c语言实现公历转为农历

要实现公历转为农历，需要用到农历计算的算法，以下是一个简单的C语言实现：

#include <stdio.h>

// 农历信息结构体
typedef struct {
    int year; // 农历年份
    int month; // 农历月份
    int day; // 农历日
    int isLeap; // 是否是闰月
} LunarDate;

// 公历转农历
LunarDate solarToLunar(int year, int month, int day) {
    // 农历信息表
    static int lunarInfo[] = {
        0x04bd8, 0x04ae0, 0x0a570, 0x054d5, 0x0d260,
        0x0d950, 0x16554, 0x056a0, 0x09ad0, 0x055d2,
        0x04ae0, 0x0a5b6, 0x0a4d0, 0x0d250, 0x1d255,
        0x0b540, 0x0d6a0, 0x0ada2, 0x095b0, 0x14977,
        0x04970, 0x0a4b0, 0x0b4b5, 0x06a50, 0x06d40,
        0x1ab54, 0x02b60, 0x09570, 0x052f2, 0x04970,
        0x06566, 0x0d4a0, 0x0ea50, 0x06e95, 0x05ad0,
        0x02b60, 0x186e3, 0x092e0, 0x1c8d7, 0x0c950,
        0x0d4a0, 0x1d8a6, 0x0b550, 0x056a0, 0x1a5b4,
        0x025d0, 0x092d0, 0x0d2b2, 0x0a950, 0x0b557,
        0x06ca0, 0x0b550, 0x15355, 0x04da0, 0x0a5d0,
        0x14573, 0x052d0, 0x0a9a8, 0x0e950, 0x06aa0,
        0x0aea6, 0x0ab50, 0x04b60, 0x0aae4, 0x0a570,
        0x05260, 0x0f263, 0x0d950, 0x05b57, 0x056a0,
        0x096d0, 0x04dd5, 0x04ad0, 0x0a4d0, 0x0d4d4,
        0x0d250, 0x0d558, 0x0b540, 0x0b5a0, 0x195a6,
        0x095b0, 0x049b0, 0x0a974, 0x0a4b0, 0x0b27a,
        0x06a50, 0x06d40, 0x0af46, 0x0ab60, 0x09570,
        0x04af5, 0x04970, 0x064b0, 0x074a3, 0x0ea50,
        0x06b58, 0x055c0, 0x0ab60, 0x096d5, 0x092e0,
        0x0c960, 0x0d954, 0x0d4a0, 0x0da50, 0x07552,
        0x056a0, 0x0abb7, 0x025d0, 0x092d0, 0x0cab5,
        0x0a950, 0x0b4a0, 0x0baa4, 0x0ad50, 0x055d9,
        0x04ba0, 0x0a5b0, 0x15176, 0x052b0, 0x0a930,
        0x07954, 0x06aa0, 0x0ad50, 0x05b52, 0x04b60,
        0x0a6e6, 0x0a4e0, 0x0d260, 0x0ea65, 0x0d530,
        0x05aa0, 0x076a3, 0x096d0, 0x04bd7, 0x04ad0,
        0x0a4d0, 0x0d0b6, 0x0d250, 0x0d520, 0x0dd45,
        0x0b5a0, 0x056d0, 0x055b2, 0x049b0, 0x0a577,
        0x0a4b0, 0x0aa50, 0x1b255, 0x06d20, 0x0ada0
    };
    int lunarYear, lunarMonth, lunarDay, isLeap;
    int leapMonth, leapMonthDays, totalDays, offsetDays;
    int i;

    // 计算1900年到当前年份之间的总天数
    totalDays = 0;
    for (i = 1900; i < year; i++) {
        totalDays += 365;
        if ((i % 4 == 0 && i % 100 != 0) || (i % 400 == 0)) {
            totalDays++;
        }
    }
    // 当年是否是闰年
    if ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0)) {
        leapMonth = 1; // 闰月为1月
    } else {
        leapMonth = 0; // 没有闰月
    }
    // 如果当年有闰月，计算闰月天数
    leapMonthDays = 0;
    if (leapMonth) {
        for (i = 1; i <= 12; i++) {
            if ((lunarInfo[year - 1900] & (0x10000 >> i)) != 0) {
                leapMonthDays = lunarInfo[year - 1900] & 0xffff;
                break;
            }
        }
    }
    // 加上当年的天数
    totalDays += day;
    // 计算当年的闰月月份
    isLeap = 0;
    for (i = 1; i <= 12; i++) {
        if (leapMonth && i == leapMonth + 1 && !isLeap) {
            i--;
            isLeap = 1;
            offsetDays = leapMonthDays;
        } else {
            offsetDays = (lunarInfo[year - 1900] & (0x80000 >> (i - 1))) != 0 ? 30 : 29;
        }
        if (isLeap && i == leapMonth + 1) {
            isLeap = 0;
        }
        totalDays -= offsetDays;
        if (totalDays <= 0) {
            break;
        }
    }
    lunarMonth = i;
    lunarDay = totalDays + offsetDays;
    lunarYear = year;
    // 如果是闰月，设置闰月标志
    if (leapMonth && i == leapMonth + 1) {
        isLeap = 1;
    } else {
        isLeap = 0;
    }
    // 返回农历日期
    LunarDate lunarDate;
    lunarDate.year = lunarYear;
    lunarDate.month = lunarMonth;
    lunarDate.day = lunarDay;
    lunarDate.isLeap = isLeap;
    return lunarDate;
}

int main() {
    int year, month, day;
    printf("请输入公历日期（格式：年 月 日）：");
    scanf("%d %d %d", &year, &month, &day);
    LunarDate lunarDate = solarToLunar(year, month, day);
    printf("农历日期：%d年", lunarDate.year);
    if (lunarDate.isLeap) {
        printf("闰");
    }
    printf("%d月%d日\n", lunarDate.month, lunarDate.day);
    return 0;
}

这个实现仅供参考，实际上农历计算的算法比较复杂，需要考虑到闰年、闰月等因素，因此建议使用现成的农历计算库，如 lunar-calendar。