factorial of large number

To calculate the factorial of a large number in C++, you can use the following approach:

1. Define a function to multiply large numbers using arrays. This function should take the number to be multiplied and the result array as parameters.

2. Initialize the result array with a single element as 1 to represent the value of 1!.

3. Use a loop to iterate through all the numbers from 2 to the given number.

4. Inside the loop, call the multiplication function to multiply the current number with the result array.

5. After the loop, the result array will contain the factorial of the given large number.

Below is a sample code snippet to demonstrate the factorial calculation of a large number in C++:

#include <iostream>
using namespace std;

#define MAX 500

void multiply(int x, int result[], int& result_size) {
    int carry = 0;
    for (int i = 0; i < result_size; i++) {
        int product = result[i] * x + carry;
        result[i] = product % 10;
        carry = product / 10;
    }

    while (carry) {
        result[result_size] = carry % 10;
        carry = carry / 10;
        result_size++;
    }
}

void factorial(int n) {
    int result[MAX];
    result[0] = 1;
    int result_size = 1;

    for (int x = 2; x <= n; x++) {
        multiply(x, result, result_size);
    }

    cout << "Factorial of the given number is: ";
    for (int i = result_size - 1; i >= 0; i--) {
        cout << result[i];
    }
    cout << endl;
}

int main() {
    int num = 100;
    factorial(num);
    return 0;
}

This code defines a function to multiply large numbers and uses it to calculate the factorial of a given large number. It demonstrates the step-by-step approach to handle large number factorials in C++.