Should this code give "cannot modify header ..." warning, and not redirect?

blackhorse

ini_set('display_errors', 1);
echo "hello world";
header("Location: http://www.mysite.com");

Should this code gives the "Cannot modify header, header already sent ..."?

But somehow on my new hosting, this code would not generate errors, and the redirect works.

My question is what is the the set up makes the above codes not generating warning message like "Cannot modify header error, header already sent ..." and make the header redirect working even there are some output before header ("Location: ..") redirect?

Thanks!

bradgrafelman

The setting that would change the above is the 'output_buffering' PHP directive. If it is enabled, then a certain amount of output for every request will be buffered in the server's memory before being truly sent as output to the client.

dewcansam

Technically it should give errors and die.
Remember that header() must be called before any actual output is sent, either by normal HTML tags, blank lines in a file, or from PHP.

<html>
<?php
/* This will give an error. Note the output
 * above, which is before the header() call */
header('Location: http://www.example.com/');
?>