Convert binary number to decimal

The variables dec and mult are first initialzed to values 0 and 1 respectively. Then the variable n is divided by 10 and saves the remainder in variable r.The quotient is saved in variable n. The remainder r is multiplied by variable mult and then it added to variable dec.The variable mult is incremented by multiplying it by variable base.This process continous until the varible n is greater than 0.When the variable n decrements to 0 ,the decimal equivalent is stored in variable dec.

#include < stdio.h >
#include < conio.h > 
void main()
	long n,dec,mult,r,base;	
	printf("\n Enter a base : ");
	printf("\n Enter a number :");
	dec = 0;
	printf("\n Decimal equivalent of base %ld number %ld is ",base,n);
	while ( n != 0 )
		r = n % 10;
		n /= 10;
		r = r * mult;
		dec = dec + r;
		mult *= base;
	} // while
} // main