C11 日期时间处理案例

所有例子在VS2019上编译运行通过

显示当前日期时间

#include 
#include 
#include 

int main()
{
    const int base = TIME_UTC;
    timespec ts;
    if (timespec_get(&ts, base) != base) {
        perror("timespec_get failure");
        return EXIT_FAILURE;
    }
    tm t;
    localtime_s(&t, &ts.tv_sec);
    char buff[512];
    strftime(buff, sizeof buff, "%Y-%m-%d %H:%M:%S", &t);
    printf("%s.%03d\n", buff, int(ts.tv_nsec / 1000 / 1000));
    return EXIT_SUCCESS;
}

得到当前日期时间的17位数字形式(YYYYmmddHHMMSSsss)

#include 
#include 
#include 
#include 

uint64_t GetNowDTime()
{
    const int base = TIME_UTC;
    timespec ts;
    if (timespec_get(&ts, base) != base) {
        perror("timespec_get failure");
        return 0;
    }
    tm t;
    localtime_s(&t, &ts.tv_sec);
    char buff[512];
    strftime(buff, sizeof buff, "%Y%m%d%H%M%S", &t);
    snprintf(buff, sizeof buff, "%s%03d", buff, ts.tv_nsec / 1000 / 1000);
    return atoll(buff);
}


int main()
{
    printf("localtime: %lld\n", GetNowDTime());
    return EXIT_SUCCESS;
}

从日期时间字符串得到time_t 类型时间戳

#include 
#include 
#include 

time_t GetTimeFromDatetimeStr(const char* const datetimeStr)
{
    tm t;
    int msec = 0.;
    if (sscanf_s(datetimeStr, "%4d-%2d-%2d %2d:%2d:%2d.%3d", &t.tm_year, &t.tm_mon, &t.tm_mday, &t.tm_hour, &t.tm_min, &t.tm_sec, &msec) == EOF) {
        perror("sscanf_s failure");
        return 0;
    }
    t.tm_year -= 1900;
    t.tm_mon -= 1;
    t.tm_isdst = -1;
    return mktime(&t);
}

int main()
{
    time_t tt = GetTimeFromDatetimeStr("2025-05-05 12:13:56.123");
    char buff[128];
    ctime_s(buff, sizeof buff, &tt);
    printf(buff);
    return EXIT_SUCCESS;
}

从时期时间字符串得到毫秒单位的时间戳

#include 
#include 
#include 
#include 

uint64_t GetTimeFromDatetimeStr(const char* const datetimeStr)
{
    tm t;
    int msec = 0.;
    if (sscanf_s(datetimeStr, "%4d/%2d/%2d %2d:%2d:%2d.%3d", &t.tm_year, &t.tm_mon, &t.tm_mday, &t.tm_hour, &t.tm_min, &t.tm_sec, &msec) == EOF) {
        perror("sscanf_s failure");
        return 0;
    }
    t.tm_year -= 1900;
    time_t tt = mktime(&t);
    const uint64_t res = tt * 1000ull + msec;
    return res;
}

int main()
{
    uint64_t timestamp = GetTimeFromDatetimeStr("2025/05/05 12:13:56.123");
    lldiv_t res = lldiv(timestamp, 1000);
    char buff[128];
    ctime_s(buff, sizeof buff, &res.quot);
    printf("%s\n", buff);
    return EXIT_SUCCESS;
}

得到当前日期时间以毫秒为单位的时间戳

#include 
#include 
#include 
#include 

uint64_t CurrTimestamp()
{
    const int base = TIME_UTC;
    timespec ts;
    if (timespec_get(&ts, base) != base)
    {
        perror("timespec_get failure");
        return 0;
    }
    const uint64_t timestamp = (ts.tv_sec * 1000ull) + (ts.tv_nsec / 1000 / 1000);
    return timestamp;
}

int main()
{
    time_t tt = CurrTimestamp() / 1000;
    if (tt == 0)
    {
        return EXIT_FAILURE;
    }
    char buff[128];
    ctime_s(buff, sizeof buff, &tt);
    printf(buff);
    return EXIT_SUCCESS;
}

一个综合案例

X一个17位数字类型的日期时间(YYYYmmddHHMMSSsss)
得到当前日期时间与X的时延,以毫秒为单位

#include 
#include 
#include 
#include 

uint64_t CurrMSecTimestamp()
{
    const int base = TIME_UTC;
    timespec ts;
    if (timespec_get(&ts, base) != base)
    {
        perror("timespec_get failure");
        return 0;
    }
    const uint64_t timestamp = (ts.tv_sec * 1000ull) + (ts.tv_nsec / 1000 / 1000);
    return timestamp;
}

uint64_t DiffFromNumTime(uint64_t dt)
{
    char buff[128];
    snprintf(buff, sizeof buff, "%lld", dt);
    tm t;
    int msec;
    sscanf_s(buff, "%4d%2d%2d%2d%2d%2d%3d", &t.tm_year, &t.tm_mon, &t.tm_mday, &t.tm_hour, &t.tm_min, &t.tm_sec, &msec);
    t.tm_year -= 1900;
    t.tm_mon -= 1;
    t.tm_isdst = -1;
    const time_t tt = mktime(&t);
    if (tt <= 0) {
        perror("mktime error");
        return 0;
    }
    const uint64_t xTimestamp = tt * 1000ull + msec;
    const uint64_t cTimestamp = CurrMSecTimestamp();
    return cTimestamp - xTimestamp;
}

uint64_t GetNowDTime()
{
    const int base = TIME_UTC;
    timespec ts;
    if (timespec_get(&ts, base) != base) {
        perror("timespec_get failure");
        return 0;
    }
    tm t;
    localtime_s(&t, &ts.tv_sec);
    char buff[512];
    strftime(buff, sizeof buff, "%Y%m%d%H%M%S", &t);
    snprintf(buff, sizeof buff, "%s%03d", buff, ts.tv_nsec / 1000 / 1000);
    return atoll(buff);
}

int main()
{
    const uint64_t dt = GetNowDTime();
    const uint64_t d = DiffFromNumTime(dt);
    printf("%lld\n", d);
    return EXIT_SUCCESS;
}