`Console.ReadKey`

This function returns immediately when a key is pressed. We can test the result by storing it in a ConsoleKeyInfo structure, and testing its properties.

Sometimes, programs written in VB.NET need to be more interactive. Waiting for the Enter key to be pressed can make a program harder to use or more confusing.

Example

Using ReadKey is significantly more complex than just calling ReadLine. It involves testing the ConsoleKey Enum, as well as properties like KeyChar.

Step 1 We call Console.ReadKey and store the result in a local variable called info. This is a ConsoleKeyInfo.

Step 2 First we test for the escape key. We use an if-statement and test Key against ConsoleKey.Escape.

Step 3 We call Console.ReadKey again. If we want to test against a char, like the lowercase letter "a," we can access the KeyChar property.

Step 4 We can access the Modifiers property, and test against ConsoleModifiers.Control (or other values) to handle complex key presses.

Module Module1

    Sub Main()

        Console.WriteLine("... Press escape, a, then control X")

        ' Step 1 : call ReadKey, store result in ConsoleKeyInfo.
        Dim info As ConsoleKeyInfo = Console.ReadKey()

        ' Step 2: test for escape.
        If info.Key = ConsoleKey.Escape Then
            Console.WriteLine("You pressed escape!")
        End If

        ' Step 3: call ReadKey, and test KeyChar.
        info = Console.ReadKey()
        If info.KeyChar = "a"c Then
            Console.WriteLine("You pressed a")
        End If

        ' Step 4: call ReadKey, and test for Modifiers.
        info = Console.ReadKey()
        If info.Key = ConsoleKey.X AndAlso
            info.Modifiers = ConsoleModifiers.Control Then
            Console.WriteLine("You pressed control X")
        End If

    End Sub

End Module... Press escape, a, then control X
?You pressed escape!
aYou pressed a
?You pressed control X

Though most VB.NET programs do not need to use Console.ReadKey, this function is useful for certain highly-interactive programs. It requires testing enums and properties, often in a loop.