[code]
#include <iostream>
using namespace std;

void sum( int n );

int main()
{
int a, b;
cout << "Enter 2 positive integers a <= b: " << flush;
cin >> a >> b;

int c = b;
int d = a;
int tmp;
for( int n = a; n <= b; n++ )
{
tmp = n - sum(n);
if( tmp < 0 )
tmp = -tmp;
if( tmp <= c )
tmp = c;
d = n;
}
cout << "The distance is minimal for " << d << " and is equal to " << min << endl;

system("pause");
return 0;
}

void sum( int &n )
{
int s = 1;
// if d is a divisor of n so is n/d avoid to search till n
for( int d = 2; d*d <= n; d++ )
if( n%d == 0 )
s += d + n/d;
return s;
}

[\code]
The program is meant to scan an interval [a, b] and return the smallest number that is the closest to its sum of divisors. I've been editing it for ages but still can't see where my mistakes are. Can someone help me please! thanx in advance!

You define

But yet, you use it


Also, you declare it void, yet you return a value from it. If it's going to return a value it must be declared as such.