## Building a C++ Loan Calculator

Explore our comprehensive guide on how to create a loan amortization calculator in C++. Whether you're a finance enthusiast or need help with your C++ assignment, this resource equips you with the skills to build a practical financial tool from scratch. Additionally, our expert team is here to provide assistance and guidance, ensuring your success in both learning and applying C++ programming concepts to real-world financial applications. Start your journey today and take control of your financial knowledge.

### 1. Header Inclusions:

```
```cpp
#include
< iostream >
#include
< iomanip >
#include
< limits >
#include
< cmath >
```
< /cmath >< /limits >< /iomanip >< /iostream >
```

- This block includes necessary C++ libraries for input/output, formatting, numeric limits, and mathematical functions.

### 2. Namespace Declaration:

```
```cpp
using namespace std;
```
```

- This line allows the code to use symbols from the `std` namespace without explicitly qualifying them.

### 3. Input Validation Functions:

- The code defines three functions to validate user inputs:
- `validDoubleRange`: Validates if a double value is within a specified range.
- `validDoublePositive`: Validates if a double value is positive.
- `validIntSeries`: Validates if an integer value is one of the valid values from an array.

### 4. Payment Calculation Function:

```
```cpp
double paymentCalculator(double principal, double monthly_interest_rate, int num_payments) {
return principal * (monthly_interest_rate * pow(1 + monthly_interest_rate, num_payments)) / (pow(1 + monthly_interest_rate, num_payments) - 1);
}
```
```

- This function calculates the monthly payment for a loan based on the principal amount, monthly interest rate, and the number of payments using the amortization formula.

### 5. Amortization Schedule Function:

```
```cpp
void loanAmortizationSchedule(int current_period, int total_periods, double payment_amount, double monthly_interest_rate, double current_balance) {
if (current_period > total_periods) {
return;
}
double interest = current_balance * monthly_interest_rate;
double principal = payment_amount - interest;
double new_balance = current_balance - principal;
// Adjust the last payment amount if necessary
if (current_period == total_periods) {
payment_amount = current_balance + interest;
principal = current_balance;
new_balance = 0;
}
cout << setw(8) << current_period << setw(10) << fixed << setprecision(2) << payment_amount << setw(10) << interest << setw(10) << principal << setw(12) << new_balance << endl;
loanAmortizationSchedule(current_period + 1, total_periods, payment_amount, monthly_interest_rate, new_balance);
}
```
```

- This function recursively generates and prints the loan amortization schedule, including period number, payment amount, interest, principal, and remaining balance.

### 6. Main Function:

```
```cpp
int main() {
double principal;
double annual_interest_rate;
int loan_term;
const int valid_loan_terms[] = {10, 15, 25, 40};
int num_valid_loan_terms = 4;
cout << "Student Name -- Lab 1 - Recursion" << endl << endl;
cout << "Loan Application Information and Amortization Schedule" << endl << endl;
do {
cout << "Principle: ";
cin >> principal;
} while (!validDoubleRange(principal, 50000, 100000));
do {
cout << "Life of loan: ";
cin >> loan_term;
} while (!validIntSeries(loan_term, valid_loan_terms, num_valid_loan_terms));
do {
cout << "Annual Interest Rate: ";
cin >> annual_interest_rate;
} while (!validDoublePositive(annual_interest_rate));
int num_payments = loan_term * 12;
double monthly_interest_rate = (annual_interest_rate / 100) / 12;
double monthly_payment = paymentCalculator(principal, monthly_interest_rate, num_payments);
cout << "Monthly payment: " << fixed << setprecision(2) << monthly_payment << endl << endl;
cout << " Payment Amount Interest Principal Balance" << endl;
cout << setw(50) << setprecision(2) << principal << endl;
loanAmortizationSchedule(1, num_payments, monthly_payment, monthly_interest_rate, principal);
//system("pause");
return 0;
}
```
```

- The main function handles the overall flow of the program, including user input, calculation, and output.

### 7. Variable Declarations:

- The main function declares variables for user inputs, such as `principal`, `annual_interest_rate`, and `loan_term`, as well as an array `valid_loan_terms` to specify valid loan terms.

### 8. User Input and Validation:

- The main function uses a series of do-while loops to obtain and validate user inputs for `principal`, `loan_term`, and `annual_interest_rate`.

### 9. Loan Calculation:

- The main function calculates the number of payments, monthly interest rate, and monthly payment amount using the `paymentCalculator` function.

### 10. Amortization Schedule Output:

- The main function prints the monthly payment and a header for the amortization schedule.
- It then calls `loanAmortizationSchedule` to generate and print the schedule.

### 11. Return Statement:

- The program returns 0 to indicate successful execution.

### 12. Commented Code:

- There's a commented-out line (`//system("pause");`) which is typically used to pause the console window, but it's commented in this code.

## Conclusion

In conclusion, this guide has provided you with the knowledge and tools to develop a powerful loan amortization calculator and schedule generator in C++. By creating your own application, you not only gain a deeper understanding of financial principles but also obtain a valuable resource for managing loans. The user-friendly interface and insightful schedule generated by this program offer a practical solution for anyone seeking to estimate and track their loan payments over time, making financial planning more accessible and informed. Start your journey to financial empowerment today.