textbox is empty but still showing the count - asp.net

Question

I have textbox1 field in asp.net and a text area to show count of records.
I want to count the records split by , in textbox1 but when textbox1 is empty text area is showing 1.
Here is the code.
int contacts = textbox1.Text.Split(',').Count();
textarea.Text = contacts.ToString();

Answer 1

String.Split always returns at least one string, if you pass string.Empty you will get one string which is the input string(so in this case string.Empty).
Documentation:
....
If this instance does not contain any of the characters in separator,
the returned array consists of a single element that contains this instance.
You have to check it, f.e. with string.IsNullOrEmpty(or String.IsNullOrWhiteSpace):
int contacts = 0;
if(!string.IsNullOrEmpty(textbox1.Text))
contacts = textbox1.Text.Split(',').Length;

Answer 2

Try this
int contacts = string.IsNullOrEmpty(string.textbox1.Text)? string.empty: textbox1.Text.Split(',').Count();
textarea.Text = contacts.ToString();

Answer 3

This is because even when textbox1.Text is an empty string, that's still treated as one item. You need to use StringSplitOptions.RemoveEmptyEntries so that empty entries are ignored when producing the result of calling Split:
var contacts = textbox1.Text.Split(new char[] { ',' }, StringSplitOptions.RemoveEmptyEntries)
.Count();
To decompose what you've written into individual statements, what you have is:
var items = textbox1.Text.Split(new char[] { ', ' }, StringSplitOptions.RemoveEmptyEntries);
var countOfItems = itemsFromText.Count();
If you look at items you'll see that it's an array of strings (string[]) which contains one entry for each item in the text from textbox1.Text.
Even if an empty string is passed in (i.e. textbox1 is empty) there's still one string to be returned, hence the fact that your code as written is returning 1, whereas in countOfItems where I've broken the code apart it will have 0 because of the use of StringSplitOptions.RemoveEmptyEntries.
The documentation on msdn of the String.Split overload that takes StringSplitOptions as a parameter has more examples and detail about this.