try this:

int n = 3;
int[] array = new int[n];
for(int i = 0;i< Math.Pow(10,n); i++)
{
int value = i;
for(int j = n - 1;j>= 0;j--)
{
int help = value / (int)Math.Pow(1 0,j);
array[j] = help;
value -= help * (int)Math.Pow(1 0,j)
Console.Write(a rray[j] + " ");
}
Console.WriteLi ne();
}