PHP output showing little black diamonds with a question mark

If you see that character (� U+FFFD "REPLACEMENT CHARACTER") it usually means that the text itself is encoded in some form of single byte encoding but interpreted in one of the unicode encodings (UTF8 or UTF16).

If it were the other way around it would (usually) look something like this: ä.

Probably the original encoding is ISO-8859-1, also known as Latin-1. You can check this without having to change your script: Browsers give you the option to re-interpret a page in a different encoding -- in Firefox use "View" -> "Character Encoding".

To make the browser use the correct encoding, add an HTTP header like this:

header("Content-Type: text/html; charset=ISO-8859-1");

or put the encoding in a meta tag:

<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">

Alternatively you could try to read from the database in another encoding (UTF-8, preferably) or convert the text with iconv().

I also faced this � issue. Meanwhile I ran into three cases where it happened:

1. substr()

   I was using substr() on a UTF8 string which cut UTF8 characters, thus the cut chars could not be displayed correctly. Use mb_substr($utfstring, 0, 10, 'utf-8'); instead. Credits

2. htmlspecialchars()

   Another problem was using htmlspecialchars() on a UTF8 string. The fix is to use: htmlspecialchars($utfstring, ENT_QUOTES, 'UTF-8');

3. preg_replace()

   Lastly I found out that preg_replace() can lead to problems with UTF. The code $string = preg_replace('/[^A-Za-z0-9ÄäÜüÖöß]/', ' ', $string); for example transformed the UTF string "F(×)=2×-3" into "F � 2� ". The fix is to use mb_ereg_replace() instead.

I hope this additional information will help to get rid of such problems.

This is a charset issue. As such, it can have gone wrong on many different levels, but most likely, the strings in your database are utf-8 encoded, and you are presenting them as iso-8859-1. Or the other way around.

The proper way to fix this problem, is to get your character-sets straight. The simplest strategy, since you're using PHP, is to use iso-8859-1 throughout your application. To do this, you must ensure that:

• All PHP source-files are saved as iso-8859-1 (Not to be confused with cp-1252).
• Your web-server is configured to serve files with charset=iso-8859-1
• Alternatively, you can override the webservers settings from within the PHP-document, using header.
• In addition, you may insert a meta-tag in you HTML, that specifies the same thing, but this isn't strictly needed.
• You may also specify the accept-charset attribute on your <form> elements.
• Database tables are defined with encoding as latin1
• The database connection between PHP to and database is set to latin1

If you already have data in your database, you should be aware that they are probably messed up already. If you are not already in production phase, just wipe it all and start over. Otherwise you'll have to do some data cleanup.

A note on meta-tags, since everybody misunderstands what they are:

When a web-server serves a file (A HTML-document), it sends some information, that isn't presented directly in the browser. This is known as HTTP-headers. One such header, is the Content-Type header, which specifies the mimetype of the file (Eg. text/html) as well as the encoding (aka charset). While most webservers will send a Content-Type header with charset info, it's optional. If it isn't present, the browser will instead interpret any meta-tags with http-equiv="Content-Type". It's important to realise that the meta-tag is only interpreted if the webserver doesn't send the header. In practice this means that it's only used if the page is saved to disk and then opened from there.

This page has a very good explanation of these things.