Array element not in other array

[NedNiederlaender]

Hello,

I have a problem getting a grip on the following task:

I have two one-dimensional arrays, filled with strings, $a1 and $a2, round about 35000 elements each.

Now I need to find all elements that are in $a1 but not in $a2...

I created a small script running through $a1 and then using the _ArraySearch function from the standard UDF, but it is fairly slow (~ 35 minutes on my desktop).

Do you see a more clever way to complete this taks?

Thanks a lot for your Input,

Ned

[BrewManNH]

Sort the array you're searching and then use _ArrayBinarySearch which is much much faster.

[NedNiederlaender]

Hello BrewManNH,

wo, that is very impressive, the same procedure went down to 15 seconds. That's fast enough then ;-)

Thanks a lot!

Ned

[BrewManNH]

If you need to keep the arrays in their original order, meaning you don't want to sort them, you can copy the array to be searched to a new temporary array, sort that one, then empty it after you're done with it to recover the memory used.

$TempArray = $a1 ; copies the $a1 array into the $TempArray
_ArraySort($TempArray) ; sorts the temp array
; do your searching
$TempArray = "" ; empty the temp array