程序代码：

#include<stdio.h>
#include<conio.h>
#include<windows.h>

struct time
{
    int hour;
    int minute;
    int second;
}t;

int main(int argc,char *argv[])
{
    FILE *fp;
    fp=fopen("Time","r");
    fread(&t,sizeof(struct time),1,fp);
    while(!kbhit())
    {
        rewind(fp);
         Sleep(1);
        fread(&t,sizeof(struct time),1,fp);
        if(t.second==59)
        {
            if(t.minute==60)
            {
                t.hour=t.hour+1;
                t.minute=0;
            }
            t.second=0;
        }
        else
            t.second=t.second+1;
        printf("%d:%d:%d\n",t.hour,t.minute,t.second);
        fp=fopen("Time","w");
        fwrite(&t,sizeof(struct time),1,fp);
        fclose(fp);
    }
    return 0;
}