Append, AppendLine

To add string data to a StringBuilder in VB.NET programs, we call the Append or AppendLine functions. These functions can be used in a single statement, or chained together.

With Append, no extra characters are added after the argument. But AppendLine adds a newline sequence, which is platform-dependent, and makes using StringBuilder more convenient.

Append example

Usually when using StringBuilder, we call Append in a loop—here we have 2 For-loops. We call Append 3 times in each loop.

Imports System.Text

Module Module1
    Sub Main()
        Const s As String = "(s)"

        ' Version 1: call Append in loop.
        Dim builder = New StringBuilder()
        For i = 0 To 2
            builder.Append("Start")
            builder.Append(s)
            builder.Append("End")
        Next

        ' Version 2: call Append in loop in same statement.
        Dim builder2 = New StringBuilder()
        For i = 0 To 2
            builder2.Append("Start").Append( s).Append("End")
        Next

        Console.WriteLine("BUILDER:   {0}", builder)
        Console.WriteLine("BUILDER 2: {0}", builder2)
    End Sub
End Module
BUILDER:   Start(s)EndStart(s)EndStart(s)End
BUILDER 2: Start(s)EndStart(s)EndStart(s)End

AppendLine example

When we call AppendLine, a newline sequence is added automatically at the end of every call. This is equal to the current platform's NewLine property.

Imports System.Text

Module Module1
    Sub Main()
    
        ' Use AppendLine.
        Dim builder = New StringBuilder()
        builder.AppendLine("One")
        builder.AppendLine()
        builder.AppendLine("Two").AppendLine("Three")
        Console.Write(builder)

    End Sub
End Module
One

Two
Three

Along with ToString, the Append and AppendLine functions are the most commonly-used ones on StringBuilder. AppendLine has the extra convenience of a newline sequence on each call.