public static int SearchFreeID(string articleMode, ObservableRangeCollection<ArticleProperty> aPropList)
{
int minusOne;
if (articleMode == "Outlay")
minusOne = -1;
else minusOne = 1;
int id;
for (int i = 1; ; i++)
{
try
{
id = ((int)aPropList.LongCount() + i) * minusOne;
}
catch (ArgumentNullException)
{
return 1 * minusOne;
}
if ((int)aPropList.LongCount() == 0)
return 1 * minusOne;
for (int n = 0; n < (int)aPropList.LongCount(); n++)
{
if (aPropList[n].ID == id)
break;
if (n == (int)aPropList.LongCount() - 1)
return id;
}
}
}