Capstone: Command-Line Bank & Account System

In Plain English

Congratulations on reaching the final capstone lesson! In this comprehensive project, you will unite everything you learned across the C++ curriculum: structs, dynamic vectors, pass-by-reference functions, conditional logic, and stream formatting to build a production-grade Bank Account system.

The Mental Model

"You now command the full C++ engine: memory addressing, machine speed, modular functions, and data encapsulation. Now let's engineer a rock-solid banking system!"

Deep Dive: How It Works

Data Architecture: BankAccount struct tracking accountId, ownerName, balance, and transaction history.

Deposit & Withdraw Functions: Passing accounts by reference (&) to safely update balances and log transactions.

Audit System: Iterating through transaction vectors to display detailed financial statements.

Syntax Blueprint

struct Account {
  std::string name;
  double balance;
};

void deposit(Account &acc, double amount) {
  acc.balance += amount;
}

A complete modular C++ application with struct data models and reference manipulation.

Core Rules to Remember

The Complete C++ Toolset: Structs + vectors + reference functions + stream formatting working in harmony.

Memory Efficiency: Zero wasteful copies thanks to pass-by-reference (&).

Blazing Fast Execution: Executes natively on the metal with sub-millisecond compile and run speed.

Common Beginner Traps & How to Fix Them

Mistake:Passing Account by value to deposit()

Why it happens: Forgetting &, which updates a temporary copy and loses user funds!

How to fix: Always pass with Account &acc.

Pro Tip: You can compile this code locally on any Mac, Linux, or Windows computer with g++ -O3 main.cpp -o bank!

Live Interactive Example

Hit Run Code to see it live

Complete Bank Account Engine

C++ 20

#include <iostream>
#include <string>
#include <vector>

struct BankAccount {
    int id;
    std::string owner;
    double balance;
    std::vector<std::string> history;
};

void deposit(BankAccount &acc, double amount) {
    acc.balance += amount;
    acc.history.push_back("Deposit: +" + std::to_string((int)amount));
}

bool withdraw(BankAccount &acc, double amount) {
    if (amount > acc.balance) {
        acc.history.push_back("Failed Withdraw: -" + std::to_string((int)amount) + " (Insufficient Funds)");
        return false;
    }
    acc.balance -= amount;
    acc.history.push_back("Withdraw: -" + std::to_string((int)amount));
    return true;
}

void printStatement(const BankAccount &acc) {
    std::cout << "================================\n";
    std::cout << "Bank Statement: " << acc.owner << " (ID: #" << acc.id << ")\n";
    std::cout << "Current Balance: $" << acc.balance << "\n";
    std::cout << "Transactions (" << acc.history.size() << "):\n";
    for (const auto &tx : acc.history) {
        std::cout << " - " << tx << "\n";
    }
    std::cout << "================================\n";
}

int main() {
    BankAccount account = {101, "Satoshi Nakamoto", 500.0, {}};

deposit(account, 250.0);
    withdraw(account, 100.0);
    withdraw(account, 1000.0); // Should fail

printStatement(account);
    return 0;
}

Output Console

Click "Run Code" to view the rendered output.

How it works: A production-grade C++ engine executing all core banking features.

Your Turn: Micro Challenge

No pressure! Edit the starter code below and test your solution with instant feedback.

Micro Exercise

Deposit funds into an account

Complete the deposit function: void deposit(BankAccount &acc, double amount) { acc.balance += amount; }
In main(), initialize BankAccount acc = {1, "Ada", 100.0};
Deposit 50.0 and print "Final Balance: $150".

Sandbox Output

Click "Run & Check" to test your solution.

Finished reading and practicing?