Mine

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define OR ||
// I like booleans. Screw you.

int main(void)
{
    int counter = 0;
    char i[256]; //number of iterations as a string, will be converted to an integer
    int iterint; //converted
    int x; //working variable sort of
    int iterlength;
    double a1 = 1;
    double a2 = 0;
    double a3 = 1;


    Menu:

    printf("This program will calculate fibonacci numbers up to\na certain point and output them to a text file, ''fibonacci.txt''");
    printf("\n\nInput number of iterations: ");

    gets(i);
    iterlength = strlen(i);
    iterint = atoi(i);
    x = 0;

     while ((x < iterlength))
    {
        if ((i[x] < '0') OR (i[x] > '9'))
        {
        printf("\n\nYOU DUN GOOFED. DON'T TYPE IN STUPID SHIT.\n\n");
        goto Menu;
        }
        x = x + 1;
    }

 while (counter < iterint)
    {
    FILE *fp = fopen("fibonacci.txt", "a+");
    fprintf(fp,"%f\n",a1);
    a1 = a2 + a3;
    a3 = a2;
    a2 = a1;
    counter = counter + 1;
    }
        return 0;
}