student_id.c

/*

[ student_id.c ]
Author : AlexZ ( alessandro.suglia@gmail.com )
Date : 22/09/2011 ( 19:29 PM )

HOW TO CHALLENGE THE LUCKY
Take your student number ID and write
a simple and easy C program that is able
to mingle together all the possible number starting
from that number that you've used.
*/

/* <------------ Header Definitions -----------------> */
#include <stdio.h>
#include <stdlib.h>
#include <time.h>

/* < ----------- Macros definition ---------------------->*/
#define TRUE 1
#define FALSE 0

/* <----------- Functions Declarations ------------------> */
int gen_num( int[], int );
int check_id ( int[], int, int );
void printArray( int[], int );
int pow_fun( int, int );

/* <-------------- main.c -------------------------> */
int main()
{
    int student_id[] = {5,8,7,1,7,6}; /* YOUR STUDENT ID divided in cifres */
    int num_count = 0; /* simple variable in order to hold the value of the counter used to count the number of numbers created */
    int len = sizeof(student_id)/sizeof(int); /* student_id's length */
    int val = 0; /* temporary variable needed to hold the value generated by gen_num() */
    int *temp; /* temp array in order to hold the new values */
    int i;

    temp = (int*)malloc( len * sizeof(int));

    /* Verify if enough memory was allocated for the temp array */
    if ( !(temp) )
        {
            perror("Malloc ERROR : Fatal..\n");
            exit(-1);
        }
    /* Inizialization of the temp array */
    for ( i = 0; i < len; i++ )
      temp[i] = 0;

    printf("THE NUMBERS THAT YOU WILL USE TO THE LOTTERY : \n");

    while ( num_count < 6 ) /* If num_count is lower than six, do something.. needed to create six random number */
    {
      val = gen_num(student_id, len);
      if ( !check_id(temp, len, val) ) /* check if the current random number is already present into the array, if not, put that value into the array and go on */
    {
      temp[num_count] = val;
      num_count++;
    }

    }

    printf("\n");
    printArray(temp, len);

    printf("\n");

    return EXIT_SUCCESS;
}

/* <-------------- Functions Definition ------------------------ > */

/* ASIOTPF : Another Stupid Implementation Of The Pow Function. Too much resorse will be needed in order to link the whole math.h header*/
int pow_fun ( int base, int esp )
{
  int i;
  int res = 1;

  for ( i = 0; i < esp; i++ )
    res *= base;

  return res;
}
/* check if the int num value is present into the a array, it returns TRUE if some value of the array match with num, FALSE in the opposite case*/
int check_id ( int a[], int len, int num )
{
    int i;

    for ( i = 0; i < len; i++ )
        if ( a[i] == num )
      return TRUE;

    return FALSE;
}
/* return a casual number starting from the STUDENT_ID specified */
int gen_num( int a[], int len )
{
  int n_cifres;
  int pos;
  int i;
  int val = 0;

  srand(time(NULL));

  n_cifres = 1 + rand() % 2;

  for ( i = 0; i < n_cifres; i++ )
    {
      pos = rand() % len;
      val += a[pos] * pow_fun(10,i);
    }

  return val;

}
/* Simple function used in order to print to video the array value*/
void printArray( int a[], int len )
{
  int i;

  for ( i = 0; i < len; i++)
    printf("[%d]\t", i+1);
  printf("\n");
  for ( i = 0; i < len; i++ )
    printf("%d\t", a[i]);
  printf("\n");

}