StartsWith, EndsWith

In VB.NET StartsWith tests the first part of a String. It checks whether one String starts with the characters in another. EndsWith checks the last characters.

StartsWith is often useful. StartsWith supports the StringComparison.OrdinalIgnoreCase argument, which makes it case-insensitive. Without this argument, it is case-sensitive.

Example

Here we use StartsWith. This call is case-sensitive. We pass the StringComparison.OrdinalIgnoreCase enumerated constant. This makes "D" equal to "d" so StartsWith returns True.

Module Module1
    Sub Main()
        Dim value As String = "Dot Net Perls"

        ' Use StartsWith.
        If value.StartsWith("Dot") Then
            Console.WriteLine(1)
        End If

        ' Use StartsWith ignoring case.
        If value.StartsWith("dot", StringComparison.OrdinalIgnoreCase) Then
            Console.WriteLine(2)
        End If

        ' It can return False.
        Console.WriteLine(value.StartsWith("Net"))
    End Sub
End Module
1
2
False

Test chars

There is another way to check the first characters of a String. It is typically much faster. We test the Length of a String and then check characters by their indexes.

Module Module1
    Sub Main()
        Dim value As String = "cat"

        ' You could use StartsWith...
        If value.StartsWith("c") Then
            Console.WriteLine(1)
        End If

        ' Or you could check the character yourself.
        If value.Length >= 1 And value(0) = "c" Then
            Console.WriteLine(2)
        End If
    End Sub
End Module
1
2

EndsWith

This tests the end part of a String. With it we specify a String that is then tested against the end characters of the first String.

Module Module1
    Sub Main()
        Dim value As String = "http://www.dotnetperls.com"
        Dim array() As String = {".net", ".org", ".edu", ".com"}

        For Each element As String In array
            If value.EndsWith(element) Then
                Console.WriteLine(element)
            End If
        Next
    End Sub
End Module
.com

StringComparison

You can pass a StringComparison enum as the second argument. The two most useful options are probably StringComparison.Ordinal and StringComparison.OrdinalIgnoreCase.

We looked at the StartsWith and EndsWith methods. EndsWith is excellent for testing to see whether a String happens to start (or end) with another String.