What is this char? 65279 ''

Question

I have two strings.

one is "\""

and the other is "\""

I think that they are same.

However, String.Compare says they are different.

This is very strange.

Here's my code:

string b = "\"";
string c = "\"";

if (string.Compare(b, c) == 0)
{
    Console.WriteLine("Good");
}

if (c.StartsWith("\""))
{
    Console.WriteLine("C");
}

if (b.StartsWith("\""))
{
    Console.WriteLine("B");
}

I expected that it may print "GoodCB".

However, it only prints "B".

In my debugger, c[0] is 65279 '' and c[1] is 34 '"'. and b[0] is '"'.

But I don't know what 65279 '' is.

Is it an empty character?

Delphinedelphinia

What does your string come from? You're probably reading it wrong. – Angus

It very commonly appears as the first character in a utf-16 encoded text file. Use StreamReader, not FileStream. – Amalburga

This is very likely related to this excellent answer/explanation here (TL;DR use StreamReader if the string was loaded from a Stream, use Encoding.GetString() if it was loaded from Encoding.GetBytes(); do not mix the two): https://mcmap.net/q/93688/-encoding-utf8-getstring-doesn-39-t-take-into-account-the-preamble-bom – Phosphorism

Answer 1

It's a zero-width no-break space.
It's more commonly used as a byte-order mark (BOM).

Angus

How can I remove that char when I cannot sure whether it starts with '' or not? – Whiggism

Thank you so much! I was hitting the wall till I found your solution! – Woebegone

Great response, which lead me to continue looking and find this this excellent answer/explanation here (TL;DR use StreamReader if the string was loaded from a Stream, use Encoding.GetString() if it was loaded from Encoding.GetBytes(); do not mix the two): https://mcmap.net/q/93688/-encoding-utf8-getstring-doesn-39-t-take-into-account-the-preamble-bom – Phosphorism

Answer 2

If you are using Notepad++, try converting to UTF-8 (no BOM), and also make sure ALL your files in the project are the same file system format.

Brumley

Answer 3

You can remove it with:

Trim(new char[]{'\uFEFF','\u200B'});

Bookmark

Answer 4

If you are reading from a file you have opened in notepad, it may have added it as it is one of several programs notorious for doing so.

Cariole

How can I remove that char when I cannot sure whether it starts with '' or not. – Whiggism

Notepad and other programs are saving UTF8 files, which is a valid and common format. The BOM only bothers you when you read the file with the wrong encoding. – Angus

I want to determine whether '' is exist or not using c[0] == '' but I cannot build this. – Whiggism

Answer 5

It is byte order mark(BOM). A BOM is a special marker at the beginning of a file that indicates the byte order of the text data in the file.

We can remove the BOM in JavaScript using the following code

    function removeBOM(jsonString) {
        if (jsonString.charCodeAt(0) === 0xfeff) {
            jsonString = jsonString.slice(1);
        } 
        return jsonString;
    }

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