bit_of_a_number_v1.c

/*

    bit_of_a_number_v1.c

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

    C library function pow()
    https://www.tutorialspoint.com/c_standard_library/c_function_pow.htm

    Writing a Custom Power Function
    https://www.edureka.co/blog/power-function-in-c/


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

    https://pastebin.com/u/dmilicev

*/

#include <stdio.h>
#include <math.h>       // required for the math function pow()

// Return base^exponent i.e. x^y. No need for #include <math.h>
int power(int base, int exponent)
{
    int result=1;

    for (exponent; exponent>0; exponent--)
    {
        result = result * base;
    }
    return result;
}

// Returns a bit of number n
/*
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.
*/
int bit_of_a_number(int bit, unsigned n)
{
    //if  ( (n & (int)pow(2,bit)) == 0)     // requires #include <math.h>
    if  ( (n & power(2,bit)) == 0)          // no need for #include <math.h>
        return 0;
    else
        return 1;
}

int main(void)
{
    int i, n;

    for(n=0; n<25; n++)
    {
        printf("\n n = %2d = ", n);

        for(i=7; i>=0; i--)
        {
            printf("%d", bit_of_a_number(i,n));
        }

        printf("\n");
    }

    return 0;

} // main()