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

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 pos; /* a kinda of variable to randomly use the cifres */
    int n_cifres; /* variable used to hold the number of cifres that will be generated */
    int len = sizeof(student_id)/sizeof(int);
    int i;
    int *temp;

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

    if ( !(temp) )
        {
            perror("Malloc ERROR : Fatal..\n");
            exit(-1);
        }

    for ( i = 0; i < len; i++ )
      temp[i] = 0;

    srand(time(NULL));

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

    while ( num_count < 6 )
    {
        n_cifres = 1 + rand() % 2;

    turn:
        for ( i = 0; i < n_cifres; i++ )
        {
            pos = rand() % len;

        if( !check_id( temp, len, pow_fun(student_id[pos], i) ) )
          temp[num_count] += ( student_id[pos] * pow_fun(10, i) );
        else
          goto turn;



        }
        printf("\t");
        num_count++;


    }

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

    printf("\n");

    return EXIT_SUCCESS;
}
/* 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;
}

/* 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");

}