Binary representation of a given number

reference: 

http://www.geeksforgeeks.org/binary-representation-of-a-given-number/

Problem Definition:

Write a program to print Binary representation of a given number.

Solution:

This is a simple problem, the reason why it is posted here is because it was a MS Interview question. Obviously, we can do it both in iterative and recursive way.

Iterative way: 

1) Let us take number 'NUM' and we want to check whether it's 0th bit is ON or OFF	
	bit = 2 ^ 0 (0th bit)
	if  NUM & bit == 1 means 0th bit is ON else 0th bit is OFF

2) Similarly if we want to check whether 5th bit is ON or OFF	
	bit = 2 ^ 5 (5th bit)
	if NUM & bit == 1 means its 5th bit is ON else 5th bit is OFF.

Recursive way: 

step 1) if NUM > 1
	a) push NUM on stack
	b) recursively call function with 'NUM / 2'
step 2)
	a) pop NUM from stack, divide it by 2 and print it's remainder.

Code:

Iterative code:

void bin(unsigned n)
{
    unsigned i;
    for (i = 1 << 31; i > 0; i = i / 2)
        (n & i)? printf("1"): printf("0");
}

recursive code:

void bin(unsigned n)
{
    /* step 1 */
    if (n > 1)
        bin(n/2);
 
    /* step 2 */
    printf("%d", n % 2);
}