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

Question

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 1

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.

Answer 2

Just use

string.Join(",", yourCollection)

This way you don't need the StringBuilder and the loop.

Answer 3

Use the following after the loop.

.TrimEnd(',')

or simply change to

string commaSeparatedList = input.Aggregate((a, x) => a + ", " + x)

Answer 4

How About this..

string str = "The quick brown fox jumps over the lazy dog,";
StringBuilder sb = new StringBuilder(str);
sb.Remove(str.Length - 1, 1);

Answer 5

I prefer manipulating the length of the stringbuilder:

data.Length = data.Length - 1;

Answer 6

I recommend, you change your loop algorithm:

• Add the comma not AFTER the item, but BEFORE
• Use a boolean variable, that starts with false, do suppress the first comma
• Set this boolean variable to true after testing it

Answer 7

You should use the string.Join method to turn a collection of items into a comma delimited string. It will ensure that there is no leading or trailing comma, as well as ensure the string is constructed efficiently (without unnecessary intermediate strings).

Answer 8

Yes, convert it to a string once the loop is done:

String str = data.ToString().TrimEnd(',');

Answer 9

You have two options. First one is very easy use Remove method it is quite effective. Second way is to use ToString with start index and end index (MSDN documentation)

Answer 10

Similar SO question here.

I liked the using a StringBuilder extension method.

RemoveLast Method

Answer 11

The most simple way would be to use the Join() method:

public static void Trail()
{
    var list = new List<string> { "lala", "lulu", "lele" };
    var data = string.Join(",", list);
}

If you really need the StringBuilder, trim the end comma after the loop:

data.ToString().TrimEnd(',');