the == checks if it’s identical.
So this is what you are trying to do ?
if (UsedLocations.Find(Your_int_index_variable) == -1)
{
//Some code
}
But What is used locations, another Ftransform as I see. You have to convert also Ftransform UsedLocations to int indexes.
So …
if (Int array data that you converted.Find(Your_int_index_variable) == -1)
You may want to get indexes then store them to int type of array and then compare not with int variable but with the int array that you stored the indexes into.
Get indexes out of your Ftransforms both of them
Crete int arrays and store the indexes inside of them that you got from vectors
Use the arrays to compare with ==
As I see you are using the arrays to compare them not some simple index variable that contains one value maybe, so the array has the whole list.