C语言实现简单的万年历

//C语言实现简单的日历 ,输入年份,就会输出整年的日历

#include <stdio.h>
#include <conio.h>

#include <windows.h>

long int f(int year, int month)
{/*f(年，月)＝年－1，如月<3;否则，f(年，月)＝年*/
if (month<3) return year - 1;
else return year;
}

long int g(int month)
{/*g(月)＝月＋13，如月<3;否则，g(月)＝月＋1*/
if (month<3) return month + 13;
else return month + 1;
}

long int n(int year, int month, int day)
{
/*N=1461*f(年、月)/4+153*g(月)/5+日*/
return 1461L * f(year, month) / 4 + 153L * g(month) / 5 + day;
}

int w(int year, int month, int day)
{
/*w=(N-621049)%7(0<=w<7)*/
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;/*年*/
char title[] = "SUN MON TUE WED THU FRI SAT";

OpenURL();

printf("Please input the year whose calendar you want to know: ");/*输入年*/
scanf("%d%*c", &year);/*输入年份值和掠过值后的回车*/
sw = w(year, 1, 1);
leap = year % 4 == 0 && year % 100 || year % 400 == 0;/*判闰年*/
for (i = 0; i<12; i++)
for (j = 0; j<6; j++)
for (k = 0; k<7; k++)
date[i][j][k] = 0;/*日期表置0*/
for (i = 0; i<12; i++)/*一年十二个月*/
for (wd = 0, day = 1; day <= day_tbl[leap][i]; day++)
{/*将第i＋1月的日期填入日期表*/
date[i][wd][sw] = day;
sw = ++sw % 7;/*每星期七天，以0至6计数*/
if (sw == 0) wd++;/*日期表每七天一行，星期天开始新的一行*/
}

printf("\n|==================The Calendar of Year %d =====================|\n|", year);
for (i = 0; i<6; i++)
{/*先测算第i+1月和第i+7月的最大星期数*/
for (wd = 0, k = 0; k<7; k++)/*日期表的第六行有日期，则wd!=0*/
wd += date[i][5][k] + date[i + 6][5][k];
wd = wd ? 6 : 5;
printf("%2d  %s  %2d  %s |\n|", i + 1, title, i + 7, title);
for (j = 0; j<wd; j++)
{
printf("   ");/*输出四个空白符*/
/*左栏为第i+1月，右栏为第i+7月*/
for (k = 0; k<7; k++)
if (date[i][j][k])
printf("%4d", date[i][j][k]);
else printf("    ");
printf("     ");/*输出十个空白符*/
for (k = 0; k<7; k++)
if (date[i + 6][j][k])
printf("%4d", date[i + 6][j][k]);
else printf("    ");
printf(" |\n|");
}
/*scanf("%*c");/*键入回车输出下一个月的日历*/

}
puts("=================================================================|");
puts("\n Press any key to quit...");
getch();
}

运行结果如图: