perfect number program in c

perfect number program in c

This program takes an input value from the user and checks a number is a perfect number or not. A perfect number is a positive number which is equal to the sum of all its divisors excluding itself. For example: 28 is a perfect number as 1 + 2 + 4 + 7 + 14 = 28.

#include <stdio.h>
int main()
{
  int n,i,sum=0;
  printf("\nEnter a value: ");
  scanf("%d",&n);
  for(i=1; i<=n/2; i++)
  {
    if(n%i==0)
     sum+=i;   //sum=sum+i;
  }
  if(n==sum&&n!=0)
   printf("\n%d IS PERFECT NUMBER",n);
  else
   printf("\n%d IS NOT PERFECT NUMBER",n);
  return 0;
}

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Output:

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Find perfect numbers within a range

This program takes two input values from user and print all perfect numbers between the range of those values

#include <stdio.h>
int main()
{
  int n,n1,n2,i,sum,count=0;
  printf("\nEnter a value: ");
  scanf("%d%d",&n1,&n2);
  for(n=n1; n<=n2; n++)
  {
    sum=0;
    for(i=1; i<=n/2; i++)
    {
      if(n%i==0)
  sum+=i;
    }
    if(n==sum)
      printf("\n%d.PERFECT NO:%d",++count,n);
    if(count==4)
     break;
  }
  return 0;
}

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Output:

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