萬年曆

#include <stdio.h>
long int f(int year,int month)
{
if(month<3) return year-1;
else return year;
}
long int g(int month)
{
if(month<3) return month+13;
else return month+1;
}

long int n(int year,int month,int day)
{
return 1461L*f(year,month)/4+153L*g(month)/5+day;
}

int w(int year,int month,int day)
{
return(int) ((n(year,month,day)%7-621049L%7+7)%7);
}

int date[12][6][7];
int day_tbl[ ][12]={{31,28,31,30,31,30,31,31,30,31,30,31},{31,29,31,30,31,30,31,31,30,31,30,31}};

main()
{
int sw,leap,i,j,k,wd,day;
int year;
char title[]="SUM MON TUE WED THU FRI SAT";

printf("Please input the year whose calendar you want to know:\
");
scanf("%d%*c",&year);

sw=w(year,1,1);
leap=year%4==0&&year%100||year%400==0;
for(i=0;i<12;i++)
for(j=0;j<6;j++)
for(k=0;k<7;k++)

date[i][j][k]=0;
for(i=0;i<12;i++)
for(wd=0,day=1;day<=day_tbl[leap][i];day++)
{
date[i][wd][sw]=day;
sw=++sw%7;
if(sw==0) wd++;
}
printf("\
|================== The Calendar of Year %d==================|\
|",year);
for(i=0;i<6;i++)
{
for(wd=0,k=0;k<7;k++)
wd+=date[i][5][k]+date[i+6][5][k];
wd=wd?6:5;
printf(" %2d %s %2d %s|\
|",i+1,title,i+7,title);
for(j=0;j<wd;j++)
{
printf("
");
for(k=0;k<7;k++)

if(date[i][j][k])

printf("%4d",date[i][j][k]);

else printf("
");

printf("
");
for(k=0;k<7;k++)

if(date[i+6][j][k])

printf("%4d",date[i+6][j][k]);

else printf("
");
printf("|\
|");
}
}
puts("==============================================================|");
}