C# programs to calculate compound interest have been shown here. Both of the iterative and recursive approaches have been covered. Computing compound interest using formula has also been shown here.

The following section covers the C# programs to calculate compound interest.

## 1. C# Program & output to calculate compound interest using formula

Code has been copied
/*****************************************************
alphabetacoder.com
C# program to calculate compound interest using formula
******************************************************/

using System;

namespace CompoundInterest
{
class Program
{
static void Main(string[] args)
{
// declare variables
double ci, amount, p, r;
int n, t;

// take input of initial principal amount,
// interest rate, periodicity of payment and year
Console.Write("Enter the principal balance = ");
Console.Write("Enter interest rate= ");
Console.Write("Enter compound frequency / year = ");
Console.Write("Enter the year  = ");

// calculate compounded value
// using formula
amount = p * Math.Pow((1 + r/(100 * n)), n*t);

//find the compound interest
ci = amount - p;

// display result upto 2 decimal places
Console.WriteLine("Compound interest = "+Math.Round(ci, 2));

// wait for user to press any key
}
}
}


Output

Enter the principal balance = 7200

Enter the annual interest rate = 6

Enter compound frequency / year = 2

Enter the year = 5

Compound interest = 2476.2

## 2. C# Program & output to calculate compound interest using loop (Iteration)

Code has been copied
/**************************************************************
alphabetacoder.com
C# program to calculate compound interest using loop (Iteration)
***************************************************************/

using System;

namespace CompoundInterest
{
class Program
{
static void Main(string[] args)
{
// declare variables
double ci, amount, p, r;
int n, t, i;

// take input of initial principal amount,
// interest rate, periodicity of payment and year
Console.Write("Enter the principal balance = ");
Console.Write("Enter interest rate= ");
Console.Write("Enter compound frequency / year = ");
Console.Write("Enter the year  = ");

// initialize
amount = p;

// calculate compounded value using loop
for(i = 0; i < n * t; i++)
amount = amount + amount * (r / (n * 100));

//find the compound interest
ci = amount - p;

// display result upto 2 decimal places
Console.WriteLine("Compound interest = "+Math.Round(ci, 2));

// wait for user to press any key
}
}
}


Output

Enter the principal balance = 35000

Enter the annual interest rate = 5.2

Enter compound frequency / year = 1

Enter the year = 10

Compound interest = 23106.6

## 3. C# Program & output to calculate compound interest using recursion

Code has been copied
/**********************************************************
alphabetacoder.com
C# program to calculate compound interest using recursion
************************************************************/

using System;

namespace CompoundInterest
{
class Program
{
// recursive function to compute compound interest
static double compound_interest(double p0, double p, double r, int n, int t, int itr){
// if number of total no of compound reached
if(itr == n * t)
return (p - p0);
// calculate interest
double interest = p * (r / (n * 100));

// call function
return compound_interest(p0, p + interest, r, n, t, itr + 1);
}

static void Main(string[] args)
{
// declare variables
double ci, p, r;
int n, t;

// take input of initial principal amount,
// interest rate, periodicity of payment and year
Console.Write("Enter the principal balance = ");
Console.Write("Enter interest rate= ");
Console.Write("Enter compound frequency / year = ");
Console.Write("Enter the year  = ");

// call function to compute compound interest
ci = compound_interest(p, p, r, n, t, 0);

// display result upto 2 decimal places
Console.WriteLine("Compound interest = "+Math.Round(ci, 2));

// wait for user to press any key
}
}
}


Output

Enter the principal balance = 90000

Enter the interest rate = 7

Enter compound frequency / year = 4

Enter the year = 20

Compound interest = 270575.27