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Language: VB7
Expertise: Intermediate
Oct 27, 2003

ArrayIndexOf - An extended version of Array.IndexOf

' An extended version of Array.IndexOf, with more options for string searches. 
' The function returns the index of the found element,
'  or -1 if no element is found
'
' Example:
'   Dim arr As String() = {"this is a string for my test", "test number 2",
'  "another String", "do you like this string?", "I like running tests"}
'   Dim i As Integer = -1

'   Do
'       i = ArrayIndexOf(arr, "string", i + 1, False, False)
'       If i > -1 Then
'           Debug.WriteLine(arr(i))
'       End If
'   Loop While i > -1

Function ArrayIndexOf(ByVal arr As String(), ByVal search As String) As Integer
    Return ArrayIndexOf(arr, search, arr.GetLowerBound(0))
End Function

' this overloaded version allows you to specify also the array's index to start 
' from
Function ArrayIndexOf(ByVal arr As String(), ByVal search As String, _
    ByVal startIndex As Integer) As Integer
    Return ArrayIndexOf(arr, search, startIndex, True)
End Function

' this overloaded version allows you to specify also whether the search is case-
' sensitive
Function ArrayIndexOf(ByVal arr As String(), ByVal search As String, _
    ByVal startIndex As Integer, ByVal caseSensitive As Boolean) As Integer
    Return ArrayIndexOf(arr, search, startIndex, caseSensitive, True)
End Function

' this overloaded version allows you to specify also whether only exact matches 
' are valid
Function ArrayIndexOf(ByVal arr As String(), ByVal search As String, _
    ByVal startIndex As Integer, ByVal caseSensitive As Boolean, _
    ByVal exactMatch As Boolean) As Integer
    ' if the search is case-sensitive and it runs against exact matches only,
    '  use the standard Array.IndexOf function
    If caseSensitive And exactMatch Then
        Return Array.IndexOf(arr, search, startIndex)
    End If

    If Not caseSensitive Then search = search.ToLower()

    Dim lastIndex As Integer = arr.GetUpperBound(0)
    Dim i As Integer
    For i = startIndex To lastIndex
        Dim currElem As String = arr(i)
        ' if the search is not case-sensitive, convert everything to lower-case
        If Not caseSensitive Then currElem = currElem.ToLower()
        If exactMatch Then
            If search = currElem Then Return i
        Else
            ' if partial matches are ok, use the String.IndexOf function,
            '  and return the
            ' current index if a partial match is found
            Dim j As Integer = currElem.IndexOf(search)
            If j > -1 Then Return i
        End If
    Next

    ' if we get here, no element matches the search options, so return -1
    Return -1
End Function
Marco Bellinaso
 
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