Coding Interview : How to calculate factorial using recursion and iteration?

Factorial of n is the product of all positive descending integers. Factorial of n is denoted by n!.

For example:
4! = 4*3*2*1 = 24
5! = 5*4*3*2*1 = 120
Here, 4! is pronounced as "4 factorial".
The factorial is normally used in Combinations and Permutations (mathematics).

Program : (Using Recursion)

package net.jubiliation.example;

/**
 * @author Gaurav
 *
 */
public class FactorialExample {

 static int factorialFunction(int number) {
  if (number == 0)
   return 1;
  else
   return (number * factorialFunction(number - 1));
 }

 public static void main(String args[]) {
  int number = 5;// It is the number to calculate factorial
  System.out.println("Factorial of " + number + " is: " + factorialFunction(number));
 }
}

Result :

Factorial of 5 is: 120

===========================================================

Program : (Using Iteration)

package net.jubiliation.example;

/**
 * @author Gaurav
 *
 */
public class FactorialExample {

 static int factorialFunction(int number) {
  int result = 1;
  for (int i = 1; i <= number; i++) {
   result = result * i;
  }
  return result;
 }

 public static void main(String args[]) {
  int number = 5;// It is the number to calculate factorial
  System.out.println("Factorial of " + number + " is: " + factorialFunction(number));
 }
}

Result :

Factorial of 5 is: 120