Console

In VB.NET, Console.WriteLine prints a message to the console. And ReadLine will get user input. ReadKey() can handle key presses immediately.

For accessing the console in VB.NET, we use the shared Console class. No instance of Console is needed—we just invoke the functions.

WriteLine example

Here we use Console.WriteLine with an integer, a string literal, a Char array, a format pattern string, and with no arguments.

Module Module1

    Sub Main()
        ' Step 1: write an integer line.
        Dim value As Integer = 7
        Console.WriteLine(value)

        ' Step 2: write a string literal line.
        Console.WriteLine("Hello World")

        ' Step 3: write character array range.
        Dim array(4) As Char
        array(0) = "d"c
        array(1) = "n"c
        array(2) = "p"c
        array(3) = "x"c
        array(4) = "x"c
        Console.WriteLine(array, 0, 3)

        ' Step 4: write format string.
        Console.WriteLine("Label: {0}, {1}", 999, "Awesome")

        ' Step 5: write empty line.
        Console.WriteLine()
        Console.WriteLine("Goodbye, friends")
    End Sub

End Module
7
Hello World
dnp
Label: 999, Awesome

Goodbye, friends

Write example

Unlike WriteLine, Console.Write() does not append a newline to the console after the data. This Sub is the same as WriteLine in other ways. It seems to be less often used.

Module Module1

    Sub Main()
        ' Write integer.
        Console.Write(8)

        ' Write string literal.
        Console.Write("perls ")

        ' Write character array.
        Dim array(2) As Char
        array(0) = "h"c
        array(1) = "i"c
        array(2) = "!"c
        Console.Write(array)

        ' Write format string.
        Console.Write("Welcome: {0}", 100)
        Console.WriteLine()
    End Sub

End Module
8perls hi!Welcome: 100

ReadLine

Writing is most common with the Console type. But we can also read lines, from the keyboard, with ReadLine. The ReadLine Function returns a String.

Module Module1
    Sub Main()
        While True

            ' Read value.
            Dim s As String = Console.ReadLine()

            ' Test the value.
            If s = "1" Then
                Console.WriteLine("One")
            ElseIf s = "2" Then
                Console.WriteLine("Two")
            End If

            ' Write the value.
            Console.WriteLine("You typed " + s)

        End While
    End Sub
End Module
1
One
You typed 1
2
Two
You typed 2
3
You typed 3

ToString

Suppose we have an Object in our VB.NET program and pass it to Console.WriteLine or Write. The ToString function is used by Console.WriteLine to print it out.

Console.ReadKey

We can use ReadKey for an immediate response that does not require the Enter key to be pressed. This can be useful for interactive VB.NET programs.

Console.WriteLine, Write and Read are often used in VB.NET programs. We can output data with colors. And format strings can be used to simplify the syntax of our programs.