Writing Recursive Functions

There is no real magic here.
Each time a function is called it gets a new version of the local variables.
- This is done on something called the run time stack.
- We talked about this before when we discussed dynamic memory.
- The old values are saved, so when we return, we "get them back".
- So each call is in some sense independent
In other words, we can just write recursive functions.
We need to be careful to avoid infinite recursion.
- This is done by checking the base case first.
- Then performing any recursive case or cases.

Consider Factorial

long Factorial(size_t n) {
    if (n == 0) {
       return 1;
    } else {
       return  n * Factorial(n-1);
    }
}

Sometimes you need multiple calls.

int Fib(size_t n) {
    if (n == 1  or n==2) {
       return 1;
    } else {
       return Fib(n-1)+Fib(n-2);
    }
}