text: #include <stdio.h>
  #include <stdlib.h>
  #include <time.h>
  
  int main() {
      time_t uninit;
      time_t now;
      struct tm *timenow;
  
      time(&now);
      printf("%d\n", now);
  
      timenow = localtime(&now);
      printf("local time is %d\t%s\n", now, asctime(timenow));
      // ctime = localtime(asctime(struct tim*));
      printf("ctime %s\n", ctime(&now));
  
      printf("ctime uninit: %s\n", ctime(&uninit));
  
      char buf[40];
      strftime(buf, 40, "%H:%M:%S %Y-%m-%d", timenow);
      printf("strftime: %s\n", buf);
      return 0;
  }
  