  • Ensures data integrity before account creation

Account Number Generation:

  • Starts from 1001 (1000 + accountCount + 1)
  • Provides unique identifiers for each account

Object Creation and Storage:

  • Uses constructor to create new BankAccount object
  • Stores object in array and increments counter
  • Demonstrates object instantiation and array manipulation

Input Validation:

  • double.TryParse() safely converts string to double
  • Additional check for non-negative balance
  • Multiple validation layers ensure data integrity

Step 6: Transaction Methods (Deposit/Withdraw/Balance Check)

C# 
// Method to deposit money  static void DepositMoney()  {  Console.WriteLine("\n--- Deposit Money ---");  Console.Write("Enter account number: ");    if (int.TryParse(Console.ReadLine(), out int accountNumber))  {  BankAccount account = FindAccount(accountNumber);    if (account != null)  {  Console.Write("Enter deposit amount: $");  if (double.TryParse(Console.ReadLine(), out double amount))  {  account.Deposit(amount);  }  else  {  Console.WriteLine("Invalid amount entered!");  }  }  else  {  Console.WriteLine("Account not found!");  }  }  else  {  Console.WriteLine("Invalid account number!");  }  }  // Method to withdraw money  static void WithdrawMoney()  {  Console.WriteLine("\n--- Withdraw Money ---");  Console.Write("Enter account number: ");    if (int.TryParse(Console.ReadLine(), out int accountNumber))  {  BankAccount account = FindAccount(accountNumber);    if (account != null)  {  Console.Write("Enter withdrawal amount: $");  if (double.TryParse(Console.ReadLine(), out double amount))  {  account.Withdraw(amount);  }  else  {  Console.WriteLine("Invalid amount entered!");  }  }  else  {  Console.WriteLine("Account not found!");  }  }  else  {  Console.WriteLine("Invalid account number!");  }  }  // Method to check balance  static void CheckBalance()  {  Console.WriteLine("\n--- Check Balance ---");  Console.Write("Enter account number: ");    if (int.TryParse(Console.ReadLine(), out int accountNumber))  {  BankAccount account = FindAccount(accountNumber);    if (account != null)  {  Console.WriteLine($"Current Balance: ${account.Balance:F2}");  }  else  {  Console.WriteLine("Account not found!");  }  }  else  {  Console.WriteLine("Invalid account number!");  }  }

ExplanationCommon Pattern in Transaction Methods:

  1. Display section header
  2. Get account number with validation
  3. Find account using FindAccount() method
  4. Perform operation if account exists
  5. Handle errors gracefully

Method Reusability:

  • FindAccount() is reused across multiple methods
  • Reduces code duplication and improves maintainability

Error Handling:

  • Multiple validation layers (input parsing, account existence, amount validation)
  • Informative error messages for user guidance

Object Method Calls:

  • account.Deposit(amount) and account.Withdraw(amount) demonstrate method invocation
  • Accessing object properties with account.Balance

Step 7: Account Management and Display Methods

C# 
// Method to view account details  static void ViewAccountDetails()  {  Console.WriteLine("\n--- View Account Details ---");  Console.Write("Enter account number: ");    if (int.TryParse(Console.ReadLine(), out int accountNumber))  {  BankAccount account = FindAccount(accountNumber);    if (account != null)  {  account.DisplayAccountDetails();  }  else  {  Console.WriteLine("Account not found!");  }  }  else  {  Console.WriteLine("Invalid account number!");  }  }  // Method to list all accounts  static void ListAllAccounts()  {  Console.WriteLine("\n--- All Accounts ---");    if (accountCount == 0)  {  Console.WriteLine("No accounts found!");  return;  }  Console.WriteLine($"{"Account#",-10} {"Name",-20} {"Type",-10} {"Balance",-10}");  Console.WriteLine(new string('-', 50));  for (int i = 0; i < accountCount; i++)  {  BankAccount account = accounts[i];  Console.WriteLine($"{account.AccountNumber,-10} {account.AccountHolderName,-20} {account.AccountType,-10} ${account.Balance,-10:F2}");  }  }

Explanation

ViewAccountDetails Method:

  • Follows same validation pattern as other transaction methods
  • Calls object's DisplayAccountDetails() method for formatted output

ListAllAccounts Method:

  • Checks if any accounts exist before displaying
  • Uses formatted string output for tabular display
  • {"Account#",-10} creates left-aligned column with width 10
  • new string('-', 50) creates separator line
  • for loop iterates through all stored accounts

String Formatting:

  • Negative numbers in format specifiers (-10) create left alignment
  • :F2 formats currency with 2 decimal places
  • Creates professional-looking tabular output

Outputs

1. Creating an Account

Screenshot-2025-09-26-152706
Creating an Account

2. Depositing money in Account

Screenshot-2025-09-26-152953
Depositing money

3. Withdrawing Money

Screenshot-2025-09-26-153349
Withdrawing money

4. Check Balance

Screenshot-2025-09-26-153450
Checking balance

5. Check Account details

Screenshot-2025-09-26-153647
Checking account details

6. List all accounts

Screenshot-2025-09-26-155341
List all accounts

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