怎么样可以用C语言编写出2006年的日历？

//用C语言编写出2006年的日历？
//察看日历今年第一天是星期天
#include <stdio.h>
main()
{
int leap,month,day,days,m;
printf("please input the date:\a");
scanf("%d,%d",&month,&day);
printf("the date is 2006,%d,%d\n",month,day);
if((2006%4==0&&2006%100!=0)||(2006%400==0))
leap=1;
else
leap=0;
days=day;
if(leap==1)
{
printf("this year is leap year\n");
if(month-1==0)
days=day;
else
switch(month-1)
{
case 11:days=days+30;
case 10:days=days+31;
case 9:days=days+30;
case 8:days=days+31;
case 7:days=days+31;
case 6:days=days+30;
case 5:days=days+31;
case 4:days=days+30;
case 3:days=days+31;
case 2:days=days+29;
case 1:days=days+31;
}
}
if(leap==0)
{
printf("the year is not leap year\