Append, AppendLine

Append adds data to a StringBuilder in C# code. Append method calls can be chained—this makes code more succinct and easier to read.

With AppendLine, .NET places a newline sequence at the end of the specified string. This method makes code easier to read as well.

Append example

Remember that StringBuilder often improves your application's performance. But excessive method calls, on separate lines, can be hard to read.

using System;
using System.Text;

const string s = "(s)";

// Version 1: call Append repeatedly.
StringBuilder builder = new StringBuilder();
for (int i = 0; i < 3; i++)
{
    builder.Append("Start");
    builder.Append(s);
    builder.Append("End");
}

// Version 2: use fluent interface for StringBuilder.
StringBuilder builder2 = new StringBuilder();
for (int i = 0; i < 3; i++)
{
    builder2.Append("Start").Append( s).Append("End");
}

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

AppendLine example

AppendLine adds strings with a newline. With AppendLine, a newline sequence is automatically inserted after the argument is added to the StringBuilder buffer.

using System;
using System.Text;

// Use AppendLine.
StringBuilder builder = new StringBuilder();
builder.AppendLine("One");
builder.AppendLine();
builder.AppendLine("Two").AppendLine("Three");

// Display.
Console.Write(builder);

// AppendLine uses \r\n sequences.
Console.WriteLine(builder.ToString().Contains("\r\n"));
One

Two
Three
True

Note, newlines

The newline sequence used in AppendLine is equal to "\r\n" which is also available by referencing Environment.NewLine.

Discussion

There are 2 ways to specify newlines: the character "\n" alone, and the sequence "\r\n". AppendLine always uses the sequence "\r\n". To save bytes, you can manually use "\n".

We can chain StringBuilder Appends in cases where we call the method multiple times. We looked at the AppendLine method and its overloads on the StringBuilder type.