new tasks

Task/Calendar/C/calendar.c

@@ -0,0 +1,125 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+int width = 80, year = 1969;
+int cols, lead, gap;
+
+const char *wdays[] = { "Su", "Mo", "Tu", "We", "Th", "Fr", "Sa" };
+struct months {
+	const char *name;
+	int days, start_wday, at;
+} months[12] = {
+	{ "January",	31, 0, 0 },
+	{ "Februray",	28, 0, 0 },
+	{ "March",	31, 0, 0 },
+	{ "April",	30, 0, 0 },
+	{ "May",	31, 0, 0 },
+	{ "June",	30, 0, 0 },
+	{ "July",	31, 0, 0 },
+	{ "August",	31, 0, 0 },
+	{ "September",	30, 0, 0 },
+	{ "October",	31, 0, 0 },
+	{ "November",	30, 0, 0 },
+	{ "December",	31, 0, 0 }
+};
+
+void space(int n) { while (n-- > 0) putchar(' '); }
+
+void init_months()
+{
+	int i;
+
+	if ((!(year % 4) && (year % 100)) || !(year % 400))
+		months[1].days = 29;
+
+	year--;
+	months[0].start_wday
+		= (year * 365 + year/4 - year/100 + year/400 + 1) % 7;
+
+	for (i = 1; i < 12; i++)
+		months[i].start_wday =
+			(months[i-1].start_wday + months[i-1].days) % 7;
+
+	cols = (width + 2) / 22;
+	while (12 % cols) cols--;
+	gap = cols - 1 ? (width - 20 * cols) / (cols - 1) : 0;
+	if (gap > 4) gap = 4;
+	lead = (width - (20 + gap) * cols + gap + 1) / 2;
+        year++;
+}
+
+void print_row(int row)
+{
+	int c, i, from = row * cols, to = from + cols;
+	space(lead);
+	for (c = from; c < to; c++) {
+		i = strlen(months[c].name);
+		space((20 - i)/2);
+		printf("%s", months[c].name);
+		space(20 - i - (20 - i)/2 + ((c == to - 1) ? 0 : gap));
+	}
+	putchar('\n');
+
+	space(lead);
+	for (c = from; c < to; c++) {
+		for (i = 0; i < 7; i++)
+			printf("%s%s", wdays[i], i == 6 ? "" : " ");
+		if (c < to - 1) space(gap);
+		else putchar('\n');
+	}
+
+	while (1) {
+		for (c = from; c < to; c++)
+			if (months[c].at < months[c].days) break;
+		if (c == to) break;
+
+		space(lead);
+		for (c = from; c < to; c++) {
+			for (i = 0; i < months[c].start_wday; i++) space(3);
+			while(i++ < 7 && months[c].at < months[c].days) {
+				printf("%2d", ++months[c].at);
+				if (i < 7 || c < to - 1) putchar(' ');
+			}
+			while (i++ <= 7 && c < to - 1) space(3);
+			if (c < to - 1) space(gap - 1);
+			months[c].start_wday = 0;
+		}
+		putchar('\n');
+	}
+	putchar('\n');
+}
+
+void print_year()
+{
+	int row;
+	char buf[32];
+	sprintf(buf, "%d", year);
+	space((width - strlen(buf)) / 2);
+	printf("%s\n\n", buf);
+	for (row = 0; row * cols < 12; row++)
+		print_row(row);
+}
+
+int main(int c, char **v)
+{
+	int i, year_set = 0;
+	for (i = 1; i < c; i++) {
+		if (!strcmp(v[i], "-w")) {
+			if (++i == c || (width = atoi(v[i])) < 20)
+				goto bail;
+		} else if (!year_set) {
+			if (!sscanf(v[i], "%d", &year) || year <= 0)
+				year = 1969;
+			year_set = 1;
+		} else
+			goto bail;
+	}
+
+	init_months();
+	print_year();
+	return 0;
+
+bail:	fprintf(stderr, "bad args\nUsage: %s year [-w width (>= 20)]\n", v[0]);
+	exit(1);
+}