#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>

int MAX_LEN=88;			/* 定義讀寫的字節數 */
int main()
{  int fd,i;			/* fd為將要用到的文件描述符 */
   char buf[MAX_LEN],readic[MAX_LEN];
   char *icc_filename[]={"/dev/iccard24c02","/dev/iccard24c04","/dev/iccard24c08",
			"/dev/iccard24c16","/dev/iccard24c32","/dev/iccard24c64"};

   for(i=0;i<MAX_LEN;i++){	/* 給數組賦值 */
     buf[i]=i+33;
   }
   
   i=0;
   while ((fd=open(icc_filename[i],O_RDWR))==-1 ){ /* 打開IC卡設備,如果出錯*/
     if (i++ < 5)continue;
     fprintf(stderr,"Open error %d : no card\n",errno);        /* 打印errno變量的值 */
     exit(1);
   }
 
   printf("Write %d bytes data to %s \n",MAX_LEN,icc_filename[i]);
   if(write(fd,buf,MAX_LEN)==-1){                    
     fprintf(stderr,"Write error %d\n",errno);
     exit(1);
   }
   
   printf("Lseek to 0 \n"); 
   if((lseek(fd,3,SEEK_SET))==-1){           
     fprintf(stderr,"Lseek error %d\n",errno);
     exit(1);
   }
   
   printf("\nRead %d bytes data from %s \n",MAX_LEN,icc_filename[i]);
   if(read(fd,readic,MAX_LEN)==-1){       
     fprintf(stderr,"Read error %d\n",errno);
     exit(1);
   }
   
   if(close(fd)==-1){		/* 關閉IC卡設備 */
     fprintf(stderr,"Close error%d\n",errno);
     exit(1);
   }
   
   for(i=0;i<MAX_LEN;i++){	/* 輸出顯示讀出的數據 */
     if((i%8)==0)
       printf("\n");
     printf("%4c",readic[i]);
   }
   printf("\n");
   
   return 0;			/* 成功返回,程序結束 */
}