C-错误的斐波那契数

Question

I have written this C code to output Fibonacci numbers but I'm lost as to why it gives the wrong value, and also why the numbers occasionally go down . What's going wrong and how can I fix it?

It gives me this sequence: 0, 0, 1, 1, 2, 1, 3, 4, 3, 5, 5, 6, 8, 7, 13, 8, 21, 9, 34.

#include <stdio.h>
#include <math.h>
int MyFibonacciFunction(int n)
{
    if (n == 0) {
        return 0;
    } else {
        if (n == 1) {
            return 1;
        } else {
            return (MyFibonacciFunction((n - 1)) + MyFibonacciFunction((n - 2)));
        }
    }
}

void main()
{

        int a = 0;
        while (a < 10) {
            {
                printf("%d\n", a);
                printf("%d\n", MyFibonacciFunction(a));
                a = (a + 1);
            }
    }
}

Answer 1

I've changed your code as follows,try this it solves your problem:

#include <stdio.h>

int MyFibonacciFunction(int n) {

      if(n == 0)
        return 0;
      else if(n == 1)
        return 1;
      else
        return (MyFibonacciFunction((n - 1)) + MyFibonacciFunction((n - 2)));

}

int main(void)
{

    int a = 0;
    while (a < 10)
        printf("%d\n", MyFibonacciFunction(a++));

    return 0;
}

Answer 2

If you don't have to use recursion, then don't use it. If this is some recursion excercise, then it's ok. Iterative programming is faster and saves memory(a lot).