1. gettimeofday(Linux和MacOS支持) ```c

   include

// prototypes: // int gettimeofday (struct timeval restrict tv, void restrict tz)

uint64_t msSinceEpoch() { struct timeval tv; gettimeofday(&tv, NULL); return tv.tv_sec * 1000 + tv.tv_usec / 1000; }

2. time(NULL) c标准
```c
#include <time.h>
// prototypes:
//  time_t time (time_t *__timer) 
void test() {
    time_t t = time(NULL);
    time_t t2;
    time(&t2);
}