C :

#include<stdio.h>
int main()
{
int i,j;
for(i=2;i<=1000;i++){
    int sum=0;
    for(j=1;j<i;j++) if(i%j==0) sum=sum+j;
    if(sum==i) printf("%d\n",i);
}
return 0;
}

C++ :

#include <iostream>
using namespace std;

bool isPerfect(int n)
{
	int sum = 1;
	for (int i = 2; i <=n/2;i++)
	{
		if (n%i == 0)
			sum+=i;
	}
	return sum == n;

}

int main()
{	
	for (int i =2; i<=1000; i++)
	{
		if (isPerfect(i))
			cout<<i<<endl;	
	}
    return 0;
}

Java :

public class Main{
    public static void main(String[] args){
        int number,chu;
        int sum = 0;
        for(number = 2;number <= 1000;number++){
            for(chu = 1;chu < number;chu++){
                if(number % chu == 0){
                    sum = sum + chu;
                }
            }
            if(number == sum){
                System.out.println(number);
            }
            sum = 0;
        }
    }
}