Write program to calculate factorial of number in C++

 #include <iostream>

using namespace std;

// function to find the factorial of a number
int factorial(int n) {
    // base case
    if (n == 0) {
        return 1;
    }
    // recursive case
    else {
        return n * factorial(n-1);
    }
}

int main() {
    int n;
    cout << "Enter a number: ";
    cin >> n;
    cout << "Factorial of " << n << " is " << factorial(n) << endl;
    return 0;
}

In this code, we define a function factorial that takes an integer argument n and returns the factorial of n. The base case of the recursion is when n is equal to 0, in which case the function returns 1. Otherwise, the function recursively calls itself with n-1 as the argument and multiplies the result by n to get the factorial of n. In the main function, we simply read in a number from the user and call the factorial function to print out the result.