Contains

This function determines if a substring exists in a source string. It returns a Boolean that indicates whether the argument string was located in the instance string.

You can either directly test the result of the Contains method, or store it in a local variable (or field). By storing it, you can avoid repeated work and speed up a method.

In this example, we see that there are 2 subroutines defined. The Test subroutine receives one input string. It prints this to the screen and then invokes the Contains method on it.

Module Module1

    Sub Main()
        ' Call the Test sub with different string literal arguments.
        Test("Dot Net Perls")
        Test("dot net perls")
    End Sub

    Sub Test(ByVal input As String)
        ' Write the formal parameter.
        Console.Write("--- ")
        Console.Write(input)
        Console.WriteLine(" ---")

        ' See if it contains this string.
        Dim net As Boolean = input.Contains("Net")
        Console.Write("Contains 'Net': ")
        Console.WriteLine(net)

        ' See if it contains this string.
        If input.Contains("perls") Then
            Console.WriteLine("Contains 'perls'")
        End If

        ' See if it does not contain this string.
        If Not input.Contains("Dot") Then
            Console.WriteLine("Doesn't Contain 'Dot'")
        End If
    End Sub

End Module
--- Dot Net Perls ---
Contains 'Net': True
--- dot net perls ---
Contains 'Net': False
Contains 'perls'
Doesn't Contain 'Dot'

We described the Contains Function and demonstrated its usage. We also showed how its Boolean result can be stored in memory for later reuse. IndexOf can also search strings.