`luc112.c`¶

Problem Statement

Rewrite the showbits() function using the _BV macro.

Metadata¶

Property	Detail
Author	Amit Dutta amitdutta4255@gmail.com
Date	08 Feb 2026
License	MIT License (See the LICENSE file for details)
Difficulty	Beginner (index: 2 / 10)

Concepts¶

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Recursion

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Source Code¶

#include <stdio.h>
#include <stdlib.h>

/* _BV(x) macro usually expands to (1 << x) */
#define _BV(x) (1 << x)

void showbits(unsigned char n);

int main()
{
    unsigned char num;

    printf("Enter an 8-bit number: ");
    scanf("%hhu", &num);

    printf("Binary representation: ");
    showbits(num);
    printf("\n");

    return 0;
}

void showbits(unsigned char n)
{
    int i;
    unsigned char mask;

    for (i = 7; i >= 0; i--)
    {
        mask = _BV(i);
        if ((n & mask) == 0)
            printf("0");
        else
            printf("1");
    }
}

Explanation¶

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Copy the prompt below and paste it into any AI assistant.

    You are explaining a C programming code to a beginner.

    STRICT RULES:

    - Only use the given code. Do NOT assume anything not present.

    - Do NOT add extra examples.

    - Keep explanation clear and short.

    - If something is unclear, say "Not clear from code".

    - Follow the exact format below. Do NOT change headings.

    FORMAT:

    [START]

    ## What it does

    (Explain the overall purpose in 1-2 sentences)

    ## Step-by-step

    (Explain how the code works in steps, simple language)

    ## Key Concepts

    (List concepts like loop, condition, function, etc.)

    ## Notes

    (Mention any limitations, errors, or assumptions)

    [END]

    CODE (luc112.c):

    #include <stdio.h>
    #include <stdlib.h>

    /* _BV(x) macro usually expands to (1 << x) */
    #define _BV(x) (1 << x)

    void showbits(unsigned char n);

    int main()
    {
        unsigned char num;

        printf("Enter an 8-bit number: ");
        scanf("%hhu", &num);

        printf("Binary representation: ");
        showbits(num);
        printf("\n");

        return 0;
    }

    void showbits(unsigned char n)
    {
        int i;
        unsigned char mask;

        for (i = 7; i >= 0; i--)
        {
            mask = _BV(i);
            if ((n & mask) == 0)
                printf("0");
            else
                printf("1");
        }
    }

luc112.c¶