Best way to remove the last character from a string built with stringbuilder

c# stringbuilder
Wesley Skeen picture Wesley Skeen · Jun 20, 2013 · Viewed 99.2k times · Source

I have the following 

data.AppendFormat("{0},",dataToAppend);

The problem with this is that I am using it in a loop and there will be a trialling comma. What is the best way to remove the trailing comma?

Do I have to change data to a string the substring it?

Answer

Mike Perrenoud picture Mike Perrenoud · Jun 20, 2013

The simplest and most efficient way is to perform this command:

data.Length--;

by doing this you move the pointer (i.e. last index) back one character but you don't change the mutability of the object. In fact, clearing a StringBuilder is best done with Length as well (but do actually use the Clear() method for clarity instead because that's what its implementation looks like):

data.Length = 0;

again, because it doesn't change the allocation table. Think of it like saying, I don't want to recognize these bytes anymore. Now, even when calling ToString(), it won't recognize anything past its Length, well, it can't. It's a mutable object that allocates more space than what you provide it, it's simply built this way.

Related questions

Newline character in StringBuilder

How do you append a new line(\n\r) character in StringBuilder?

Read More
Difference between string and StringBuilder in C#

What is the difference between string and StringBuilder? Also, what would be some examples for understanding?

Read More
What is the simplest way to write the contents of a StringBuilder to a text file in .NET 1.1?

I have to use StringBuilder instead of a List of strings because of being stuck with .NET 1.1 for this project. I want to write a series of debug messages I've written to a file to study at my leisure, as …

Read More