How to find the proper divisor?

This is a discussion on How to find the proper divisor? within the C Programming forums, part of the General Programming Boards category; The problems says "a program will find the sum of the proper divisors of a give number n. The proper ...

  1. #1
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    How to find the proper divisor?

    The problems says "a program will find the sum of the proper divisors of a give number n. The proper divisors on n are the numbers less than n that divides it evenly, they do not include n itself." I have no idea for this program, which function should i use?

  2. #2
    Registered User stormbringer's Avatar
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    use modulo

    Code:
    if ((x % y) == 0)
        is divisor
    else
       ain't

  3. #3
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    Just loop from Div = N - 1 to 1 and check if that N % Div is zero. If it is then print Div. Feel free to use my code as an example, but you aren't allowed to use it for any educational credits.
    Code:
    /* (c) Copyright 2002 Daniel Raxter, All Rights Reserved. */
    #include <stdio.h>
    #include <stdlib.h>
    
    void ListProperDivs (int N)
    {
      int Div = N;
    
      while (--Div > 0){
        if ((N % Div) == 0)
          printf ("%d ", Div);
      }
    }
    
    int main (void)
    {
      int N;
    
      printf ("Enter a number: ");
      if (scanf ("%d", &N) != 1){
        fprintf (stderr, "Bad Input\n");
        exit (EXIT_FAILURE);
      }
      /* Okay so far */
      ListProperDivs (N);
    
      return (EXIT_SUCCESS);
    }

  4. #4
    Green Member Cshot's Avatar
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    And you can loop through 1...n/2, since anything greater than n/2 is not possible.

    Also the code above does not find the sum. But you can implement that easily.
    Last edited by Cshot; 07-24-2002 at 10:28 AM.

  5. #5
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    Oops, that should teach me to read threads more carefully. But as Cshot said, it's a trivial change so I won't repost the code.

  6. #6
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    I don't need anyone to coding for me. i need idea of this program

  7. #7
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    Code:
    #include <stdio.h>
    #include <stdlib.h>
    
    void List (int N);
    int N = 0;
    void main (void)
    {
      while (N < 40)
      {
        N++;
        printf("\n%d = ", N);
        List (N);
      }
    
    }
    
    void List (int N)
    {
      int Div = N;
    
      while (--Div > 0){
        if ((N % Div)== 1 )
          printf ("%d ", Div);
      }
    }

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