Question

How to use Array.TrueForAll() method to determine whether all array elements match a condition in VB.NET

Answer 1

Module Module1

    Sub Main()

        Dim arr As String() = {"hhh10", "ccc100", "bbb1000", "ggg10000",
                               "eee100000", "aaa100000", "ddd333"}

        If Array.TrueForAll(arr, AddressOf EndsWithInteger) Then
            Console.WriteLine("All elements end with integer")
        Else
            Console.WriteLine("Not all elements end with an integer")
        End If

    End Sub

    Private Function EndsWithInteger(value As String) As Boolean
        Dim s As Integer
        Return Int32.TryParse(value.Substring(value.Length - 1), s)
    End Function

End Module

' run:
' 
' All elements end with integer

 

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Answer 2

Module Module1

    Sub Main()

        Dim arr As String() = {"hhh", "ccc100", "bbb1000", "ggg10000", "eee100000"}

        If Array.TrueForAll(arr, AddressOf EndsWithInteger) Then
            Console.WriteLine("All elements end with integer")
        Else
            Console.WriteLine("Not all elements end with an integer")
        End If

    End Sub

    Private Function EndsWithInteger(value As String) As Boolean
        Dim s As Integer
        Return Int32.TryParse(value.Substring(value.Length - 1), s)
    End Function

End Module

' run:
' 
' Not all elements end with an integer

 

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Answer 3

Module Module1

    Sub Main()

        Dim arr As String() = {"hhh12345", "ccc100", "bbb1000", "ggg10000"}

        If Array.TrueForAll(arr, Function(value)
                                     Dim s As Integer
                                     Return Int32.TryParse(value.Substring(value.Length - 1), s)
                                 End Function) Then
            Console.WriteLine("All elements end with integer")
        Else
            Console.WriteLine("Not all elements end with an integer")
        End If

    End Sub

End Module

' run:
' 
' All elements end with integer

 

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