C program to Find binary to decimal and vise versa

SOURCE CODE:
#include<stdio.h>
#include<conio.h>
void main()
{
 long int i,a,b,n=1,sum=0;
 clrscr();
 printf("Enter binary no.");
 scanf("%ld",&i);
 while(i>0)
 {

  a=i%10;
  b=a*n;
  sum=sum+b;
  i=i/10;
  n=n*2;
 }
 printf("\ndecimal is %ld",sum);
 sum=0;
 n=1;
 printf("\n\nEnter decimal no.");
 scanf("%ld",&i);
 while(i>0)
 {
  b=i%2;
  i=i/2;
  sum=sum+b*n;
  n=n*10;
 }
 printf("\nbinary is %ld",sum);
 getch();
}