Custom lookup using search in VBA - excel

Question

I am not sure, how to fix this function.
if Isnumber(search) is true, then get value from lookup_table
after 2nd round, it ends
Image of excel data
Function Slookup(lookup_value As String, lookup_table As Range) As String
Dim i As Integer
On Error GoTo Err
Dim valuetxt As Boolean
Dim cc As Integer
cc = lookup_table.Rows.Count
For i = 1 To cc
valuetxt = IsError(Application.WorksheetFunction.Search(lookup_table.Cells(i, 1), lookup_value))
If Not valuetxt Then
Slookup = lookup_table.Cells(i, 2)
Exit Function
End If
Slookup = ExcelError.ExcelErrorNA
Err:
Next i
End Function

Answer 1

Tim Williams is correct in noting that IsError() cannot trap a run-time error (1004). So, your IsError() isn't doing much, except providing the necessary False for If Not valuetxt Then when there is no error.
The real problem lies with the fact that your error handler stays within the loop. On Error GoTo Err will not be triggered once you are already inside Err:. The code fails at the third example, because it is the second time you run into an error.
I.e. in your third example, you'll get an error at
IsError(Application.WorksheetFunction.Search("A", "E G F")) and are moved to Err:. However, you're not exiting the loop, so now you'll get another error at IsError(Application.WorksheetFunction.Search("B", "E G F")) and the thing breaks down. (So, your second example actually also encountered an error, but it never encountered another.)
You can fix this as follows:
Function SlookupAdj(lookup_value As String, lookup_table As Range) As String
Dim i As Integer
Dim valuetxt As Boolean
Dim cc As Integer
cc = lookup_table.Rows.Count
For i = 1 To cc
On Error Resume Next
valuetxt = IsError(Application.WorksheetFunction.Search(lookup_table.Cells(i, 1), lookup_value))
If Err Then
Err.Clear
Else
If Not valuetxt Then
SlookupAdj = lookup_table.Cells(i, 2)
Exit Function
End If
End If
SlookupAdj = ExcelError.ExcelErrorNA
Next i
End Function
In this modified code, we run into the same error, but simply skip it, deal with the fact that there is an error (If Err Then), clear it, and then make sure we never reach the evaluation of If Not valuetxt Then.
Again, Tim Williams is correct in noting that the thing you are trying to do, is more easily accomplished using Instr(). Like so:
Function InstrMethod(lookup_value As String, lookup_table As Range) As String
Dim i As Integer
Dim valuetxt As Boolean
Dim cc As Integer
cc = lookup_table.Rows.Count
For i = 1 To cc
valuetxt = InStr(lookup_value, lookup_table.Cells(i, 1))
If valuetxt Then
InstrMethod = lookup_table.Cells(i, 2)
Exit Function
End If
Next i
End Function