Fibos

#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include <limits.h>

#define DEBUG 1 // for debuging purpose

int fibs( int howMany );

int fibs( int howMany )
{
    unsigned long int *dataArr;
    int i = 0;

    unsigned long int result = 0;

    if( 3 > howMany )
    {
        if( DEBUG )
        {
            printf("The amount of years is less then 3\n");
        }

        return 0;
    }

    dataArr = ( unsigned long int* )malloc( sizeof( unsigned long int ) * ( howMany + 1 ) );

    if( NULL == dataArr )
    {
        if( DEBUG )
        {
            printf("Memory for storing fibs data wasn't allocated\n");
        }
        return 0;
    }

    dataArr[1] = dataArr[2] = 1;

    if( DEBUG )
    {
        printf("Amount of rabbits in 1 year is: %lu\n", dataArr[ 1 ] );
        printf("Amount of rabbits in 2 year is: %lu\n", dataArr[ 2 ] );
    }

    for( i = 3; i <= howMany; i++ )
    {
        dataArr[ i ] = dataArr[ i - 1 ] + dataArr[ i - 2 ];
        if( DEBUG )
        {
            printf("Amount of rabbits in %d year is: %lu\n", i, dataArr[ i ] );
        }
    }

    result = dataArr[ howMany ];
    free( dataArr );

    return result;
}

// Second parameter might be the amount of years
int main( int argc, char **argv )
{
    // Timing
    time_t start, end;
    clock_t start1, end1;
    double dif;
    double dif1;

    //unsigned long int years = ULONG_MAX; // by default it should be minimum, so 3
    int years = 3;
    unsigned long int howManyResult = 0;

    if( ! DEBUG )
    {
        printf("It's: %d\n", years);
        return 0;
    }

    if( argc >= 2 )
    {
        years = atoi( argv[1] );
    }

    time( &start );
    start1 = clock();
    //printf("We started at %ld\n", start);

    howManyResult = fibs( years );

    time( &end );
    end1 = clock();
    //printf("We ended at %ld\n", end);

    if( 0 != howManyResult )
    {
        printf("For %d years the amount of rabbits is: %lu\n", years, howManyResult);
    }

    dif = difftime( end, start );
    dif1 = ((double)(end1 - start1)) / CLK_TCK;

    printf("It took program %.2lf seconds\n", dif);
    printf("It took program %3.3lf seconds\n", dif1);

    return 0;
}