timeval 转换为年月日

#include <stdio.h>
#include <stdlib.h>
#include <sys/time.h>
#include <time.h>
char time_string[40];
char *getLocalTime(char *timeStr, int len, struct timeval tv )
{
struct tm *ptm;
// char time_string[40];
    long milliseconds;
 ptm = localtime (&(tv.tv_sec));
 strftime(time_string,len, "%Y-%m-%d %H-%M-%S", ptm );
 milliseconds = tv.tv_usec/1000;
 sprintf(timeStr, "%s.%03ld", time_string,milliseconds );
return time_string;
}
int main(int argc, const char **argv)
{
    char local_time_str[128];
    char *p = NULL;
    struct timeval tv;
    gettimeofday(&tv, NULL);
    p = getLocalTime(local_time_str, sizeof(local_time_str), tv);
    printf("Get local time: \n%s\n", local_time_str);
    return 0;
}