Console.WriteLine If Property Shared String Length String.IsNullOrEmpty

Empty

An empty string has length 0. It is not Nothing. We can specify in VB.NET an empty string with "" but the String.Empty property is easier to read.

With IsNullOrEmpty, we can test to see if a string is either Nothing or has length 0. The 2 checks often come together, and the helper Shared function makes code clearer.

In this example, we introduce a string variable called "value." We assign it to the String.Empty property. Then we test it against "": this check evaluates to true.

Detail We use the IsNullOrEmpty function. This function correctly detects the empty string.

Detail Finally we access the Length property of the string. We print the value 0 to the console.

Module Module1

    Sub Main()
        ' Assign a string to String.Empty.
        Dim value As String = String.Empty

        ' It equals an empty literal.
        If value = "" Then
            Console.WriteLine(1)
        End If

        ' It is detected by IsNullOrEmpty.
        If String.IsNullOrEmpty(value) Then
            Console.WriteLine(2)
        End If

        ' It has length 0.
        Console.WriteLine(value.Length)
    End Sub

End Module1
2
0

Shared

String.Empty is a shared property. It is not a constant, so it has a tiny difference with an empty literal. A load must occur to read it.

But For almost all programs, no difference is going to be detected. For maximum performance, I recommend directly using the empty literal.

`IsNullOrWhiteSpace`

A string with only whitespace is not empty. But in some programs we might want to test for whitespace-only or null strings. IsNullOrWhiteSpace helps here.

Empty is a handy property to know about: it can make some code more self-documenting. The empty literal may be more mysterious. String.Empty clearly indicates its contents.