Question

C Programming

Write a C program that asks the user for a positive number n (n ≥ 1) then, the program displays all the perfect numbers up to (including) n. A number n is said to be a perfect number if the sum of all its positive divisors (excluding itself) equals n. For example, the divisors of 6 (excluding 6 itself) are 1,2 and 3, and their sum equals 6, thus, 6 is a perfect number. Display the numbers with a space separation and finish with a newline, as usual.

Answer 1

#include <stdio.h>

int main()
{
int n,j;
long long int s,i;
printf("Enter a positive number: ");
scanf("%d",&n);
  
if(n>=1){

for(j=2;j<=n;j++){
s=1;
for(i=2;i*i<j;i++)
{
if(j%i==0){
if(i*i!=n)
s=s+i+j/i;
else
s=s+i;
}
  
}
  
if(s==j && j!=1)
printf("%d ",j);
}
  
  
}

else
printf("Not a positive integer");
  
printf("\n");

return 0;
}