Why Do Special Characters Appear as Black Diamonds with a Question Mark in PHP?

PHP Character Encoding Issue: Little Black Diamonds with a Question Mark

Users frequently encounter a peculiar issue when retrieving data from a database using PHP: special characters such as quotes appear as black diamonds with a question mark (�). This problem arises from discrepancies between the data's encoding and the encoding used to display it.

To resolve this issue, you can implement various approaches:

1. HTTP Header: Add an HTTP header to specify the correct character encoding for the browser:

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

2. Meta Tag: Include a meta tag in the HTML document to declare the encoding:

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

3. Database Connection: Consider retrieving data from the database using a different character encoding, such as UTF-8.
4. Iconv Conversion: Utilize the iconv() function to convert the retrieved text to the desired encoding:

$converted = iconv("ISO-8859-1", "UTF-8", $text);

Understanding the underlying encoding issue is crucial. Typically, the data is encoded in a single-byte format like ISO-8859-1 (Latin-1) but is incorrectly interpreted in a unicode encoding (UTF-8 or UTF-16).

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