#include <stdio.h> #include <stdlib.h> int fibofnc (int n) { if (n <= 0) return 0; if (n == 1) return 1; return fibofnc (n - 1) + fibofnc (n - 2); } int main (int argc, char *argv[]) { int n; int res; char *p; if (argc >= 2) { n = strtol (argv[1], &p, 0); if ((p == argv[1]) || *p) { fprintf (stderr, "The \"%s\" string is not a number\n", argv[1]); return 1; } } else { printf ("Input number: "); scanf ("%d", &n); } res = fibofnc (n); printf ("fibofnc(%d)=%d\n", n, res); return 0; }