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luc111.c

Problem Statement

Receive an 8-bit number. Check if 3rd and 5th bits are OFF. If yes, put them ON.

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: 1 / 10)

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Source Code

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

int main()
{
    unsigned char num;
    unsigned char mask = (1 << 3) | (1 << 5);

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

    // Check if bits are OFF. (num & mask) should be 0.
    if ((num & mask) == 0)
    {
        printf("Bits 3 and 5 are OFF. Turning them ON...\n");
        num = num | mask;
    }
    else
    {
        printf("Bits 3 and 5 are NOT both OFF. No change.\n");
    }

    printf("Final Value: %d (0x%02X)\n", num, num);

    return 0;
}

Explanation

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    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 (luc111.c):

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

    int main()
    {
        unsigned char num;
        unsigned char mask = (1 << 3) | (1 << 5);

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

        // Check if bits are OFF. (num & mask) should be 0.
        if ((num & mask) == 0)
        {
            printf("Bits 3 and 5 are OFF. Turning them ON...\n");
            num = num | mask;
        }
        else
        {
            printf("Bits 3 and 5 are NOT both OFF. No change.\n");
        }

        printf("Final Value: %d (0x%02X)\n", num, num);

        return 0;
    }