title: UnicodeDecodeError on python3
body: <p>Im currently trying to use some simple regex on a very big .txt file (couple of million lines of text). The most simple code that causes the problem:</p>
  
  <pre><code>file = open("exampleFileName", "r")  
      for line in file:  
          pass
  </code></pre>
  
  <p>The error message:</p>
  
  <pre><code>Traceback (most recent call last):
    File "example.py", line 34, in &lt;module&gt;
      example()
    File "example.py", line 16, in example
      for line in file:
    File "/usr/lib/python3.4/codecs.py", line 319, in decode
      (result, consumed) = self._buffer_decode(data, self.errors, final)
  UnicodeDecodeError: 'utf-8' codec can't decode byte 0xed in position 7332: invalid continuation byte
  </code></pre>
  
  <p>How can i fix this? is utf-8 the wrong encoding? And if it is, how do i know which one is right?</p>
  
  <p>Thanks and best regards!</p>