C > Beginners Lab Assignments

Program to display the decimal equivalent of an input hexadecimal number

Program to display the decimal equivalent of an input hexadecimal number
(Hexadecimal to Decimal)

#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#include <math.h>
void htod(char b[]);
int c;
void main()
{

 char a[3];
 int j;
 clrscr();
 printf("How many digits in input?  ");
 scanf("%d",&c);
 printf("
Digits of your i/p no. must not exceed entered limit or 3(max).");
 printf("
Enter a hexadecimal no.");
 printf("
No. will be accepted if you press ENTER after inputting no.");
 printf("
NUMBER:-  ");
 scanf("%s",a);
 htod (a);
 getch();
 }

  void htod(char b[])
  {
  int i,e,n,k=0,t=0,s=0;
  n=*b;
  for (i=c-1;i>=0;--i)
  { e =(c-1)-i;
	if (i>0)
	 *b=*(b+i);
	else
	 *b=n;
   k = pow(16,e);
   if (*b =='1')
   {
	t=1*k;
	s=s+t;
   }
   else if (*b=='2')
   {
	t=2*k;
	s=s+t;
   }
   else if (*b=='3')
   {
	t=3*k;
	s=s+t;
   }
   else if (*b=='4')
   {
	t=4*k;
	s=s+t;
   }
   else if (*b=='5')
   {
	t=5*k;
	s=s+t;
   }
   else if (*b=='6')
   {
	t=6*k;
	s=s+t;
   }
   else if (*b=='7')
   {
	t=7*k;
	s=s+t;
   }
   else if (*b=='8')
   {
	t=8*k;
	s=s+t;
   }
   else if (*b=='9')
   {
	t=9*k;
	s=s+t;
   }
   else if (*b=='a'||*b=='A')
   {
	t=10*k;
	s=s+t;
   }
   else if (*b=='b'||*b=='B')
   {
	t=11*k;
	s=s+t;
   }
   else if (*b=='c'||*b=='C')
   {
	t=12*k;
	s=s+t;
   }
   else if (*b=='d'||*b=='D')
   {
	t=13*k;
	s=s+t;
   }
   else if (*b=='e'||*b=='E')
   {
	t=14*k;
	s=s+t;
   }
   else if (*b=='f'||*b=='F')
   {
	t=15*k;
	s=s+t;
   }
   else if (*b=='0')
   {
	t=0;
	s=s+t;
   }
   else
   {
	printf("
ERROR");
	getch();
	exit(0);
   }
  }
  printf("
Its decimal equivalent is %d.",s);

  return;
 }