All elements of String() Array ToLower, using LINQ

Question

How Can I set to lower all the elements of an string array using LINQ?

Dim fileExtensions() As String = {"Mp3", "mP4", "wMw", "weBM", Nothing, ""}

Dim ToLower_fileExtensions = fileExtensions().Select...

(not using For)

Sergey Kalinichenko · Accepted Answer · 2013-10-17T09:31:14.527

2

Try this:

Dim ToLower_fileExtensions = From w in fileExtensions Select IF(w Is Nothing, Nothing, w.ToLower())

edited Oct 17 '13 at 09:31

answered Oct 17 '13 at 09:25

Sergey Kalinichenko

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It works fine for normal strings but throws an exception for empty fields (Nothing, ""), can you please update it with the needed clausures ? I think I need to add a where clausule to check if the field is empty or not. – ElektroStudios Oct 17 '13 at 09:29
Done, thanks again: From w In fileExtensions Where Not String.IsNullOrEmpty(w) Select w.ToLower() – ElektroStudios Oct 17 '13 at 09:30
1

@ElektroHacker That would eliminate `Nothing`s; my edit would preserve them. – Sergey Kalinichenko Oct 17 '13 at 09:32

score 2 · Answer 2 · answered Oct 17 '13 at 09:28

The easy and efficient way:

For i As Int32 = 0 To fileExtensions.Length - 1
    fileExtensions(i) = fileExtensions(i).ToLower()
Next

Since you've asked for linq, this is less efficient since it needs to create a new collection:

fileExtensions = fileExtensions.Select(Function(str) str.ToLower()).ToArray()

score -1 · Answer 3 · answered Oct 17 '13 at 09:46

Just a simple and generic function I've did based on @dasblinkenlight solution:

Private Function ArrayToLower(ByVal [Array] As IEnumerable) As IEnumerable

    Return From str In [Array] _
            Select If(String.IsNullOrEmpty(str), _
                      String.Empty, _
                      str.ToLower())

End Function

PS: Nice to convert it to a extension

All elements of String() Array ToLower, using LINQ

3 Answers3