Question: How can I determine that a particular file (which may or may not have an ".mp3" file extension) is in fact an MP3 file? I wish to do this in C#.

Answer: 
```
string[] filePath = Directory.GetFiles(fbdialog.SelectedPath.ToString(),".mp3", 
                                       SearchOption.AllDirectories);

foreach (string str in filePath)
{
    MessageBox.Show("It's mp3 file");
}

```
C# code:

```
bool isMP3(byte[] buf)
{
    if (buf[0] == 0xFF && (buf[1] & 0xF6) > 0xF0 && (buf[2] & 0xF0) != 0xF0) 
    {
         return true;
    }
    return false;
}

```