Question

I am attempting to re-write this bash function in C, but the a little unsure of how to convert this function into a C loop.

Here I have variables set. This I already have

n=10
r=4

This is where I get a little lost on how to re-write this. This seems to be calling the function with its own function and I pretty sure C will not do that (safely at least ) Also it does not need to be a function at all, I just need to plug in the same variables and have it come out with the same result.

factorial() {
if (($1)); then
    echo $(($1 * $(factorial $(($1-1)))))
else
    echo 1
fi
}

The last bit, is what would be the best way to express the code below in C? Would the bracketing in bash carry over?

result=$(($(factorial $n)/($(factorial $r)*$(factorial $(($n-$r))))))

Answer 1

It’s totally legal for C functions to call themselves – this is called recursion. In C, it would look like this:

int factorial(int n) {
    if (n == 0) return 1;
    return n * factorial(n - 1);
}

You could also write this directly as a loop:

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

Hope this helps!