c语言打印月历

下面是使用 C 语言打印月历的示例代码：

#include <stdio.h>

int main() {
    int year, month, day;
    int days_of_month[] = {31,28,31,30,31,30,31,31,30,31,30,31};
    char *months[] = {"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"};

    printf("Enter year and month (format: yyyy mm): ");
    scanf("%d %d", &year, &month);

    // Check if it's a leap year
    if ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0) {
        days_of_month[1] = 29;
    }

    // Print month and year header
    printf("\n     %s %d\n", months[month-1], year);
    printf("--------------------\n");
    printf(" Su Mo Tu We Th Fr Sa\n");

    // Find the day of the week of the first day of the month
    day = 1;
    for (int i = 1900; i < year; i++) {
        if ((i % 4 == 0 && i % 100 != 0) || i % 400 == 0) {
            day += 366;
        } else {
            day += 365;
        }
    }
    for (int i = 0; i < month-1; i++) {
        day += days_of_month[i];
    }
    int first_day_of_month = day % 7;

    // Print calendar
    int days_in_month = days_of_month[month-1];
    for (int i = 0; i < first_day_of_month; i++) {
        printf("   ");
    }
    for (int i = 1; i <= days_in_month; i++) {
        printf("%3d", i);
        if ((i + first_day_of_month) % 7 == 0 || i == days_in_month) {
            printf("\n");
        } else {
            printf(" ");
        }
    }

    return 0;
}

其中，`days_of_month` 存储每个月的天数，`months` 存储月份的字符串表示。用户输入年份和月份后，程序会计算该月的第一天是星期几，然后按照日历格式打印出来。需要注意的是，该程序没有进行输入的合法性检查，实际应用中建议加上相应的代码。