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Factorial Calculation

Steilla Mitchel 387 11-Jun-2024

Create a C# program to calculate the factorial of a given non-negative integer n. The factorial of a number is the product of all positive integers less than or equal to n.

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Updated on 14-Jun-2024

Steilla Mitchel

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1 Answers

Ashutosh Kumar Verma

14-Jun-2024

C# Factorial Calculation

When calculating the factor of a number, any positive whole number less than that number must be multiplied by that number. The product of the number n (denoted as n!) is the product of all positive integers less than or equal to n.

Syntax-

5! = 5 * 4 * 3 * 2 * 1 = 120.

3! = 3 * 2 * 1 = 6.

There are two ways mentioned below to calculate the factorial of an integer,

Iterative Approach

Example-

using System;
class FactorialCalculator
{
   static void Main()
   {
       Console.WriteLine("Enter a non-negative integer to calculate its factorial:");
       if (int.TryParse(Console.ReadLine(), out int number) && number >= 0)
       {
           Console.WriteLine("The factorial of {0} is {1}.", number, CalculateFactorial(number));
       }
       else
       {
           Console.WriteLine("Invalid input. Please enter a non-negative integer.");
       }
        Console.ReadLine();
   }
   // function to calculate factorial
   static long CalculateFactorial(int number)
   {
       long result = 1;
       for (int i = 1; i <= number; i++)
       {
           result *= i;
       }
       return result;
   }
}

In the above example-

Main method- Asks the user to enter a non-negative integer and verifies the input using int.TryParse and verifies that the number is non-negative. If true, calculate the factor using the CalculateFactorial method.

CalculateFactorial Method- Uses a recursive method with a for loop to calculate a factorial by multiplying the result by any integer from 1 to a given number.

Output-

Enter a non-negative integer to calculate its factorial:
5
The factorial of 5 is 120.

Recursive Approach

Here is an alternative approach for calculate the factorial of a integer for educational purpose,

Example-

using System;
class FactorialCalculator
{
   static void Main()
   {
       Console.WriteLine("Enter a non-negative integer to calculate its factorial:");
       if (int.TryParse(Console.ReadLine(), out int number) && number >= 0)
       {
           Console.WriteLine("The factorial of {0} is {1}.", number, CalculateFactorial(number));
       }
       else
       {
           Console.WriteLine("Invalid input. Please enter a non-negative integer.");
       }
        Console.ReadLine();
   }
   static long CalculateFactorial(int number)
   {
       if (number <= 1)
       {
           return 1;
       }
       return number * CalculateFactorial(number - 1);
   }
}

In the above example-
Main method- Same as the general method.

CalculateFactorial Method- Uses recursion to calculate factorial. The base case occurs when the number is 1 or less, in which case it returns 1. Otherwise, it calls itself with the number - 1 and multiplies the result by the number.