/*案例代碼文件名：AL4_3.C。*/
/*功能：說明if語句的嵌套格式和用法。*/
main()
{ int year,leap=0;			/* leap=0：預置為非閏年*/
  printf("Please input the year:");
  scanf("%d",&year);
  if (year % 4==0)
     {if (year % 100 != 0) leap=1;}
  else
     {if (year%400==0) leap=1; }
  if (leap) 
     printf("%d is a leap year.\n",year);
  else
     printf("%d is not a leap year.\n",year);
}