cal.c

自己做的常用库和实现的数据结构。public domain.

/* Demo of simple calendar rountine.
 *
 * Written by Cyril Hu ([e-mail]), public domain.
 */

#include<stdio.h>

int main(void)
{
	int day_code, days_in_month, leap_year, day, month, flag;

	do {
		puts("Enter day code[0,6] and leap year code[0,1]:");
		scanf("%d%d", &day_code, &leap_year);
	} while(day_code < 0 || day_code > 6 || 
		(leap_year != 0 && leap_year != 1));

	for(month = 1; month <= 12; month++) {
		switch(month) {
			case 1: puts("January"); days_in_month = 31; break;
			case 2:
				puts("February");
				days_in_month = leap_year ? 29 : 28;
				break;
			case 3: puts("March"); days_in_month = 31; break;
			case 4: puts("April"); days_in_month = 30; break;
			case 5: puts("May"); days_in_month = 31; break;
			case 6: puts("June"); days_in_month = 30; break;
			case 7: puts("July"); days_in_month = 31; break;
			case 8: puts("August"); days_in_month = 31; break;
			case 9: puts("September"); days_in_month = 30; break;
			case 10: puts("October"); days_in_month = 31; break;
			case 11: puts("November"); days_in_month = 30; break;
			case 12: puts("December"); days_in_month = 31; break;
		}
		puts("Sun  Mon  Tue  Wed  Thu  Fri  Sat");
		for(day = 0; day < day_code * 5; day++) 
			printf(" ");
		for(day = 1; day <= days_in_month; day++) {
			printf("%3d", day);
			if( (day + day_code) % 7 > 0 ) {
				printf("  ");
				flag=0;
			}
			else {puts(""); flag=1;}
		}
		if(flag)
			puts("");
		else 
			puts("\n");
		day_code = (day_code + days_in_month) % 7;
	}
	return 0;
}