Recursive factorial, what is wrong with my code?

got access violation when running in VC++ 6

Code:

---

#include<stdio.h>


void p(int n){
 
  if(n > 0){
    p(n - 2);
    printf("%d ", n);
    p(n - 1);
    }
}
int main(void) {
  p(4);
 
return 0; 
}

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I don't see anything in the code that would cause you to go too deep on a recursion to get an access violation.

Just out of curiosity, how does that function calculate a factorial recursively? It really should look a bit more like this:

Code:

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int f(int n)
{
  if (n < 2) {
    return 1;
  }

  return n * f(n - 1);
}

---

;)

Quote:

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Originally Posted by xephyr

got access violation when running in VC++ 6

Code:

---

#include<stdio.h>


void p(int n){
 
  if(n > 0){
    p(n - 2);
    printf("%d ", n);
    p(n - 1);
    }
}
int main(void) {
  p(4);
 
return 0; 
}

---

---

You aren't using recursion there dude, take a look here:
http://cboard.cprogramming.com/showthread.php?t=55061
That's a good example of recursion explained step by step.

Um any function that calls itself IS recursion. In fact there are two recursion points in that function.

Quote:

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Originally Posted by Thantos

Um any function that calls itself IS recursion. In fact there are two recursion points in that function.

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Can you please me point them cause I see just one? :confused:

Code:

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p(n-2)
...
p(n-1)

---

Quote:

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Originally Posted by sean_mackrory

Code:

---

p(n-2)
...
p(n-1)

---

---

Wow I should be drunk when I posted before, sorry dude now I got it:eek:

it's strange that people first learn recursion by writing the factorial function, it's simple, but terribly inefficient and really a poor use of recursion and it's capabilities. Recursion is better used in text analysis, sorting and data structure manipulation.

>it's strange that people first learn recursion by writing the factorial function
Not strange at all really. As you said, it's simple and easy to trace. That makes it a good candidate for a first step into the concept of recursion. The same goes with the fibonacci recursive solution. Neither of them should be used in any real code, but they're a critical step for beginners.

Code:

---

#include <stdio.h>
int factorial(int n);
int main()
{
 
  factorial(2);
  for(;;);
  return 0;
}
int factorial (int n)
{
        int answer;
                if (n==1) return 1;
                answer=factorial(n-1)*n;
                printf("%d\n", answer);
               
                return answer;
}

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