Displaying the rightmost digit of a positive number

This is a discussion on Displaying the rightmost digit of a positive number within the C Programming forums, part of the General Programming Boards category; Hi all, I recently received the following programming assignment and am a little stumped. The question is as follows: "Write ...

  1. #1
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    Question Displaying the rightmost digit of a positive number

    Hi all,

    I recently received the following programming assignment and am a little stumped. The question is as follows:

    "Write a program to take a non-negative integer and display its rightmost (least significant) digit, and the number with its rightmost digit zeroed.

    Example input/output:

    Please enter a non-negative integer >> 128
    Right-most digit = 8
    Number with right-most digit zeroed = 120

    Hint: Consider using the following operators: / and % (divide and modulus)"

    As for the first part, displaying the rightmost digit, I have no idea how to approach it so if anyone could simply start me off that'd be great.

    To display the number with its rightmost digit zeroed I know how to do it if the user enters a number already zeroed eg 130 but I do not know how to change say 135 to 130. The only piece of code I have so far is as follows(and is only a rough draft):

    Code:
    #include <stdio.h>
    
    int main (void)
    {
    	int pos_num, num_zeroed = 0;
    	printf("Please enter a positive integer:");
    
    	scanf("%d", &pos_num);
    	if (pos_num >= 0) 
    	{
    		if (pos_num % 10 == 0)
    		{
    			num_zeroed = pos_num;
    			printf("The number zeroed is %d\n", num_zeroed);
    		}
    
    	}
    	else 
    		printf("Number entered must be a positive integer\n");
    		printf("please enter a positive integer:");
    }
    Thanks in advance for your help

  2. #2
    and the Hat of Guessing tabstop's Avatar
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    Hint: Consider using %.

  3. #3
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    Then perhaps you should take some time out to brush up on basic math skills before diving into programming.

  4. #4
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    I second the suggestion that you brush up on some basic arithmetic. I would also second the suggestion you look into modulus. Here's a very suggestive hint:

    122 mod 10 = 2

  5. #5
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    Yep I get it thanks. Also how to zero the number:
    Code:
    if (x % 10 == 0)//if number is evenly divisible by ten the right most digit is already 0
    			{
    				num_zeroed = x;
    				printf("The number zeroed is %d\n", num_zeroed);
    			}
    
    			else 
    			{
    				num_zeroed = x - x%10;
    				printf("The number zeroed is %d\n", num_zeroed);
    			}

  6. #6
    ATH0 quzah's Avatar
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    More basic math. What happens when you divide by ten and then multiply by ten?


    Quzah.
    Hope is the first step on the road to disappointment.

  7. #7
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    It'll give me the same result as the code above.
    The code above works fine as far as I can tell.

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