<p>I want to run text through a filter to ensure it is all UTF-8 encoded.  What is the recommended way to do this with PHP?</p>

[{'answer_id': 79950, 'author': 'Don Neufeld', 'author_id': 13097, 'author_profile': 'https://Stackoverflow.com/users/13097', 'pm_score': 2, 'selected': False, 'text': '<p>Your question is unclear, are you trying to encode something?  If so <a href="http://us2.php.net/manual/en/function.utf8-encode.php" rel="nofollow noreferrer"><strong>utf8_encode</strong></a> is your friend.  Are you trying to determine if it doesn\'t need to be encoded?  If so, <strong>utf8_encode</strong> is still your friend, because you can check that the result is the same as the input!</p>\n'}, {'answer_id': 79982, 'author': 'Bahadır Yağan', 'author_id': 3812, 'author_profile': 'https://Stackoverflow.com/users/3812', 'pm_score': 1, 'selected': False, 'text': '<p>Check the multi-byte string functions <a href="http://be.php.net/manual/en/ref.mbstring.php" rel="nofollow noreferrer">here</a></p>\n'}, {'answer_id': 80013, 'author': 'Thomas', 'author_id': 14637, 'author_profile': 'https://Stackoverflow.com/users/14637', 'pm_score': 0, 'selected': False, 'text': '<p>You need to know in what character set your input string is encoded, or this will go nowhere fast.</p>\n\n<p>If you want to do it correctly, this article may be helpful: <a href="http://www.joelonsoftware.com/articles/Unicode.html" rel="nofollow noreferrer">The Absolute Minimum Every Software Developer Absolutely, Positively Must Know About Unicode and Character Sets (No Excuses!)</a></p>\n'}, {'answer_id': 80019, 'author': 'DGM', 'author_id': 14253, 'author_profile': 'https://Stackoverflow.com/users/14253', 'pm_score': 0, 'selected': False, 'text': "<p>Given a stream of bytes, you have to know what encoding it is to begin with - email  use mime headers to specify the encoding, http uses http headers to specify the encoding.  Also, you can specify the encoding  in a meta tag in a web page, but it is not always honored.</p>\n\n<p>Anyway, once you know what encoding you want to convert from, use <strong>iconv</strong> to convert it to utf8.  look at the iconv section of the php docs, there's lots of good info there.</p>\n\n<p>Ah, Thomas posted the link I was looking for.  A must read.</p>\n"}, {'answer_id': 83711, 'author': 'Tometzky', 'author_id': 15862, 'author_profile': 'https://Stackoverflow.com/users/15862', 'pm_score': 0, 'selected': False, 'text': "<p>The easiest way to check for <em>UTF-8</em> validity:</p>\n\n<ol>\n<li><p>If only one line allowed:</p>\n\n<pre><code>preg_match('/^.*$/Du', $value)\n</code></pre></li>\n<li><p>If multiple lines allowed:</p>\n\n<pre><code>preg_match('/^.*$/sDu', $value)\n</code></pre></li>\n</ol>\n\n<p>This works for <strong>PHP >= 4.3.5</strong> and does not require any non-default PHP modules.</p>\n"}]
['https://Stackoverflow.com/questions/79928', 'https://Stackoverflow.com', 'https://Stackoverflow.com/users/-1/']