[excel] Writing a VLOOKUP function in vba

I'm trying to lookup a value on a spreadsheet within a table array using the VLOOKUP function in my vba code. I don't know how to write it correctly.

Here is the normal VLOOKUP formula with all the references:

=VLOOKUP(DATA!AN2,DATA!AA9:AF20,5,FALSE)

Please find the code below for Vlookup:

Function vlookupVBA(lookupValue, rangeString, colOffset)
vlookupVBA = "#N/A"
On Error Resume Next
Dim table_lookup As range
Set table_lookup = range(rangeString)
vlookupVBA = Application.WorksheetFunction.vlookup(lookupValue, table_lookup, colOffset, False)
End Function

As Tim Williams suggested, using Application.VLookup will not throw an error if the lookup value is not found (unlike Application.WorksheetFunction.VLookup).

If you want the lookup to return a default value when it fails to find a match, and to avoid hard-coding the column number -- an equivalent of IFERROR(VLOOKUP(what, where, COLUMNS(where), FALSE), default) in formulas, you could use the following function:

Private Function VLookupVBA(what As Variant, lookupRng As Range, defaultValue As Variant) As Variant
    Dim rv As Variant: rv = Application.VLookup(what, lookupRng, lookupRng.Columns.Count, False)
    If IsError(rv) Then
        VLookupVBA = defaultValue
    Else
        VLookupVBA = rv
    End If
End Function

Public Sub UsageExample()
    MsgBox VLookupVBA("ValueToFind", ThisWorkbook.Sheets("ReferenceSheet").Range("A:D"), "Not found!")
End Sub

How about just using:

result = [VLOOKUP(DATA!AN2, DATA!AA9:AF20, 5, FALSE)]

Note the [ and ].

Dim found As Integer
    found = 0

    Dim vTest As Variant

    vTest = Application.VLookup(TextBox1.Value, _
    Worksheets("Sheet3").Range("A2:A55"), 1, False)

If IsError(vTest) Then
    found = 0
    MsgBox ("Type Mismatch")
    TextBox1.SetFocus
    Cancel = True
    Exit Sub
Else

    TextBox2.Value = Application.VLookup(TextBox1.Value, _
    Worksheets("Sheet3").Range("A2:B55"), 2, False)
    found = 1
    End If

        Public Function VLOOKUP1(ByVal lookup_value As String, ByVal table_array As Range, ByVal col_index_num As Integer) As String
        Dim i As Long

        For i = 1 To table_array.Rows.Count
            If lookup_value = table_array.Cells(table_array.Row + i - 1, 1) Then
                VLOOKUP1 = table_array.Cells(table_array.Row + i - 1, col_index_num)
                Exit For
            End If
        Next i

        End Function