boolean variable being returned by UDF is not recognized by stock Excel OR function

Question

Alright, I have written a UDF, which searches a given cell for a specific sub-string. It then returns TRUE is the sub-string is found in the cell, and FALSE if it is not found.

Here is the code for the UDF (named the contains function)

Function contains(substring As String, testString As String) As String
'testString = cell to be tested for substring
Dim result As Boolean
result = False
testString = UCase(testString)
substring = UCase(substring)

For i = 1 To Len(testString)
If Mid(testString, i, Len(substring)) = substring Then result = True
Next

contains = result

End Function

The reason I created this function is so that I can nest it within stock Excel functions, mainly IF functions, AND functionS, and OR functions.

However, when I use it with an OR function, the OR function does not seem to "recognize" the result of the =contains function.

Here is a screenshot of the issue within Excel:

EDIT Here is what the =contains function is doing in the above pic =contains("Hello",A2)

Obviously, since the =Contains function in column C is returning True, then the OR function in column D should be returning True as well. But for some reason it is as if the stock Excel OR function doesn't recognize the result of my contains function.

Answer 1

Make the function return a boolean:

Function contains(substring As String, testString As String) As boolean

Not sure why you are looping as you are, you can just use:

contains = InStr(1, testString, substring, vbTextCompare) > 0