title: Determining day of the week using Zeller's Congruence
body: <p>I tried writing the code for finding the day of the week for a given date using <a href="http://en.wikipedia.org/wiki/Zeller%27s_congruence" rel="nofollow">Zeller's Congruence</a> but I'm not getting the correct output. What's wrong with my code?</p>
  
  <pre><code>#include &lt;stdio.h&gt;
  #include &lt;math.h&gt;
  int main()
  {
    int h,q,m,k,j,day,month,year;
    printf("Enter the date (dd/mm/yyyy)\n");
    scanf("%i/%i/%i",&amp;day,&amp;month,&amp;year);
    if(month == 1)
    {
      month = 13;
      year--;
    }
    if (month == 2)
    {
      month = 14;
      year--;
    }
    q = day;
    m = month;
    k = year % 100;
    j = year / 100;
    h = q + floor(13/5*(m+1)) + k + floor(k/4) +  floor(j/4) + 5 * j;
    h = h % 7;
    switch(h)
    {
      case 0 : printf("Saturday.\n"); break;
      case 1 : printf("Sunday.\n"); break;
      case 2 : printf("Monday. \n"); break;
      case 3 : printf("Tuesday. \n"); break;
      case 4 : printf("Wednesday. \n"); break;
      case 5 : printf("Thurday. \n"); break;
      case 6 : printf("Friday. \n"); break;
    }
    return 0;
  }
  </code></pre>