如何动态抓取系统时间并以字符串形式保存。

#include <time.h>
#include <stdio.h>
#include <stdlib.h>
#include<string.h>
int
main(int argc, char *argv[])
{
    char outstr[200];
    time_t t;
    struct tm *tmp;
    t = time(NULL);
    tmp = localtime(&t);
    if (tmp == NULL) {
        perror("localtime");
        exit(EXIT_FAILURE);
    }
   strftime(outstr,sizeof(outstr),"%Y:%m:%d",tmp);
 puts(outstr);
strcat(outstr,".xml");
puts(outstr);

} /* main */