Factorial program in C++ using function

 #include <iostream>

using namespace std;

int factorial(int n) {
    int fact = 1;
    for (int i = 1; i <= n; i++) {
        fact *= i;
    }
    return fact;
}

int main() {
    int n;
    cout << "Enter a number: ";
    cin >> n;

    int result = factorial(n);

    cout << "The factorial of " << n << " is " << result << endl;

    return 0;
}

In this program, we define a function factorial that takes an integer argument n and returns the factorial of n. We initialize a variable fact to 1 and loop from 1 to n, multiplying fact by the current loop variable at each iteration. This gives us the factorial of n.

In the main function, we prompt the user to enter a number and read it in using cin. We call the factorial function with the user's input as the argument and store the result in a variable result.

Finally, we print out the result using cout. The program returns 0 to indicate successful execution.