linux下关于夏令时取时间戳的问题

csmtv 2009-06-15 11:13:04

根据用户输入需要对应的日期转成时间戳传给程序，用的是struct tm赋值, mktime(&tm)转时间戳。
问题是，当系统的时区调到支持夏令时区时，（.e.g. GMT-5）则会在进出夏令时有问题，

测试程序如下：



//GMT-5



        struct tm tm1;

        struct tm tm2;

        time_t clock;

        //3-8 00:00



        memset(&tm1, 0, sizeof(tm1));

        memset(&tm2, 0, sizeof(tm2));

        tm1.tm_year = 109;

        tm1.tm_mon = 2;

        tm1.tm_mday = 8;

        tm1.tm_hour = 0;

        tm1.tm_min = 0;

        tm1.tm_sec = 0;

        tm1.tm_isdst = 0;

        printf("before: %04d-%02d-%02d %02d:%02d:%02d\n", tm1.tm_year+1900,tm1.tm_mon+1,tm1.tm_mday,tm1.tm_hour,tm1.tm_min,tm1.tm_sec);

        printf("before: tm_isdst = %d\n", tm1.tm_isdst);

        clock = mktime(&tm1);

        printf("%d\n", (int)clock);

        localtime_r(&clock, &tm2);

        printf("after: %04d-%02d-%02d %02d:%02d:%02d\n", tm2.tm_year+1900,tm2.tm_mon+1,tm2.tm_mday,tm2.tm_hour,tm2.tm_min,tm2.tm_sec);

        //printf("%s\n", tm1.tm_zone);



        

        printf("------------------------------\n");

        

        //11-2 00:00



        memset(&tm1, 0, sizeof(tm1));

        memset(&tm2, 0, sizeof(tm2));

        tm1.tm_year = 109;

        tm1.tm_mon = 10;

        tm1.tm_mday = 1;

        tm1.tm_hour = 0;

        tm1.tm_min = 0;

        tm1.tm_sec = 0;

        tm1.tm_isdst = 0;

        printf("before: %04d-%02d-%02d %02d:%02d:%02d\n", tm1.tm_year+1900,tm1.tm_mon+1,tm1.tm_mday,tm1.tm_hour,tm1.tm_min,tm1.tm_sec);

        printf("before: tm_isdst = %d\n", tm1.tm_isdst);

        clock = mktime(&tm1);

        printf("%d\n", (int)clock);

        localtime_r(&clock, &tm2);

        printf("after: %04d-%02d-%02d %02d:%02d:%02d\n", tm2.tm_year+1900,tm2.tm_mon+1,tm2.tm_mday,tm2.tm_hour,tm2.tm_min,tm2.tm_sec);

当tm.tm_isdst = 0 (不启用夏令时)时，则进入夏令时OK,出夏令时会多一个小时。
root@UTM25:/opt/CPSecure/webui/private# ./test
before: 2009-03-08 00:00:00
before: tm_isdst = 0
1236488400
after: 2009-03-08 00:00:00
------------------------------
before: 2009-11-01 00:00:00
before: tm_isdst = 0
1257051600
after: 2009-11-01 01:00:00

当tm.tm_isdst = 1(启用夏令时) 时，则进入夏令时时间会提前一个小时,出夏令时OK。
root@UTM25:/opt/CPSecure/webui/private# ./test
before: 2009-03-08 00:00:00
before: tm_isdst = 1
1236484800
after: 2009-03-07 23:00:00
------------------------------
before: 2009-11-01 00:00:00
before: tm_isdst = 1
1257048000
after: 2009-11-01 00:00:00

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