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  1. #1
    Join Date
    Feb 2022
    Posts
    29

    New with C programming, question about a loop situation

    Hi all,

    I'm new to the C language, trying to do an exercice where I have to print the "fifth" bit of a given number (0 to 255).The condition of this exercice is to not use operators of affectation (such as >>x or <<x, etc.).

    I need to do it with modulo and divisions.

    I'm really blocked, tried many things, also searched for solutions on the web, but no success so far. If anyone could
    guide threw, I would be thankful as heck.

    Pasting my poorly written code, then I will do a comment as what is my idea behind this.

    int main(void)

    {

    int number_user;
    int bit;
    int i;

    printf("Please put an integer between 0 and 255: ");
    scanf("%d", &number_user);


    i = 0;

    while (i <= 4)

    {

    number_user /= 2;
    i++;
    }

    bit = number_user % 2;


    printf ("your fifth bit is %d: \\n", bit);

    return EXIT_SUCCESS;
    }

  2. #2
    Join Date
    Feb 2017
    Posts
    661

    Re: New with C programming, question about a loop situation

    You have not explained what is wrong, but your code effectively shifts the input integer five times to the right and then extracts the rightmost bit. For example, given input 32, which has a binary representation of 100000, the code will return a 1. Whether you call this bit the fifth or the sixth depends on whether you call the rightmost bit the zeroeth or the first.

  3. #3
    2kaud's Avatar
    2kaud is offline Super Moderator Power Poster
    Join Date
    Dec 2012
    Location
    England
    Posts
    7,661

    Re: New with C programming, question about a loop situation

    Code:
    #include <stdio.h>
    
    int main() {
    	for (unsigned i = 0; i < 255; ++i)
    		printf("The fifth bit of %u is %u\n", i, (i / 16) % 2);
    		//printf("The fifth bit of %u is %u\n", i, (i >> 4) & 1);	// Using bits (1)
    		//printf("The fifth bit of %u is %u\n", i, (i & 16) == 16);	// Using bits (2)
    }
    Last edited by 2kaud; August 14th, 2022 at 10:57 AM.
    All advice is offered in good faith only. All my code is tested (unless stated explicitly otherwise) with the latest version of Microsoft Visual Studio (using the supported features of the latest standard) and is offered as examples only - not as production quality. I cannot offer advice regarding any other c/c++ compiler/IDE or incompatibilities with VS. You are ultimately responsible for the effects of your programs and the integrity of the machines they run on. Anything I post, code snippets, advice, etc is licensed as Public Domain https://creativecommons.org/publicdomain/zero/1.0/ and can be used without reference or acknowledgement. Also note that I only provide advice and guidance via the forums - and not via private messages!

    C++23 Compiler: Microsoft VS2022 (17.3.4)

  4. #4
    Join Date
    Feb 2022
    Posts
    29

    Re: New with C programming, question about a loop situation

    @wolle thank you so much for your response and suggestion

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