Loop termination in C fibonacci implementation

Question

My task is to find fibonacci series elements not larger than given in input. The problem is that I get one extra result (larger then number from input).

for example: when I enter 15 as a max, I get 1,1,2,3,5,8,13,21 which is incorrect.

My code:

#include <stdio.h>


int main()
{
    int n, first = 0, second = 1, next =0, c;

    printf("Enter max value\n");
    scanf("%d",&n);

    printf("Values smaller than %d  :-\n",n);

    for ( c = 1 ; n>=next; c++)
    {
        if ( c <= 1 )
           next = c;
        else
        {
            next = first + second;
            first = second;
            second = next;
        }
        printf("%d\n",next);
    }  
    return 0;
}

Any ideas?

Answer 1

You should check the new element for being to big, not the last found element for being smaller.
I won't go into more detail, because you said it's homework and probably don't need more.

Answer 2

If you get values higher than your max it's because you do this test first: n>=next (inside the for) THEN

next = first + second;

Which mean next>=n for the last iteration will be true. You shoud change the limit test or when the results are printed (eg before next = first + second;)

Answer 3

The problem is with your last loop. Work with a debugger if you need; or you can just go step by step in your mind. In your case, when next == 13, first == 5 and second == 8. then first becomes 8, and second becomes 13. However, at this moment next is still 13, so when it goes back the loop, n >= next still returns true, and it will go on one more loop, thus one more output than you expected. I won't tell you how to change it, cuz as others said, it's homework. I just want to show you how to find the problem.