A question that seems to come up pretty frequently on various PHP mailing lists is how to convert "smart quotes" to real quotes. Dan Convissor provided a simple example that performs such a conversion a year or two ago on the NYPHP mailing list. I've modified it slightly to fit my own style preferences:

1.  
2. function convert_smart_quotes($string)
3. {
4.     $search = array(chr(145),
5.                     chr(146),
6.                     chr(147),
7.                     chr(148),
8.                     chr(151));
9.  
10.     $replace = array("'",
11.                      "'",
12.                      '"',
13.                      '"',
14.                      '-');
15.  
16.     return str_replace($search, $replace, $string);
17. }
18.  

(This function also converts an emdash into a hyphen.)

If you want "smart quotes" to actually appear in a browser, you can use the following $replace array to convert each of these characters into HTML entities:

1.  
2. $replace = array('‘',
3.                  '’',
4.                  '“',
5.                  '”',
6.                  '—');
7.  

These entities render properly in most browsers I've tried, including lynx. Here's some example HTML:

1. “double quotes”

Here is how these entities render in your browser:

1. “double quotes”

The htmlentities() man page has other useful examples in the user notes at the bottom, some of which convert a wide variety of characters into valid HTML entities.