C语言实现万年历程序

#include <stdio.h>
int year(int y)
{
 if ((y%4==0) && (y%100!=0) || y%400==0)
 return 366;
 else
 return 365;
}
int main()
{
 int y;
 int i,j,sum=0; 
 int begin,week;
 int days[12]={31,28,31,30,31,30,31,31,30,31,30,31};
 scanf("%d",&y);
 for(i=1;i<y;i++)
 sum+=year(i);
 week=(sum+1)%7; //表示该年1月1日为星期几
 if(year(y)==366)
 days[1]=29; 
 printf("\n%d年日历如下：\n\n",y);
 for(i=0;i<12;i++)
 {
 printf(" %d月  \n",i+1);
 printf(" 7 1 2 3 4 5 6\n");
 printf("=====================\n");
 begin=1;
 for(j=0;j<week;j++)
 printf(" ");
 while(begin<=days[i])
 {
 printf("%3d",begin);
 begin++;
 week=(week+1)%7;
 if(week%7==0)
 printf("\n");
 }
 printf("\n\n");
 }
 return 0;
}