Fibbonacci Code

Hey all, Programming newbie here.

I'm programming the Fibbonacci code, but I can't figure out how to set the condition

"if NOT EQUAL to any numerical value"

This is what I have so far:

Code:

---


#include <stdio.h>
#include <conio.h>

long fib(int);

int main()
{
  int n;

  printf("Enter the Fibbonacci number you would like to view: ");
  scanf("%i", &n);

  if (WHAT GOES HERE?)
  {
    printf("Input error.\n");
    getch();
  }
  else if (n<0) {
    printf("Fibonacci is undefined for negative integers.\n");
    getch();
  }
  else {
    printf("The %i-th Fibonacci number is %ld\n", n, fib(n));
  }
  getch();
  return 0;
}

long fib(int n)
{
  if (n == 1 || n == 2)
  {
    return 1;
  }
  else
  {
    return (fib(n-1) + fib(n-2));
  }
}

---

Thanks for the help in advance!

Steel.

This should be on the C board, not C++ as that code is written in pure C.

Code:

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conio.h

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this is non-standard, read the FAQ to find out other ways to stop the console window closing, dependant on your IDE, getchar() is usually best.

Quote:

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Originally Posted by swgh

This should be on the C board, not C++ as that code is written in pure C.

Code:

---

conio.h

---

this is non-standard, read the FAQ to find out other ways to stop the console window closing, dependant on your IDE, getchar() is usually best.

---

Ok, thanks for the help, I'll re-post this in the C Board. Sorry for the inconvenience.

Most of us'd replace the scanf() with fgets(), then use strtol() to extract the number with error-checking.

Code:

---

char buffer[BUFSIZ];
char *endp;

fgets(buffer, BUFSIZ, stdin);
n = strtol(buffer, &endp, 10);
if (endp == buffer)
        printf("Input error\n")

---

Integer can only be numerical... I don't know if it is 0 when a string is entered or it is something else...

Thanks for the reply. I've only been coding for a Computer science course for about a week now, and I've never heard of those functions (although i'm certain their more efficent). Is there any way I can keep the remainder of my code intact, only changing what's in the
if (...) structure? Such as creating a condition where "all non-integers" output "input error".

Thanks

Quote:

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Originally Posted by zx-1

Use logical-OR operator. (||)

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I've tried that, using

Code:

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if ( (n<0) ||  (n>0) )

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Yet even all inputs, even valid, ourput "invalid output"

Carry on here - http://cboard.cprogramming.com/showthread.php?t=83217