c++中怎么将unix时间戳转换为标准时间，有函数吗

#include <stdio.h>
#include <time.h>

int main(void)
{
        time_t tick;
        struct tm tm;
        char s[100];

        tick = time(NULL);
        tm = *localtime(&tick);
        strftime(s, sizeof(s), "%Y-%m-%d %H:%M:%S", &tm);
        printf("%d: %s\n", (int)tick, s);

        return 0;
}