I found a normal loop to do so!
<pre lang="cs">private void setPos()
{
recBom Bom;
int position = 0;
for (int level = 1; level < 10; level++)
{
for (int i = 0; i < arrBom.Count; i++)
{
Bom = arrBom[i];
if (Bom.Level > level) continue;
if (Bom.Level == level)
{
position += 10;
Bom.Position = position.ToString();
}
else
{
position = 0;
}
}
}