找linux的mktime()和gmtime()等源码,找了一个
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const unsigned long m_lBaseSec19710101 = 719499l;<br />time_t mktime(const struct tm *tm_time)<br />{<br /> unsigned long year = tm_time->tm_year + 1900;<br /> unsigned long mon = tm_time->tm_mon + 1;<br /> unsigned long day = tm_time->tm_mday;<br /> unsigned long hour = tm_time->tm_hour;<br /> unsigned long min = tm_time->tm_min;<br /> unsigned long sec = tm_time->tm_sec;<br /> <br /> if (0 >= (int) (mon -= 2))<br /> {<br /> /* 1..12 -> 11,12,1..10 */<br /> mon += 12; /* Puts Feb last since it has leap day*/<br /> year -= 1;<br /> }<br /> <br /> return (((<br /> (unsigned long) (year/4l - year/100l + year/400l + 367l * mon / 12l +<br /> day) + year*365l - m_lBaseSec19710101<br /> )*24l + hour /* now have hours */<br /> )*60l + min /* now have minutes */<br /> )*60l + sec; /* finally seconds */<br />}<br /><br />const char Days[12] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};<br /><br />/*++ <br /><br /> Function:<br /> gmtime<br /><br />Modification History<br /><br />Jurassic 2002.1 Created. <br />*/<br />struct tm *gmtime(time_t time)<br />{<br /> static struct tm tm_time;<br /> unsigned long n32_Pass4year;<br /> unsigned long n32_hpery;<br /><br /> //计算时差<br /><br /> //取秒时间<br /> tm_time.tm_sec = (int)(time % 60);<br /> time /= 60;<br /> //取分钟时间<br /> tm_time.tm_min = (int)(time % 60);<br /> time /= 60;<br /> //取过去多少个四年，每四年有 1461*24 小时<br /> n32_Pass4year = time / (1461l * 24l);<br /> //计算年份<br /> tm_time.tm_year = (n32_Pass4year << 2) + 70;<br /> //四年中剩下的小时数<br /> time %= 1461l * 24l;<br /> //校正闰年影响的年份，计算一年中剩下的小时数<br /> for (;;)<br /> {<br /> //一年的小时数<br /> n32_hpery = 365 * 24;<br /> //判断闰年<br /> if ((tm_time.tm_year & 3) == 0)<br /> {<br /> //是闰年，一年则多24小时，即一天<br /> n32_hpery += 24;<br /> }<br /><br /> if (time < n32_hpery)<br /> {<br /> break;<br /> }<br /> tm_time.tm_year++;<br /> time -= n32_hpery;<br /> }<br /> //小时数<br /> tm_time.tm_hour = (int)(time % 24);<br /> //一年中剩下的天数<br /> time /= 24;<br /> //假定为闰年<br /> time++;<br /> //校正润年的误差，计算月份，日期<br /> if ((tm_time.tm_year & 3) == 0)<br /> {<br /> if (time > 60)<br /> {<br /> time--;<br /> }<br /> else<br /> {<br /> if (time == 60)<br /> {<br /> tm_time.tm_mon = 1;<br /> tm_time.tm_mday = 29;<br /> return &tm_time;<br /> }<br /> }<br /> }<br /><br /> //计算月日<br /> for (tm_time.tm_mon = 0; Days[tm_time.tm_mon] < time;tm_time.tm_mon++)<br /> {<br /> time -= Days[tm_time.tm_mon];<br /> }<br /><br /> tm_time.tm_mday = (int)(time);<br /><br /> return &tm_time;<br />}<br />
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