/*Program for determining the decimal equivalent of a given 4-bit binary
  number*/
/*Author : Shekhar*/
main()
{
 int a,b,c,d,e,f,g,h,x;
 clrscr();
 x=100;
 while(x!=0)
 {
  clrscr();
  printf("\n\t\tThis program will help you to find the decimal equivalent");
  printf("\n\t\t            of a given 4-bit binary number.\n");
  printf("\n\t\tNote that the entered binary number should strictly be an");
  printf("\n\t\t        integer and should be exactly of Four Bits.");
  printf("\n\n\t\t     Type 0 to Exit and 1 to continue the program :- ");
  scanf("%d",&x);
  switch(x)
  {
   case 0:clrscr();
	  printf("\n\n\n\n\n\n\n\t\t\t\tPROGRAM TERMINATED !");
	  printf("\n\n\n\t\t\tPress any key to return to object file...");
	  getch();
	  break;
   case 1:printf("\n\n\t\t       Enter the Four-Bit Integer Binary Number:");
	  scanf("%d",&a);
	  b=a%10;
	  c=a/10;
	  d=c%10;
	  e=c/10;
	  f=e%10;
	  g=e/10;
	  h=(b*1)+(d*2)+(f*4)+(g*8);
	  if((b<0)||(b>1)||(d<0)||(d>1)||(f<0)||(f>1)||(g<0)||(g>1))
	  {
	   clrscr();
	   printf("\n\n\n\n\n\n\n\n\t\t\t\t  INVALID INPUT !");
	   printf("\n\n\n\n\t\t\t  THE NUMBER IS EITHER NOT BINARY ");
	   printf("\n\n\t\t\t       OR EXEEDS FOUR BITS !");
   	   getch();
	   break;
	  }
	  else
	  {
	   printf("\n\n\n\t\t\t\t\tA N S W E R");
	   printf("\n\n\t\t\tThe decimal equivalent of the number is %d.",h);
	   printf("\n\n\t\t\t\tPress any key to continue...");
	  }
	  getch();
	  break;
   default:clrscr();
	   printf("\n\n\n\n\n\n\n\t\t\t\tINVALID INPUT !");
	   printf("\n\n\n\t\t\t  Press any key to continue...");
	   getch();
	   break;
  }
 }
}