CompareTo Console.WriteLine Enum Sort String LastIndexOf

`String.Compare`

In VB.NET, 2 Strings can be compared. With Compare, CompareOrdinal, and CompareTo, we can determine whether one String is ordered before another String.

Compare is used to implement sorting routines. Compare returns just three values: -1, 0 and 1. This number indicates the relation of the two strings being compared.

Example

First we declare two String local variables. Next we call the Shared String.Compare function. It returns -1—this means that String a is smaller than, or comes before, String b.

Next The result of 1 indicates that String "b" is larger than String a. And 0 means the two Strings are equal.

Note CompareOrdinal treats each character as an ordinal value. This means Chars are treated by their numeric value.

Note 2 With CompareTo, we use String instances to perform the comparison. The results are the same as for String.Compare.

Module Module1
    Sub Main()
        Dim a As String = "a"
        Dim b As String = "b"

        Dim c As Integer = String.Compare(a, b)
        Console.WriteLine(c)

        c = String.CompareOrdinal(b, a)
        Console.WriteLine(c)

        c = a.CompareTo(b)
        Console.WriteLine(c)

        c = b.CompareTo(a)
        Console.WriteLine(c)

        c = "x".CompareTo("x")
        Console.WriteLine(c)
    End Sub
End Module-1
1
-1
1
0

Discussion

In a sort, each String must be compared to other Strings. With Compare and CompareTo, an Enum of StringComparison type can be specified as an argument.

And Internally, those methods will use a Compare method based on the Enum argument.

So StringComparison.Ordinal will result in the CompareOrdinal method being used in some way.

With these methods, if the first String is ordered first, we receive the value -1. If the Strings are equal, we receive 0. And we receive 1 if the second String is first.