Printing perfect numbers

[DRBILOUKOS]

Hello,
these are my first steps in C.
I need some help in the following code:

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

main()
{
     int n,i,j,t;
     printf("Enter N:");
     scanf("%d", &n);
     i=2;

     while(i<=n)
     {
     j=2;
                    while(j<=i)
                    {
                               if(i%j==0) 
                               {
                                        t=i/j;
                                        printf("%d ",t);
                               }
                               j++;     
                    }              
     i++;
     }
     system("pause");
     return 0;
}

So far my vars are as:

i j i%j i/j sum group by i
2 2 0 1 1
3 2 1
3 3 0 1
4 2 0 2 3
4 3
4 4 0 1
5 2 1
5 3
5 4
5 5 0 1
6 2 0 3 6
6 3 0 2
6 4
6 5
6 6 0 1


I have manage to display i/j, but I cant make it work for the last column, to add the result of the division where the mod is 0 grouped by i counter.

Any help will be much apreciated.

[tabstop]

So, is that the output you want, or the output you are getting? I can't see really why sometimes you have five numbers, sometimes four, sometimes three, and sometimes two.

[DRBILOUKOS]

Hello,
Sorry I forgot to mention:
The output is when I run the program for n:6
the final output should be:

1


3

1



1
6

[quzah]

I'd use for loops here. I still don't know what it is you're trying to do, but I'd do it this way:

main()
{
     int n,i,j,t;
     printf("Enter N:");
     scanf("%d", &n);
     i=2;

     for( j = 2; i <= n; j++ )
     {
          for( /* why are you only ever setting i once? */ ; j <= i; j++ )
          {
               if(i%j==0) 
               {
                    t=i/j;
                    printf("%d ",t);
               }
          }              
     }
     system("pause");
     return 0;
}

You still probably want to be setting i to something in that inner loop. I guess. I don't know. You also may want to actually add a check there in that if to make sure j isn't zero.

Quzah.

[DRBILOUKOS]

Hello again I am trying to print the perfect numbers from 1 - 6
6 is a perfect number:
6/6+6/3+6/2=6 (do not divide with 6)
28 is perfet: 1+2+4+7+17=28
......
PS . this is not a a school asignment.

[laserlight]

What have you tried?

[anduril462]

This thread is a duplicate of: http://cboard.cprogramming.com/c-pro...loop-help.html.

[whiteflags]

1+2+4+7+17 = 31 by the way

[anduril462]

This thread is a duplicate of: http://cboard.cprogramming.com/c-pro...loop-help.html.

Woah! Was I hallucinating when I wrote this or did somebody modify the Loop Help thread?

[DRBILOUKOS]

How did this happened ? I replied to my original thread :-S
Maybe an admin splited my post ?

Anyway

[anduril462]

Anyhow, on to business, the idea is that, for some number n, you run through all the numbers from 1 to n/2, and if n is divisible by that number, then add it to sum. Once you've reached the end of that loop, if the sum equals the number, then it's a perfect number. This should involve 1 for loop for any given n. Use the modulo (%) operator to test divisibility. Hope that gets you going in the right direction.

[DRBILOUKOS]

OK figured it out:

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

main()
{
     int n,i,j,t;
     printf("Enter N:");
     scanf("%d", &n);
     i=2;

     while(i<=n)
     {
     j=2;
     t=0;
                    while(j<=i)
                    {
                               if(i%j==0) 
                               {
                                        t=t+i/j;
                                        
                               }
                               j++;     
                    }
                    if(t==i)
                            {
                            printf("%d ",t);
                            }              
     i++;
     }
     system("pause");
     return 0;
}

It will print all perfect numbers from 1 to N :-)
Thank you all people.

[laserlight]

*magically merges threads back together again*

It would be easier to read if you wrote it as:

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

int main()
{
    int n, i, j, t;
    printf("Enter N:");
    scanf("%d", &n);

    for (i = 2; i <= n; i++)
    {
        t = 0;
        for (j = 2; j <= i; j++)
        {
            if (i % j == 0)
            {
                t += i / j;
            }
        }

        if (t == i)
        {
            printf("%d ", t);
        }
    }

    system("pause");
    return 0;
}