In this post, we will learn **how to calculate compound interest using C++** Programming language.

**Compound Interest** is the interest on a loan or deposit calculated based on both the initial principal and the accumulated interest from previous periods.

The formula to calculate compound interest is: **Compound Interest = P x (1 + r/n)nt – P**

Where,

- P is the principal amount.
- r is the rate of interest (decimal)
- n is the no. of times the interest is compounded annually
- t is the overall time duration

Since, we are taking **n = 1** in the below program, therefore the formula becomes **CI = P x (1 + r)t – P**.

We will use this formula in the below program to calculate compound interest.

So, without further ado, let’s begin this tutorial.

**C++ Program to Calculate Compound Interest**

// C++ Program to Calculate Compound Interest #include <iostream> #include <math.h> using namespace std; int main(){ float p, r, t, CI, amount; // Asking for input cout << "Enter the principal amount: "; cin >> p; cout << "Enter the rate of interest: "; cin >> r; cout << "Enter the time period in years: "; cin >> t; // Calculating compound interest amount = p * (pow((1 + r/100), t)); CI = amount - p; // Displaying output cout << "Compound interest is = " << CI << endl; return 0; }

**Output**

```
Enter the principal amount: 50000
Enter the rate of interest: 4
Enter the time period in years: 5
Compound interest is = 10832.6
```

**How Does This Program Work?**

```
float p, r, t, CI, amount;
```

In this program, we have declared **five integer data type** variables named **p**, **r**, **t**, **CI **and **amount**.

```
// Asking for input
cout << "Enter the principal amount: ";
cin >> p;
cout << "Enter the rate of interest: ";
cin >> r;
cout << "Enter the time period in years: ";
cin >> t;
```

Then, the user is asked to enter the principal amount, rate of interest and time period (in years). The entered values get stored in the **p**,** r**, and** t** named variables respectively.

```
// Calculating compound interest
amount = p * (pow((1 + r/100), t));
CI = amount - p;
```

Compound Interest is calculated using the formula:** CI = P x (1 + r)t – P**.

The **pow()** function is used to find the value of a base raised to the power of another number. It is defined in the **math.h **header file.

```
// Displaying output
cout << "Compound interest is = " << CI << endl;
```

Finally, the compound interest computed above is displayed on the screen using the **cout** statement.

**Conclusion**

I hope after going through this post, you understand **how to calculate compound interest using the C++** Programming language.

If you have any doubts regarding the program, then contact us in the comment section. We will be delighted to assist you.

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