Missing From ArrayAfter using the Are Arrays Equal function in LotusScript for a while, a comment came from one of our developers: "This is good and all, but how do I know what is different about the two arrays?" The other function simply exits when finding a difference. So it makes sense to just keep track of the differences and then return those differences somehow. But there's two types of differences:
- Elements that exist in array 1 but not array 2
- Elements that exist in array 2 but not array 1
The function takes it code from the Are Arrays Equal function, and slightly modifies it. It also only needs to go though once, since we don't care if all the elements in array 1 are in array 2 (we're only checking the one way). It also doesn't exit once a difference is found. Instead, that difference is placed into the array to be returned.
Function MissingFromArray(baselineArray As Variant, compareArray As Variant) As Variant
Dim i As Integer
Dim key As String
Dim tempList List As Integer
Dim results As Variant
Dim x As Integer
If Not Isarray(baselineArray) Or Not Isarray(compareArray) Then
MissingFromArray = "BOTH PARAMETERS MUST BE ARRAYS"
This code first makes sure that both parameters are arrays. This is something that is necessary for a reusable function.
For i = Lbound(baselineArray) To Ubound(baselineArray)
key = Typename(baselineArray(i)) & "~" & Cstr(baselineArray(i))
If Iselement(tempList(key)) Then
tempList(key) = tempList(key) + 1
tempList(key) = 1
Build a list containing the data type of the element (so we can differentiate between the number 1 and the string "1") followed by the value. For elements that are duplicated, keep track of the number of appearances of the value. This list is then used to compare to the second array.
For i = Lbound(compareArray) To Ubound(compareArray)
key = Typename(compareArray(i)) & "~" & Cstr(compareArray(i))
If Not Iselement(tempList(key)) Then
If Not Isarray(results) Then
Redim results(1) As String
x = Lbound(results)
x = Ubound(results)+1
Redim Preserve results(x)
results(x) = Cstr(compareArray(i))
tempList(key) = tempList(key) - 1
If tempList(key) = 0 Then Erase tempList(key)
MissingFromArray = results
Go through the second array. If the value is a match for something in the first array, remove it from the list built from the first array. (If the element is in the first array multiple times, just subtract 1 from the value). If the value is not in the first array, then add it to the results array. Note that the code above is converting everything to strings for the results array. If you truly want the values, then the line:
Redim results(1) As String
Redim results(1) As Variant
and when keeping the results, don't convert it to string. The line should instead be:
results(x) = compareArray(i)
We chose to convert everything to strings because this function is going to be used most often to report on the differences betwen arrays.
At the bottom of the function, the variable results either has never been defined (never been redimmed) if there were no differences or it's an array. If it's never been redimmed, then Variant variables by default get an empty string value, so an empty string will be returned. If an array is returned, then the array holds the elements in array 2 that are absent from array 1.