How to set HTTP header to UTF-8 using PHP which is valid in W3C validator

I have several PHP pages echoing out various things into HTML pages with the following code.

<meta http-equiv="Content-type" content="text/html; charset=utf-8" />

However, when I validate using the W3C validator it comes up with:

The character encoding specified in the HTTP header (iso-8859-1) is different from the value in the element (utf-8).

I am quite new to PHP, and I was wondering if I could and should change the header for the PHP files to match the HTML files.

Use header to modify the HTTP header:

header('Content-Type: text/html; charset=utf-8');

Note to call this function before any output has been sent to the client. Otherwise the header has been sent too and you obviously can’t change it any more. You can check that with headers_sent. See the manual page of header for more information.

First make sure the PHP files themselves are UTF-8 encoded.

The meta tag is ignored by some browser. If you only use ASCII-characters, it doesn't matter anyway.

http://en.wikipedia.org/wiki/List_of_HTTP_header_fields

header('Content-Type: text/html; charset=utf-8');

This is a problem with your web server sending out an HTTP header that does not match the one you define. For instructions on how to make the server send the correct headers, see this page.

Otherwise, you can also use PHP to modify the headers, but this has to be done before outputting any text using this code:

header('Content-Type: text/html; charset=utf-8');

More information on how to send out headers using PHP can be found in the documentation for the header function.

You can also use a shorter way:

<?php header('Content-Type: charset=utf-8'); ?>

See RFC 2616. It's valid to specify only character set.