binary_representation_of_a_number_v1.c

/*

    binary_representation_of_a_number_v1.c

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


    You can find all my C programs at Dragan Milicev's pastebin:

    https://pastebin.com/u/dmilicev

*/

#include <stdio.h>

// Representation of a given number, iterative method
/*
How to check whether its i-th bit is 0(OFF) or 1(ON) by
bitwise ANDing it with “2^i” (2 raise to i).
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 == bit 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 == bit means its 5th bit is ON else 5th bit is OFF.
*/
void bin_iterative(unsigned n)
{
    unsigned i, k=0;

    for (i=1<<31; i>0; i=i/2)
    {
        if(k>7)
        {
            printf(" ");
            k=0;
        }
        k++;

        //(n & i) ? printf("1") : printf("0");
        if(n & i)
            printf("1");
        else
            printf("0");
    }
}

// Representation of a given number, recursive
/*
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.
*/
void bin_recursive(unsigned n)
{
    if (n > 1)              // step 1
        bin_recursive(n/2);

    printf("%d", n%2);      // step 2
}

// Representation of a given number, recursive using bitwise operator
/*
step 1: Check n > 0
step 2: Right shift the number by 1 bit and recursive function call
step 3: Print the bits of number
*/
void bin_recursive_using_bitwise_operator(unsigned n)
{
    if (n > 1)
        bin_recursive_using_bitwise_operator(n>>1);

    printf("%d", n&1);
}


int main(void)
{
    int i;

    for(i=0; i<20; i++)
    {
        printf("\n %2d = ", i);
        //bin_iterative(i);
        //bin_recursive(i);
        bin_recursive_using_bitwise_operator(i);
    }

    return 0;

} // main()