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SkyeBoniwell
SkyeBoniwell

Reputation: 7122

difference between string.empty and isNullOrEmpty?

I have the following short piece of code that is never returning the string "selected".

Protected Function SelectedType(ByVal val As String) As String
    If val <> String.Empty Then Return "selected"
End Function

However, if I change it to this, it works. Is there anything wrong when my shorthand code above? -Thanks

Protected Function SelectedType(ByVal val As String) As String
    If Not String.IsNullOrEmpty(val) Then
        Return "selected"
    End If
End Function

Upvotes: 3

Views: 2217

Answers (3)

Stephane Delcroix
Stephane Delcroix

Reputation: 16232

String.Empty is "", null is Nothing.

you can compare if a string is null, if it's empty, or both at the same time with IsNullOrEmpty ()

Upvotes: 4

Reed Copsey
Reed Copsey

Reputation: 564831

When you call If Not String.IsNullOrEmpty(val) Then, you're checking to see if the value is equal to String.Empty or if the value is equal to Nothing.

This would be more like writing your first example as:

Protected Function SelectedType(ByVal val As String) As String
    If val <> Nothing And val <> String.Empty Then 
        Return "selected"
    End If
End Function

Upvotes: 3

Aghilas Yakoub
Aghilas Yakoub

Reputation: 29000

IsNullOrEmpty offers additional security against null values, where otherwise your code would fail

Upvotes: 1

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