Question

I am currently taking a Foundation of Programming course where we are being taught Java. We were shown how to make a program to calculate factorials recursively, how could I create an iterative method that could calculate factorials?

Answer 1

Any problem which can be solved by recursion can be solved by iteration as well and vice versa. The factorial of a number is the product of all positive numbers which are less than of equal to the number. To calculate factorial of a number n, in iterative manner a simple for loop can be used which will multiply all positive numbers less than of equal to n.

Below is the JAVA program for the same.

I have documented the code. Hope it helps.

Cheers!!  

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public class solution
{
public static void main(String args[])
{
// Line below initializes the number for which factorial needs to be calculated
// modify the value as per your desire
int inputNumber = 6;

// since the value of factorial can be very large the datatype for factorial is long
// it is initialized to 1 so that numbers can be multiplied to it
long factorial = 1;

// now we implement the for loop. The loop counter 'i' is initialized to the input number
// and is decremented in each iteration until it is reduced to 1 and in each iteration
// we multiply the current value of i to the variable 'factorial' so that by the end of all
// iterations it will store the final result
for(int i = inputNumber; i>=1 ; i--)
{
// multiplying the value of i to factorial
factorial = factorial*i;
}

// printing the final output
System.out.println("Factorial of given number is:"+factorial);
}
}