学步园

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <string.h>
#include <unistd.h>

#define STRSIZE 1024

int main(int argc,char *argv[])
{
 FILE *fp = stdout;
 time_t stamp;
 time_t stamp1;
 struct tm *tm;
 char timestr[STRSIZE],fmt[STRSIZE];
 int c;
 
 fmt[0] = '\0';

 stamp = time(NULL);
 tm = localtime(&stamp);

 while(1)
 {
  c = getopt(argc,argv,"-H:MSy:md");
  if(c < 0)
   break;
  switch(c)
  {
   case 1:
    if(fp == stdout)
    {
     fp = fopen(argv[optind-1],"w"); 
     if(fp == NULL)
     {
      perror("fopen");
      fp = stdout;
     }
    }
    break;

   case 'H':
    if(strcmp(optarg,"12") == 0)
     strncat(fmt,"%I(%P) ",STRSIZE);
    else if(strcmp(optarg,"24") == 0)
      strncat(fmt,"%H ",STRSIZE);
      else
      fprintf(stderr,"Invalid argument of -H\n");

    break;
   
   case 'M':
    strncat(fmt,"%M ",STRSIZE);
    break;
   
   case 'S':
    strncat(fmt,"%S ",STRSIZE);
    break;
   
   case 'y':
    if(strcmp(optarg,"2") == 0)
                    strncat(fmt,"%y ",STRSIZE);
                else if(strcmp(optarg,"4") == 0)
                        strncat(fmt,"%Y ",STRSIZE);
                     else
                        fprintf(stderr,"Invalid argument of -y\n");

    break;
   
   case 'm':
    strncat(fmt,"%m ",STRSIZE);
    break;
   
   case 'd':
    strncat(fmt,"%d ",STRSIZE);
    break;
   
   default:
    break;
  }
 }

 strncat(fmt,"\n",STRSIZE);
 strftime(timestr,STRSIZE,fmt,tm);
 fputs(timestr,fp);

 exit(0);
}