How to GetBytes() in C# with UTF8 encoding with BOM?

Question

I'm having a problem with UTF8 encoding in my asp.net mvc 2 application in C#. I'm trying let user download a simple text file from a string. I am trying to get bytes array with the following line: `var x = Encoding.UTF8.GetBytes(csvString);` but when I return it for download using: `return File(x, ..., ...);` I get a file which is without BOM so I don't get Croatian characters shown up correctly. This is because my bytes array does not include BOM after encoding. I triend inserting those bytes manually and then it shows up correctly, but that's not the best way to do it. I also tried creating UTF8Encoding class instance and passing a boolean value (true) to its constructor to include BOM, but it doesn't work either. Anyone has a solution? Thanks!

Accepted Answer

Try like this:

```
public ActionResult Download()
{
    var data = Encoding.UTF8.GetBytes("some data");
    var result = Encoding.UTF8.GetPreamble().Concat(data).ToArray();
    return File(result, "application/csv", "foo.csv");
}
```

The reason is that the UTF8Encoding constructor that takes a boolean parameter doesn't do what you would expect:

```
byte[] bytes = new UTF8Encoding(true).GetBytes("a");
```

The resulting array would contain a single byte with the value of 97. There's no BOM because UTF8 doesn't require a BOM.

How to GetBytes() in C# with UTF8 encoding with BOM?

Solution

Problem